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https://killexams.com/exam_list/HPKillexams : Fix Hard Drive Not installed problem on Windows 11/10
If you’re encountering the error message Hard Drive – Not installed on your Windows 11 or Windows 10 computer, then this post is intended to help you. In this post, we will identify the possible causes, as well as provide the most appropriate solutions you can try to help you remediate this issue.
As per user reports, you’re most likely to encounter this error on an HP, Lenovo, or a Dell computer.
There are several reasons why your Dell computer reports no hard drive installed, detected or missing operating system error on startup:
If you’re faced with this Hard Drive Not installed problem on Windows 11/10, try this first:
Unplug the system and remove the base cover. Disconnect the battery and hard drive. Then hold the power button for 30 sec. Reconnect both and power up – check to see if the drive is recognized.
If it’s not, and the system is under warranty – call Dell for a drive replacement.
However, if you wish to do a bit of troubleshooting yourself, you can try our recommended solutions below in no particular order and see if that helps to resolve the issue.
Continuously press the F1 key
Check BIOS setting
Check hard drive cable
Perform PC hard reset
Test the Hard Drive for physical damage
Perform a Windows Repair Install
Let’s take a look at the description of the process involved concerning each of the listed solutions.
1] Continuously press the F1 key
If your Dell computer shows the Hard Drive – Not installed error, you can press F1 to continue. It is a BIOS error message. Pressing F1 is a contingency procedure that can work around an error, and the computer may load into Windows correctly after pressing F1.
You may encounter this error if the computer isn’t physically connected to the hard drive. So you can check the hard drive cable to ensure whether it has a loose cable connection or the SATA cable and power cable may have worn out. If it is, you can reconnect the cables from both the hard drive and the MOBO, or replace the cable with a new one.
A hard or forced reset erases all information in the computer memory and might restore functionality. Resetting your computer forces the system to clear and reestablish the software connections between the BIOS and the hardware.
Do the following:
Turn off the computer.
Remove the computer from any port replicator or docking station.
Disconnect all external devices from your computer, unplug the AC adapter from the computer.
Remove the battery from the battery compartment.
Press and hold down the Power button for about 15 seconds to drain any residual electrical charge from the capacitors that protect the memory.
Insert the battery, and plug the AC adapter back into the computer, but do not connect any of the peripheral devices such as USB storage devices, external displays, printers, etc.
Turn on the computer.
If a start menu opens, select Start Windows Normally with arrow keys and hit Enter.
Remove the hard drive from the computer and connect it to another computer to see whether it still works. if it doesn’t, you should replace the hard drive with a new one. If it does, you can test the hard drive to see if it has bad sectors.
6] Perform a Windows Repair Install
A bad Windows installation may cause errors and prevent Windows from loading. Consequently, the Dell computer may show this error when booting. In this case, you can try running a repair installation to fix it. If Windows sees the hard drive when running a repair install, the drive is probably not broken.
If the repair install doesn’t work, the drive may be infected with a boot sector virus, which you need to fix by formatting the hard drive.
Solder connections on processors seem to be a very common failure point in modern electronics. Consider the Red Ring of Death (RRoD) on Xbox 360 or the Yellow Light of Death (YLoD) on PlayStation 3. This time around the problem is a malfunctioning Nvidia GPU on an HP Pavilion TX2000 laptop. The video is sometimes a jumbled mess and other times there’s no video at all. If the hardware is older, and the alternative to fixing it is to throw it away, you should try to reflow the solder connections on the chip.
This method uses a heat gun, which we’ve seen repair PCBs in the past. The goal here is to be much less destructive and that’s why the first step is to test out how well your heat gun will melt the solder. Place a chunk of solder on a penny, hold the heat gun one inch above it and record how long it takes the solder to flow. Once you have the timing right, mask off the motherboard (already removed from the case) so that just the chip in question is accessible. Reflow with the same spacing and timing as you did during the penny test. Hopefully once things cool down you’ll have a working laptop or gaming console again.
Sat, 06 Aug 2022 11:59:00 -0500Mike Szczysen-UStext/htmlhttps://hackaday.com/2011/02/24/heat-gun-gpu-reflow-fixes-laptop/Killexams : Major test of first possible Lyme vaccine in 20 years begins
DUNCANSVILLE, Pa. (AP) — Researchers are seeking thousands of volunteers in the U.S. and Europe to test the first potential vaccine against Lyme disease in 20 years -- in hopes of better fighting the tick-borne threat.
Lyme is a growing problem, with cases rising and warming weather helping ticks expand their habitat. While a vaccine for dogs has long been available, the only Lyme vaccine for humans was pulled off the U.S. market in 2002 from lack of demand, leaving people to rely on bug spray and tick checks.
Mon, 08 Aug 2022 08:47:00 -0500en-UStext/htmlhttps://www.timesunion.com/news/article/Major-test-of-first-possible-Lyme-vaccine-in-20-17359919.php?IPID=Times-Union-HP-nation-world-packageKillexams : HP Chromebase All-in-One 22 review
HP Chromebase All-in-One 22: Two-minute review
The HP Chromebase All-in-One 22 is helping usher all-in-one PCs into the mainstream market, and it’s about damn time. Even now, most AIO PCs on the market are pricey and tend to target professionals who need a minimalist yet powerful solution for their demanding computing workloads.
Also, anything under $800 / £800 tends to feel slightly underpowered, especially when running a full-fledged operating system like Windows 11.
Here is the HP Chromebase All-in-One 22 configuration sent to TechRadar for review CPU: Intel Core i3-10110U (2.1 GHz up to 4.1 GHz, 4 MB L3 cache, 2 cores) Graphics: Intel UHD Graphics RAM: 16 GB DDR4-2666 MHz Screen: 21.5" diagonal, FHD (1920 x 1080), touch, IPS, BrightView, 250 nits, 72% NTSC Storage: 256 GB PCIe NVMe M.2 SSD Ports: 2x SuperSpeed USB Type-C (with Power Delivery, DisplayPort 1.2), 2x SuperSpeed USB Type-A, 1x headphone/microphone combo Connectivity: Intel Wi-Fi 6 AX 201 (2x2), Bluetooth 5 combo Camera: HP True Vision 5 MP privacy camera and integrated dual array digital microphones, 1.4 ųm camera sensor Weight: 15.37 lb (6.97 kg) tablet, keyboard and mouse included Size: 19.98 x 6.87 x 17.89 in (507.5 x 174.5 x 454.4 mm, WxHxD)
The HP Chromebase All-in-One 22 fixes all that by using similar specs, but utilizing the lightweight Chrome OS instead. Bridging the gap between the popular (and usually affordable) Chromebooks and the minimalist appeal of AIOs, it offers a snappier performance than its Windows 11 counterparts – not to mention, an attractive design – while keeping its price within easy reach of most consumers.
Among its many notable features are its 21.5-inch touchscreen display with portrait mode, a 2,592 × 1,944-resolution webcam with impressive noise reduction, a two-step privacy cover, and a pair of 5W speakers with plenty of volume.
There are some compromises here – unsurprising considering its price – but there excellent premium features as well, namely its beautiful compact design and its browser multitasking prowess. Finally, users whose daily needs largely involve browsing, streaming, and sending emails now have a budget-realistic AIO option.
If you're looking for an all-in-one for everyone in your household, your work-from-home setup, or the matriculating member of your family, the HP Chromebase All-in-One 22 is a tough contender to beat.
HP Chromebase All-in-One 22: Price and availability
Several configurations on offer
Limited availability in the UK
How budget-friendly is the HP Chromebase All-in-One 22 exactly? At the moment, it’s available in several configurations in the US, starting at $629 / £629. This base configuration comes with an Intel Pentium 6405U, Intel UHD graphics, and 8GB of memory as well as 128GB SSD. While that might sound a little underpowered, remember that it’s also running a lightweight operating system that doesn’t need robust specs.
If you do need something more robust, the most kitted-out configuration – the same configuration that was sent to TechRadar for testing – will provide you an Intel Core i3-10110U, 16GB of RAM, 256GB SSD, and the same integrated graphics for $699 / £699.
Unfortunately, consumers in the Australia would have to wait to get their hands on an HP Chromebase as it’s currently unavailable in the region. It's also currently unavailable in the HP UK store, but you should be able to find some configurations available at some UK online retailers. On the bright side, the UK HP store suggests that it will soon become available.
Value: 4 / 5
HP Chromebase All-in-One 22: Design and features
Beautiful, premium design
Thoughtful design details
HP doesn’t pull any punches when it comes to the HP Chromebase All-in-One 22’s design. This is meant to be a space-saving, minimalist, and appealing all-in-one, and it succeeds in that regard with its 21.5-inch display, compact conical stand that stores all the innards, ports, and speakers, and beautiful white finish that makes it look pricier than it is.
The display size might not be ideal for power users and multi-taskers, but it’s certainly enough for this computer’s target market. Plus, its touch capability is beautifully responsive, something you’d expect from pricier models.
There’s also a decent port selection that’s more than enough for the average user. Not that you’d be needing peripherals as it does come with its own Bluetooth keyboard and mouse, both of which get the job done.
The keyboard is comfortable to type on, despite lacking some keys, including media keys (apart from the volume buttons). The mouse could be better – there’s a little more resistance on its buttons than we’d like – but it also does what it’s supposed to do. Users who aren’t very particular with their peripherals will be satisfied.
There are thoughtful design features as well, some of which even the iMac 24-inch doesn’t have, namely the pivot-capable display that will let you switch from landscape to portrait mode with just, quite literally, a finger.
There aren’t any swivel or horizontal adjustments here, but if you require that vertical space to read news articles, work on your book, or help the kids with their essays, you’ll appreciate the fact that portrait mode is on hand and just a push of a finger away. There’s also some up and down tilt for more comfortable viewing.
Another thoughtful design feature is its webcam’s privacy shutter, which allows you to block any video feed and turn the mic off completely when not in use.
Having this feature prevents hackers and other malicious people on the Internet from using your webcam and mic to spy on you, or worse.
Design: 4.5 / 5
HP Chromebase All-in-One 22: Performance
Browser performance is ace
Speakers loud but not the best sounding
It proves that in practice as well. On test, we often have it run 20 or more tabs at the same time, several of which have Google Docs Editors suite pages and online publications open, as well as shopping sites and streaming services, and it handles those without signs of a slowdown. This is an all-in-one made for demanding browser needs and multitasking.
