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Jeffrey A. Woods and Brandt D. Pence

Exercise immunology is a relatively new discipline in the exercise sciences that seeks to understand how exercise affects the immune system and susceptibility to infectious and chronic diseases. This brief review will focus on three major observations that have driven the field to date including: (1) acute exercise-induced leukocytosis, (2) the observation that intense, prolonged exercise results in upper respiratory tract symptoms, and (3) the paradoxical effect of acute and chronic exercise on inflammation. This framework will be used to examine the mechanisms and implications behind these seminal observations. Data generally support the conclusion that moderate intensity exercise enhances immune function, whereas prolonged, intense exercise diminishes immune function.

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Jeffrey A. Woods, Russell R. Pate, and Maria L. Burgess

Field tests of upper body muscular strength and endurance (UBMSE) are often administered to children, but little is known about the determinants of performance on these tests. Therefore the purpose of this investigation was to examine potential determinants of performance on several common field tests of UBMSE including pull-ups, flexed-arm hang, push-ups, and two types of modified pull-ups. Subjects were 56 girls and 38 boys, ages 9 to 11 years. Potential determinants assessed were age, height, weight, gender, % fat, physical activity, and laboratory measures of muscular strength and endurance. Multiple regression analysis revealed that the laboratory measures of UBMSE failed to account for significant fractions of variance in performance on four of the five tests. However, % fat was significantly associated with performance on four of five tests. These results indicate that factors other than muscular strength and endurance account for most of the variance in performance, and that % fat appears to be a particularly important determinant of performance.

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William A. Burgess, J. Mark Davis, William P. Bartoli, and Jeffrey A. Woods

The effects of ingesting a low dose of CHO on plasma glucose, glucoregulatory hormone responses, and performance during prolonged cycling were investigated. Nine male subjects cycled for 165 min at ≈67% peak VO2 followed by a two-stage performance ride to exhaustion on two occasions in the laboratory. Every 20 min during exercise, subjects consumed either a flavored water placebo (P) or a dilute carbohydrate beverage (C). Blood samples were collected immediately before, every 20 min throughout, and immediately after exercise. Plasma was analyzed for glucose, lactate, free fatty acids (FFA), and various glucoregulatory hormones. VO2, RER, heart rate, perceived exertion, and exercise performance were also measured. Lactate, FFA, epinephrine, norepinephrine, ACTH, cortisol, and glucagon increased with exercise whereas glucose and insulin decreased (p≤05). Except for a small difference in glucose at 158 min of exercise and at exhaustion, no significant differences were found between drinks for any of the variabfes studied (p ≥ 05). Ingestion of 13 g carbohydrate per hour is not sufficient to maintain plasma glucose, attenuate the glucoregulatory hormone response, and improve performance during prolonged moderate intensity cycling.