VO2 max and Cyclists: Important or Irrelevant
VO2 max is one of the most commonly measured physiological variables. Endurance athletes spend countless hours discussing, comparing and worrying about their VO2 max scores. Cyclists are always quoting VO2 max scores for one top rider or another. Is all the attention that this physiological variable gets really worth all the effort?
VO2 max is the maximum amount of oxygen that your body can take in and use. It is a function of both the body’s ability to deliver oxygen via the heart, lung and blood and the body’s ability to use oxygen in the working muscles and other tissues. While there are some exceptions, Elite cyclists typically have VO2 max scores in the 70-75 ml/kg/min range, similar to that seen in well trained amateur cyclists and some very fit age group riders. In an aerobic sport oxygen consumption is tightly tied to energy expenditure and generally producing more energy means more power and work. The relationship between power and oxygen consumption is not perfect; efficiency or economy play an important role in determining how strong the relationship is in each person.
Gross efficiency, the ratio of power output to power input, is a key determinant of cycling performance (1). A higher efficiency allows a cyclist to work at lower percentages of the VO2 max to accomplish the same or more work as a less efficient cyclist. In fact, a high efficiency rating can make up for lower VO2 max scores. Alejandro Lucia and coworkers (2) from the Universidad Europea de Madrid examined the relationship between VO2 max and cycling efficiency and gross efficiency in a group of elite cyclists. The subjects in this study were all world class riders having won at least one major professional race, defined as stage in the Tour de France, Giro d’Italia or the Vuelta a Espana, or finished in the top three at the World Championships. Hemoglobin and hematocrit levels were measured prior to the start of the study to ensure they were within normal physiological ranges. All subjects performed a VO2 max test following standard protocols. Later the same day they performed a 20 minute constant load test where they road at 80% of their VO2 max. VO2 max values in the subjects varied from a high of 82.5 ml/kg/min to a low of 65.5 ml/kg/min. Cycling efficiency varied from 97.9 watts/L O2/min to 72.1 watts/L O2/min. There was a significant inverse correlation between VO2 max and cycling efficiency. This means that those with the higher VO2 max scores had the lowest efficiencies and those with lower VO2 max scores had higher efficiency. A similar pattern was seen in gross efficiency. Power to weight ratio at VO2 max was not significantly different between riders, they were all in the 4.9-5.4 W/kg range. Interestingly two of the most accomplished riders, a road race and time trial world champion and climbing specialist who had won five stages in the Tour de France both had VO2 max score under 70 ml/kg/min.
This study clearly shows that VO2 max is less important than efficiency in cycling performance and that a high level of efficiency can make up for a lower VO2 max. This pattern is not unique to cycling it has also been seen in running (3) and rowing. In an upcoming article we will look at the various factors that contribute to efficiency and how to improve your cycling efficiency.
So the next time someone start bragging about their VO2 max score ask them about their efficiency rating. Their high VO2 max may just mean that they are very inefficient riders.
- Coyle, E. (1995). Integration of the physiological factors determining endurance performance ability. Exerc Sport Sci rev. 23: 25-64.
- Lucia, A. et al. (2002). Inverse relationship between VO2 max and economy/efficiency in world class cyclists. Med Sci Sports Exerc. 34: 2079-2084.
- Saltin et al. (1995). Morphology, enzyme activities, and buffer capacity of Kenyan and Scandinavian runners. Scand J. Med Sci Sports. 5: 222-230.