Meanwhile, the built-in 5W stereo speakers, which again are housed in the stand, are good as well. They aren’t as crisp and detailed as the speakers you’d find on pricier all-in-ones, but they get pretty loud with decent bass response to fill a room… or at least a small- to medium-sized one.
Fair warning, however: pump that volume up to 100%, and they’ll sound as if tiny little ice picks are stabbing at your eardrums. So, best keep that volume under 90%.
Performance: 4 / 5
HP Chromebase All-in-One 22: Webcam and mic
Excellent noise reduction
Crisp and clear mic
If you plan on using the webcam and mic for work meetings and video calls with loved ones, you’ll be happy to know that you’re getting a decently high 2,592 × 1,944 resolution here. It’s not the most detailed webcam we’ve used, and there’s not a lot of contrast or dynamic range. However, it excels in noise reduction, keeping that luminance and chromatic noise well-controlled even in low lighting.
The mic is also great, although it comes with its own compromise. Your voice will come out crisp and clear, but as will any background noise since there isn’t any noise rejection – not surprising since this isn’t a premium all-in-one PC.
Webcam: 4 / 5
Should I buy the HP Chromebase All-in-One 22?
Buy it if…
Don’t buy it if…
HP Chromebase All-in-One 22: Report card
All-in-ones tend to be pricey, but this AIO brings that price back down closer to the ground in Chrome OS form.
4 / 5
It has adopted that minimalist AIO design and premium feel without upping the price. Thoughtful design features are also on hand.
4.5 / 5
Excellent browser and multitasking performance allows this Chromebase to stand out, despite more powerful rivals. Its built-in speakers are plenty loud as well.
4 / 5
With a resolution higher than 720p and great noise reduction capabilities, its webcam is deserving of praise. Especially with that two-step privacy cover.
4 / 5
How we test
We pride ourselves on our independence and our rigorous review-testing process, offering up long-term attention to the products we review and making sure our reviews are updated and maintained - regardless of when a device was released, if you can still buy it, it's on our radar.
Instant inkGet ink when you need it, starting with six months free
If you’re going to call your inkjet printer the ENVY Inspire 7220e, it ought to be rather good. On paper, HP’s high-end home multifunction peripheral (MFP) looks like it is.
It’s bristling with useful features such as automatic duplex printing and a dedicated photo paper tray. It also has touchscreen controls to make everyday jobs easier.
But while it also offers cheap ink through HP’s Instant Ink scheme, you’ll need to accept certain restrictions in order to benefit. Here are my thoughts on how it stacks up against the best printers available.
Design and features
Recycled materials, but still lots of plastic
Brilliant colour touchscreen controls
Useful photo paper tray
The HP ENVY Inspire 7220e sits towards the top end of HP’s range of home MFPs. It can print, scan and copy, but it has no fax modem or automatic document feeder for multi-page scans or copies.
All the same, this is a well-specified device, supporting wireless networks, offering automatic duplex (double-sided) printing, and being controlled via a smart colour touchscreen.
While rivals Epson and Canon are extending their refillable ink tank printer ranges, HP seems instead to be focusing on lowering the cost of cartridge printing. The 7220e is compatible with HP’s Instant Ink subscription service, which sees the printer order new cartridges as your existing ones get low on ink.
This printer also supports HP+. Sign up for that and you’ll get Instant Ink free for six months, after which monthly subscriptions range from 99p for up to 10 pages per month, to £22.49 for 700 pages. Pick the recommended 100-page plan for £4.49, print all 100 pages every month, and that’s 4.5p per page – about half what you’d pay to run a typical, cartridge-based inkjet.
There are a couple of catches, however. To use Instant Ink you’ll need an internet connection, and you must agree to provide HP with certain information on your printer use. And if you also enable HP+, you agree to firmware updates that may prevent you using third-party (i.e. non-HP) cartridges.
Don’t like the sound of that? You’ll have to buy HP’s 303XL cartridges instead, which will work out at an expensive 12p per page.
Whether you’re buying the cartridges or having them sent through Instant Ink, your running costs will be higher than with an ink tank printer, which typically cost less than 1p per page to run. However, the Envy Inspire 7220e is significantly cheaper to buy than its ink tank rivals. If you only print in small volumes, it could prove better value.
HP’s cartridges can be returned for refilling, and the printer itself is made from a claimed 45% recycled plastic. That’s better for the environment, but it’s disappointing that the 7220e arrives in plastic shrink wrap, and is cushioned by non-recyclable plastic foam. HP is by no means the only offender among printer manufacturers, but I do wish everyone would use only cardboard buffers, which have been around for decades.
This is an easy printer to set up on an Android or iOS device. It’s easy to set up on a PC, too, but only if you stick with the default HP Smart package – and this only includes a WIA scan driver, which offers limited control and functionality.
We need better for our tests, so I searched Google to find the HP Easy Start software, which includes a full TWAIN scan driver. HP’s latest printers are protected by an eight-digit PIN, which you need to find and enter to finish the Easy Start install, or make any configuration changes via the printer’s web interface.
With the cartridges and software installed, all that remains is to load plain paper in the main tray, and optionally add 10x15cm (6×4″) or 13x18cm (5×7″) photo paper to the second tray.
Print speed and quality
Good plain paper print quality
Swift performance, especially printing
I experienced some connectivity issues
It’s not unusual to encounter problems when installing a printer, but the Envy Inspire 7220e saved up a bout of misbehaviour for the day after I first set it up. When I returned to begin our timed tests, I immediately noticed that print jobs were spooling very slowly, with the printer taking more than 30 seconds to even begin printing a first page of text. Then it would stall, failing to complete the job.
After the usual round of reboots, I tried installing the printer on a different PC only to experience the same problem. Repositioning the 7220e closer to our wireless router didn’t appear to help, either. I’ve previously encountered an issue where two exact HP printers wouldn’t work happily with WPA3 encryption, but switching this off didn’t help this time.
Eventually I found that this MFP worked perfectly from my Chromebook, which I used to perform our timed print tests. I couldn’t scan from the Chromebook, but by the next day the problems had magically resolved themselves and I was able to make our timed scan tests from a PC as usual. Unfortunately by this point the 722e was too low on ink to repeat our print tests. While frustrating for me, I’d be wary of drawing any firm conclusions from this – it’s possible there’s just something specific about my network that exact HP printers don’t like.
Issues aside, the Inspire 7220e proved to be a reasonably quick printer. It needed 17 seconds to produce a first page of text, and went on to complete five pages in 39 seconds – a rate of 7.7 pages per minute (ppm). On our 20-page job it reached 10.2ppm.
Unusually, it wasn’t much slower in colour, hitting 6.4ppm over five pages, and an impressive 8.1ppm over 20 pages. The 7220e printed six postcard-sized photos in just over seven minutes, but I couldn’t set the usual high quality options using my Chromebook – I’d expect each print to take around two minutes at the very highest quality available on a PC.
This MFP has a quick enough scanner. It could preview a document in 10 seconds, and get a 150 dots-per-inch (dpi) A4 scan in just 11 seconds. At a more detailed 300dpi, the same job took 20 seconds.
At 600dpi, I captured a 10x15cm photo in 47 seconds, which isn’t bad, but at the maximum 1200dpi the same job took two and a half minutes. In black only, photocopies were quick: a standard A4 job took 21 seconds. This printer needed 40 seconds for a colour page, but the quality of both tests was good.
The HP ENVY Inspire 7220e uses a pigmented black ink, which helps it produce crisp and dark text on plain paper. To the naked eye, printed type is almost as good as you’d get from a laser device. This printer’s cyan, magenta and yellow colour inks are dye-based, but they still deliver strong colour graphics.
It’s a bit more of a mixed bag on photo papers, given that pigment inks tend to sit on top of the paper’s gloss coating. While pictures from the 7220e looked good, they had an inconsistent finish on darker subjects, with the darkest shades noticeably less glossy.
The Envy Inspire 7220e is a perfectly good document scanner, making nicely balanced, crisply focused copies of our magazine page test. I was also impressed by its dynamic range: it could distinguish all but the darkest couple of shades in our challenging test target.
Photo scans also looked good at a glance, but HP’s scan interface seems to apply some digital sharpening which can’t be turned off. Zoom in and you might notice colour boundaries looking artificially strong, with the loss of some fine detail elsewhere.
Should you buy it?
You want a competent MFP that’s easy to use:
The HP Inspire 7220e is fairly quick, produces decent results, and can be quite cheap to run
You want more than competence:
Save for its touchscreen, this MFP doesn’t really do anything brilliantly
This is a fairly priced MFP that ought to cover the requirements of the typical home. It’s relatively quick, and generally produces decent results. It has reasonable running costs, too, but only if you embrace the idea of paying a subscription to print. While Instant Ink works well for many, I generally prefer the idea of buying ink for myself when I need it, particularly if it’s cheaper still and comes in big bottles.
How we test
Every printer we review goes through a series of uniform checks designed to gauge key things including print quality, speed and cost.
We’ll also compare the features with other printers at the same price point to see if you’re getting good value for your money.
Tested printing with monochrome and coloured ink
Measured the time it takes to print with various paper
Easy-to-use software, affordable ink, a long warranty, and plenty of thoughtful touches make this inkjet all-in-one less annoying than the competition. Results look sharp, too.
*At the time of publishing, the price was $230.
17.3 x 13.48 x 10.94 in
Print, copy, fax, scan
Cost per page:
2.2¢ per black and 8.9¢ for color
The HP OfficeJet Pro 9015e is likely to be the easiest printer you’ve ever had to set up, and that alone is enough to recommend it. But it also prints beautifully (and quickly), scans well, has great apps for PCs and mobile devices, and prints for an affordable 2.2¢ per page in black or 8.9¢ per page in color. If you print a lot of photos, you can opt for HP’s Instant Ink program (a six-month trial is included with your initial purchase), which brings the cost of each color page to as little as 2.9¢, including glossies. It looks great in any office, thanks to a clean, compact design, and it comes with a two-year warranty that’s twice as long as what you’d get with most competing printers. The 9015e replaces our former pick, the OfficeJet Pro 9015, but it’s identical from a hardware perspective; the only differences are the longer warranty, the longer Instant Ink trial, and some added software features that are bundled into the new HP+ printing ecosystem. If you’re not interested in the extras HP+ has to offer, the older 9015 is a great machine that you might be able to find at a discount.
