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  • Author: Scott W. Trappe x
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Matthew S. Hickey, David L. Costill and Scott W. Trappe

This study investigated the influence of drink carbonation and carbohydrate content on ad libitum drinking behavior and body fluid and electrolyte responses during prolonged exercise in the heat. Eight competitive male runners completed three 2-hr treadmill runs at 60% VO2max in an environmental chamber maintained at 30 C° and 40% RH. Three test drinks were used: 8% carbohydrate, low carbonation (8%-C); 8% carbohydrate, noncarbonated (8%-NC), and water (0%-NC). Blood samples were taken preexercise (0), at 60 and 120 min of exercise, and at 60 min of recovery (+60 min). The data suggest that while reports of heartburn tend to be higher on 8% carbohydrate drinks than on 0%-NC, this does not appear to be a function of drink carbonation. Similarly, the increased frequency of heartbum did not significantly reduce fluid consumption either during exercise or during a 60-min recovery period. Importantly, no differences were observed between fluid and electrolyte, or thermoregulatory responses to the three sport drinks. Thus, consumption of low-carbonation beverages does not appear to significantly influence drinking behavior or the related physiological responses during prolonged exercise in the heat.

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Michael P. Godard, David L. Williamson, David A. Porter, Gregory A. Rowden and Scott W. Trappe

This investigation examined alterations in neuromuscular drive for dynamic and static muscle contractions, muscle strength, and cross-sectional area (CSA) with a 12-week progressive resistance-training program (PRT). Nine healthy men (70.0 ± 1.7 years) were evaluated for maximal and submaximal neuromuscular drive (integrated electromyography [IEMG]), whole-muscle strength, isokinetic power, and thigh CSA. The results demonstrated no significant differences pre- to post-PRT in the submaximal IEMG signals (p > .05). IEMG increased (p < .05) for the maximal static contraction (29% ± 12%) and isokinetic velocities concentrically and eccentrically. There was an increase (p < .05) in maximal static strength (27% ± 5%), isokinetic concentric and eccentric strength, muscle power, IRM (47% ± 6%), and CSA (6% ± 1%; p < .05). The results reveal significant neuromuscular-drive alterations in concentric and eccentric dynamic contractions with PRT in older men and indicate that their neuromuscular drive contributes significantly to improving their concentric and eccentric skeletal-muscle strength.

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Christopher Barnett, David L. Costill, Mathew D. Vukovich, Kevin J. Cole, Bret H. Goodpaster, Scott W. Trappe and William J. Fink

This study examined the effects of 14 days of L-camitine supplementation on muscle and blood camitine fractions, and muscle and blood lactate concentrations, during high-intensity sprint cycling exercise. Eight subjects performed three experimental trials: control 1 (CON I, Day 0), control I! (CON II, Day 14), and L-camitine (L-CN, Day 28). Each trial consisted of a 4-rain ride at 90% VO2max, followed by a rest period of 20 min, and thee five repeated 1-min rides at 115% VO2max (2 min rest between each). Following CON n, all subjects began dietary supplementation of L-camitine for a period of 14 days (4 g/day). Plasma total acid soluble and free camitine concentrations were significantly higher (p < .05) at all time points following supplementation. L-camitine supplementation had no significant effect on muscle camitine content and thus could not alter lactate accumulation during exercise.

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Kevin J. Cole, David L. Costill, Raymond D. Starling, Bret H. Goodpaster, Scott W. Trappe and William J. Fink

The purpose of this investigation was to determine the effect of caffeine ingestion on work output at various levels of perceived exertion during 30 min of isokinetie variable-resistance cycling exercise. Ten subjects completed six trials 1 hr after consuming either 6 mg · kg−1 caffeine (3 trials) or a placebo (3 trials). During each trial the subjects cycled at what they perceived to be a rating of 9 on the Borg rating of perceived exertion scale for the first 10 min, a rating of 12 for the next 10 min, and a rating of 15 for the final 10 min. Total work performed during the caffeine trials averaged 277.8 ± 26.1 kJ, whereas the mean total work during the placebo trials was 246.7 ± 21.5 kJ (p < .05). Blood glycerol and free fatty acid levels increased over time to a significantly greater degree in the caffeine trials than in the placebo trials (p < .05). However, there were no significant differences between conditions in respiratory exchange ratio. These data suggest that caffeine may play an ergogenic role in exercise performance by altering both neural perception of effort and substrate availability.