EFFECT OF SPORTS DRINK ON REPEATED PERFORMANCE IN HEALTHY THAI MALES AFTER GLYCOGEN DEPLETION

Abstract

Background: Thus, for no research has differentiated the effect of carbohydrate with and without electrolyte drinks on endurance performance. The purpose of this study was, therefore, to examine the effects of acute sports drink on endurance performance, and on cardiorespiratory variables. Method: Fourteen healthy males age-ranged 18-25 years old participated in 3 trials with 1 week separated in each. Three consecutive sessions in each trial; glycogen depletion, recovery session and endurance exercise (cycling at 70% VO2peak) were employed. Subjects were randomly assigned either sports drink10% carbohydrate ( CHO) ,0.16%electrolytes (SD), placebo 10%CHO only (PL) or plain water (WT) during 2 h recovery. Cardiorespiratory variables ( heart rate, stroke volume, cardiac output, end-diastolic volume, systemic vascular resistance, ejection fraction, respiratory rate, tidal volume and minute ventilation) were collected at pre- and postendurance exercise, time to exhaustion(TTE)and work done (WD)were recorded during 70% VO2peak. Results: The results showed longer time to exhaustion in SD group (52.93 ± 6.98 min) than PL group (45.05 ± 4.47 min) and WT group (37.95 ± 4.92 min), but significant difference was observed only between SD and WT (p<0.05). Significantly higher work done under SD and PL compared with WT group, significantly higher ejection fraction (%EF) (p<0.05) in SD than PL and WT. Moreover, significantly higher minute ventilation under SD than PL and WT ( p<0.05) was found. Conclusion: Carbohydrate with electrolyte ( SD) did not affect to cardiorespiratory function. It probably provide a longer time to exhaustion than carbohydrate alone (PL) despite no difference. At least, one of cardiac function, ejection fraction, was enhanced by using sports drink.

Keywords: Sports drink / Endurance performance /Glycogen depletion / Carbohydrate / Electrolyte