How does the anaerobic system affect performance in distance events?

The anaerobic system is one of the main determinants of the lactate threshold, which is key to performance in a distance event such as a marathon, a triathlon, a road cycling race and any other event over 15-20 minutes. See See lactate threshold.

The anaerobic system has been engaged to a level that lactate and other metabolites will continue to increase unless the athlete slows down to an effort below this threshold. So when one is discussing the lactate threshold, one is really referring to the level of output of the anaerobic system. Here is what we say on the lactate threshold page about anaerobic capacity and endurance races.

• First, , anaerobic capacity helps determine aerobic power and thus the lactate threshold, because it interacts with aerobic capacity. Briefly, the anaerobic system limits the body's use of the aerobic system by putting out more lactate and hydrogen ions than the aerobic system can absorb, inhibiting muscle contraction. We refer to this as the gate-keeping effect, which is discussed in detail on the CD-ROM and elsewhere in the triathlon site. If the anaerobic capacity is too high the athlete will be slowed down by the excess acidosis that accompanies lactate production. So for endurance events it is necessary to train the anaerobic capacity down. The lower it is the more the aerobic system can be utilized before acidosis occurs.   But, it can’t be TOO low because you need some anaerobic capacity for speed....


• Second, anaerobic capacity affects performance by determining the total amount of carbohydrates available for the aerobic system during competition. Unless the anaerobic system is generating enough carbohydrate fuel for the aerobic system, the aerobic system will have to use more fats, which metabolize slower and slow the athlete down. Thus, if the anaerobic capacity is too low, the athlete will be driven to less effective fat metabolism. This is why an athlete will consume glucose supplements as the race progresses so that he/she can utilize more of faster metabolizing carbohydrate fuels.