Why We Test Lactate Threshold - Part 2

Updated: Oct 31, 2020


What is wrong with the model of performance introduced at the end of the previous section?  Lets introduce a study of road cyclists and what differentiates one from the other.  It may be useful to go back quickly to the initial table slide about 4 different cyclists in Part 1.

Coyle, E. F., et al. (1988). "Determinants of endurance in well-trained cyclists." Journal of Applied Physiology 64(6): 2622-2630.


In conclusion, the present results indicate that individuals with a similar VO2 max can vary greatly in glycogen utilization and time to fatigue when cycling at the same work rate and percentage of V02 max.


These differences in performance ability during high-intensity submaximal cycling are highly related (r = 0.96; P c 0.001) to a combination of lactate production (i.e., %VO~ max at LT) and muscle capillary density (e.g., lactic acid removal). Muscle mitochondrial activity, which can be a primary determinant of lactate production, was not different in groups L and H, nor was their blood lactate responses when running uphill.


The factors associated with a high %VO2 rnax at LT when cycling and performance ability were years of cycling experience and percent type I muscle fibers. It appears that intense cycle training performed for -5 yr compared with 2-3 yr promotes continued neurological and/or muscular adaptations that reduce muscle glycogenolysis specifically when cycling.


Notice some things in the above conclusion. Cyclists with a similar VO2 max have different thresholds. But they also exhibit other differences. The ones with the lower threshold have higher glycogen utilisation levels and higher lactate production. It also said that certain fiber types reduce lactate/pyruvate production. One group of these cyclists are not utilising a lot of the aerobic energy that is available to them while the other group is using much more of their VO2 max.

Why?


Key finding of this study

An important finding of this study suggests that endurance during submaximal exercise is closely related to the factors that control muscle glycogenolysis* and blood lactate concentration.


A thought provoking comment from this study is


It is interesting to discuss the possible factors that contribute to the widely differing rates of glycogen utilization, lactate production, and exercise time to fatigue in these athletes when cycling.


So what are these factors? These factors are generally ignored by most coaches.