No difference in net uptake or disposal of lactate by trained and untrained forearms during incremental sodium lactate infusion

A number of training adaptations in skeletal muscle might be expected to enhance lactate extraction during hyperlactataemia. The aim of the present study was to determine whether resting endurance-trained forearms exhibit an increased net lactate removal during hyperlactataemia. Six racquet-sport players attended the laboratory for two experiments, separated by 2 weeks. In the first experiment incremental handgrip exercise to fatigue was performed to identify trained (TRFA, n=6) and untrained (UTFA, n=5) forearms. In the second experiment net forearm lactate exchange was compared between TRFA and UTFA during an incremental infusion of sodium lactate. TRFA performed more work than UTFA during handgrip exercise mean (SE) TRFA, 66.1 (9.5) J·100 ml^–1; UTFA, 35.1 (2.3) J·100 ml^–1; P=0.02] and UTFA exhibited a greater increase in net lactate output relative to work load (P=0.003). During lactate infusion net lactate uptake across the resting forearms increased linearly with the arterial lactate concentration in both groups (TRFA, r=–0.95 (0.03); UTFA, r=–0.92 (0.04); P<0.02], with no difference in the regression slopes TRFA, –1.06 (0.13); UTFA, –1.07 (0.27); P=0.97] or y-intercepts TRFA, 0.67 (0.20); UTFA, 1.36 (0.67); P=0.37] between groups. Almost all of the lactate taken up was disposed of by both groups of forearms TRFA, 99.6 (0.2)%; UTFA, 98.5 (1.0)%; P=0.37]. It was concluded that the net uptake and removal of lactate by resting skeletal muscle is a function of the concentration of lactate in the blood perfusing the muscle rather than the muscle training status. Electronic Publication