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Effects of Carbohydrate Feeding on Multiple-bout Resistance Exercise.

Lambert, Charles P.; Flynn, Michael G.; Boone, James B. Jr.; Michaud, Thomas J.; Rodriguez-Zayas, Jorge
Journal of Strength & Conditioning Research: November 1991
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Seven experienced resistance athletes were studied to evaluate the influence of glucose polymer ingestion on performance during a resistance training workout. Each subject participated in two randomly assigned trials separated by at least one week. On one occasion the subjects ingested a 10 percent glucose polymer solution (GP) (one gram CHO per kilogram of body weight) immediately before exercise, while on another occasion a similarly colored and flavored placebo (P) was ingested. The subjects then performed leg extensions (Nautilus Inc., Deland, Florida) at 80 percent of their previously determined 10-repetition maximums (10 RM), with three minutes of rest between sets. Subjects performed 10 repetitions on the first set and continued until they failed to perform seven repetitions for a set (fatigue). Additional GP (0.17 gram CHO per kilogram of body weight) or P solutions were given after the fifth, 10th and 15th sets. Venous forearm blood samples were taken before exercise, after the seventh set and at the point of fatigue, and were analyzed for glucose and lactate. Blood glucose was significantly higher (p < 0.05) in the GP treatment after the seventh set and at fatigue (10.00 +/- 1.00 mM and 8.44 +/- 0.70 mM, respectively) compared to the P treatment (6.90 +/- 0.25 mM and 6.13 +/- 0.24 mM, respectively). Blood lactate was significantly higher for the GP treatment after the seventh set compared to the P treatment (7.10 +/- 0.31 mM for GP and 5.57 0.19 mM for P). Performance measured in number of sets (17.1 +/- 2.0 for GP and 14.4 +/- 1.7 for P) and repetitions (149 +/- 16 for GP and 129 +/- 12 for P) was greater for GP than for P, and these differences approached but did not achieve statistical significance (p = 0.067 for sets and p = 0.056 for repetitions). The results suggest that glucose polymer ingestion elevates glucose and lactate in the blood and tends to improve performance during multiple-bout (approximately 15 sets) resistance exercise.

(C) 1991 National Strength and Conditioning Association