In 1922, a very British man, called Archibald Hill was handed the Nobel Prize in physiology or medicine for his work about muscle energy metabolism. With his findings he introduced the concepts of maximal oxygen uptake and oxygen debt.
This was the beginning of a factor experts call today “A major performance determinant”. The VO2max.
In support of his own research, he even used himself as a subject. He ran every morning from 7.15 to 10.30 to prove that running a dash relies on energy stores that are replenished afterwards by increased oxygen consumption.
Eventually, the great-grandfather of VO2max wasn’t simply a physiologist, but apparently an ambitious athlete. If only for research purposes.
Yet, for almost a century entire generations of scientists viewed VO2max as a genetically predetermined performance ceiling. No matter how hard you ride your bike there was nothing you could do about it. There were just the chosen ones.
But evidence about endurance training is refined a lot. A more modern and sophisticated take on VO2max shows it to be quite sensitive to training. In some circles even a cult-like obsession evolved around VO2max. And with that, dangers come about that can cost you a whole season.
With the right training sessions, however, VO2max is very trainable. First we should understand what it is.
What is VO2max
Maximal oxygen uptake (VO2max) describes the highest rate at which oxygen can be taken up, delivered to and utilized by the muscles during intensive exercise. We refer to it as maximum aerobic capacity as well and express it two ways: absolute and relative. Absolute is just milliliters/minute. Relative takes your weight into account and is expressed in millimeters/kilogram/minute. Therefore, individuals are better comparable.
Adaptations are two fold: central and peripheral. While central factors refer to the diffusion of oxygen from the lungs and the transport of it by the heart to the muscles, peripheral factors refer to parts engaged in oxygen diffusion, in muscles in particular, like mitochondria and capillaries.
It’s central factors with the heart’s stroke volume that create the biggest improvements in aerobic capacity for beginners. Consequently, your heart can pump more blood volume with one beat and more oxygen can be carried to the muscles. But as you get more highly trained the stroke volume will get close to maximum. And this is the reason why Archibald Hill and the following generations of cyclists and scientists thought of VO2max being predetermined and limited.
As recent science reveals it’s the peripheral factors that cause your VO2max to increase through exercise. The more capillaries are formed around the muscle, the more oxygen can enter it. The more Mitochondria is built in muscles, the more oxygen can be used to produce energy and power aerobically in the form of ATP (adenosine triphosphate).
The greatest challenge of VO2max training is riding at the right intensity and the right amount. Because even at this high intensity, there’s too high of intensity and too much of it.
Here’s why this is important…
The Unsung Caveat of VO2max Training
What we overlook at VO2max training is that it’s an anaerobic type of training. You produce way more lactate than your body can clear because you’re riding above your FTP (functional threshold power). Lots of lactate gets accumulated during an effort. We train anaerobic glycolysis. So, we’re burning a tremendous amount of carbohydrates and almost no fat. And we can’t sustain that high power for long.
It’s a very fatiguing training session. You can’t do it too often or you blow up. The higher the intensity, the higher the accumulation of lactate. This leads to an increase in our lactate production. Read more about lactate production (VLamax).
An increased lactate production always means a higher anaerobic capacity. And a high anaerobic capacity is the enemy of an aerobic base needed for endurance and ultra-endurance events .
No matter if you’re a sprinter or a climber, riding too high intensity or doing the wrong intervals will bring you into trouble. The climber won’t be able to keep up with the best uphill and the sprinter will be dropped on the last climb of the day and lose all hopes for victory.
But how does the right VO2max interval strategies translate into the real world? Let’s talk about that now.
Intensive and Extensive Intervals
As we’ve talked about peripheral factors, it isn’t just hard interval workouts that increase VO2max. It’s an important part of it, but all aerobic training plays a role too. Long endurance rides (Zone 2) increase mitochondrial density and capillarization as well.
The intervals that best stimulate VO2max, however, are shorter, high intensity efforts. For these efforts to be effective we need to exceed 90-100% of our individual VO2max power. You can also track intervals by heart rate, but the problem with heart rate is the delayed response and day to day fluctuation. Power remains the gold standard. Extensive intervals should be 2-8 minute length at 106-120% of your FTP. And intermittent intensive intervals of 30-40 seconds length at 130-140% of your FTP. The more intense the higher the anaerobic contribution, indeed.
To see the desired adaptations total time-in-zone should be 15-30 minutes. With recovery periods being a 1:1 or 2:1 work-rest-ratio.
There are many interval strategies to reach the time. Assuming we should all do the same intervals and always shoot for the upper end of time-in-zone is misleading. As we differ from one another as rider types our interval training should be no other.
A Better Way to Structure VO2max Intervals
Perhaps the greatest difference between a sprinter and a climber is their anaerobic capacity and their FTP.
The climber has a higher fractional utilization. This is the amount of VO2max used at FTP expressed as a percentage. The higher the fractional utilization the less time-in-zone you need for VO2max intervals. Because your oxygen rate is activated way quicker. A climber should do less intervals at VO2max, a sprinter, in contrast, should do more of the intervals.
There are many interval strategies to reach the time-in-zone. At first we should master the fundamentals. Let’s discuss two that proved to be effective and applicable. We do it for a sprinter and a climber.
The first effective interval session is 4 minute intervals. A rider with low anaerobic capacity like a climber can do 3×4 minutes at 110% of FTP. A sprinter with high anaerobic capacity can do 6×4 minutes at 110% of FTP. This ensures that both types of athletes create a great stimulus for aerobic capacity without overdoing it.
The second effective interval session is Billat 30/30. One consistent finding across scientists is that even during the recovery periods your metabolism is still ramped up to VO2max for a considerable amount of time. The whole interval counts. This transfers for a climber to 3x5x30/30 intervals at 140% of FTP. A sprinter should aim for more time like 3x10x30/30 at 130-140% of FTP. Read more about 3 simple workouts you can do right now to boost your VO2max.
To determine your individual VO2max Zone do a FTP test, a seated 5 minute all out interval or the powertest from Aerotune. Read more about how to determine your individual training zones.
The Promise of VO2max Training
Humans have a remarkable capacity to improve their performance in nearly any area of endurance physiology if they train in the correct way. Not even aerobic capacity can stop them. This is easier said than done.
VO2max training is not a comfortable activity. It requires sustained effort and concentration in not doing more harm than good. A 4 week block of focused VO2max training with 3 weeks of progression and 1 week of rest should see great improvements in your aerobic capacity.
The cyclists who master the art of VO2max training are committed to balancing intensity and aerobic base–always exploring and experimenting and refining.
VO2max training is no magic pill, but if you can manage to maintain your focus and stay true to your abilities, then the promise is quite compelling: to get stronger and faster when it counts.
Interval training at VO2max: effects on aerobic performance and overtraining markers: https://pubmed.ncbi.nlm.nih.gov/9927024/
Significance of the velocity at VO2max and time to exhaustion at this velocity: https://pubmed.ncbi.nlm.nih.gov/8857705/