What is VO2max and should I have mine tested?

The question

The answer

VO2max is a term that surfaces whenever feats of great endurance are in the news, such as the gruelling Tour de France that wrapped up last weekend. It refers to "maximum oxygen uptake," the amount of oxygen you're able to deliver to your muscles when you're exercising at your hardest.

The more oxygen you can process, the faster you'll go - which is why many athletes seek out the VO{-2}max testing available at universities and labs around the country for around $100 to $150. But what do they really get from it?

"At the end of the test, you get a number," says Adam Johnston, a coach and director of The Endurance Lab in Toronto, which offers a range of performance-testing options. "But what you do with that number is up to you."

For some, it's a way of optimizing their training and learning about their ultimate potential. But research shows that VO2max is only one part of the mix for endurance success, and you may get more useful information from testing other parameters such as your lactate threshold.

Take, for example, Lance Armstrong, who was tested repeatedly for more than a decade by University of Texas exercise physiologist Edward Coyle. Not surprisingly, Mr. Armstrong had an extremely high VO{-2}max of at least 85 millilitres of oxygen per minute for each kilogram of body weight (ml/min/kg) while he was winning the Tour de France earlier this decade, compared to a typical value of 44 to 51 ml/min/kg for an active male college student.

"We estimate that if Lance were to become a couch potato, his VO2max would not decline below 60 ml/min/kg," Dr. Coyle noted in a summary of the research on his website. "Furthermore, if the normal college student were to train intensely for two or more years, his VO{-2}max would not increase above 60 ml/min/kg."

But this naturally high VO{-2}max doesn't distinguish Mr. Armstrong from many of his competitors. During his rise to world domination between 1992 and 1999, his VO2max remained pretty much constant. It was his efficiency - how fast he was able to bike while using a given amount of oxygen - that increased by 8 per cent and gave him an edge.

Unfortunately, neither scientists nor coaches have been able to figure out exactly how or why efficiency in sports like running and cycling improves. (Swimming efficiency, in contrast, can be improved by working on form.)

Still, measuring your VO2max does offer some insight into how your training is going - if it's higher than last time, you know you're progressing. Also, the test provides very accurate guidance about where your "aerobic" and other training zones are, compared to simply taking a percentage of your maximum heart rate.

But for those purposes, Mr. Johnston actually recommends testing lactate threshold rather than VO{-2}max. This threshold is the pace at which the slow accumulation of lactate in your blood begins to accelerate - a feature that is highly sensitive to training and crucial to race performance.

The athletes in Mr. Johnston's WattsUp Cycling program receive lactate testing every four months as they prepare for races.

"It's very empowering for the athlete to see the definite differences after four months of training," Mr. Johnston says. "And it also helps to detect when things aren't working, so we can make changes."

Of course, there are many other ways to monitor your training, starting with the humble stopwatch. But if you crave objective data, love cutting-edge technology and have always wondered how you stack up with Lance, the tests are easily available.

"There's a misconception that it's only serious, elite athletes who do this," Mr. Johnston says. "But we see a huge range of people. It's for anyone who wants to be fit, but also has a performance goal they're working toward."

Alex Hutchinson blogs about

research on exercise and athletic performance at http://www.SweatScience.com.

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The VO2 max test is a progressive exercise test that starts at an easy pace, gradually accelerates and finishes at " voluntary exhaustion" after 10 to 12 minutes. It's typically performed on a treadmill or exercise bike, with tubing attached to your head that measures all the gases going in and out of your mouth. ( Your nose is plugged for the duration.)

The amount of oxygen youíre using increases steadily the faster you go, but usually starts to plateau shortly before you stop - that's the VO2 max. Lactate threshold testing also involves speeding up incrementally, with a pinprick of blood extracted at each stage, and lasts 20 to 60 minutes.