Double blind carbohydrate ingestion does not improve exercise duration in warm humid conditions.
The positive effects of carbohydrate (CHO) supplementation on endurance exercise are well documented but the placebo (PLA(c)) effect can make the ergogenic qualities of substances more difficult to determine. Therefore, this study tested the effect of double blind ingestion of PLA(c) and CHO(c) in capsules versus known capsule (CHO(k)) ingestion on prolonged exercise heat stress. Nine well trained male volunteers (mean+/-S.D.: 23+/-3 years; 62.4+/-6.5 kg and 65.8+/-5.2 mL kg(-1) min(-1) peak oxygen consumption) exercised at 60% of maximum power output until volitional exhaustion (TTE) in the three different conditions. Capsules were ingested with 252+/-39 mL of water. Blood glucose in CHO(c) and CHO(k) was similar but higher (p<0.05) than PLA(c) from 45 min to end of exercise. There were no differences in TTE between PLA(c) (125.2+/-37.1 min) or CHO(c) (138.8+/-47.0 min) or between CHO(c) and CHO(k) (155.8+/-54.2 min). Time to volitional exhaustion was different between PLA(c) and CHO(k) (p<0.05). Increased TTE resulted when participants and researchers knew the capsule content, but not in the double blind condition. The difference could be related to a combined effect of CHO ingestion and knowledge of what was ingested possibly acting as a potent psychological motivator.
Nassif
Camila
C
School of Human Movement Studies, Charles Sturt University, Australia.
Ferreira
Ana Paula Araujo
AP
Gomes
Aline Regina
AR
Silva
Luciana De Martin
Lde M
Garcia
Emerson Silami
ES
Marino
Frank E
FE
D000328:Adult; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D018882:Heat Stress Disorders / Q000517:prevention & control; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D008297:Male; D010919:Placebos
D004040:Dietary Carbohydrates; D010919:Placebos