Sun28November0440PM 48

Which of the following physiological adaptions to exercise is the best predictor of performance in endurance athletes?

(Please select 1 option)

High turnover of fat metabolism in muscle

Velocity of blood lactate accumulation This is the correct answer

Increased percentage of slow twitch muscles

Reduction in heart rate for a given exercise intensity Incorrect answer selected

Increased capillary density in muscle

Explanation

Sjödin and Jacobs1 write:

"With marathon running velocity (VM) as the dependent variable, multiple regression analysis showed that velocity of lactate accumulation (VOBLA) accounted for 92% of the variation in VM, and VOBLA plus training volume prior to the marathon accounted for 96% of this variation. All performance variables were positively correlated to % ST muscle fiber distribution (r = 0.55-0.69) and capillary density (r = 052-0.63). Thus, marathon running performance was closely related to VOBLA and to the ability to run at a pace close to that velocity during the race. These properties were in turn related to % ST, capillary density, and training volume."

Another metabolic adaptation compared with normal individuals is the selection of fat for oxidation by muscle at an early stage, particularly when the availability of glucose during high exercise intensity is limited. This delays the onset of muscle fatigue but not necessarily VOBLA.

Training can also result in cardiovascular adaptation with increased heart size, increased contractility and a slower heart rate for a given level of exercise. The increase in maximal oxygen consumption (VO2 max) is improved by all these factors but ultimately genetic factors play a large part in an athlete's performance, despite intensive training.

Reference:

Sjödin B, Jacobs I. Onset of blood lactate accumulation and marathon running performance. Int J Sports Med. 1981;2:23-6.

Answer Statistics

1

3%

2

30%

3

26%

4

33%

5

10%

Times answered: 240