Brother’s entry-level AIO isn’t the fastest, best designed, or easiest to use, but it is cheap to operate, and it still produces great-looking prints and scans.
*At the time of publishing, the price was $130.
17.3 x 13.48 x 10.94 in
Print, copy, fax, scan
Cost per page:
2.2¢ per black-and-white and 8.9¢ for color
If you just want the cheapest prints possible and don’t care about speed, fancy apps, or looks, the Brother MFC-J805DW is an excellent choice. At a mere 0.9¢ per black-and-white page and 4.7¢ for color, it’s one of the most cost-efficient printers you can buy, and the results look great, too. You’d wait longer to get them than you would with the HP 9015e, but for casual use that isn’t a big deal.
This business-class machine checks all the boxes for a home office or small business: It’s faster, sharper, more durable, and more secure than our other picks.
*At the time of publishing, the price was $600.
16.4 x 18.6 x 15.7 in
Print, copy, fax, scan
Cost per page:
2.3¢ per black and 14¢ for color
If your work finds you printing and scanning all day, every day, you should be willing to upgrade to a business-oriented color laser AIO like the HP Color LaserJet Pro MFP M479fdw. It prints and scans faster, sharper, and more reliably than inkjet alternatives, and it includes robust admin and security settings designed for situations that may involve sensitive data. We don’t think it’s necessary for most homes or even the average home office. But if you run a business with modest printing and paper-handling needs, or if you’ve grown exasperated with your inkjet AIO’s failings, the M479fdw should hit the sweet spot.
Tue, 24 Feb 2015 22:01:00 -0600entext/htmlhttps://www.nytimes.com/wirecutter/reviews/best-all-in-one-printer/Killexams : A beginner’s guide to bouldering in the Hudson Valley
The easiest route to the sport of climbing is via bouldering: a full-body workout that only requires some shoes that grip, a pad to fall on, and some chalk to soak up the hand sweat.
In fact, bouldering is now the most common form of indoor climbing, with gyms sprouting up in cities as well as more rural areas that have popular outdoor climbing areas, like the Shawangunk Ridge, which is rich in rock-climbing routes and history as well as simple to complex bouldering puzzles.
Tue, 02 Aug 2022 07:25:00 -0500en-UStext/htmlhttps://www.timesunion.com/hudsonvalley/outdoors/article/bouldering-beginners-guide-17345284.php?IPID=Times-Union-HP-latest-newsKillexams : What laptop should I get? Top 12 things to consider
Which laptop should I get?
With so many laptops to choose from, selecting the best one to fit your budget can be like navigating a minefield. Even making sense of the ever-changing list of product specifications is no easy feat. Laptops vary greatly by CPU speed, graphics capability, size, drive storage, and RAM, among other things. What’s more, your laptop needs may be completely different to someone else’s, only adding to the confusion.
For some, a flashy 4K screen may be important. Others may want a high-performing CPU, like AMD’s new Ryzen 6000 processors, to provide them a competitive edge in games. Getting value for money can be tricky too, since newer technologies don’t always mean better performance. For example, older-generation CPUs can sometimes outperform newer products in benchmark tests. For these reasons it pays to do your homework before you purchase a laptop.
To simplify the process for you we’ve put together a list of 12 criteria that you can use as a guide for what to look for. It may seem laborious delving into each category, but there are a lot of things to consider. At the end of the day, taking time to research your new device will mean you avoid making a costly mistake and get a laptop that’s just right for you.
1. Size & form-factor
When it comes to laptops, size matters.
Depending on what you plan to be doing with your next laptop, you’ll want to make sure you pick the size that’s the right fit for you. Size isn’t like the RAM or ROM of a laptop, you can’t upgrade it later. You’re locked into whatever form-factor you select up-front, so choose wisely.
Laptops sizes tend to start at 11.6-inches and go all the way up to 17.3 inches. Most brands and OEMS like HP, Dell, ASUS and Acer tend to offer three display sizes - 13.3-inch, 15.6-inch and 17.3-inches. However, some vendors do sell laptops that fall outside these sizes including 11.6-inches, 12.5-inches and 14-inches.
Obviously, if portability is your priority, you’ll want to go for a smaller-sized Windows laptop. They tend to be thinner and lighter than their larger counterparts. Look for laptops that have a screen that is either 12.5-inches or 13.3-inches in size, and a weight between 1kg and 1.5kgs.
However, keep in mind that smaller-sized 13.3-inch machines often don’t support the same high-end Intel Core CPUs or discrete graphics cards you’ll be able to find in their 15.6-inch counterparts. Most of the time, they’ll also feature a less-robust selection of ports. If the kind of work you intend to be using your new laptop for necessitates a larger display or standalone graphics, you’ll probably need to look at a larger size.
By contrast, Notebooks tend to offer a good mix of power and portability. If you’re looking at notebooks, a good place to start is the Lenovo Yoga 9i and HP’s Envy x360.
Convertibles (also known as 2-in-1 laptops or 2-in-1 PCs) expand on this by adding the ability to fold away (or remove) the keyboard and use your new laptop as you would a tablet. Products like Microsoft’s Microsoft Surface Pro 7 and HP Chromebook x2 11 fall into this category.
Finally, traditional clamshell and gaming laptops tend to boast bulkier form-factors but significantly-beefier specs.
The most important thing to consider here when looking for the best laptop you can buy is what you’re actually going to need that laptop to do. It’s rarely ever a case of one size fits all. Some users need something lighter and more portable. Other users need discrete graphics for things like video editing or running high end games. If you need a PC with an optical drive or long battery life, you’ll almost certainly have to look for something larger.
Once you’ve worked out the size and form-factor of laptop you’re looking for, the search for the best one becomes that much easier - since you can begin to filter your search results by those parameters.
2. Display quality
Since you’ll probably end up staring at your laptop display hours at a time, you’ll probably want to make sure it's as painless as possible to do so. For this, you'll need a display that is comfortable to look at and feels natural to use.
To start with, you’ll want to consider whether you want your next laptop to have a touchscreen at all. These days, touchscreens are very common and they can make some tasks easier than others. Some brands include this feature as standard. Others will demand a modest surcharge for its inclusion.
Unfortunately, opting for a touchscreen can sometimes add a glossiness to the display. Though not a universal trait among touch-sensitive displays, glossier screens are often a little more susceptible to glare. This can be a definite drawback if you’re gaming, watching content or editing images and video content.
Modern touchscreens are much better than their predecessors but, some of the above details persist and if you're more of a natural typist, you might want to consider going for a laptop that doesn’t have a touchscreen.
Next up, be sure to look at the resolution on any laptop you’re thinking of buying. A 1920x1080-pixel resolution (Full HD) should be considered the minimum if you want plenty of space to line up windows and keep things in view. If you splurge on something a little sharper, you probably won't regret it though.
Select modern laptops also now offer 4K resolutions. However, these high-end display panels are generally a costly add-on to an already-expensive product. 4K is an extra that's only really going to be worth it for those who really need it such as content creation professionals.
Photographers and videographers will also want to go for laptops that offer better color accuracy and support wider color gamut and HDR standards over those that don't. The key things you're looking for here are Delta E < 1 color accuracy and 100% coverage of the DCI-P3 color gamut.
If you’re a gamer, it’s also worth taking the time to check the refresh rate on the display of any potential laptop. A faster refresh rate can often provide a competitive advantage in online games, as it enables a smoother and more responsive play experience. Ideally, you want something with less than 5ms response time or a refresh rate greater than 144Hz. We're starting to see laptops now with 300Hz refresh rates - laptops like the MSI GS66 Stealth (review here) and the super powerful Asus ROG Strix G15 Advantage Edition (review here) and while this is considered exceptionally good right now, it might soon be the norm.
Lastly, viewing angles are extremely important. A laptop screen that touts IPS (in-plane switching) technology offers the widest viewing angles and the best user comfort. Chances are you’re not always going to be using your laptop in its natural habitat, so a laptop with an IPS display is usually preferred over the opposite.
If possible, take the time to go into a store and try to feel out the differences between different displays for yourself. If your eyes can't see much of a difference between a laptop with a FHD display and one with a 4K one, it might not be worth paying the premium for the latter.
Just keep in mind that display models usually have the settings cranked to the maximum in order to catch your eyes. Otherwise, be sure to check out reviews like those on PC World to get a good overview of the product and whether or not its screen will be able to suit your needs. In 2022, most major laptop displays hit the mark but those that don't make themselves quickly known when subjected to the scrutiny of a professional reviewer.
3. Keyboard quality
For long typing sessions, you’ll need to get a laptop that has a comfortable keyboard. You don’t want to get a keyboard that packs in every key under the sun (think keyboards that have squished in number pads) because that can translate to a poor overall user experience when hunting for specifics like the arrow or delete keys.
Ideally, you want a keyboard that has a comfortable layout with full-sized keys and some space around the arrow keys. The keys should have adequate travel on the downstroke and snappy responsiveness when you let them go.
Make sure the keyboard is also backlit. At face value, that might seem like a superficial detail but backlit keys make it much easier to see what you're typing in dimly lit environments. Gaming laptops like the Asus ROG Zephyrus S17 (review here) and MSI Katana GF76 (review here) come with attractive RGB key backlighting to allow gaming at night or in dimly lit environments. Note: While backlit keys are useful, they will drain your battery sooner, so take that into consideration when choosing your laptop.
As with the display, it helps to try before you buy - especially if your main task will be typing. Chances are, you're going to find the most comfort with what you know here. If you're used to typing on a laptop keyboard that stretches all the way to the edge of the chassis, you're probably going to find laptops that opt for the same or a similar layout to be easier to type on than the alternatives.
It’s hard to go past any of Intel’s Core-based CPUs when buying a new laptop. Even if you're not versed in the technical details, there's a good chance you've seen the stickers plastered on all new laptops for the silicon giant's Core i3, Core i5, and Core i7 processors.
For many users, an Intel Core Processor offers the best performance when it comes to multitasking and multimedia tasks. Core i3-based notebooks are generally found in entry-level systems, while Core i5 and Core i7 make up the majority of mainstream computers.
Core i7-based systems are for those of you who want the best performance from your laptop. However, note that with a Core i7-based system, heat coming through the base of the laptop can be a cause for concern, especially if you plan to actually use the laptop on your lap a lot of the time.
