The effect of glycogen depletion and supercompensation on the physical working capacity at the fatigue threshold

Summary

The purpose of this investigation was to determine the effect of glycogen depletion and super-compensation on the physical working capacity at the fatigue threshold (PWC_FT). Ten adult males (mean age 23 years, SD 3) volunteered as subjects for this study. During the first laboratory visit the subjects performed a maximal bicycle ergometer test for the determination of maximum oxygen consumption$\left( {\dot V_{O_{2 max} } } \right)$. Between 48 and 72 h later, the subjects pedaled to exhaustion at a power output which corresponded to a mean of 76% of$\left( {\dot V_{O_{2 max} } } \right)$ (range, 72–80%) for the purpose of glycogen depletion. For the next 3 days, the subjects were fed a 10.5 MJ · day⁻¹ low carbohydrate diet which consisted of 7.5% carbohydrates, 22.0% protein and 70.5% fat. The subjects then performed an incremental cycle ergometer test to the onset of fatigue or PWC_FT, which was estimated from integrated electromyographic voltages of the vastus lateralis muscle. For the next 3 days the subjects were fed a 10.5 MJ high carbohydrate diet which consisted of 72.2% carbohydrates, 12.4% protein and 15.4% fats for the purpose of glycogen supercompensation. The subjects then performed a second PWC_FT test. A paired t-test indicated that there was no significant (p > 0.05) difference between the means of the PWC_FT values (depletion 246 W, SD 30; supercompensation 265 W, SD 28) and they were highly correlated atr=0.884. The results of this investigation suggested that the methods commonly used to affect glycogen depletion or supercompensation had no effect on PWC_FT.