Muscle Glycogen Utilization During an Australian Rules Football Game.

Abstract

To better understand the carbohydrate (CHO) requirement of Australian Football (AF) match play by quantifying muscle glycogen utilization during an in-season AF match. After a 24-h CHO-loading protocol of 8 and 2g/kg in the prematch meal, 2 elite male forward players had biopsies sampled from m. vastus lateralis before and after participation in a South Australian Football League game. Player A (87.2kg) consumed water only during match play, whereas player B (87.6kg) consumed 88g CHO via CHO gels. External load was quantified using global positioning system technology. Player A completed more minutes on the ground (115 vs 98min) and covered greater total distance (12.2 vs 11.2km) than player B, although with similar high-speed running (837 vs 1070m) and sprinting (135 vs 138m). Muscle glycogen decreased by 66% in player A (pre: 656mmol/kg dry weight [dw], post: 223mmol/kg dw) and 24% in player B (pre: 544mmol/kg dw, post: 416mmol/kg dw). Prematch CHO loading elevated muscle glycogen concentrations (ie,>500mmol/kg dw), the magnitude of which appears sufficient to meet the metabolic demands of elite AF match play. The glycogen cost of AF match play may be greater than in soccer and rugby, and CHO feeding may also spare muscle glycogen use. Further studies using larger sample sizes are now required to quantify the interindividual variability of glycogen cost of match play (including muscle and fiber-type-specific responses), as well examining potential metabolic and ergogenic effects of CHO feeding.