Diet and muscle glycogen concentration in relation to physical performance in Swedish elite ice hockey players

The effects of carbohydrate (CHO) loading on physical characteristics including muscle fiber distribution, muscle glycogen concentration, and physical performance were studied in two top Swedish ice hockey teams. Players were randomly allocated to two groups: those consuming a CHO-enriched diet (CHO group) and those consuming a mixed diet (controls). Biopsies from the vastus lateralis muscle were taken three times: after Game 1, before Game 2, and after Game 2. Muscle fiber distribution averaged 50 +/- 2% slow twitch fibers (mean +/- 1 SEM). Muscle glycogen concentrations (measured in mmol glucose units . kg(-1) wet muscle) were as follows: after Game 1, 43 +/- 4 (all players); before Game 2, 99 +/- 7 (CHO group) and 81 +/- 7 (controls); and after Game 2, 46 +/- 6 (CHO group) and 44 +/- 5 (controls). Distance skated, number of shifts skated, amount of time skated within shifts, and skating speed improved with CHO loading. It was concluded that individual differences in performance could be related to muscle glycogen metabolism.