Cellular responses in skeletal muscle to a season of ice hockey

Abstract

We hypothesized that a season of ice hockey would result in extensive remodeling of muscle. Tissue sampled from the vastus lateralis of 15 players (age = 20.6 ± 0.4 years; mean ± SE) prior to (PRE) and following (POST) a season was used to characterize specific adaptations. Measurement of representative metabolic pathway enzymes indicated higher maximal activities in POST than in PRE (p < 0.05) for succinic dehydrogenase (3.26 ± 0.31 vs. 3.91 ± 0.11 mol·mg protein–1·min–1), citrate synthase (7.26 ± 0.70 vs. 8.70 ± 0.55 mol·mg protein–1·min–1), and phosphofructokinase (12.8 ± 1.3 vs. 14.4 ± 0.96 mol·mg protein–1·min–1) only. The season resulted in an increase in Na+-K+-ATPase concentration (253 ± 6.3 vs. 265 ± 6.0 pmol·g–1wet weight), a decrease (p < 0.05) in maximal activity of the sarcoplasmic reticulum Ca2+-ATPase (107 ± 4.2 µmol·g protein–1·min–1vs. 92.0 ± 4.6 µmol·g protein–1·min–1), and no change in the distribution (%) of fibre types. A smaller (p < 0.05) cross-sectional area (CSA) for both type I (–11.7%) and type IIA (–18.2%) fibres and a higher (p < 0.05) capillary count/CSA for type I (+17.9%) and type IIA (+17.2%) were also found over the season. No changes were found in peak oxygen consumption (51.4 ± 1.2 mL·kg–1·min–1vs. 52.3 ± 1.3 mL·kg–1·min–1). The results suggest, based on the alterations in oxidative and perfusion potentials and muscle mass, that the dominant adaptations are in support of oxidative metabolism, which occurs at the expense of fibre CSA and possibly force-generating potential.