Some larger laptops also now incorporate Intel's i9 Core processors. Laptops running on Core i9 processors are even more powerful than laptops running on Core i7 processors. They're able to rival desktops for performance, but they do come with a significantly-higher cost than a laptop with an i7, i5 or i3 Core Processor.
Vendors also offer laptops and notebooks that run on AMD’s Ryzen Mobile CPUs. If you’re a gamer, this can be a particularly compelling option worth considering. Ryzen Mobile CPUs tend to be paired with AMD’s own Radeon graphics chipsets.
There are a few caveats here but since laptops powered by AMD's Ryzen Mobile chips tend to be slightly cheaper than their Intel counterparts, they can represent better value for money. Just be sure to read up on our breakdown of the differences first.
In the old days, you rarely needed more than 4GB of RAM to get the best out of your system.
More RAM allows for more applications to be run at the same time and for more data to be quickly accessible by the system at any one time, which comes in handy for tasks such as editing photos or video content.
There are a few interesting terms that you might see when looking into RAM specs, here's what you essentially need to know about them. Alongside the brand and capacity of any RAM stick, you're gonna find the letters DDR. There's also usually a number attached. For example, the MSI GE76 Raider laptop (review here) has two 16GB sticks of DDR5 RAM. This acronym stands for Double Data Rate and the number that comes after it refers to the generation of component design.
The most exact generation of RAM hardware is DDR5. As a rule, higher numbers are better than lower numbers here and most motherboards can only support certain generations of RAM. Thankfully, since you're looking at buying a laptop, you don't have too much to worry about since no sane OEM is going to stick incompatible RAM into a prebuilt machine.
The number after DDR also denotes the transfer speed. Similar to the clock-speed on a CPU, this number measures the default theoretical maximum transfer speed. Again, higher is better here. Higher speeds means stuff happens faster.
Another detail to note is whether or not the RAM in your laptop is single or dual-channel. In most everyday use cases, this might not make a huge difference but if you're trying to weigh up your options, a laptop with dual-channel is generally more desirable than one with an equivalent amount of single-channel memory clocked at the same transfer speed. This is because dual-channel RAM is able to transfer a greater amount of data at once.
In conclusion, while having more RAM is always going to be better than having less RAM, most users aren't going to feel the difference between having 16GB or 32GB unless they're running RAM-heavy applications where that 16GB or a secondary channel is going to make a big difference. Since RAM is relatively cheap and often easy to upgrade in modern laptops, it's usually smarter and safer to buy a laptop with RAM that you know you will need rather than what you think you might need.
Hard drives used to be all the rage, but these days they’re mostly out of favor, especially for thin and light laptops. This is because they can be slow, somewhat bulky, and produce noticeable heat and noise.
A solid state drive (SSD), on the other hand, offers a lot more speed than a hard drive, runs silently, and can be installed in a form factor that doesn’t add too much to the weight and bulk of a laptop. As a result of these clear benefits, most OEMs have embraced SSD storage as the standard for laptops.
Stick to an SSD for your new laptop and you’ll love the speed with which it can load programs, access your data, and also how quickly it can boot up your system.
Just a few years ago SSDs didn't offer as much raw capacity as hard drives. Additionally, this kind of storage was often more expensive in terms of dollars-to-gigabytes than traditional hard drives. In 2022 these problems are no longer. Laptops now have comparatively large SSD drives to hard drives and aren't astronomically expensive.
The newest, fastest laptops have NVMe solid-state drives which are faster than traditional SSDs. If you're buying a new laptop in 2022, you'll preferably want one with an NVMe SSD. However, that being said, don't feel overly pressured to spend extra on the latest model here. While it is true that more exact SSDs boast better speeds than older models, the biggest advantages you'll enjoy are tied more to the fundamental advances that SSDs offer over traditional hard drive storage.
When it comes to the SSD storage capacity you should look for we recommend at least 512GB as the very minimum. Games and programs are getting larger every year as they become more advanced and complex so you'll want to ensure you have a little left in your storage after you load on your must-have programs and personal files. It's also worth noting that your operating system will take up some of that 512GB right off the bat, so you won't have exactly that number to play.
If you install a lot of programs or have an extensive game or movie library, you'll probably want to opt for 1TB or more of SSD storage. You'd be surprised how fast it is to fill up even 1TB or 2TB, but with the extra GB on board, you will have a greater capacity to branch out and get a little more things you like on there. Trust us, you won't decry the extra space when you can get that game you really wanted from Steam.
Another thing worth mentioning here is cloud storage. Cloud storage is extremely popular since it allows users to store any number of files safely and remotely, without the need for your device's storage. Software developers are starting to build cloud storage into their software ecosystems. The best example of this is Microsoft's OneDrive application which comes bundled with Windows at purchase.
If you intend to store most of your files in the cloud or on an external drive, you may choose to save money on a laptop by buying one with a smaller 128GB or 256GB SSD. If you do this though you'd be advised to remember that you will need to be connected to the Internet to retrieve your files when you need them.
7. Battery life
Manufacturer-quoted battery life is almost never indicative of what the real-world experience of using a laptop is like.
There are simply too many variables that affect battery life. There is the screen brightness, the screen resolution, the number of applications you have running in the background plus whether or not you actively remain connected to Wi Fi networks or Bluetooth devices.
The operating system a laptop runs on can also play a major role in determining battery life. It’s for this reason that ultrabooks and convertibles running on Chrome OS tend to offer superior battery life than those running on Windows 11.
If you run programs that need lots of processing, stream lots of online video, play graphics-intensive games or if you transfer lots of files over a wireless network, then your battery will drain a lot sooner than what the vendor has quoted.
A good practice here is to look at the rating of the battery in Watt-hours (Wh) or milliamp-hours (mAh). The larger these figures are, the longer the battery can last. For a 13.3-inch Ultrabook, for example, a battery with a rating from 50Wh to 60Wh will provide you the best results.
Another key thing to look for here is fast-charging. Much like modern smartphones, many new laptops also support fast-charging, which is always good in a pinch.
8. USB Type-C
These days, if a laptop has only one USB Type-C port on it, you probably ought to look at buying another laptop. Ideally, you should look for a laptop that has at least a couple of these ports. They're the most common connector port in the industry and, while you can find a dongle for anything on Amazon, it's usually a better bet to just make sure your next laptop has them.
In addition to the baseline utility you get from USB Type-C ports (which allow you to plug in an external hard or SSD drive and backup your data or use conventional mouse or a fancy keyboard with your laptop), USB Type-C ports are substantially faster than USB 2.0 and 3.0 ports. This means that data transfers over USB Type-C ports take significantly less time.
Many modern peripherals also tend to deliver the best performance on or require USB Type-C to function at all.
Among the Type-C ports Thunderbolt 4 ports are the best option. Thunderbolt 4 ports have a peak data transfer speed of 40 gigabits per-second. They also offer faster charging and allow you to connect multiple 4K displays or one 8K display to your laptop, which is compelling functionality.
9. Biometric security
Fingerprint readers are great for logging into mobile devices and the latest Windows 11 Operating System makes further use of them with its Windows Hello system. People can guess your password, but few can fake a fingerprint. In order to keep the contents of your laptop secure, a portable PC with a fingerprint reader is usually the best way forward.
Thankfully, this feature is a pretty common inclusion on many modern laptops from major OEMs like ASUS, Dell and HP. Some have even integrated the fingerprint sensor into the keyboard, making it feel like a more cohesive part of the package rather than a bolt-on.
It's cool to see the modern laptops continue to raise the bar on this particular front even if the degree to which it matters is largely personal preference. For most people, a standard fingerprint sensor is going to provide more than enough peace of mind.
10. Build quality
No matter how careful we are, most laptops are inevitably going to find themselves, dropped, thrown and knocked around by the rigors of everyday use. For that reason, it's worth checking out how much testing a laptop has undergone (the manufacturer usually crows about it) or whether there's any sort of certification that you can put your confidence behind.
Modern laptops are often ruggedized to withstand rain and dust. Some are built especially for the brutal educational environments - and come with military-grade protection certifications. The most common of these you're going to see is MIL-STD 810G.
MIL-STD-810G is a standard used by the US Military to indicate a guaranteed minimum level of durability. Compliant products have made it through a gauntlet of 29 separate tests that measure resistance to shock, heat, cold, humidity and more. Though originally developed as a way to win government contracts, MIL-STD-810G has become increasingly common in consumer tech in exact years.
On one hand, it's good for consumers that most major manufacturers have adopted the same language and standards for measuring durability at all. However, on the other, the reality is that having a product be MIL-STD-810G compliant doesn't always translate into the kind of ruggedness you'd hope it would.
Although the MIL-STD-810G standard was developed externally, there's no single independent party that's responsible for handing out certification to the standard nor any regulator that's able to call out bad actors for misusing or misrepresenting MIL-STD-810G.
Manufacturers can absolutely take their testing in-house, "ace" it and put the sticker on the box. There's no limit on how many attempts a product has to pass a certain test, nor even a limit on whether the same product demo needs to survive all 29 tests or whether they can replace it with a fresh model every step of the way. They don't even need to provide proof that the testing ever happened.
From the perspective of any everyday consumer, there's zero difference in how a product that was properly and independently tested to meet MIL-STD-810G looks and how a product that "fudged" their way into compliance with the standard looks. This is obviously problematic.
For those reasons, MIL-STD-810G is best used as starting place when it comes to thinking about durability and build quality in your next laptop. It shouldn't be your one and only consideration.
A better way to approach the problem is to look at the laptops design and what specific claims are being made around durability. Are the manufacturers talking up drop-tests or spill resistance that goes beyond the usual MIL-STD-810G spiel? That's probably a good sign.
11. LTE, Wi-Fi, or Ethernet?
When it comes to purchasing a laptop, a big question you should ask is: Should I buy a laptop with LTE? Unlike laptops with built-in network cards, laptops with LTE can connect to mobile data signals. That means instead of having to connect to a wireless network at home, in the office, or at Wi-Fi hotspots, your laptop can connect directly to a mobile ISP for internet access. The main benefit of this is you can use your laptop just about anywhere—when outdoors, traveling on the bus, or even on the beach. If that convenience sounds good, this option may be perfect for you. However, there are a few caveats.
