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Eur J Appl Physiol (2013) 113:23812389 DOI 10.1007/s00421-013-2674-z
ORIGINAL ARTICLE
Relationship between core temperature, skin temperature, and heat ux during exercise in heat
Xiaojiang Xu Anthony J. Karis Mark J. Buller
William R. Santee
Received: 26 February 2013 / Accepted: 30 May 2013 / Published online: 18 June 2013 Springer-Verlag Berlin Heidelberg (outside the USA) 2013
AbstractPurpose This paper investigates the relationship between core temperature (Tc), skin temperature (Ts) and heat ux (HF) during exercise in hot conditions.
Method Nine test volunteers, wearing an Army Combat Uniform and body armor, participated in three sessions at 25 C/50 % relative humidity (RH); 35 C/70 % RH; and 42 C/20 % RH. Each session consisted of two 1-h tread-mill walks at *350 W and *540 W intensity. Ts and HF from six sites on the forehead, sternum, pectoralis, left rib cage, left scapula, and left thigh, and Tc (i.e., core temperature pill used as a suppository) were measured. Multiple linear regressions were conducted to derive algorithms that estimate Tc from Ts and HF at each site. A simple model was developed to simulate inuences of thermal conductivity and thickness of the local body tissues on the relationship between Tc, Ts, and HF.
Results Coefcient of determination (R2) ranged from0.30 to 0.88, varying with locations and conditions. Good sites for Tc measurement at surface were the sternum, and a combination of the sternum, scapula, and rib sites. The combination of Ts and HF measured at the sternum explained *75 % or more of variance in observed Tc in
hot environments. The forehead was found unsuitable for exercise in heat due to sweating and evaporative heat loss. The derived algorithms are likely applicable only for the
same ensemble or ensembles with similar thermal and vapor resistances.
Conclusion Algorithms for Tc measurement are location-specic and their accuracy is dependent, to a large degree, on sensor placement.
Keywords Non-invasive measurement Heat strain
Human Heat transfer
Introduction
Heat illness and fatalities are a signicant threat to military operations. There were 362 incident cases of heat stroke and 2,652 incident cases of other heat injury among US Armed Force active component members in 2011 (Armed Forces Health Surveillance Center 2012). The prevention of heat illness is especially challenging for critical occupations such as...