Title

The Effect of Fluid Volume and Temperature on Physiological Strain and Performance in the Heat

Presentation Type

Poster

Abstract

Established hydration standards are based on ambient temperature. However, limited research has investigated the relationship between ingested fluid volume and temperature on thermoregulation. PURPOSE: To determine physiological strain and performance in the heat with varied fluid volume and temperature. METHODS: Eleven recreationally active males (age 24.7±5.9 years, height 179.0±7.3cm, weight 78.4±6.4kg, peak VO258.2±6.0 ml∙kg-1∙min-1, body fat 14.3±5.9%) completed two trials. in a randomized cross-over design (ice slurry (0.5 ml/kg) (Slurry) or ambient temperature water (1.0 ml/kg) (Room) every 10 minutes).. Study participants walked at 40% VO2 max for 25 minutes, rested for 5 minutes, and then completed a one mile time trial at maximum effort in an environmental chamber (35.5°C, 50% RH) over 180 minutes. Heart rate and core temperature were continuously monitored and used to calculate physiological strain index (PSI). RESULTS: Body weight demonstrated a significant decrease over time (2.2±0.2 and 3.0±0.2% loss for Room and Slurry, respectively, p<0.05) but was not different between trials. PSI increased significantly during the steady state segment over time for both trials (p<0.05). However, there were no significant differences between trials (Room = 3.5±1.0, 7.9±1.5; Slurry = 3.6±1.1, and 6.9± 0.7 for segment 1 and 3, respectively). Peak PSI at the completion of each time trial increased significantly (p<0.05). However, there were no significant differences between trials (Room = 6.7±1.2, 9.5±1.3; Slurry = 6.9±0.7, and 9.4± 0.9 for time trials 1 and 3, respectively). Time trials were significantly slower over time for both trials (p<0.05). However there were no significant differences between trials (Room = 9.7±1.3, 12.8±2.4; Slurry = 10.1±1.6, and 12.7±2.6 for time trials 1 and 3, respectively). CONCLUSION: Despite consuming half of the recommended fluid volume, when very cold fluids are consumed, the overall physiological strain and performance are not significantly different compared to higher volume, room temperature water.

Category

Life Sciences

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Apr 15th, 11:00 AM Apr 15th, 12:00 PM

The Effect of Fluid Volume and Temperature on Physiological Strain and Performance in the Heat

Established hydration standards are based on ambient temperature. However, limited research has investigated the relationship between ingested fluid volume and temperature on thermoregulation. PURPOSE: To determine physiological strain and performance in the heat with varied fluid volume and temperature. METHODS: Eleven recreationally active males (age 24.7±5.9 years, height 179.0±7.3cm, weight 78.4±6.4kg, peak VO258.2±6.0 ml∙kg-1∙min-1, body fat 14.3±5.9%) completed two trials. in a randomized cross-over design (ice slurry (0.5 ml/kg) (Slurry) or ambient temperature water (1.0 ml/kg) (Room) every 10 minutes).. Study participants walked at 40% VO2 max for 25 minutes, rested for 5 minutes, and then completed a one mile time trial at maximum effort in an environmental chamber (35.5°C, 50% RH) over 180 minutes. Heart rate and core temperature were continuously monitored and used to calculate physiological strain index (PSI). RESULTS: Body weight demonstrated a significant decrease over time (2.2±0.2 and 3.0±0.2% loss for Room and Slurry, respectively, p<0.05) but was not different between trials. PSI increased significantly during the steady state segment over time for both trials (p<0.05). However, there were no significant differences between trials (Room = 3.5±1.0, 7.9±1.5; Slurry = 3.6±1.1, and 6.9± 0.7 for segment 1 and 3, respectively). Peak PSI at the completion of each time trial increased significantly (p<0.05). However, there were no significant differences between trials (Room = 6.7±1.2, 9.5±1.3; Slurry = 6.9±0.7, and 9.4± 0.9 for time trials 1 and 3, respectively). Time trials were significantly slower over time for both trials (p<0.05). However there were no significant differences between trials (Room = 9.7±1.3, 12.8±2.4; Slurry = 10.1±1.6, and 12.7±2.6 for time trials 1 and 3, respectively). CONCLUSION: Despite consuming half of the recommended fluid volume, when very cold fluids are consumed, the overall physiological strain and performance are not significantly different compared to higher volume, room temperature water.