Lactate uptake by forearm skeletal muscles during repeated periods of short-term intense leg exercise in humans

Abstract

We investigated the role of the forearm skeletal muscles in the removal of lactate during repeated periods of short-term intensive leg exercise, i.e. a force-velocity (FV) test known to induce a marked accumulation of lactate in the blood. The leg FV test was performed by seven untrained male subjects. Arterial and venous blood samples for determination of arterial ([la⁻]_a) and venous ([la⁻]_v) plasma lactate concentrations were concomitantly taken at rest before the test, during the FV test at the end of each period of intensive exercise just before the 5-min between-sprint recovery period, and after the completion of the test at 2, 4, 6, 8, 10, 15, and 20 min of the final recovery. The arteriovenous difference in concentration for plasma lactate ([la⁻]_a−v) was determined for each blood sample. During the test, [la⁻]_a and [la⁻]_v increased significantly (P < 0.001;P < 0.001) with significantly higher values for [la⁻]_a (P < 0.001). At the onset of the test, [la⁻]_a−v became positive and increased up to a braking force of 6 kg, correlating significantly with [la⁻]_a (r = 0.61,P < 0.001) with power (r = 0.58,P < 0.001) during the test. At the end of the test, [la⁻]_a, [la⁻]_v and [la⁻]_a−v decreased (P < 0.001;P < 0.001;P < 0.001 respectively) but were still higher than the basal values after 20-min of passive recovery. In conclusion, forearm skeletal muscles would seem to have been involved in the removal of lactate from the blood during the leg FV test, with an increase in lactate uptake proportional to the increase in plasma lactate concentration and power.