Akute und chronische Anpassung des humanen Skelettmuskels auf Kraft- und Ausdauerbeanspruchungen

Publication: Book/ReportDissertations

Abstract

Introduction: The conception of practical training applications is predominantly carried out after generalized principles. Although these guidelines entail a good framework for the planning of training strategies, the basis of these principles is not founded on comprehensible biological mechanisms of skeletal muscle adaptation. Hence, anticipated adaptations of skeletal muscle in response to exercise programs pursue mainly the principle of “Try and Error” than being precisely comprehensible as a consequence of defined exercise interventions. Purpose: The present study endeavored to link the level of molecular and cellular skeletal muscle adaption with defined modulations of relevant exercise determinants for resistance and endurance exercise. It was aimed to add further knowledge concerning training conception in resistance exercise, the time course of fatiguing mechanisms in acutely loaded skeletal muscle and myofiber type transformations in response to endurance exercise. Methods: Within the scope of the present work three distinct studies were conducted. Study 1: Three different resistance exercise modes with distinct resistance exercise intensity but equalized time under tension were applied to 22 male subjects. Acutely after exercise several muscle biopsies were collected to assess the acute signaling response of loaded skeletal muscle and to compare signaling dynamics concerning the most effective training stimulus induced by these exercise modes. Study 2: Maximal eccentric resistance exercise was applied to 7 male subjects. Several muscle biopsies were collected in an early time course upon resistance exercise and were further investigated on potential phosphorylation events of ryanodine receptor-1 which plays a key role in facilitating myocellular Ca2+-handling and skeletal muscle fatigue. Study 3: By the elevation of extensive cycling training volume over 12 weeks we applied increased neuromuscular activity to 21 male subjects. Muscle biopsies were collected “Pre” and “Post” to the exercise intervention and changes in skeletal muscle myofiber distribution were assessed. We aimed to comprehend whether potential increases in neuromuscular activity induces the general transition of myofiber types towards increased type I myofiber abundance, regardless of a basal heterogeneous myofiber type disposition. Results: We determined three key results. Study 1: Higher resistance exercise intensity induces a stronger response of anabolic signaling in skeletal muscle compared to exhausting and submaximal resistance exercise. Study 2: Intense resistance exercise induces the phosphorylation of RyR1 up to 60 min after stimulation and hereby generates the potential to decline skeletal muscle contractility. Study 3: Extensive cycling exercise over several weeks induces the increased expression of type I myofibers in dependency of basal myofiber distribution and individual performance levels. Conclusion: The depicted relations of the present work are of high importance for applied exercise sciences since the effects of major exercise parameters are linked with well determined facts of skeletal muscle adaptation. These findings may contribute to a more sensitive conception of acute and long term applied exercise interventions, when acute variables for exercise determinants, e.g exercise intensity, are stronger reconsidered. The obtained results importantly attribute the intensity of muscle contractions to be of crucial importance for the maintenance and facilitation of skeletal muscle adaptation in response to intensive resistance and extensive endurance exercise interventions.
Original languageGerman
Place of PublicationKöln
PublisherDeutsche Sporthochschule
Number of pages61
Publication statusPublished - 2013

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