Title

Fuel Utilization in Response to Two Commercially Available Beverages During Exercise in the Heat

Presentation Type

Poster

Abstract

INTRODUCTION: Wildland firefighters (WLFF) use sports drinks to retain fluid, and provide electrolytes and carbohydrates during long duration exercise in the heat. PURPOSE: The purpose of this study is to compare two commercially available beverages, DD (60.9 mM Na+, 3.4% CHO ) vs G (18.4 mM Na+, 5.9% CHO) on their ability to affect fat and carbohydrate metabolism during submaximal exercise in the heat. METHODS: Ten aerobically fit males (22.5± 3.9 yrs, 82.2± 10.1 kg, 53.9± 5.9 ml•kg-1•min-1 VO2 max) completed two 90-minute heat stress trials (39º C, 30% RH) walking at 50% VO2 max followed by a 30-minute rest period. Respiratory gases were collected mid (45 min) and post-exercise (90 min). At 45 minutes, subjects consumed either G or DD with volume equivalent to 150% of the weight lost. Blood glucose was measured pre- and post-exercise, and post-trial. RESULTS: Ventilation (VE) did not differ between G and DD (72.1 ± 8.4 vs. 69.4 ± 7.5 L•min-1; p=0.5). Oxygen consumption (VO2) was not different between trials (2.4 ± 0.1 vs. 2.4 ± 0.2 L·min-1; p=0.3). Carbohydrate oxidation was not significantly different between the beverages (2.1 ± 0.2 vs. 1.8 ± 0.2 g·min-1; p=0.2) for G vs. DD respectively. However, significant differences in fat oxidation and respiratory exchange ratio (RER) were found (0.38 ± 0.03 vs. 0.47 ± 0.05 g·min-1; p=0.049, and 0.89 ± 0.02 vs. 0.87 ± 0.01; p=0.04) in GG vs. DD respectively. Blood glucose was significantly greater post-trial in G vs. DD (116.0 ± 5.7 vs. 103.1 ± 3.9 mg·dL-1; p=0.01).

CONCLUSION: Following the consumption of a bolus of G (5.9% CHO) resulted in increased RER and reduced fat oxidation compared to a bolus of DD (3.4% CHO). Blood glucose was greater following ingestion of G. These data may prove critical for WLFF during work in the field.

Category

Life Sciences

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Apr 28th, 11:00 AM Apr 28th, 12:00 PM

Fuel Utilization in Response to Two Commercially Available Beverages During Exercise in the Heat

UC South Ballroom

INTRODUCTION: Wildland firefighters (WLFF) use sports drinks to retain fluid, and provide electrolytes and carbohydrates during long duration exercise in the heat. PURPOSE: The purpose of this study is to compare two commercially available beverages, DD (60.9 mM Na+, 3.4% CHO ) vs G (18.4 mM Na+, 5.9% CHO) on their ability to affect fat and carbohydrate metabolism during submaximal exercise in the heat. METHODS: Ten aerobically fit males (22.5± 3.9 yrs, 82.2± 10.1 kg, 53.9± 5.9 ml•kg-1•min-1 VO2 max) completed two 90-minute heat stress trials (39º C, 30% RH) walking at 50% VO2 max followed by a 30-minute rest period. Respiratory gases were collected mid (45 min) and post-exercise (90 min). At 45 minutes, subjects consumed either G or DD with volume equivalent to 150% of the weight lost. Blood glucose was measured pre- and post-exercise, and post-trial. RESULTS: Ventilation (VE) did not differ between G and DD (72.1 ± 8.4 vs. 69.4 ± 7.5 L•min-1; p=0.5). Oxygen consumption (VO2) was not different between trials (2.4 ± 0.1 vs. 2.4 ± 0.2 L·min-1; p=0.3). Carbohydrate oxidation was not significantly different between the beverages (2.1 ± 0.2 vs. 1.8 ± 0.2 g·min-1; p=0.2) for G vs. DD respectively. However, significant differences in fat oxidation and respiratory exchange ratio (RER) were found (0.38 ± 0.03 vs. 0.47 ± 0.05 g·min-1; p=0.049, and 0.89 ± 0.02 vs. 0.87 ± 0.01; p=0.04) in GG vs. DD respectively. Blood glucose was significantly greater post-trial in G vs. DD (116.0 ± 5.7 vs. 103.1 ± 3.9 mg·dL-1; p=0.01).

CONCLUSION: Following the consumption of a bolus of G (5.9% CHO) resulted in increased RER and reduced fat oxidation compared to a bolus of DD (3.4% CHO). Blood glucose was greater following ingestion of G. These data may prove critical for WLFF during work in the field.