Effects of Precooling with Cold Water Ingestion on Thermoregulatory Response of Obese Men during Moderate Intensity Exercise in Hot and Humid Environment

J Med Assoc Thai. 2016 Feb;99(2):197-205.


Objective: 1) To determine rectal temperature (Tre) and fluid loss (FL) of obese men (OM) compared to non-obese men (NM) during exercise in cool conditions (CC) and hot and humid conditions (HC), and 2) to investigate the effects of cold water (CW; 0.5 ± 0.5°C) ingestion before exercise in HC in OM MATERIAL AND METHOD: Twelve OM and 12 NM completed 2 treadmill exercise sessions, in CC and HC, in a randomized order Each session was performed for 30 minutes at 45-50% of heart rate reserve with a 5-minute warm up and 5-minute cool down.

Results: There were no differences in Tre in response to exercise between OM and NM both in CC (OM 37.77 ± 0.08°C, NM 37.68 ± 0.08°C; p = 0.463) and in HC (OM 37.82 ± 0.06°C, NM 37.85 ± 0.06°C; p = 0.725). Heart rate, perceived exertion and thermal sensations were not significantly different between OM and NM. However, compared to NM, fluid loss (FL) was approximately 160 mL greater in OM (OM 443.33 ± 98.65 mL, NM 283.33 ± 108.15 mL; p ≤ 0.001) in CC, and was 194 mL greater (OM 632.50 ± 126.57 mL, NM 438.33 ± 126.62 mL; p ≤ 0.001) in HC. In HC, the 12 OM performed additional 2 bouts of exercise, with CW vs. ambient temperature water (AW; 30.5 ± 0.5°C) ingestions prior to the start of exercise. Precooling with CW ingestion, compared to AW ingestion, showed no significant difference in Tre but CW was able to reduce FL (CW 646.67 ± 139.82 mL, AW 735 ± 126.95 mL; p = 0.010).

Conclusion: OM may continuously exercise about 30 minutes at moderate intensity in HC without the increase of Tre to dangerous levels. However, OM should drink approximately 200 mL more water in HC and 160 mL more water in CC than NM. Precooling with CW ingestion is a good method of reducing risk of exertional heat illnesses in obese individuals during exercise in HC, as it decreases the amount of FL induced by exercise.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Body Temperature*
  • Cold Temperature*
  • Exercise Test
  • Exercise*
  • Heart Rate
  • Hot Temperature
  • Humans
  • Humidity
  • Male
  • Obesity*
  • Water / administration & dosage*
  • Water-Electrolyte Balance*
  • Young Adult


  • Water