Carbohydrate loading in practice: high muscle glycogen concentration is not certain

It is believed that muscle glycogen resynthesis can be stimulated by depleting the glycogen stores by heavy physical exercise and then eating a diet rich in carbo-hydrates. In this study, we compared muscle glycogen concentrations after two different depletion and loading procedures in six male runners. The depletion runs for the procedures were a half-marathon race and an easier fartlek. The mean muscle glycogen concentrations (±s.e.m.), analysed after the procedures, did not differ significantly between the race and the fartlek being 285 (±25) mmol/kg d.w. (dry weight) versus 315 (±32) mmol/kg d.w. (P> 0.05). Moreover, the subjects ' glycogen concentrations were not clearly increased above the predepletion values following either procedure. The results show that higher glycogen levels do not necessarily occur after classical carbohydrate-loading procedures