Associations between skeletal muscle phenotype, positional role, and on-ice performance in elite male ice hockey players.

Abstract

We evaluated associations between muscle phenotype, positional role, and on-ice performance in male U20 Danish national team ice hockey players. Sixteen players (10 forwards, six defensemen) participated in a game with activity tracking. Resting thigh muscle biopsies were analyzed for metabolic enzyme activity and protein expression linked to performance. On-ice intermittent exercise capacity, repeated sprint ability, and maximal isometric knee-extensor torque were also assessed. No significant position-specific muscle phenotype characteristics were found, but forwards generally exhibited higher levels of several membrane proteins (p = 0.100-0.991). NAKα₂, NAK∑, K_ATP, ClC-1, and NHE1 showed significant correlations with total distance (r = 0.52-0.59, p = 0.016-0.046), however, within positions these only persisted for K_ATP (r = 0.70, p = 0.024) and NAKα₂ (r = 0.57, p = 0.085) in forwards, where CS enzyme activity also displayed a strong association with distance covered (r = 0.75, p = 0.019). For high-intensity skating, NAKα₂ (r = 0.56, p = 0.025) and K_ATP (r = 0.50, p = 0.048) similarly exhibited the strongest associations, persisting within forwards (r = 0.63, p = 0.052 and r = 0.72; p = 0.018, respectively). In conclusion, although several muscle proteins involved in ion and metabolic regulation were associated with performance, only NAKα₂ and K_ATP displayed consistent relationships within positions. Moreover, CS enzyme activity was strongly related to total distance within forwards, coherent with the proposed importance of oxidative capacity in intense intermittent exercise.