THE EFFECT OF A CHROMIUM-CONTAINING BEVERAGE ON SPRINT CYCLING PERFORMANCE AFTER A SUBMAXIMAL EXERCISE BOUT

Abstract

PURPOSE: to investigate the effect of a 7% carbohydrate-electrolyte (CE) beverage (Reliv Innergize©, Chesterfield, MO) either with or without added niacin-bound trivalent chromium (Cr+3) (ChromeMate©, Inter Health Nutraceuticals, Benecia, CA) on sprint capacity immediately following 60 min submaximal (75% VO2Max) cycling. METHODS: After an overnight fast, six male trained cyclist participated in three exercise sessions on a Monark stationary ergometer. Mean age(yr), weight(kg), and height(cm) of the subjects were 24 ± 6.91, 74.92 ± 9.69, 179.1 ± 4.75, respectively. Subjects' V02max was determined during the first exercise session and mean values were 61.08 ± 6.2 ml/kg/min (4.54 L/min). Subjects participated in the remaining two exercise sessions approximately two weeks apart. Following a double-blind, crossover design, the subjects cycled at 75% V02max for 60 min and then immediately performed a 30 s Wingate Anaerobic Power Test (WAPT), eliciting approximately 85% VO2max. During each trial, subjects were randomly given either 3 ml/kg of a 7% CE beverage (CE-only trial) or a CE beverage containing 50 mg of niacin-bound chromium/240 cc (CE+Cr trial) distributed at 10, 20, 30, and 40 min of the submaximal exercise bout. Mean intake per hour of carbohydrate (CHO), chromium (Cr), and niacin was 65 ± 7.0 g, 188 ± 10.0 μg, and 1692 ± 0.0 μ respectively. Blood glucose and lactate concentrations were determined from capillary blood at min 25 and 50 of the submaximal exercise bout, and at 45 s post-sprint. Resting values of blood glucose were also determined at each exercise trial. V02, VC02, and RER were determined in each exercise trial via open circuit spirometry, immediately before and after the sprint. RESULTS: Total power (kpm/min or watts) during the WAPT was significantly (p < 0.05) higher for the CE+Cr vs. CE-only trial. There were no significant differences between trials for VO2, VCO2 or RER, however, there tended to be higher mean VO2, and VCO2 values and lower mean RER values in the CE+Cr vs. CE-only trial. Blood glucose (mM) was higher, but not significantly higher, in the CE-only trial vs. CE+Cr trial at min 0 and 25 of the submax bout. At 50 min of the submax ride, the CE-only trial had significantly higher (p = 0.031) blood glucose compared to the CE+Cr trial. Blood lactate (mmol/L) concentrations were significantly lower (p = 0.022) after the WAPT in the CE+Cr trial, however, there were no differences in lactate values in the two trials during the submax exercise bouts. CONCLUSION: a CE beverage with added niacin-bound Cr improved exercise performance in elite cyclists as measured by power output.