effects of creatine supplementation on cardiovascular, metabolic, and thermoregulatory responses during exercise in the heat in endurance-trained humans

• Published in: International journal of sport nutrition and exercise metabolism 2004-08, Vol.14 (4), p.443-460
• Main Authors: Kilduff, L.P, Georgiades, E, James, N, Minnion, R.H, Mitchell, M, Kingsmore, D, Hadjicharlambous, M, Pitsiladis, Y.P
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Adult; Blood Volume; Body Temperature Regulation - drug effects; Body Temperature Regulation - physiology; Body Water - drug effects; Body Water - metabolism; Creatine - administration & dosage; Creatine - pharmacology; Dietary Supplements; Double-Blind Method; Energy Metabolism - drug effects; Energy Metabolism - physiology; Exercise - physiology; Heart Rate - drug effects; Heart Rate - physiology; Hot Temperature; Humans; Male; Muscle, Skeletal - drug effects; Muscle, Skeletal - metabolism; Oxygen Consumption - drug effects; Oxygen Consumption - physiology; Physical Endurance - physiology; Time Factors
• ISSN: 1526-484X; 1543-2742
• DOI: 10.1123/ijsnem.14.4.443

The effects of creatine (Cr) supplementation on cardiovascular, metabolic, and thermoregulatory responses, and on the capacity of trained humans to perform prolonged exercise in the heat was examined. Endurance-trained males (n = 21) performed 2 constant-load exercise tests to exhaustion at 63 ± 5 % VO(2max) in the heat (ambient temperature: 30.3 ± 0.5 °C) before and after 7 d of Cr (20 g · d-1 Cr + 140 g · d-1 glucose polymer) or placebo. Cr increased intracellular water and reduced thermoregulatory and cardiovascular responses (e.g., heart rate, rectal temperature, sweat rate) but did not significantly increase time to exhaustion (47.0 ± 4.7 min vs. 49.7 ± 7.5 min, P = 0.095). Time to exhaustion was increased significantly in subjects whose estimated intramuscular Cr levels were substantially increased ("responders": 47.3 ± 4.9 min vs. 51.7 ± 7.4 min, P = 0.031). Cr-induced hyperhydration can result in a more efficient thermoregulatory response during prolonged exercise in the heat.