Validity of Field Expedient Devices to Assess Core Temperature During Exercise in the Cold

BAGLEY JR, JUDELSON DA, SPIERING BA, BEAM WC, BARTOLINI JA, WASHBURN BV, CARNEY KR, MUNOZ CX, YEARGIN SW, CASA DJ. Validity of field expedient devices to assess core temperature during exercise in the cold. Aviat Space Environ Med 2011; 82:1098-1103. Introduction: Exposure to cold environments affects human performance and physiological function. Major medical organizations recommend rectal temperature (T-REC) to evaluate core body temperature (T-CORE) during exercise in the cold; however, other field expedient devices claim to measure T-CORE. The purpose of this study was to determine if field expedient devices provide valid measures of T-CORE during rest and exercise in the cold. Methods: Participants included 13 men and 12 women (age = 24 +/- 3 yr. height = 170.7 +/- 10.6 cm, mass = 73.4 +/- 16.7 kg, body fat = 18 +/- 7%) who reported being healthy and at least recreationally active. During 150 min of cold exposure, subjects sequentially rested for 30 min, cycled for 90 min (heart rate = 120-140 bpm), and rested for an additional 30 min. Investigators compared aural (T-AUR), expensive axillary (T-AXLe), inexpensive axillary (T-AXLi), forehead (T-FOR), gastrointestinal (T-GI), expensive oral (T-ORLe), inexpensive oral (T-ORLi), and temporal (T-TEM) temperatures to T-REC every 15 min. Researchers used mean difference between each device and T-REC (i.e., mean bias) as the primary criterion for validity. Results: T-AUR, T-AXLe, T-AXLi, T-FOR, T-ORLe, T-ORLi, and T-TEM provided significantly lower measures compared to T-REC and fell below our validity criterion. T-GI significantly exceeded T-REC at three of eleven time points, but no significant difference existed between mean T-REC and T-GI across time. Only T-GI achieved our validity criterion and compared favorably to T-REC. Conclusion: T-GI offers a valid measurement with which to assess T-CORE during rest and exercise in the cold; athletic trainers, mountain rescuers, and military medical personnel should avoid other field expedient devices in similar conditions.