No effect of glycogen level on glycogen metabolism during high intensity exercise

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This study examined the effect of glycogen supercompensation on glycogen breakdown, muscle and blood lactate accumulation, blood-pH, and performance during short-term high-intensity exercise. Young healthy volunteers performed two supramaximal (125% of VO2max) exercise tests on a bicycle ergometer, either for 1 min 45 s (protocol 1; N = 18) or to exhaustion (protocol 2; N = 14). The exercise tests were preceded by either 5 d on a controlled normal (N) diet, or by 2 d of glycogen-depleting exercise accompanied by the normal diet followed by 3 d on a carbohydrate-rich (CHR) diet. In protocol 1, preexercise muscle glycogen concentrations were 364 +/- 23 and 568 +/- 35 mumol.g-1 d.w. in the N and CHR condition, respectively (P < 0.05). During the exertion, glycogen concentration in the M. quadriceps decreased to the same extent in both groups. Accordingly, the exercise-induced increases in muscle and blood-lactate, and the fall in blood-pH were similar during N and CHR. In protocol 2, time to exhaustion was identical for N and CHR. It is concluded that during short-term intense exercise during which muscle glycogen availability exceeds glycogen demand, rate of glycogen breakdown, lactate accumulation, and performance are regulated irrespective of the preexercise muscle glycogen level.

TidsskriftMedicine and Science in Sports and Exercise
Udgave nummer9
Sider (fra-til)1278-1283
Antal sider6
StatusUdgivet - 1995

ID: 154754820