Lactate
“Oh, he’s blown on the steep section of the climb. You can almost feel the lactic acid coursing through his veins and making his legs explode…” says the TV commentator during a mountain stage.
Actually, this is an imaginary quote but not far off what a viewer might hear during coverage of the Tour de France.
It is used to here to illustrate the common misconception of lactic acid, or more accurately lactate. Lactate is often viewed as the cause of fatigue and the enemy of the endurance athlete.
It is true that lactate levels rise with increasing levels of effort. However, higher levels of lactate are not the cause of fatigue. Rather, the current thinking in sports science is that increases in hydrogen ions are the culprit.
In reality, the body uses lactate as a fuel source. At lower intensities of effort, the body is able to recycle lactate produced by exercising muscles so that there is only a slight increase in lactate concentration relative to levels present during a resting state. At higher intensities, the body can’t recycle all of the lactate produced and so lactate levels continue to rise until the level of effort is reduced.
Nonetheless, lactate is an important “biomarker” in measuring the underlying metabolism of the individual athlete. Lactate analysis is a critical component in the Athlos Sports Physiological Test.
Here’s a link to a New York Times article which presents further information on the current sports science view of lactate.