Body Temperature Measurement Method Called Into Question

Main Category: Sports Medicine / Fitness
Also Included In: Medical Devices / Diagnostics
Article Date: 05 Jul 2007 - 1:00 PDT

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Temporal scanning thermometry may not be a reliable measurement of core body temperature, according to a study published recently in Medicine & Science in Sports and Exercise®, the official journal of the American College of Sports Medicine (ACSM). The method, now widely used in clinical and home settings, may be particularly ineffective in measuring internal temperature related to heat stress.

Temporal scanners involve the use of an infrared scanner to detect the highest temperature of forehead skin, presumably from the temporal artery. Based on that value, the device estimates core temperature.

In the study, 16 people dressed in a specialized body suit and were subjected to gradual heat stress to increase internal temperature. Temperatures were obtained with a temporal scanner and with an ingestible pill that tracks intestinal temperature. Pre-heat stress temperatures as well as temperatures throughout the heat stress were recorded.

Heart rate, skin temperature, skin blood flow, and sweat rate were all significantly elevated at the end of heating. Pre-heat stress temporal-derived temperature was not different from intestinal temperature. However, after 30 minutes of heating, temporal-derived temperature decreased to below pre-heat stress baseline, whereas intestinal temperature increased as expected. After 50 minutes of heating, intestinal-derived internal temperature remained increased, while temporal-derived temperature continued to remain below pre-heat stress temperatures. The research team believes these results demonstrate that temporal scanning does not accurately track internal temperature as compared to intestinal temperature when the temperature of the body is changing.

"We recommend temporal scanning not be used to assess core body temperature," said Craig Crandall, Ph.D., FACSM, an author of the study. "This is a critical issue during the summer months, as people are moving their exercise regimen outdoors and athletes are beginning training camp. Heat and activity combined can contribute to heat illness, and properly assessing core body temperature is crucial for diagnosis and treatment."

"During races, training, or indeed any exercise in hot weather, using the temporal scanner to measure body temperature in sick or even collapsed athletes-although quick and "easy"-may lead to erroneous diagnosis and life-threatening delays in treatment," added co-author Benjamin D. Levine, M.D., FACSM.

Heat injuries most often occur when people exercise in hot and humid conditions they are not accustomed to or exercise harder than usual in high temperatures. The heat generated by the muscles is not removed by sweat evaporation from the body in humid conditions and rising body temperatures are the end result.

ACSM Position Stands, "Exercise and Fluid Replacement" and "Exertional Heat Illness during Training and Competition," address preparation and prevention strategies for heat illness and injuries.

The American College of Sports Medicine is the largest sports medicine and exercise science organization in the world. More than 20,000 International, National, and Regional members are dedicated to advancing and integrating scientific research to provide educational and practical applications of exercise science and sports medicine.

American College of Sports Medicine