title: No difference in net uptake or disposal of lactate by trained and untrained forearms during incremental sodium lactate infusion.
abstract: 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.
authors.affiliation: Centre for Research in Education and Sports Science, University of South Australia, Underdale. j.buckley@unisa.edu.au
authors.forename: J D
authors.initials: JD
authors.lastname: Buckley
authors.forename: G C
authors.initials: GC
authors.lastname: Scroop
authors.forename: P G
authors.initials: PG
authors.lastname: Catcheside
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D005542:Forearm / Q000502:physiology*; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism; D015865:Racquet Sports / Q000502:physiology; D012039:Regional Blood Flow / Q000502:physiology; D019354:Sodium Lactate / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D019354:Sodium Lactate