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Efficacy of air and liquid cooling during light and heavy exercise while wearing NBC clothing.
Aviat Space Environ Med. 1999 Aug; 70(8):802-11.AS

Abstract

BACKGROUND

Studies, to date, have not revealed the extent to which the heat strain of continuous heavy exercise while wearing NBC protective clothing can be reduced by providing liquid- or air-cooling and whether one system is more effective than the other in aiding heat transfer from the body and the clothing. It was of interest to know to what extent present-day cooling technologies can reduce the heat strain of light and heavy exercise in NBC clothing and to compare these reductions to other strategies that have employed changes in clothing design.

HYPOTHESIS

It was hypothesized that there would be no difference between the liquid and air cooling systems and that sufficient cooling power would be delivered to the body to reduce the heat strain of heavy exercise to a level similar to that experienced with light exercise when no cooling was provided.

METHODS

Eight males performed 6 randomized exposures for a maximum of 3 h at 40 degrees C and 30% relative humidity that involved either light (L) (walking at 3.5 km x h(-1) or heavy (H) (walking at 4.8 km x h(-1) and a 5% grade) exercise while wearing the NBC protective clothing ensemble with no cooling (N), liquid (L) or air (A) cooling.

RESULTS

For L exercise, tolerance time was significantly increased from 100 min with N to the maximum of 3 h with either cooling system. There was no difference between L and A cooling in the extent of the changes in rectal temperature, heart rate and heat flow. For H exercise, tolerance time was significantly increased 150% from 57 min with N to 149 min with L and 140 min with A. These latter values for HL and HA were not different from each other but both were significantly greater than L exercise with N. Rectal temperature increased more quickly during HL compared with HA during the first 60 min of exposure but there were no differences between cooling trials for the remainder of the heat exposure.

CONCLUSIONS

It was concluded that sufficient cooling power could be delivered to the body to effectively reduce the heat strain of wearing NBC protective clothing during heavy exercise in a hot environment to a level comparable to or slightly lower than that experienced with light exercise and no cooling.

Authors+Show Affiliations

Human Protection and Performance Sector, Defence and Civil Institute of Environmental Medicine, North York, Ontario, Canada. tmclella@dciem.dnd.caNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
Journal Article
Randomized Controlled Trial

Language

eng

PubMed ID

10447055

Citation

McLellan, T M., et al. "Efficacy of Air and Liquid Cooling During Light and Heavy Exercise While Wearing NBC Clothing." Aviation, Space, and Environmental Medicine, vol. 70, no. 8, 1999, pp. 802-11.
McLellan TM, Frim J, Bell DG. Efficacy of air and liquid cooling during light and heavy exercise while wearing NBC clothing. Aviat Space Environ Med. 1999;70(8):802-11.
McLellan, T. M., Frim, J., & Bell, D. G. (1999). Efficacy of air and liquid cooling during light and heavy exercise while wearing NBC clothing. Aviation, Space, and Environmental Medicine, 70(8), 802-11.
McLellan TM, Frim J, Bell DG. Efficacy of Air and Liquid Cooling During Light and Heavy Exercise While Wearing NBC Clothing. Aviat Space Environ Med. 1999;70(8):802-11. PubMed PMID: 10447055.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Efficacy of air and liquid cooling during light and heavy exercise while wearing NBC clothing. AU - McLellan,T M, AU - Frim,J, AU - Bell,D G, PY - 1999/8/14/pubmed PY - 1999/8/14/medline PY - 1999/8/14/entrez SP - 802 EP - 11 JF - Aviation, space, and environmental medicine JO - Aviat Space Environ Med VL - 70 IS - 8 N2 - BACKGROUND: Studies, to date, have not revealed the extent to which the heat strain of continuous heavy exercise while wearing NBC protective clothing can be reduced by providing liquid- or air-cooling and whether one system is more effective than the other in aiding heat transfer from the body and the clothing. It was of interest to know to what extent present-day cooling technologies can reduce the heat strain of light and heavy exercise in NBC clothing and to compare these reductions to other strategies that have employed changes in clothing design. HYPOTHESIS: It was hypothesized that there would be no difference between the liquid and air cooling systems and that sufficient cooling power would be delivered to the body to reduce the heat strain of heavy exercise to a level similar to that experienced with light exercise when no cooling was provided. METHODS: Eight males performed 6 randomized exposures for a maximum of 3 h at 40 degrees C and 30% relative humidity that involved either light (L) (walking at 3.5 km x h(-1) or heavy (H) (walking at 4.8 km x h(-1) and a 5% grade) exercise while wearing the NBC protective clothing ensemble with no cooling (N), liquid (L) or air (A) cooling. RESULTS: For L exercise, tolerance time was significantly increased from 100 min with N to the maximum of 3 h with either cooling system. There was no difference between L and A cooling in the extent of the changes in rectal temperature, heart rate and heat flow. For H exercise, tolerance time was significantly increased 150% from 57 min with N to 149 min with L and 140 min with A. These latter values for HL and HA were not different from each other but both were significantly greater than L exercise with N. Rectal temperature increased more quickly during HL compared with HA during the first 60 min of exposure but there were no differences between cooling trials for the remainder of the heat exposure. CONCLUSIONS: It was concluded that sufficient cooling power could be delivered to the body to effectively reduce the heat strain of wearing NBC protective clothing during heavy exercise in a hot environment to a level comparable to or slightly lower than that experienced with light exercise and no cooling. SN - 0095-6562 UR - https://www.unboundmedicine.com/medline/citation/10447055/Efficacy_of_air_and_liquid_cooling_during_light_and_heavy_exercise_while_wearing_NBC_clothing_ L2 - https://medlineplus.gov/heatillness.html DB - PRIME DP - Unbound Medicine ER -