Repeated high-intensity exercise modulates Ca2+ sensitivity of human skeletal muscle fibers

Gejl, K. D.Univ Southern Denmark, SDU Muscle Res Cluster, Dept Sports Sci & Clin Biomech, Campusvej 55, DK-5230 Odense M, Denmark (författare)

The effects of short-term high-intensity exercise on single fiber contractile function in humans are unknown. Therefore, the purposes of this study were: (a) to access the acute effects of repeated high-intensity exercise on human single muscle fiber contractile function; and (b) to examine whether contractile function was affected by alterations in the redox balance. Eleven elite cross-country skiers performed four maximal bouts of 1300m treadmill skiing with 45min recovery. Contractile function of chemically skinned single fibers from triceps brachii was examined before the first and following the fourth sprint with respect to Ca2+ sensitivity and maximal Ca2+-activated force. To investigate the oxidative effects of exercise on single fiber contractile function, a subset of fibers was incubated with dithiothreitol (DTT) before analysis. Ca2+ sensitivity was enhanced by exercise in both MHC I (17%, P<0.05) and MHC II (15%, P<0.05) fibers. This potentiation was not present after incubation of fibers with DTT. Specific force of both MHC I and MHC II fibers was unaffected by exercise. In conclusion, repeated high-intensity exercise increased Ca2+ sensitivity in both MHC I and MHC II fibers. This effect was not observed in a reducing environment indicative of an exercise-induced oxidation of the human contractile apparatus.

Hvid, L. G.Univ Southern Denmark, SDU Muscle Res Cluster, Dept Sports Sci & Clin Biomech, Campusvej 55, DK-5230 Odense M, Denmark (författare)
Willis, Sarah J.Mittuniversitetet,Avdelningen för hälsovetenskap,NVC(Swepub:miun)sarwil (författare)
Andersson, ErikMittuniversitetet,Avdelningen för hälsovetenskap,NVC(Swepub:miun)eriand (författare)
Holmberg, Hans-ChristerMittuniversitetet,Avdelningen för hälsovetenskap,Swedish Olympic Comm, Stockholm, Sweden,NVC(Swepub:miun)hanhol (författare)
Jensen, R.Univ Southern Denmark, SDU Muscle Res Cluster, Dept Sports Sci & Clin Biomech, Campusvej 55, DK-5230 Odense M, Denmark (författare)
Frandsen, U.Univ Southern Denmark, SDU Muscle Res Cluster, Dept Sports Sci & Clin Biomech, Campusvej 55, DK-5230 Odense M, Denmark (författare)
Hansen, J.Rigshosp, Ctr Inflammat & Metab, Dept Infect Dis, DK-2100 Copenhagen, Denmark (författare)
Plomgaard, P.Rigshosp, Ctr Inflammat & Metab, Dept Infect Dis, DK-2100 Copenhagen, Denmark (författare)
Ortenblad, N.Univ Southern Denmark, SDU Muscle Res Cluster, Dept Sports Sci & Clin Biomech, Campusvej 55, DK-5230 Odense M, Denmark (författare)
Univ Southern Denmark, SDU Muscle Res Cluster, Dept Sports Sci & Clin Biomech, Campusvej 55, DK-5230 Odense M, DenmarkAvdelningen för hälsovetenskap (creator_code:org_t)

Ingår i:Scandinavian Journal of Medicine and Science in Sports: Wiley26:5, s. 488-4970905-71881600-0838

Av författaren/redakt...: Gejl, K. D.; Hvid, L. G.; Willis, Sarah J.; Andersson, Erik; Holmberg, Hans-C ...; Jensen, R.; visa fler...; Frandsen, U.; Hansen, J.; Plomgaard, P.; Ortenblad, N.; visa färre...

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