Use of an ingestible telemetry sensor to measure core temperature under chemical protective clothing

The purpose of this study was to describe core temperatures measured by esophageal temperature and a swallowed telemetry sensor in women during exercise when wearing clothing with high thermal resistance (R-T, 0.4 m-(2).K-1.W-1). Resting esophageal temperature (T-es) averaged 37.11 +/- 0.21 degrees C and resting pill temperature (T-pill) averaged 37.17 +/- 0.27 degrees C. The combination of exercise (225 +/- 30 W m(-2)), clothing and ambient temperature (T-a = 30 degrees C) caused T-es to increase to an average of 38.67 +/- 0.28 degrees C and T-pill to increase to an average of 38.71 +/- 0.33 degrees C during the hour of treadmill walking. The two temperature measurements were compared by least squares regression techniques. For the eight individual experiments run, the regression coefficient (r) averaged 0.98 +/- 0.01. The calibrated temperature sensor ingested in these experiments provided accurate, usable core temperature data during logistically difficult experimental conditions. (C) 1997 Elsevier Science Ltd. All rights reserved.