Running Endurance in 27-hour Fasted Humans
Nine male marathon runners were exercised to exhaustion to determine the effects of a 27-hour fast on endurance performance. Each subject completed two exercise tests at 72% peak oxygen uptake (Vo2max), one following a 27-hour fast and one three hours after a pre-exercise meal, in random order. Fasting caused a 44.7±5.8% (±SE) decrease in endurance performance (p2(9.3±2.0%), heart rate (8.4±2.4%), rating of perceived exertion (RPE), and psychological fatigue, evident within the first 60 minutes of exercise. There was no difference in plasma glucose or epinephrine levels. Muscle glycogen degraded at the same rate (0.48±.15 vs 0.47±.28 u moles • g -1.min-1 in the non-fasted and fasted tests, respectively) despite lower respiratory exchange ratio (R) and elevated free fatty acid (FFA) levels. Lactate, insulin,. norepinephrine (NE), and 3,4-dihydroxyphenylacetic acid (dopac) were all increased in the fasted test (p
Exercise Physiology, Nutrition, Running; Fasting
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