Gait After Cold Water Immersion And Subsequent High-intensity Exercise

Hypohydration from cold water immersion impairs post-immersion exercise performance. Changes in gait during activity are associated with slip, trip, and fall risk. However, the influence of immersion diuresis and post-immersion exercise on gait is not well described. PURPOSE: To assess gait after cold water immersion and subsequent military-relevant exercise in a warm environment. METHODS: Five male participants (24 ± 2 y; 175.4 ± 7.7 cm; 75.1 ± 13.1 kg) completed three, 4 h seated cold water (18 °C) immersions. Participants then completed a 60-min loaded (20.4 kg) ruck march followed by an intermittent high intensity exercise performance test in a warm environment (30 °C, 50% RH). Complete rehydration was provided with water, a 6.5% carbohydrate beverage, or a 6.5% carbohydrate and electrolyte solution. Core temperature (Tc) and peak heart rate (HR) was measured during immersion and exercise. Gait testing was completed before and after immersion, and after exercise. Comparisons of 13 gait variables including stride length, total double support time, and stride width were analyzed using repeated measures ANOVA. RESULTS: Participants experienced an average of 2.6 ± 0.6% body mass loss after immersion in all trials. Tc decreased during immersion (37.1 ± 0.4 °C vs 36.5 ± 0.5 °C) and increased after exercise (38.4 ± 0.3 °C; both p < 0.01) but did not differ across conditions (p = 0.20). Peak HR was 177 ± 9 bpm during exercise across all conditions. An effect on stride width by rehydration condition was observed (p = 0.03). Stride length and total double support time were not different between rehydration conditions (p = 0.82 and p = 0.89, respectively) or over time (p = 0.52 and p = 0.28, respectively). No other effects on gait were identified. CONCLUSIONS: Minimal changes in gait were associated with hypohydration and post-immersion exercise in a military relevant scenario. Gait was generally unaffected by rehydration strategy, with the exception of stride width, which may indicate increased risk of fall through increased gait variability.