What VO2max is and why it matters
VO2max refers to the maximal rate at which your body can process oxygen over time. Very importantly, it is measured in millilitres of oxygen per kg of body mass in kilograms, per minute. A runner runs on a treadmill at their fastest pace, preferably for longer than 6 minutes and their inhaled O2 and exhaled CO2 are measured. From looking at how we measure VO2max, we can see that if an athlete could process 4000ml (4L) of Oxygen per minute, and the athlete weighed 80kg, his VO2max would be (4000/80) = 50ml/kg/min. In layman’s terms, the athlete would have a VO2max of 50.
If this athlete then improves his ability to process oxygen from 4000ml per minute, to 4100ml. This will come about because his muscle cells will have increased in the amount and efficiency of his mitochondria and he will also increase the amount of enzymes that break down glycogen within his muscle cells. His VO2max is now 4100/80 = 55. In speed terms, this correlates to approximately an 8% improvement in his running speed. We now see that although we have “only” increased his oxygen uptake by 2.5%, we have a significant increase in VO2max and also running speed.
World class athletes are world class because they train very hard, but they also carry very little excess body fat. This reflects in their VO2max results. What many people don't realise is that by simply by reducing your body weight, you will improve your VO2max. If our hypothetical 80kg athlete managed to reduce his weight by 5kg, and yet maintain his ability to process oxygen, his VO2max would increase from 50 to 53; a 6% improvement without having gained any extra actual fitness!
VO2max testing tells us about an athlete’s potential, but it is not the full story. There have been many examples of athletes with relatively low VO2max values, who have defied logic and run world class times, and there have been countless athletes with VO2max values off the charts, who underperform relative to their VO2max potential. The best predictor of performance will always be performance itself.
Running economy is the other ingredient that forms part of this equation and is equally as important as VO2max. To be the best, you need to have the 5L Ferrari engine but also the economy of a Toyota Prius. Although VO2max is harder to improve, it is not impossible with the correct focus. Similarly, running economy can be improved significantly through the correct training methods.
In the end, VO2max testing can estimate your potential performance, but actual performance is way better, and far a more consistent predictor of performance. At the end of the day what matters is who crosses the finish line first, and not what numbers you generated in the sports-science lab. Instead of going in to the lab and running on a treadmill with a mask on your face, get out there and do your MPG performance assessments. They are far more accurate at performance prediction, and far more user-friendly too.