Chin Leong Lim1, Christopher Byrne, Serena A N Chew, Laurel T Mackinnon. 1. Military Physiology Laboratory, Defence Medical and Environmental Research, DSO National Laboratories, 27 Medical Drive, #09-01, Singapore 117510, Republic of Singapore. limcl@dso.org.sg
Abstract
PURPOSE: This study investigated leukocyte subset responses to moderate-intensity exercise under heat stress, with water (W) or carbohydrate (CHO) drink ingestion. METHODS: In repeated trials, 13 soldiers consumed either a W or CHO drink during 3 h of walking at 4.4 km x h(-1) with a 5% gradient (15 min rest per hour) under heat stress (35 degrees C and 55% relative humidity). The soldiers wore combat uniforms and carried water bottles and dummy rifles and ammunition, altogether weighing about 11.5 +/- 1.0 kg. RESULTS: Plasma glucose concentration was significantly higher with CHO than W ingestion during exercise (p < 0.01). There were no significant differences between W and CHO conditions in exercise performance, plasma cortisol concentration, heart rate, or core temperature. CHO ingestion significantly moderated the increases in leukocyte (83% in W, 28% in CHO; p < 0.001), monocyte (60% in W, 34% in CHO; p < 0.05), and granulocyte counts (120% in W, 30% in CHO; p < 0.001), but not in lymphocyte count (41% in W, 25% in CHO). CONCLUSIONS: The increases in leukocyte and subset counts during moderate-intensity exercise under heat stress may be comparable to those observed during intense exercise in cool conditions. The response of immune cell counts is blunted by CHO intake during moderate-intensity exercise in the heat, and may not occur through the cortisol pathway.
PURPOSE: This study investigated leukocyte subset responses to moderate-intensity exercise under heat stress, with water (W) or carbohydrate (CHO) drink ingestion. METHODS: In repeated trials, 13 soldiers consumed either a W or CHO drink during 3 h of walking at 4.4 km x h(-1) with a 5% gradient (15 min rest per hour) under heat stress (35 degrees C and 55% relative humidity). The soldiers wore combat uniforms and carried water bottles and dummy rifles and ammunition, altogether weighing about 11.5 +/- 1.0 kg. RESULTS: Plasma glucose concentration was significantly higher with CHO than W ingestion during exercise (p < 0.01). There were no significant differences between W and CHO conditions in exercise performance, plasma cortisol concentration, heart rate, or core temperature. CHO ingestion significantly moderated the increases in leukocyte (83% in W, 28% in CHO; p < 0.001), monocyte (60% in W, 34% in CHO; p < 0.05), and granulocyte counts (120% in W, 30% in CHO; p < 0.001), but not in lymphocyte count (41% in W, 25% in CHO). CONCLUSIONS: The increases in leukocyte and subset counts during moderate-intensity exercise under heat stress may be comparable to those observed during intense exercise in cool conditions. The response of immune cell counts is blunted by CHO intake during moderate-intensity exercise in the heat, and may not occur through the cortisol pathway.
Authors: J Romeo; D Jiménez-Pavón; M Cervantes-Borunda; J Wärnberg; S Gómez-Martínez; M J Castillo; A Marcos Journal: J Physiol Biochem Date: 2008-09 Impact factor: 4.158