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RESEARCH PRODUCT

Blood lactate production and recovery from anaerobic exercise in trained and untrained boys.

subject

description

Blood lactate production and recovery from anaerobic exercise were investigated in 19 trained (AG) and 6 untrained (CG) prepubescent boys. The exercises comprised 3 maximal test performances; 2 bicycle ergometer tests of different durations (15 s and 60 s), and running on a treadmill for 23.20±2.61 min to measure maximal oxygen uptake. Blood samples were taken from the fingertip to determine lactate concentrations and from the antecubital vein to determine serum testosterone. Muscle biopsies were obtained from vastus lateralis. Recovery was passive (seated) following the 60 s test but that following the treadmill run was initially active (10 min), and then passive. Peak blood lactate was highest following the 60 s test (AG, 13.1±2.6 mmol·l−1 and CG, 12.8±2.3 mmol·l−1). Following the 15 s test and the treadmill run, peak lactate values were 68.7 and 60.6% of the 60 s value respectively. Blood lactate production was greater (p<0.001) during the 15s test (0.470±0.128 mmol·l−1·s−1) than during the 60s test (0.184±0.042 mmol·l−1·s−1). Although blood lactate production was only nonsignificantly greater in AG, the amount of anaerobic work in the short tests was markedly greater (p<0.05-0.01) in AG than CG. Muscle fibre area (type II%) and serum testosterone were positively correlated (p<0.05) with blood lactate production in both short tests. Blood lactate elimination was greater (p<0.001) at the end of the active recovery phase than in the next (passive) phase. It is concluded that blood lactate production in prepubescent boys is related to serum testosterone level and muscle type II fibre area, indicating the role of maturation and training. Submaximal exercise is likely to increase blood lactate removal during recovery.