Influence of a 3.5 Day Fast on Physical Performance Running Heading: Fasting and Performance,
ARMY RESEARCH INST OF ENVIRONMENTAL MEDICINE NATICK MA
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The influence of a 14 h fast or a 3.5 day fast on physical performance was investigated in 8 young men. In both conditions they were tested for isometric strength, isokinetic strength elbow flexors, 30 degssec and 180 degssec, anaerobic capacity and aerobic endurance. Anaerobic capacity was evaluated by having subjects perform 50 rapidly repeated isokinetic contractions of the elbow flexors at 180 degssec. Aerobic endurance was measured as time to volitional fatigue during a cycle ergometer exercise at 45 VO2 max. Measures of VO2, V sub E, heart rate, and ratings of perceived exertion were obtained prior to and during the cycle exercise. The 3.5 day fast did not influence isometric strength, anaerobic capacity or aerobic endurance, but isokinetic strength was significantly reduced approx. 10 at both velocities. VO2, V sub E and perceived exertion were not affected by fasting. Fasting significantly increased heart rate during exercise but not at rest. It was concluded that there are minimal impairments in physical performance as a result of a 3.5 day fast provided there is little physical activity during the fasting period. Keywords Starvation, Muscle strength, Oxygen uptake, and Ventilation.
- Stress Physiology