Effects of Eight Weeks of Bicycle Ergometer Sprint Training on Human Muscle Buffer Capacity

Abstract

This investigation was undertaken to determine whether human skeletal muscle buffer capacity (BC_m) is affected by training. Eight untrained males participated in 8 weeks of sprint training on bicycle ergometers. Muscle biopsy samples were taken from the vastus lateralis before and at several times following an incremental bicycle ergometer test (0 min, 5 min, 15 min). These subjects were tested before (PRE) and following (POST) the training period. Seven endurance-trained cyclists (ET) were also tested for the purpose of comparing the BC_m of ET to that of PRE and POST. Biopsy samples were quick-frozen in liquid nitrogen and later analyzed for lactate concentration (HLa_m), homogenate pH (pH_m), and creatine phosphate concentration. BC_m was calculated from the change in HLa_m and pH_m observed from rest to exhaustion and was expressed as mmol · kg^-1 · pH^-1 (Slykes). There was no significant difference in resting HLa_m or resting pH_m among the groups. There was a significant difference in HLa_m at exhaustion between PRE (21.41 ± 1.65 mmol · kg^-1), POST (25.61 ± 2.38 mmol · kg^-1), and ET (11.16 ± 0.31 mmol · kg^-1) but no significant difference in pH_m at exhaustion between PRE (6.65 ± 0.03 pH units) and POST (6.69 ± 0.06 pH units). pH_m at exhaustion for the ET group was significantly higher than the others at 6.91 ± 0.02 pH units. A significant difference between PRE and POST BC_m was found (PRE: 44.68 ± 3.03 S1; POST: 61.04 ± 4.11 S1) while ET BC_m (47.21 ± 7.26 S1) was not significantly different from PRE. These data indicate that muscle buffer capacity is increased with highly intense sprint training but provide no evidence to suggest that muscle buffer capacity is affected by endurance training.

Key words

Acid-base balance - buffer capacity - enzymes - exercise - lactic acid - muscle - pH