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Eighty-four hours of sustained operations alter thermoregulation during cold exposure.
Med Sci Sports Exerc 2003; 35(1):175-81MS

Abstract

PURPOSE; This study examined the effects of short-term (3.5 d) sustained military operations (SUSOPS) on thermoregulatory responses to cold stress.

METHODS

Ten men (22.8 +/- 1.4 yr) were assessed during a cold-air test (CAT) after a control week (control) and again after an 84-h SUSOPS (sleep = 2 h.d (-1), energy intake = approximately 1650 kcal.d(-1), and energy expenditure = approximately 4500 kcal.d(-1). CAT consisted of a resting subject (seminude) being exposed to an ambient temperature ramp from 25 degrees C to 10 degrees C during the initial 30 min of CAT, with the ambient temperature then remaining at 10 degrees C for an additional 150 min.

RESULTS

SUSOPS decreased (P< 0.05) body weight, % body fat, and fat-free mass by 3.9 kg, 1.6%, and 1.8 kg, respectively. During CAT, rectal temperature decreased to a greater extent (P< 0.05) after SUSOPS (0.52 +/- 0.09 degrees C) versus control (0.45 +/- 0.12 degrees C). Metabolic heat production was lower (P< 0.05) after SUSOPS at min 30 (55.4 +/- 3.3 W.m (-2)) versus control (66.9 +/- 4.4 W.m(-2)). Examination of the mean body temperature-metabolic heat production relationship indicated that the threshold for shivering was lower (P< 0.05) after SUSOPS (34.8 +/- 0.2 degrees C) versus control (35.8 +/- 0.2 degrees C). Mean weighted skin temperatures (degrees C) were lower during the initial 1.5 h of CAT in SUSOPS versus control. Heat debt was similar between trials.

CONCLUSION

These results indicate that sustained (84-h) military operations leads to greater declines in core temperature, due to either a lag in the initial shivering response or heat redistribution secondary to an insulative acclimation.

Authors+Show Affiliations

US Army Research Institute of Environmental Medicine. Natick, MA 01760-5007, USA. john.castellani@na.amedd.army.milNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

12544652

Citation

Castellani, John W., et al. "Eighty-four Hours of Sustained Operations Alter Thermoregulation During Cold Exposure." Medicine and Science in Sports and Exercise, vol. 35, no. 1, 2003, pp. 175-81.
Castellani JW, Stulz DA, Degroot DW, et al. Eighty-four hours of sustained operations alter thermoregulation during cold exposure. Med Sci Sports Exerc. 2003;35(1):175-81.
Castellani, J. W., Stulz, D. A., Degroot, D. W., Blanchard, L. A., Cadarette, B. S., Nindl, B. C., & Montain, S. J. (2003). Eighty-four hours of sustained operations alter thermoregulation during cold exposure. Medicine and Science in Sports and Exercise, 35(1), pp. 175-81.
Castellani JW, et al. Eighty-four Hours of Sustained Operations Alter Thermoregulation During Cold Exposure. Med Sci Sports Exerc. 2003;35(1):175-81. PubMed PMID: 12544652.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Eighty-four hours of sustained operations alter thermoregulation during cold exposure. AU - Castellani,John W, AU - Stulz,Dean A, AU - Degroot,David W, AU - Blanchard,Laurie A, AU - Cadarette,Bruce S, AU - Nindl,Bradley C, AU - Montain,Scott J, PY - 2003/1/25/pubmed PY - 2003/4/16/medline PY - 2003/1/25/entrez SP - 175 EP - 81 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 35 IS - 1 N2 - UNLABELLED: PURPOSE; This study examined the effects of short-term (3.5 d) sustained military operations (SUSOPS) on thermoregulatory responses to cold stress. METHODS: Ten men (22.8 +/- 1.4 yr) were assessed during a cold-air test (CAT) after a control week (control) and again after an 84-h SUSOPS (sleep = 2 h.d (-1), energy intake = approximately 1650 kcal.d(-1), and energy expenditure = approximately 4500 kcal.d(-1). CAT consisted of a resting subject (seminude) being exposed to an ambient temperature ramp from 25 degrees C to 10 degrees C during the initial 30 min of CAT, with the ambient temperature then remaining at 10 degrees C for an additional 150 min. RESULTS: SUSOPS decreased (P< 0.05) body weight, % body fat, and fat-free mass by 3.9 kg, 1.6%, and 1.8 kg, respectively. During CAT, rectal temperature decreased to a greater extent (P< 0.05) after SUSOPS (0.52 +/- 0.09 degrees C) versus control (0.45 +/- 0.12 degrees C). Metabolic heat production was lower (P< 0.05) after SUSOPS at min 30 (55.4 +/- 3.3 W.m (-2)) versus control (66.9 +/- 4.4 W.m(-2)). Examination of the mean body temperature-metabolic heat production relationship indicated that the threshold for shivering was lower (P< 0.05) after SUSOPS (34.8 +/- 0.2 degrees C) versus control (35.8 +/- 0.2 degrees C). Mean weighted skin temperatures (degrees C) were lower during the initial 1.5 h of CAT in SUSOPS versus control. Heat debt was similar between trials. CONCLUSION: These results indicate that sustained (84-h) military operations leads to greater declines in core temperature, due to either a lag in the initial shivering response or heat redistribution secondary to an insulative acclimation. SN - 0195-9131 UR - https://www.unboundmedicine.com/medline/citation/12544652/Eighty_four_hours_of_sustained_operations_alter_thermoregulation_during_cold_exposure_ L2 - http://Insights.ovid.com/pubmed?pmid=12544652 DB - PRIME DP - Unbound Medicine ER -