miller jz2If you have any physiology, performance, or nutrition related questions, email Ben at:


On various social media dedicated to the local Fort Collins cycling scene, there has been much discussion on the importance of certain local training rides and how to increase rider participation. In general, those that care about the rides have been very responsive and sensitive to suggestions to improve the rides. There is one discussion that has popped up repeatedly over the years that I would like to address. The discussion usually goes something like this: “These hard rides are the best way to get stronger. At first you get dropped, but you keep trying and you keep getting stronger and eventually you hang in there.” There is usually this addition too: “Just look at Joe Blow, he used to get dropped all the time but he kept coming out and now he is kicking our butts.” At the risk of really dating myself, I like to refer to this last part as the George Burns argument. George Burns lived to 100 years old and smoked cigars every day of his life, so that must mean that smoking will not kill you. There are of course people that defy the odds, but those people should not be considered the norm (because they defy the odds). In the same manner, there are those that get their butt kicked and keep coming back and get better, but there are many others who no matter how hard they try - and of no fault of their own - will not be able to hang. Below I will explain further.

It is generally agreed that a high VO2max is requisite for elite endurance exercise performance. This statement does not mean that a high VO2max guarantees elite performance, and it does not mean that elite performance is tightly correlated with VO2max (or else we would just do VO2 max tests and call it good), it simply means that it is a minimal requirement. The ability to have a high VO2max is largely genetically determined. Through intense training (starting from no training) one can realistically expect to increase VO2max by 9-17%. However, there are some studies that have reported improvements of around 20-25%. If you had a VO2max of 40 ml/kg/min, that training could get you to 48-50 ml/kg/min, which is still not enough to be an elite endurance athlete. If you are genetically gifted, and already have a fairly high VO2max, those improvements mean a great deal and could push you to the elite level. A recently published paper (referenced at the end of this column) profiled Olympic medalists and also-rans (from the Olympics) in XC skiing and cycling. The VO2max in male competitors (non-medalists and medalists) spanned the very narrow range of 77-83 ml/kg/min. Therefore, there is clearly a requisite VO2max that not everyone can obtain.

You may ask then, what limits the ability to improve VO2max? VO2 max is largely determined by the ability to deliver oxygen (heart and blood) and the ability to use oxygen (mitochondria in muscle). The ability of the heart to get the blood (and hence oxygen) to the system is the cardiac output. Cardiac output is then determined by heart rate and volume pumped per beat (stroke volume). Maximal heart rate is not really trainable, thus training-induced benefits must be through stroke volume enhancement. Although this can improve, it cannot improve infinitely. The oxygen is carried through the blood bound to hemoglobin. It has been shown that elite endurance athletes have very high hemoglobin mass (concentration x blood volume). Therefore, they have a great ability to deliver oxygen. This factor has limited trainability, but is the target of other means to improve performance (altitude training, EPO, etc). Finally, the muscle has mitochondrial that can use the oxygen, but the improvements from increased mitochondrial mass is a little different and discussed below.

If we have a limited ability to improve our VO2max, how else could we improve performance? The one with the most potential is mechanical efficiency. What mechanical efficiency refers to is the ability to do more work with a given amount of oxygen. Therefore, you can do more work before reaching your maximal ability to use oxygen. Although it is pretty clear that years of training can improve running economy (not strictly the same thing, but close enough for our discussion) it is doubtful that mechanical efficiency improves with cycling training. What can improve with cycling are the benefits from mitochondrial adaptations. With training you can increase mitochondrial mass and therefore the ability to sustain a higher percentage of your VO2max. Your max ability to perform work may not improve, but your ability to sustain a higher percentage of max does. This adaptation is a primary benefit of training.

To circle back a little now, a high VO2max is required for elite endurance exercise performance; however, the ability to improve VO2max is limited. Exercise training improves mitochondrial function and may (big maybe here) improve mechanical efficiency allowing one to get the most out of their VO2max. Through training, we all have the ability to improve within our maximal VO2max. What that means is that through training, we can all be the best our physiology will allow us to be. However, there are some out there, unfortunately, that will never be able to improve to the point of being able to compete at a high level. These are not people who are not trying hard enough, or are not motivated, they are genetically limited and are doing the best with what they have. There are those out there who by attending a hard group ride will be able to improve to the level to be able to compete. These individuals are trying hard, but also have the genetic predisposition to get to a high performance level. But, there are those that no matter how hard they try, will not be able to get to that level. It is not for a lack of trying, it is from the lack of genetic predisposition. I therefore take exception when it is implied that the hardest group ride in town is “the only way they will get better.” There are other rides that will allow them to get better without simultaneously discouraging their participation (or ways to design a ride to accommodate all abilities). Participation in cycling in general is what is important, not on a specific ride. We should do what we can to be encouraging to all abilities so they can compete within their comfort range and ability.


Reference of interest: Performance Enhancement: What Are the Physiological Limits? Lundby C, Robach P. Physiology (Bethesda). 2015 Jul;30(4):282-92. PMID: 26136542.