ABSTRACT
AIM: We have explored in the following study the glucoregulatory responses (glycemia, insulinemia, catecholamines) at the end of 2 supramaximal tests of different durations. METHODS: Seven untrained male subjects (21.9+/-0.3 y) performed an isolated exercise of 6 s (T6) and a Wingate-test of 30 s. To determine the levels of lactate (La), plasma concentrations of glucose, insulin, adrenaline (A) and noradrenaline (NA), blood samples have been collected successively at rest, after a warm-up period of 15 min, immediately after T6 and T30, and after 5, 10, 20, and 30 min of recovery. RESULTS: Whether expressed as absolute or relative values, the peak power recorded during the 2 tests is statistically the same in T6 and T30. The maximal value of lactate (L(amax)) measured 5 min after the end of the 2 exercises is significantly greater after T30 (12.3+/-0.9 mmol x L(-1)) than after T6 (5.4+/-0.4 mmol x L(-1)) and T30 (4.2+/-0.2 mmol x L(-1)). No significant difference is observed between the plasma glucose concentrations recorded after the 2 tests until the first 10 min of recovery. However the plasma glucose values recorded after 20 and 30 min of recovery are significantly higher after T6 than after T30. Whatever the duration of the test, the insulinemia level remains unchanged at the end of the exercise and during the 30 min of recovery. On the other hand, the values of adrenaline and noradrenaline after T6 and T30 become considerably higher than those recorded at rest. However, the increase remains significantly higher after T30 (13.5+/-1.8 nmol x L(-1) for NA and 2.7+/-0.7 nmol x L(-1) for A) than after T6 (4.9+/-0.3 nmol x L(-1) for NA and 1.2+/-0.2 nmol x L(-1) for A). CONCLUSION: These results suggest that the mechanism responsible for increasing blood glucose surpass those which decrease it during supramaximal exercise. However, plasma glucose concentrations is affected by the duration of supramaximal exercise. The lower increase of plasma glucose concentration after T30 than after T6 might be explained by the resting of muscle glycogen stores which are more used during T30 than after T6, but in the absence of muscle glycogen content measurement we cannot conclude.
