DiStefano, L. J., VanSumeren, M., Karslo, R., DeMartini, J. K., Stearns, R. L., Huggins, R., Armstrong, L., maresh, C., & Casa, D. J. (2012). Effects of hyperthermia, hypohydration, and fatigue on balance. Presentation 1451 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

This study evaluated the effects of hyperthermia, dehydration, and fatigue on balance ability, and therefore a possible predisposition to injury. Healthy males (N = 12) completed four randomized test sessions in a climate-controlled chamber. Sessions varied based on environmental conditions and hydration status (Euhydrated Temperate, Euhydrated Hot, Hypohydrated Temperate, and Hypohydrated Hot. Temperate and hot conditions were performed in ~18ºC, ~50% relative humidity, and ~34ºC, 45% relative humidity, respectively. Dynamic balance during a 10-second unilateral landing task was assessed three times per session: before exercise, after exercise, and after recovery. A 90-minute treadmill exercise protocol required Ss to walk carrying a 20.5 kg backpack (1.34-1.78 m/s; 5% grade). Ss sat quietly in the test environment during a 60-minute recovery period. Mean sway velocity and elliptical sway area were calculated from force plate data.

Body mass loss differed across sessions being highest in the hypohydrated conditions. Regardless of time, the hypohydrated hot condition resulted in the highest values for sway velocity and sway area. Post-exercise sway velocity was higher than before exercise and after recovery, regardless of condition.

Implication. Regardless of hydration status and environmental conditions, fatigue appears to decrease balance ability. Dehydration in a hot environment also impairs balance ability. It is suggested that fatigue and fluid loss in hot conditions cause balance to be degraded, predisposing athletes to injury.

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