LTE technology sits in the higher-end laptop category, so you will pay for the privilege. Also, just like with your phone, you'll need to either be on a data plan or buy prepaid data to use your LTE. And as such, your experience will be influenced by the speed of your laptop’s network connection and by the amount of data in your plan.
Know what LTE network your laptop will connect to, since this will determine your internet speeds. The most common LTE technology in laptops in Australia today supports connection to the 4G networks. 4G is capable of maximum get speeds of 1Gbs, which is close to most home broadband speeds. But 5G laptops will soon be coming to Australia. These laptops, when available, will feature significantly faster speeds of between 10-30Gbs. If superfast internet is a priority, go for 5G.
If you are not fussed about having LTE or want to avoid the ongoing fees, a laptop with Wi-Fi-only functionality will do just fine. Most laptops come with built-in network cards so you won’t need to fuss over installations or affix dongles. You can also use mobile Wi-Fi tethering as a source of Wi-Fi on the fly.
The last thing to consider with your internet connectivity, is whether you need an Ethernet (RJ-45) port. Most people don’t use this functionality anymore, since Wi-Fi connectivity is so widespread. But, if you're plagued by a weak Wi-Fi signal, or lack Wi-Fi altogether, you should consider it. Otherwise, it’s not necessary.
12. Wi-Fi speed
Wi-Fi speeds are determined by many different factors, such as signal strength and the level of interference between your laptop and your router, but the one factor that you should think about when purchasing a new laptop is the Wi-Fi speed of your laptop’s network card.
The speed at which your laptop transfers data from an internet router to your laptop and back is called its link speed and it is measured in bits per second (bps). Even if your internet connection is fast, if your link speed is lousy, your Wi-Fi speed will struggle.
Most laptops with network cards connect to wireless hotspots on either the 2.4GHz or 5GHz frequency band, meaning they are capable of maximum link speeds of 1Gbs or 3.5Gbs. When it comes to Wi-Fi generations, Wi-Fi 5 is getting a bit old now but will still perform well for almost anything you'd need to do online, such as browsing webpages, watching videos, and running browser-based applications.
Most new laptops though will have network cards that support either Wi-Fi 6 or the newer Wi-Fi 6E. If you are a gamer who likes playing fast-paced multiplayer content, or if you stream high-quality video, we recommend you look for either of these options. The main benefit here is lower latency - Wi-Fi 6 and Wi-Fi 6E offer substantial speed benefits (up to 9.6Gbs). Wi-Fi speeds won’t always be listed in the product descriptions online or in retail outlets, but they will be listed in the detailed product specifications, so check there if you’re unsure.
Meet your needs and budget
Of course, you need to balance these features with your budget and your needs, and you might have to make some compromises. Rarely does a laptop come along that ticks all the boxes, especially when it comes to price.
Let us know in the comments below if you consider other aspects of a laptop to be more important (maybe you want better gaming performance or a rugged build, maybe you want a laptop that can turn into a tablet), and especially let us know if you’ve already found the perfect laptop for your needs.
This article was updated by Dominic Bayley in May 2022.
Thu, 08 Jul 2021 02:18:00 -0500en-AUtext/htmlhttps://www.pcworld.idg.com.au/article/556585/top-10-things-consider-when-buying-new-laptop/Killexams : Tested: 1974 Porsche 911 vs. 911S Targa, 911S Carrera
From the February 1974 issue of Car and Driver.
The tachometer needle is closing in on the fourth gear redline. The speedometer indicates 105 mph. Bobby Allison is feeling the Porsche 911 into the wide, banked Turn One of Pocono's short road course. He has driven this section of the tri-oval dozens, maybe tens of dozens, of times before, always in a stock car . . . and always in the other direction. But that doesn't matter. Now he is turning right instead of left.
"You could really hang up your spare parts in this corner if something went wrong."
At this speed, the Porsche is toeing an awkward threshold. Aerodynamic forces have lifted its front enough to make the steering light and vague, yet very twitchy. The rear has lifted too and the tires are light enough to want to break out into a drift.
"I can feel it trying to hang but it can't quite do it."
Each time the tail comes loose, Allison catches it with a microscopic correction of the steering and an adjustment of his foot on the gas. But almost as soon as it's caught, the rear comes unstuck again. And each time it does, the onrushing boiler-plate wall seems to click into even sharper focus.
"It's telling me to expect something bad, it doesn't say how bad. It's not really a strain at this speed . . . we might even be able to run right to the mat in a few laps . . . but I just know better than to crowd it too soon. Porsches are quite a bit different from anything else I've driven . . . except maybe a Volkswagen and I've only driven VWs a minimum number of times."
Bobby Allison, successful driver and equally successful race car builder, feels no reverence toward the name Porsche. Which makes him the perfect driver to test the 1974 line-up of 2.7-liter Porsches. It's easy to find someone who has raced Porsches successfully, someone with a factory deal . . . or someone trying to carve out a factory deal . . . who will be more than happy to help out on a test such as this. And you'll get a glowing report. But Allison is non-aligned. With him, the chips fall where they may. And he points out exactly where that might be in a precise, deep, gentle drawl that does not leave room for misinterpretation. To be sure, Bobby Allison is a stock car driver, and, with more than forty NASCAR wins, an exceedingly competent one. But he is much too diverse to be categorized in that narrow pigeon hole. He has also won on road courses—Riverside this past summer to name a exact one—and driven open-wheelers for Roger Penske at Indy. He has even raced Porsches, at the Lime Rock Trans-Am last season and most recently as one of the select field of 12 at the International Race of Champions at Riverside just before this test. In fact, he even bought a new 911T to drive on the street in preparation for the IROC.
Like many of today's best drivers, Allison turns out to be more than just a driver. He is also a car builder. His shop in Hueyton, Alabama turns out parts and completed stock cars, as many as a hundred a year, for serious racers. So Bobby Allison knows about automobiles from both sides of the steering wheel. With credentials such as these, Allison's assignment for Car and Driver was to probe the performance and personality of Porsche's newest collection of road cars as represented by three models: a 911, a 911S Targa and a Carrera, $42,940 worth of rear-engine machinery.
Porsche's model line-up has undergone a substantial overhaul. The T and E models are gone. At the bottom of the new heap is the no-suffix 911 which lists for $9950 POE East Coast, plus everything. Up from there is the 911S. And that, in turn, is topped by the Carrera at $13,575, at that price as naked as the Venus de Milo.
There is bound to be confusion over the Carrera. You're probably thinking—or at least hoping—that it has much in common with the Carrera RSRs that have been mowing down the opposition around the world in GT racing and that made up the field for the IROC. It doesn't. It's a 911S overlayed with a few of the RSR's accoutrements: Carrera side stripes, the upturned rear deck spoiler (a "mandatory option" at $285), slightly flared rear fenders and wider (seven inches compared to six in front) rear wheels mounted with appropriately fatter tires.
This is in bold contrast to the European Carrera, known as the RS, which is strictly a stripped homologation special. It is very light—just under 2000 lbs. dry—with a high compression engine and is strictly verboten on public roads here because of smog and safety laws. Upon special order, the factory will convert the RS into the RSR, which is a pure racing car, the kind that ran in the IROC. These cars have 3.0-liter engines that produce 330 hp (DIN) at 8000 rpm, fiberglass bumpers and widely flared fenders, special suspensions, brakes from the 917, wide wheels (9.0-inch in front, 12.0-inch in back) and all the racing equipment you need, right down to a 6-point seat belt, roll bar and on-board fire extinguisher. The RS and RSR have about the same relationship to the U.S.-market Carrera that Bobby Allison's number 12 Chevelle has to the one you'll find covered with shipping wax in your local Chevy dealer's lot.
All of the new Porsches have 2.7-liter 6-cylinder engines, big-bore versions of the 2.4-liter powerplant introduced in 1972. They also have a new fuel injection system from Bosch known as the K-Jetronic, a continuous flow type with nozzles directed at the underside of the intake valves. It determines fuel flow by measuring the quantity of intake air, the same principle as the original Rochester device introduced on 1957 Corvettes.
For 1974, the engines come in only two stages of tune. The regular 911 has what is basically the old "T" engine, but with 300cc additional displacement. It has an 8.0-to-1 compression ratio and is rated at 143 hp (net) at 5700 rpm. The S and the Carrera share a similarly enlarged "S" engine. It has a higher (8.5-to-1) compression ratio, larger intake ports and a cam with more lift and duration on the intake lobes. It is rated at 167 hp (net) at 5800 rpm. Though, in comparison to the old T and S, quarter-mile acceleration of the new models is virtually unchanged, the new engines are clearly less fussy to drive. The increased displacement and less overlap in the cams (for emission control) has made them both highly tractable. The S still has a noticeable rise in the torque curve as you approach 3500 rpm, but even it will slug through traffic without trauma. In past models, we felt the output curve of the S was too peaky for U.S. driving conditions and, in fact, the E was quicker at speeds below 100 mph. But the new S is at least as flexible as the old E and we no longer have reservations about it. To compliment the two larger engines, fourth and fifth gear ratios in the 5-speed transmission have been slightly changed—lengthened for quieter cruising and better fuel economy.
The new 911s have undergone other changes to make them more compatible with Uncle Sam's requirements. The new bumpers with wide aluminum face bars add 5.0 inches to overall length. For the American market they are mounted on hydraulic shock absorbers (another "mandatory" option at $135) so that they will be self-restoring after a low-speed crash. Surprisingly, this has been done without adding much weight. The new models are only about 50 lbs. heavier than their predecessors. And at least half of that can be charged off to the enlarged fuel tank (21 gallons, up from 16.4).
There are other changes beneath the surface and some of them do not seem like progress. To help weight distribution, Porsche has for years fitted the 911 with two small batteries, one on each side just forward of the front wheels. This year, there is just one, a large one, located at the left front. In 1972 the dry sump oil tank was moved forward of the right rear wheel, also to Excellerate weight distribution. A year later it was moved back behind the axle into the engine compartment. The front anti-sway bar has also been redesigned for 1974 to a less costly, but also less efficient, arrangement.
All of these moves provide the appearance of being cost reductions . . . except that you'd never know it by the price, which has gone up about $2500 in two years with the blame being laid on fluctuations in the international money market and inflation in Germany. Perhaps some of the changes in weight distribution are made up for by the new, cast light-alloy semi-trailing arms in the rear that replace the previous steel suspension components. On the other hand, perhaps small differences in weight distribution make very little difference. That's why we went to Pocono. To find out. And that's why we summoned Bobby Allison, as a non-aligned driver, to provide us an impartial view.
