Effects of Short-Term Concentric vs. Eccentric Resistance Training on Single Muscle Fiber MHC Distribution in Humans
| Autor: | Brian T. Terpstra, D. L. Williamson, Ulrika Raue, Scott Trappe, Philip M. Gallagher |
|---|---|
| Rok vydání: | 2005 |
| Předmět: |
Adult
Male medicine.medical_specialty Adolescent Weight Lifting Strength training Muscle Fibers Skeletal Physical Therapy Sports Therapy and Rehabilitation Concentric Internal medicine Myosin medicine Humans Eccentric Knee Orthopedics and Sports Medicine Exercise physiology Muscle Skeletal Exercise Myosin Heavy Chains Chemistry Skeletal muscle Anatomy Adaptation Physiological Endocrinology medicine.anatomical_structure Eccentric training Densitometry |
| Zdroj: | International Journal of Sports Medicine. 26:339-343 |
| ISSN: | 1439-3964 0172-4622 |
| Popis: | The purpose of this investigation was to determine the effects of a concentric vs. eccentric resistance training program on single muscle fiber myosin heavy chain (MHC) adaptations in humans. Fifteen sedentary, healthy males were divided into three groups: concentric training (CTG) (n = 6, 24.2 +/- 1.7 y, 181 +/- 2 cm, 82.5 +/- 4.6 kg), eccentric training (ETG) (n = 6, 23.7 +/- 1.6 y, 178 +/- 3 cm, 90.4 +/- 6.1 kg), and control (CTL) (n = 3, 23 +/- 1.5 y, 181 +/- 2 cm, 97 +/- 13.2 kg). The subjects performed 4 sets of 8 unilateral repetitions starting at 80 % of concentric 1-RM, 3 days/week for a total of 4 weeks. Subjects were tested pre- and post-training for concentric 1-RM. Muscle biopsies were obtained from the vastus lateralis pre- and post-training for determination of single fiber MHC isoform distribution using SDS-PAGE/silver staining (100 fibers analyzed/subject pre- and post-training). Fibers expressing more than one MHC isoform (i.e., hybrid fibers) were analyzed for relative MHC isoform proportions via densitometry. The training program resulted in a 19 % 1-RM strength gain for CTG (p < 0.05) with no change in ETG or CTL. MHC-IIx fibers decreased by 7 % in CTG (p < 0.05) and ETG had an 11 % increase in total hybrids (MHC-I/IIa + MHC-IIa/IIx) (p < 0.05). No other differences were noted in MHC distribution among the three groups. Densitometry analysis of hybrid fibers showed no change in relative MHC isoform proportions pre- to post-training for any group. These data suggest that the MHC distribution did not change dramatically as a result of 4 weeks of concentric vs. eccentric resistance training despite the increase in whole muscle strength from concentric muscle actions. |
| Databáze: | OpenAIRE |
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