Lactate accumulation in muscle and blood during submaximal exercise

Abstract

Muscle and blood lactate concentration was studied in 10 healthy [human] males during cycling exercise. For each subject the exercise intensity corresponding to a blood lactate concentration of 4 mmol .cntdot. l-1 (OBLAw) was assessed by a step-wise increased exercise intensity protocol. In a 2nd series of experiments the same protocol was performed but exercise was terminated at OBLAw and a muscle biopsy for subsequent analysis of lactate concentration was obtained from m. [musculus] vastus lateralis. Biopsies were also taken at rest for histochemical determination of fiber type composition and capillary supply. The exercise intensity, which corresponded to OBLAw, averaged 159(117-216)W, equal to 65 (range 55-84%) of .ovrhdot.VO2 max, and was correlated to capillaries/fiber of the exercising muscle (r = 0.83, P > 0.01). Muscle lactate concentration averaged 6.9 (range 2.1-12.6) mmol .cntdot. kg-1 wet wt. The change in blood lactate concentration (prior to and 1 min post exercise) was correlated to muscle lactate concentration (r = 0.71, P > 0.05). Great individual variations in the muscle/blood lactate gradient do exist during submaximal steady-state exercise, performed at a certain blood lactate level.