It is a tribute to Porsche that we find it necessary to test its models on the race track. It all comes down to the fact that the Porsche 911 is one of the very few truly high performance street cars in production today. Because of its racing successes, its capabilities are legend. But reputations cut no ice in road tests. What the car actually does is what counts. And at Pocono we explored the extremes of three new 911s.
The 911's uniqueness looms up as soon as you fit yourself into the seat. Allison discussed the difficulties he found in adapting: "Compared to the pedals, the steering wheel is way too far away. The height and angle would be fine if it were about two inches closer. All the stock car guys at Riverside complained about that. Petty, who is used to driving right up on top of the wheel, really had a problem—when he got somewhere close to what his arms wanted he had to work the pedals with his knees.
"The pedal position and the shifter are all so very strange. I never missed the clutch at Riverside, but I did originally in that first Porsche I drove at Lime Rock . . . and even in my street car. It's over so far to the right compared to a normal car I had to work to get used to it.
"I've found the shifter itself to be a problem in the car I bought as well as the race cars. It's very mushy in feeling. At Lime Rock I only got a couple laps of practice before the race and had to start at the rear of the grid. In the race I had come from 33rd to tenth in like ten laps. Then there was a spin out. In order to miss a spinning car, I tried to make a quick shift while I was in a turn. Instead of going from fourth to third, I went from fourth to first. It blew the engine up. That showed me right there that I'd better find out where the gears were."
With that as motivation, Allison bought his own street Porsche a few months later when he committed to run the IROC. But he still doesn't find shifting easy.
"On a road course, with any kind of cornering pressure on the car—which transfers into your body also—you can't find the detent for the gear you want."
Allison is not the only one to have this problem. At Riverside, Petty, Johncock, McClusky and even Denny Hulme were having trouble finding the gear they wanted when they wanted it. And at Pocono we discovered that the problem is not confined to the RSR. The stock cars work well enough on the street where, even though the linkage might be somewhat imprecise, you'll probably never miss a gear. But on the track, sometimes you move the lever and you can't find anything. Or worse yet, you get the wrong gear. And while it's possible that the driver is hurrying the operation under those circumstances, driver error is only partially responsible. We strongly suspect that certain combinations of cornering, braking and acceleration loads on the car, in conjunction with high engine speeds, produce distortions somewhere in the long shift mechanism that prevent it from working properly. Allison agrees and considers this to be one of the major problem areas in the car.
When it comes to handling, Allison approaches the Porsches from years of professional experience and quickly sights in on their uniqueness. "Compared to American cars that have a good, positive front end feel and a back end that just trails along meekly, the Porsches are very much more aggressive. They are very quick reacting, almost squirrelly, in what would be a normal maneuver in any other car. I've driven my car pretty fast on interstate highways and, when you get it up to speed, it's pretty comfortable. But you better not move the steering wheel very much. If you want to change lanes at 70 mph, you learn quickly to do it very carefully. The cars are heavy in the rear and very light in front—which makes the steering light. It's a feeling you really have to get used to."
Allison's point is that, unlike an American car, the Porsche's back end doesn't trail meekly behind the front. And it's this feeling that convinces so many street drivers that they are in the world's best handling car. At low speeds, city traffic and brisk marches through winding lanes, a 911 is supremely agile. The steering is quick and the car instantly changes direction with only the lightest touch. It feels for all the world like a civilized formula racer and gives great pleasure. But the Porsche's personality changes drastically as you approach its limit. Then the tail swings heavily, and the car responds to an unpracticed and unsubtle touch with a vengeance. Moderate street drivers never learn of this; the venturesome ultimately will find out. Allison, of course, has already served his apprenticeship on the race track.
"The hard thing to really get used to in the race cars at Riverside was, when you go too deep into a corner and lifted, the car would begin to spin. And if you went ahead and did the natural thing, lifted—or put on the brakes—the car would spin. But if you could make yourself put your foot back on the gas pedal, the car would drive out of the spin. That was how (Emerson) Fittipaldi crashed—he knew he had to get back on the gas, but while he was doing it he went too deep and ended up with his front—rather than back—end against the wall. Naturally, Mark (Donohue) and George Follmer knew this. The rest of us just had to kind of find out. It's a completely opposite reaction to a stock car. When you lift in a stock car, it tends to straighten out.
"The other thing is that Porsches tend to oversteer very badly at first, and then correct. When you would expect it to be either lost or in a controlled broadslide, it snaps back straight, sometimes even over center toward the other direction. Which I feel would get an inexperienced driver into trouble.
"These cars react the same way the race cars do. Naturally the RSR with the racing suspension and the big, fat racing tires will corner better. But these cars at 50 mph feel exactly the same as the race cars do at 70 or 80.
Curiously, the factory engineers speak of neutral handling as the reason for the Carrera's tire set-up: 185/70 radials on 6.0-inch wheels in front and 215/60 radials on the 7.0-inch rims in back. Intuitively, this sounds like the right approach—bigger tires on the end with the most weight. But in practice, we found no circumstance in which any of the 911s fit our, or Allison's, definition of neutral. In skid-pad testing, they all understeered heavily when under power. And if we lifted abruptly without correcting the steering, they all spun in little more than the length of the car. It was like having a choice of power-on understeer, lift-throttle oversteer and nothing in between. Moreover, the consistency of this reaction in all three cars indicated that the Carrera's wide rear wheels and rear tires make no noticeable difference.
The brand of tire, however, does make an enormous difference in cornering power. The basic 911 and the Carrera had identical suspension set-ups: optional Bilstein shock absorbers (which are very harsh for street use) and front and rear anti-sway bars (standard on the Carrera, optional on the 911). The 911 also had the optional 6.0-inch wide wheels (5.5-inch wide is standard). The only difference was tires—Michelin XWX on the 911 and Dunlops on the Carrera—and of course the Carrera's wider rear wheels. The Michelin-shod 911 was far quicker on the skid pad, generating 0.83 G in cornering force compared to 0.80 G for the Carrera. The 911S Targa, also on Dunlops but burdened with air conditioning and lacking the optional rear anti-sway bar was a distant third at 0.74 G. The basic 911, contrary to all that is right, also managed to be easily the fastest on the road course. The high-back bucket seats—new this year—provide excellent lateral support, the Michelin tires are clean and clear in their response, and the optional suspension underpinnings are well suited to track driving. Allison was able to circulate easily at 1:22.0 (78.9 mph).
He did not, however, find the Targa's road course behavior to his liking and his running commentary shows it. "Boy, this thing is top heavy compared to that other one . . . very soft suspension. We're way slower through here than we were in the other car. I ensure you, you'd have to drive this thing all the way around . . . Yeah, now see, right here the car begins to mush over and pick up oversteer or understeer, depending upon where my throttle pedal foot is."
Six laps of that was enough and he parked it, having recorded a best of 1:23.9 (77.2 mph). The conclusion was that the Targa's extra weight and the Dunlop tires were more than enough to offset the extra power of the "S" engine. In addition, the lack of a rear anti-sway bar on the Targa increased the roll angle considerably which, besides making the car awkward to drive, also presented the tires to the road at a less favorable camber angle (one of the intricacies of the Porsche order form, to wit: A 16mm front bar is standard on the 911 and 911S. But if you order the optional rear sway bar you also get a larger-20mm front bar—so that the understeer/oversteer nature of the two set-ups will be approximately the same). So the standard suspension Targa was slower, by a lot.
Of course, everyone had high hopes for the Carrera. It's price tag says it's the best, right? But Allison just takes them as they come. ". . . this one doesn't handle as bad as the Targa (911S) and its engine runs nice and strong. But it's still very mushy compared to the 911. In handling, I'd say this one is about one-third better than the Targa and two-thirds poorer than the 911. I can feel the spoiler at high speeds, it pushes the nose up. But on the infield it's just something I can see in the rear-view mirror." The Carrera finished the road course trials in a reasonably close second place at 1:22.8 (78.3 mph). It was agreed that the wide rear wheels and tires made no noticeable difference and that Dunlops in general were less sticky than Michelins. The spoiler is a mixed blessing. In the critical high speed banked turn it definitely discouraged the rear end from its nervous tendency to hang out, but at the same time it increased the vagueness of the steering (See sidebar on aerodynamics, page 6).
Allison is emphatic about Porsche handling. "The most unnatural thing is, when you see that you are in a little bit of a problem and you lift off the gas, the problem increases. Then you're in trouble. What do you do next? With the race cars we found out you stomp your foot down and start steering like a wild man. But I don't think an inexperienced driver is going to do that. These cars do have a strong reputation . . . but I don't see why. I'd guess it comes first of all from the racing versions, and then from its quickness at well under its limit."
On the subject of handling, at least, we are in agreement. When you get used to a Porsche, you can make it do some pretty amazing things. But the idea of evading emergency situations by applying power is so unnatural for most drivers that it is unreasonable in a car intended for street use.
"The dealer where I bought my car happens to be a personal friend and I suppose he'll be greatly disturbed by my comments about his little Kraut wagon." Allison grins and continues, "To be fair, the car has unique characteristics and some people may like it. I don't. I think they are $12,000 imported Corvairs."
Allison, it turns out, sold his 911T within hours after he finished up at the Riverside IROC. And his reactions, we think, are typical of the general sports-car-driving public. There is no middle ground, you either like Porsches or you hate them. But in all cases, you consider yourself among the fortunate few if you can afford one.
You've laid out the extra money to insure that the factory will inscribe "Carrera" across the rocker panels of your new Porsche. And as a $285 "mandatory option," your 911S will sport the boldest aerodynamic device to land on a street car since the awesome stabilizers of Plymouth's Superbird. But does that ski jump built into the Carrera's deck-lid really do anything? Or is it simply a stylistic lure? Here is the answer.
The Carrera's rear spoiler will indeed do more than turn heads at every stoplight. It does, in fact, coerce air molecules rushing over its gelcoat surface into doing genuinely useful work. Namely, the creation of substantial vertical down forces at the rear of the car.
To precisely measure the effects of the spoiler, we instrumented our test Carrera and ran countless high speed laps on the tri-oval at Pocono International Raceway. An onboard strip-chart recorder plotted the information we were after: first of all, car velocity; and secondly, changes in wheel loadings—exactly how much force was pressing the tires to the pavement.
