Medicine & Science in Sports & Exercise:
F-22C Free Communication/Slide Carbohydrate and Performance
1Loughborough University, UK
(Sponsor: Ron J. Maughan, FACSM)
Ninety minutes of simulated soccer activity (LIST) leads to a reduction in muscle glycogen concentration. This can be attenuated by the ingestion of carbohydrate (CHO) throughout exercise. As there is an increasing occurrence of extra-time in matches it would be pertinent to investigate whether the provision of exogenous CHO allows players to maintain work rate beyond 90 min.
To determine whether the ingestion of a hypotonic CHO solution would allow soccer players to maintain performance up to and beyond 90 min of intermittent exercise.
Nine male soccer players aged 21.0 ± 0.4 years (mean±SEM); height 1.79 ± 0.02 m; mass 75.7 ± 2.7 kg; VO2max 61.9 ± 0.7ml.kg−1.min−1; volunteered to participate in this investigation. Subjects performed two trials of LIST in a cross-over design and were randomly allocated either a 6.4% hypotonic carbohydrate-electrolyte solution (CHO-E) or a placebo (P) prior to exercise (5ml.kg−1BM) and every 15min thereafter (2ml.kg−1BM) until fatigue.
Time to fatigue for the CHO-E and P trials were 106.6 ± 5.9 min and 103.0 ± 6.8 min respectively. Plasma glucose concentration was maintained within the normal range in both trials although it was higher in the CHO-E trial throughout (p < 0.05) as was serum insulin concentration (p < 0.05). Analysis of the subjects' diets in the days preceding the trials revealed that CHO intake exceeded 5g.kg−1BM.day−1. It appears that the physiological demands of simulated soccer activity are of an intensity that can be sustained for a 90 min match but not for the additional 30 min that constitute extra-time. The mechanisms responsible for this are not clear. As the provision of exogenous CHO failed to attenuate this decrement in exercise capacity it would suggest that it was neither due to a reduction of muscle glycogen concentration below a critical concentration nor through hypoglycaemia.
Exercise capacity in soccer might not be enhanced by the ingestion of a 6.4% CHO-E solution when players have adequate pre-exercise carbohydrate intakes.