Lactate Accumulation in Muscle and Blood during Submaximal Exercise

摘要

Muscle and blood lactate concentration was studied in 10 healthy males during cycling exercise. For each subject the exercise intensity corresponding to a blood lactate concentration of 4 mmol/l (OBLA sub W) was assessed by a stepwise increased exercise intensity protocol. In a second series of experiments the same protocol was performed but exercise was terminated at OBLA sub W and a muscle biopsy for subsequent analysis of lactate concentration was obtained from m. vastus lateralis. Biopsies were also taken at rest for histochemical determination of fiber type composition and capillary supply. The exercise intensity, which corresponded to OBLA sub W, averaged 159 (117-216) W, equal to 65 (range 55-84) % of maximum oxygen uptake, and was found to be correlated to the capillary frequency of the exercising muscle (r=0.83, p<0.01). Muscle lactate concentration averaged 6.9 (range 2.1-12.6) mmol/kg w.w. The muscle to blood lactate gradient as well as the change in blood lactate concentration (prior to and 1 min post exercise) were correlated to muscle lactate concentration (r=0.89, p<0.001 and r=0.71, p<0.05). It is concluded that great individual variations in the muscle/blood lactate gradient do exist during submaximal steady-state exercise, performed at a certain blood lactate level.