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CREATINE SUPPLEMENTATION AND ACUTE DEHYDRATION
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1999
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NutritionPhysical ActivityNeuromuscular CoordinationBody CompositionKinesiologySkeletal Muscle CrampingSport NutritionExerciseBiochemical NutritionPhysical ExerciseApplied PhysiologyClinical ExerciseSport PhysiologyPhysical MedicineHealth SciencesPhysical FitnessCr SupplementationClinical Exercise PhysiologyClinical NutritionAcute DehydrationHuman PhysiologyAthletic TrainingExercise ScienceExercise PhysiologyPhysiologyMetabolismMedicine
1276 Creatine (Cr), a widely used dietary supplement, has been demonstrated to enhance muscular strength and anaerobic power. However, coaches, trainers, professional sports teams, and physicians have raised concerns regarding its safety. There is specific concern with numerous anecdotal reports suggesting that Cr supplementation will compromise an individual's heat tolerance during exercise, subsequently leading to an increase of skeletal muscle cramping and tearing. The purpose of this study was to investigate the effects of oral Cr supplementation and acute dehydration on plasma volume, electrolyte and mineral balance, and anaerobic exercise performance. Using a randomized double-blind design, 15 subjects ingested either 20 g·d1 of Cr monohydrate (CR) (N=8) or a placebo (PL) (N=7) for 5-d and then undertook two consecutive 80-min dehydration protocols resulting in −1.5% (D1) and −3% (D2) decreases in body mass (BM). After 5-d of supplementation, there was a significant increase in BM in both groups (PL: 0.6 ±0.5; CR:1.5 ±0.1 kg), but there was no difference between groups (P = 0.09). There were no significant changes in body composition; plasma volume (PV); serum electrolytes (Na, K, CI), minerals (Mg, Zn, Ca), osmolality; and anaerobic exercise performance measures of maximum power (MP), total work (TW), or fatigue index (FI) as determined from ten, 6-s sprints on a cycle ergometer. As expected, the two 80-min dehydration sessions resulted in a significant ΔPV in both groups at D1 (PL: −10.9±2.0; CR: −9.2±1.6%) and D2 (PL: −15.6±2.1; CR: −16.5±1.6%) but, no difference between groups. There were no significant differences between groups at either D1 or D2 for measures of serum electrolytes, minerals, osmolality, MP, TW, or FI. The results suggest that a 5-d loading dose of Cr does not negatively affect plasma volume or serum electrolyte and mineral balance. However, it also does not appear to enhance the performance of repeated bouts of anaerobic exercise. Supplement provided by Experimental and Applied Sciences, Inc.