A fifth wheel trailing behind the rear bumper delivered forward velocity data to the recorder. Tire loadings, on the other hand, came from a position transducer. It was actually capable of measuring suspension deflections while the car was moving. That information could be translated into "weight on the tires" only after the following pit-side calibration procedure. With the aid of a Turner wheel scale and a floor jack, we cycled the Carrera's height up and down, plotting wheel weight indicated by the scales versus suspension deflation on the chart recorder. With this base-line data, we then knew exactly what force linked the rubber to the road at any speed from zero to the all-out maximum.
The results show that without the spoiler (the test Carrera had been fitted with the Targa's decklid for this comparison) airflow begins lifting the rear of the car at 30 mph. And by 100 mph, the rear of the car is "lighter" by 200 lbs. But with the Carrera spoiler, weight loss stabilizes above 65 mph at only 35 lbs. As a result, the rear tires can develop more cornering force with the spoiler, because they have more vertical load forcing them to the pavement. And you don't have to peg the speedometer before those benefits are delivered. The spoiler begins working to your advantage at 30 mph.
Front wheel weights are also affected—to a lesser extent. With or without the Carrera decklid, the front tires' weight loss due to airflow is approximately 200 lbs. between 60 and 100 mph. But by 120 mph, the rear spoiler is actually a disadvantage, because it unloads the front end by an additional 60 lbs. over the non-spoilered car. Clearly, some sort of snow plow is needed in the front to match the effectiveness of the ski ramp in the rear.
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Fri, 22 Jul 2022 03:20:00 -0500en-UStext/htmlhttps://www.caranddriver.com/reviews/comparison-test/a15142825/1974-porsche-911-vs-911s-targa-911s-carrera-archived-comparison-test/Killexams : Assessment of ventilatory thresholds during graded and maximal exercise test using time varying analysis of respiratory sinus arrhythmia
Objective: To test whether ventilatory thresholds, measured during an exercise test, could be assessed using time varying analysis of respiratory sinus arrhythmia frequency (fRSA).
Methods: Fourteen sedentary subjects and 12 endurance athletes performed a graded and maximal exercise test on a cycle ergometer: initial load 75 W (sedentary subjects) and 150 W (athletes), increments 37.5 W/2 min. fRSA was extracted from heart period series using an evolutive model. First (TV1) and second (TV2) ventilatory thresholds were determined from the time course curves of ventilation and ventilatory equivalents for O2 and CO2.
Results:fRSA was accurately extracted from all recordings and positively correlated to respiratory frequency (r = 0.96 (0.03), p<0.01). In 21 of the 26 subjects, two successive non-linear increases were determined in fRSA, defining the first (TRSA1) and second (TRSA2) fRSA thresholds. When expressed as a function of power, TRSA1 and TRSA2 were not significantly different from and closely linked to TV1 (r = 0.99, p<0.001) and TV2 (r = 0.99, p<0.001), respectively. In the five remaining subjects, only one non-linear increase was observed close to TV2. Significant differences (p<0.04) were found between athlete and sedentary groups when TRSA1 and TRSA2 were expressed in terms of absolute and relative power and percentage of maximal aerobic power. In the sedentary group, TRSA1 and TRSA2 were 150.3 (18.7) W and 198.3 (28.8) W, respectively, whereas in the athlete group TRSA1 and TRSA2 were 247.3 (32.8) W and 316.0 (28.8) W, respectively.
Conclusions: Dynamic analysis of fRSA provides a useful tool for identifying ventilatory thresholds during graded and maximal exercise test in sedentary subjects and athletes.
AT, anaerobic threshold
HP, heart period
HPV, heart period variability
RSA, respiratory sinus arrhythmia
heart period variability
time varying model
The spectral approach of heart period variability (HPV) has highlighted the fact that respiratory sinus arrhythmia (RSA) during exercise is the main mechanism regulating short term heart period (HP) fluctuations.1–3 RSA results from modulation of sinus node activity by breathing. Indeed, strong correlations have been found between the centred frequency of respiratory sinus arrhythmia (fRSA) and respiratory frequency (fR).3–5 Classical spectral analysis requires stationarity of the studied signal. Consequently, studies of HPV and RSA during exercise are scarce. To overcome these limitations, time varying models have been developed which allow us to depict a signal divided into its instantaneous frequency and power components. During pyramidal exercises, the dynamic behaviour of fRSA has been accurately extracted and strong links between fRSA and fR dynamic behaviours have been pointed out.6 This original approach to signal processing may be used in practice. For instance, Anosov et al4 have found that the dynamic behaviour of fRSA extracted from HP series, recorded during a ramp load protocol, demonstrates significant changes in the region of the anaerobic threshold (AT). Previously, James et al showed that during graded exercise, the AT could be detected in healthy adults by fR analysis. Moreover, ventilation (V˙I) time course analysis reveals two disproportionate increases in V˙o2,7 defining the first and second ventilatory thresholds. These disproportionate increases are related to exercise induced acidosis compensation and are mainly linked to fR increase.8,9 Although disagreement exists,10,11 ventilatory thresholds are closely related to lactate thresholds12–16 and could provide reliable indices of changes in response to endurance training or be useful when prescribing exercise training.17–19
As the two disproportionate increases in V˙I are explained by fR disproportionate increases, analysis of fRSA dynamic behaviour during a graded and maximal exercise test could reveal both the first and second ventilatory thresholds and provide practical applications as previously suggested. Such a method would be non-invasive and less expensive than the ventilatory flow and gas measurements required by ventilatory methods.
The first objective of this study was to use the signal processing method we previously developed6 to extract fRSA from HP series recorded during graded and maximal exercise tests. Dynamic behaviours of fRSA and ventilatory indices were then compared as regards exercise intensity in sedentary and athlete groups.
Fourteen sedentary healthy men (mean (SD) age: 24.5 (2.3) years) and 12 endurance athletes (age: 25.7 (2.8) years; >12 h of training/week) (characteristics shown in table 1) participated in the study. All subjects were non-smokers and none was taking medication. Physical activity and consumption of alcohol and caffeinated beverages were prohibited 24 h before the exercise testing session. Written informed consent was obtained prior to participation and ethical approval was granted by the Local Ethics Committee.
Anthropometric and maximal ergometric characteristics of the subjects
Subjects performed a graded and maximal exercise test on a cycle ergometer (Ergomedic 824 E, Monark Exercise, Vansbro, Sweden) in a quiet room at a controlled temperature of 21°C, at least 3 h after the last meal. In the sedentary and the athlete groups, the initial load was fixed at 75 and 150 W, respectively, and increased by 37.5 W every 2 min until exhaustion. The pedalling rate was kept constant at 75 rev/min.
Ventilatory indices and gas exchanges were measured using an automatic ergospirometer on a breath by breath basis (Metasys TR-M, Brainware, Toulon, France). Subjects breathed through a silicon facemask connected to a two-way non-rebreathing valve (Hans Rudolph, Kansas City, MO). Inspired and expired O2 and CO2 concentrations were measured using paramagnetic and infrared sensors, respectively. Averages every 10 s were then established for V˙I (l/min), O2 uptake (V˙o2, l/min), CO2 production (V˙co2, l/min), respiratory ratio (R), and ventilatory equivalents for O2 (V˙I/V˙o2) and CO2 (V˙I/V˙co2). fR was calculated on a breath by breath basis. Before each test, the gas analysers were calibrated with gases of known composition and an accurate controlled volume syringe was used to adjust the pneumotachograph. During the exercise tests, a one lead ECG (Cardiocap II, Datex Engstrom, Helsinki, Finland) was recorded and digitised on line by a 12 bit analog-to-digital converter (DAS 1600, Keithley Instruments, Taunton, MA) at a sampling rate of 1000 Hz, on a personal computer. Oxygen uptake was considered maximal (V˙o2max) if three of the following criteria were met: levelling off of V˙o2 despite increasing load, R greater than 1.10, and inability to maintain the fixed pedalling rate. The power corresponding to V˙o2max defined the maximal aerobic power (Wmax).
R wave peak occurrence was estimated using a threshold technique applied to the filtered and demodulated ECG signal. HP series were visually inspected to ensure the absence of artefacts. In case of artefacts arising from a spurious R wave detection, the HP was restored by summing the two or more spuriously short periods. In cases of undetected R wave, the erroneous HP was replaced by using the two adjacent HP values. Artefacts did not exceed 1‰ of the total HP series. The first 20 s of exercise, which correspond to a marked HP decrease, were removed to limit sources of non-stationarity. In addition, the local mean HP was also removed using a polynomial approximation po(k) (order equal to 20) and a 100th order high pass finite impulse response filter was applied to the detrended HP series.
Since the stationarity conditions are not fulfilled under dynamic exercise, classical spectral analysis methods were replaced by a previously described method.6,20 Using this method, the dynamic behaviour of fRSA was extracted.
ECG preprocessing was performed using Matlab software 6.0 R12 (MathWorks, Natick, MA).
Determination of ventilatory and RSA thresholds
Ventilatory thresholds were determined from the time course curves of V˙I, V˙I/V˙o2, and V˙I/V˙co2 by a first independent operator. TV1 corresponded to the last point before a first non-linear increase in both V˙I and V˙I/V˙o2. TV2 corresponded to the last point before a second non-linear increase in both V˙I and V˙I/V˙o2, accompanied by a non-linear increase in V˙I/V˙co2.7 The fRSA thresholds were determined from the time course curve of fRSA by a second independent operator. The first fRSA threshold (TRSA1) corresponded to the last point before a first non-linear increase in fRSA. The second fRSA threshold (TRSA2) corresponded to a second non-linear increase in fRSA.
Thresholds were expressed in terms of absolute (W) and relative (W/kg) power and percentage of Wmax.
Differences between the sedentary and athlete groups were tested using unpaired Student’s t test. Comparison and relationship between ventilatory and fRSA thresholds were tested using paired Student’s t test and a linear regression analysis, respectively. Individual relationships between fRSA and fR were tested by calculating Pearson’s r correlation coefficients. The mean (SD) of all individual correlation coefficients was then calculated. Statistical significance was set at p<0.05. Results are means (SD). Statistical analysis was performed using Statistica software 5.5 (StatSoft, Tulsa, OK).
Athletes showed significantly higher values of V˙o2 and Wmax when compared to sedentary subjects (see table 1).
