For cyclists like me, reading Bicycling Magazine, Road Bike Magazine, Mountain Bike Magazine, etc, is the equivalent of politicos reading the New York Times, the Wall Street Journal, and the Economist—I get in depth analysis about current cycling events, new gear, and the science behind various training techniques.  And just like in the daily political news where certain topics keep coming up, or cycling (pun intended), a few topics recur in the bicycle news world—doping allegations, the 29er vs 26er debate, which electrolyte replacement works the best, and what makes you fast(er).  While I am curious about whether or not Heed is better than Cytomax, the topic that has always piqued my interest the most is the last one: why and how are certain cyclists so darn fast.  Words like “Vo2 max” and “Lactate Threshold” abound in these articles, and like any obsessive-compulsive cyclist, I wanted to know what these terms mean, and, of course, what MY Vo2 max and Lactate Threshold are.

Vo2 Max Testing at UCSD / EPARC

Fortuitously, a couple of weeks ago, I was asked to participate in a Vo2 max and Lactate Threshold test by a small group of undergraduate student researchers at San Diego State University (SDSU).  It sounded like a great opportunity for me further my investigation, and because it was free, I couldn’t say no.

Before my testing, I read up on Vo2 max, Lactate Threshold (LT), and various other markers of fitness so that I could be an informed guinea pig. Here are the results of my research….

Four components are used to measure an athlete’s physical “fitness”: aerobic threshold, economy, lactate threshold, and Vo2 max. Aerobic threshold is the heart rate at which breathing begins to increase in depth. Typically this is the heart rate during Zone 2 riding. Economy is the rider’s ability to use less fuel to produce the same amount of power. Lactate threshold (LT), also known as anaerobic threshold, is the point at which the body switches from using fat and oxygen as its fuel source, to using glycogen. When this happens, acid, known as lactate, builds up in the blood, and when it reaches a high enough level, there is no option but to slow down and allow the body to metabolize it and flush it out. Vo2 max is maximum amount of oxygen that the athlete’s body can process to produce movement during all-out endurance exercise.

Aerobic threshold, economy, and lactate threshold are all things that can be improved with training.  In fact, LT training is the most popular method of improving an athlete’s high intensity performance. LT is also the best predictor of endurance performance—someone with a high LT is more likely to win a race.

Vo2 max is somewhat different from the other three components because it is mostly determined by genetics and cannot be significantly increased with training—it is more a measure of an athlete’s “natural ability” than anything else. It is limited by such physiological factors as gender, heart size, heart rate, heart stroke volume, blood hemoglobin content, mitochondrial density, and muscle fiber type. Additionally, it also decreases with age, sometimes up to as much as 1% per year after age 25.

The highest Vo2 max results are seen in endurance athletes, particularly those training at high altitude such as cross country skiers. An average untrained male will have a Vo2 max of about 45 ml/kg/min, while olympic level athletes will be between 75 and 85 ml/kg/min. The highest Vo2 max scores ever can be seen here.. http://www.topendsports.com/testing/records/vo2max.htm.

This kind of “natural ability” can be measured in different ways but requires a maximal physical effort. For my test, I road a bike on a trainer and increased my power output by 50 watts every 2 minutes.   While riding, I was breathing into a mask that was connected to a computer. The computer measured the concentration of oxygen and carbon dioxide of my inhaled and exhaled air. The Vo2 max is when the oxygen level remains steady despite an increase in the workload. My Vo2 max was measured at 64.7 ml/kg/min. According to the various charts I’ve found online, this seems to be about right for a cyclist / athlete my age (38).  Here is one of many charts I found.. http://www.sport-fitness-advisor.com/VO2max.html.

My LT was tested concurrently with my Vo2 max. Every 2 minutes, blood samples collected by finger pricks were immediately run through a piece of test equipment to determine the lactate concentration in my blood stream.  Along with blood lactate concentration, my heart rate and power output were measured and recorded. This process continued until the blood lactate concentration increases significantly and noticeably spiked.

My test lasted about 20 minutes and ended at a max heart rate of 189 and  +/- 450 watts. I reached my LT at 84% of my VO2 max.

So, what did I learn about myself from all this???.. Not much other than that I need to keep on training as planned and continue to push that lactate threshold up.

I’ve since been asked to participate in a similar study at the University of California San Diego (UCSD).  While the equipment at UCSD is more advanced, it is still assumed that my Vo2 max will remain the same, but perhaps (fingers crossed!) the training that I will do between now and then will raise my lactate threshold. We’ll soon see enough!

For more information about Vo2 max, lactate threshold, and the other measures of fitness please refer to Joe Friel’s The Cyclist’s Training Bible, 4th ed.