AbstractsMedical & Health Science

Effect of carbohydrate ingestion during exercise on performance measures of wheelchair athletes

by Heather Hynes




Institution: University of Saskatchewan
Department:
Year: 2010
Keywords: spinal cord injury; wheelchair athletes; carbohydrate ingestion during exercise; sport nutrition guidelines; performance measures
Record ID: 1860282
Full text PDF: http://hdl.handle.net/10388/etd-09212009-100505


Abstract

The primary purpose of this study was to determine the effect of ingesting an 8% carbohydrate (CHO) beverage during a moderate intensity exercise trial on performance outcomes, fuel utilization and blood glucose levels of wheelchair athletes (spinal cord injury (SC I) or cerebral palsy (CP)). The secondary purpose was to analyze the dietary intake of the eight participants and to determine if they were meeting current sport nutrition guidelines for macronutrients and fluids recommended in the joint position statement developed by the American Dietetic Association (ADA), the American College of Sports Medicine (ACSM) and Dietitians of Canada (DC). Under random, double blind conditions eight athletes (6 males, 2 females); mean age 36 ± 8.5 y with a SCI (n = 7) or CP (n = 1) completed two exercise trials on an adapted stationary hand cycle; each trial was 60 minutes in duration at 65 % VO2peak followed immediately by a 30-minute performance trial. During the first 60-minutes the participants were given four 200 ml dosages (15, 30, 45, 60-min) of an 8% CHO beverage or a taste-matched placebo beverage. Blood lactate and glucose levels were sampled during the 60-minute exercise trial (pre, 20, 40, 60-min) and immediately after the 30-minute performance trial (post, 2, 5, 10-min). Heart rate was monitored continuously during the exercise and performance trial. Expired gas samples were also taken for 5-min periods during the exercise trial and then continuously during the performance trial. These values were used to calculate respiratory exchange ratio (RER) and carbohydrate oxidation. Dietary intake was assessed with a three day food record. No significant differences were apparent between beverage trials for total distance (km), average speed (km•hr-1) or maximum speed achieved (km•hr-1). Significant differences were evident for blood glucose values, RER and CHO oxidation between the two beverage trials (p< .05). At the end of the 30-minute performance trial blood glucose values were significantly higher in the CHO trial (4.8 ± 1.3 mmol.l-1 vs. 4.0 ± 0.5 mmol.l-1 for placebo trial; p< .05). The CHO beverage resulted in higher CHO oxidation during the last 5 minutes of the performance trial, 2.1 ± 1.0 g•min-1 vs. the placebo beverage 1.9 ± 1.0 g•min-1 (p< .05). The CHO beverage trial resulted in significantly higher RER values during the final 5 minutes of the exercise trial and during the final 10 minutes of the performance trial. At the 20-25 minute mark RER values were significantly higher with the CHO beverage trial (1.04 ± 0.10) vs. the placebo trial (1.01 ± 0.11) (p< .05). During the final 5 minutes of the performance trial RER values were also significantly higher with the CHO beverage trial (1.06 ± 0.11) vs. the placebo trial (1.01 ± 0.10) (p< .05). The results indicated the participants were not meeting the current dietary guidelines for able-bodied athletes and active adults. Only 25% of the participants met the daily caloric requirements for active adults. Carbohydrate recommendations of 6 to 10 g•kg-1 body…