A conspicuous high frequency oscillation synchronous with ƒR was found in all ECG recordings, clearly indicating the persistence of RSA over the entire graded and maximal exercise protocol. The dynamic evolution of ƒRSA was accurately extracted from the HP series and ƒRSA positively correlated (r = 0.96 (0.03), p<0.01) with ƒR (fig 1).
Representation of the dynamic behaviour of RSA frequency (ƒRSA, solid line) and respiratory frequency (ƒR, dashed line) recorded in one subject during graded and maximal exercise test.
fRSA dynamic behaviour
Two non-linear increases were observed in ƒRSA in 21 of the 26 subjects. These non-linear increases coincided with TV1 and TV2, respectively (see fig 2) and no statistical difference was observed between TRSA1 and TV1 (absolute power: p = 0.98; relative power: p = 0.90; percentage of Wmax: p = 0.91) and TRSA2 and TV2 (absolute power: p = 0.57; relative power: p = 0.79; percentage of Wmax: p = 0.78). Power values and percentages of Wmax at TRSA1, TRSA2, TV1, and TV2 are presented in table 2. When expressed as absolute or relative power and percentage of Wmax, TRSA1, TRSA2, TV1, and TV2 were significantly higher in athletes than in their sedentary peers. Linear regression analysis showed high correlation between TRSA1 and TV1 (absolute power: r = 0.99, p<0.001 (fig 3); relative power: r = 0.99, p<0.001; percentage of Wmax: r = 0.95, p<0.001) and TRSA2 and TV2 (absolute power: r = 0.99, p<0.001 (fig 3); relative power: r = 0.99, p<0.001; percentage of Wmax: r = 0.96, p<0.001).
First and second thresholds obtained from fRSA and ventilatory indices, in sedentary and athlete groups
Example of threshold determination using ƒRSA (A) and ventilatory (B) methods. ƒRSA, respiratory sinus arrhythmia frequency; TRSA1, first ƒRSA threshold; TRSA2, second ƒRSA threshold; TV1, first ventilatory threshold; TV2, second ventilatory threshold; V˙I, ventilation; V˙I/V˙o2, ventilatory equivalents for O2; V˙I/V˙co2, ventilatory equivalents for CO2.
Relationships between absolute power measured at TRSA1 and TV1 (A) and TRSA2 and TV2 (B). Solid lines represent the regression lines. • Athlete group; ▴ sedentary group. TRSA1, first respiratory sinus arrhythmia frequency (ƒRSA) threshold; TRSA2, second ƒRSA threshold; TV1, first ventilatory threshold; TV2, second ventilatory threshold.
In the five remaining subjects (three athletes and two sedentary subjects) only one non-linear increase was clearly identifiable and occurred close to TV2 (fig 4).
Example of lack of clear change in ƒRSA (A) and ƒR (B) in the region of TV1. ƒR, respiratory frequency; ƒRSA, respiratory sinus arrhythmia frequency; TRSA2, second ƒRSA threshold; TV1, first ventilatory threshold.
To assess HPV and RSA during non-stationary exercise conditions, we developed and validated an original method.6 In the present study, this method was used to process the cardiac electrical signal during a maximal and graded exercise test.
Using our original approach, the dynamic pattern of fRSA was accurately extracted from R-R interval series; RSA and breathing have been shown to develop dynamically at the same frequency. This result confirms previous findings3–5 which showed that during exercise, heart rate is modulated by breathing at the fR. When ƒRSA was considered, we were able to point out two successive non-linear increases in 81% of our population. First, we observed that TRSA1 was closely related to TV1. This finding is consistent with those of Anosov et al4 who reported that significant changes in the behaviour of fRSA occurred in the region of the AT. As the fRSA pattern is closely linked to fR, we could state that the first disproportionate increase in V˙I observed at TV1 is mainly induced by an increase in fR. This is confirmed by the study of James et al8 who concluded that the first ventilatory threshold (referred as the AT in their study) could be detected by fR analysis.
Second, we observed that TRSA2 was closely related to TV2, suggesting that the second disproportionate increase in V˙I is again related to fR increase. It has been reported that TV2 determines the workload before a marked fall in capillary pH.7 This exercise induced metabolic acidosis then causes ventilation increase through an increase in fR.9
The concept of ventilatory thresholds is closely linked in the literature to the concept of AT. AT is defined as the intensity of exercise, involving a large muscle mass, above which the oxidative metabolism cannot account for all the required energy and the anaerobic contribution to energy demand increases.21 Numerous studies have been conducted to detect one or two thresholds in metabolic (lactate for instance) or ventilatory indices time course curves. This diversity in methods of detection as well as lack of consensus on the theoretical basis have led to confusion and misinterpretation (see Bosquet et al19 and Svedahl and MacIntosh21 for reviews). Using blood lactate concentration is probably the most direct and reliable method to detect the AT.19 However, this method is invasive and requires frequent blood sampling which is uncomfortable during continuous exercise. The indirect technique using ventilatory indices could be thus preferable. Indeed, although disagreement exists,10,11 ventilatory thresholds are known to be closely related to lactate thresholds.12–16 Ventilatory threshold detection is usually based on assessment of successive disproportionate increases in V˙I, and fR is known to play a major role in these increases.8,9 It is also known that heart activity is modulated by breathing at the fR and this modulation represents the RSA which is vagally mediated at rest.22–24 Although cardiac vagal tone is totally abolished over ±60% of V˙o2max25 to adapt heart activity to cell metabolic demand,26,27 RSA was retrieved over our entire exercise test. This finding confirms that RSA persistence at intense exercise could be related to enhancement of a non-neural mechanism in response to V˙I increase. Indeed, changes in thoracic pressure induced by breathing influence filling of the right ventricle.29 Increased right ventricle filling during inspiration consequently increases transmural pressure and stretches the sinus node, thus activating positive chronotropic response via mechanosensitive Cl− channels.30,31
Thus, using fRSA to detect ventilatory thresholds has the advantages of being non-invasive and cheap and may have field application in ambulatory heart rate monitors. Moreover, this technique appears to be reliable in most athletes and sedentary subjects. fRSA thresholds of athletes were detected at higher values than those of their sedentary peers, whatever the mode of expression, confirming that the AT is significantly improved with endurance training.32,33 Thus, this fRSA method could be used for the determination of human ventilatory thresholds over a broad range of physical abilities. However, in 19% of our population only one increase close to TV2 was clearly identifiable in ƒRSA, whereas two ventilatory thresholds were detected. As V˙I is the product of ƒR and VT, it could be expected that the first non-linear increases in V˙I and V˙I/V˙o2 were mainly related to VT increase. Indeed, as shown in fig 4, no clear change in ƒR was observed around absolute power corresponding to TV1.
Visual detection of both ventilatory and fRSA thresholds can lead to subjective results and may represent a methodological limitation of our study design. Indeed, it has been shown that different evaluators can choose different ventilatory thresholds from the same data.34 However, reliability of the ventilatory method is known to be enhanced when test conditions are kept constant and evaluators are experienced,21 which was the case in our study. Detection of ventilatory threshold is known to be dependant both on stage duration and load increase in graded exercise.35 As no exercise protocol test seems consensual, the standard protocol test used in our laboratory was thus preferred.
We have shown that, in most of our subjects, two successive non-linear increases are observed in fRSA. These thresholds are closely related to the first and second ventilatory thresholds, respectively. Thus, the method we developed provides a useful tool for identifying the ventilatory thresholds during graded and maximal exercise test in athletes and sedentary subjects as well as for assessing endurance levels. The next step could be to process HP series recorded during an adapted field test using modern heart rate monitors and time varying modelling.
What is already known on this topic
Respiratory sinus arrhythmia results from modulation of sinus node activity by breathing and during exercise is the main mechanism regulating short term heart period fluctuations. Strong correlations have been found between the centred frequency of respiratory sinus arrhythmia and respiratory frequency.
What this study adds
Two successive non-linear increases observed in respiratory sinus arrhythmia frequency are closely related to the first and second ventilatory thresholds, respectively. We have developed a useful method for identifying the ventilatory thresholds during graded and maximal exercise test in athletes and sedentary subjects as well as for assessing endurance levels.
We thank the Brainware Company for their technical support.
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Yoshida T, Nagata A, Muro M, et al. The validity of anaerobic threshold determination by a Douglas bag method compared with arterial blood lactate concentration. Eur J Appl Physiol Occup Physiol1981;46:423–30.
Caiozzo VJ, Davis JA, Ellis JF, et al. A comparison of gas exchange indices used to detect the anaerobic threshold. J Appl Physiol1982;53:1184–9.
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Farrell PA, Wilmore JH, Coyle EF, et al. Plasma lactate accumulation and distance running performance. Med Sci Sports1979;11:338–44.
Meste O, Blain G, Bermon S. Some considerations on the IPFM model for the heart rate variability analysis. In: Computers in Cardiology, 2003. Thessaloniki, Greece: IEEE Computer Society Press, 2003:709–12.
Robinson BF, Epstein SE, Beiser GD, et al. Control of heart rate by the autonomic nervous system. Studies in man on the interrelation between baroreceptor mechanisms and exercise. Circ Res1966;19:400–11.
Blain G, Meste O, Bermon S. Influences of breathing patterns on respiratory sinus arrhythmia in humans during exercise. Am J Physiol Heart Circ Physiol2005;288 (2) :H887–95.
Kang J, Chaloupka EC, Mastrangelo MA, et al. Physiological comparisons among three maximal treadmill exercise protocols in trained and untrained individuals. Eur J Appl Physiol2001;84:291–5.
During the past 20 years, very many studies have indicated that parameters measured during submaximal exercise may be better markers of endurance performance than Vo2max, the anaerobic (or ventilatory) and lactate thresholds being useful parameters to evaluate functional capability in various types of endurance performance. Both gas analysis and ventilatory flow measurements, as well as blood lactate determinations, can be used to estimate the anaerobic threshold as a predictor of endurance capacity. A procedure that would be simple, relatively inexpensive, and non-invasive would be welcome. Procedures based on maximal heart rate (or a percentage of it) are simple but not reliable. Thus, the determination of ventilatory thresholds by time varying analysis of respiratory sinus arrhythmia, as proposed in this paper, appears to be quite promising, providing that it can be used with data obtained by ambulatory heart rate monitors.