Scientific studies of athletes’ physiology tend to establish the average metabolic behavior of athletes undergoing a specific exercise. 

But each athlete’s reality always varies from that of the others, with a subjective metabolic profile. 

Confronted by the same physical activity, each cyclist uses his own ‘motor’ in a different way. 

Over the years, I have checked this reality by collecting data on cyclists of every level attacking different grades, putting out maximum effort, as in uphill time trials. 

Limiting participation in my tests to professional riders, I usually use three climbs, of varying lengths. 

On Italy’s Monzuno climb (4.2 km with a vertical gain of 390 m), with timed output from 12 to 15 minutes and a VAM of 1950 to 1560 m/h, the concentration of lactic acid in the blood immediately after the test is on average 9.7 mM/l. But there are athletes with 6 mM, others with 14 mM and yet others with intermediate levels. 

The same thing happens on the Col de S. Agnes, in France (6.7 km, vertical gain of 540 m) with an average lactic concentration of 6.7 mM, but with individual variants from 4.8 to 11.3 mM/l. Or on the Vilaflor climb in Spain (10 km, vertical gain of 750 m), with average levels of 7.2 mM/l and individual variants of 5.3 to 11.7 mM/l. 

There is no relationship between performance and lactic acid concentration. That is, it cannot be said that the rider with the lowest lactic acid level (or the highest) will obtain the best times. 

Every athlete always behaves in the same way, i.e. he will accumulate very similar quantities of lactic acid each time he faces the uphill time trial even as years go by or after modifying training regimens. Thus there are riders who put out effort in a more aerobic manner (those that display lower lactic acid levels), and others with more anaerobic metabolism (higher lactic acid levels). Usually, the “aerobic” riders are better suited to stage races, while the “anaerobic” riders are more competitive in one-day races. 

But this is not always the case. In my case studies, among the “anaerobics” there are two cyclists who won the Giro d’Italia, and another two who reached the podium.

 

In fact, even if it is true that lactic acid is poorly tolerated in the muscles, and if the speed of its elimination is high, between periods of effort it is re-utilized as an energy source by the heart, liver and the muscles themselves. 

The half-life of lactic acid (that is the time it takes for its concentration level to be reduced by half) is on average 12 to 15 minutes. But I have seen this time span cut to 6 minutes in high level cyclists. 

That means that only a few minutes of descent after a climb can be sufficient to eliminate a large part of accumulated lactic acid, rendering it utilizable as fuel during successive periods of effort output.