Placing a thermocouple on your arm while doing push-ups allows you to monitor the temperature changes on the skin's surface. A thermocouple can be placed anywhere on the body, but for the best results it should be placed on the muscles that work the hardest during the project, such as the biceps or triceps when performing push-ups or the quadriceps when completing squats.
Using rectal thermocouples in heat chambers that are heated to 35 C is a highly accurate means to measure internal body temperature. Subjects cycle on stationary bicycles as long as possible or for one hour while the project manager monitors their body temperature, not allowing it to surpass 39 C. For safety reasons, the project should be terminated if subjects complain of dizziness, nausea or pain because they are indications of a heat illness such as heat stroke. Timers are used to monitor how long it takes for the subjects' temperature to reach 39 C and to keep track of the time. Subjects must rest for 48 hours and then return to the laboratory. Room temperature should be maintained at 26 C. Subjects then ride the stationary bikes as long as possible or for one hour. A comparison of the data should indicate that heat significantly impacts performance.
For another project, sick friends or family members may volunteer to have their temperature taken using an oral thermometer; with argument, they may agree to the use of a rectal thermocouple as well. A standard oral thermometer works best when placed under the subject's tongue. Each thermometer alerts the user that the final temperature has been observed by beeping or flashing the temperature. Inserting a rectal thermocouple about 3 or 4 inches into the rectum will give you an accurate temperature reading. A comparison of the two temperature measurements should help you determine if the rule of adding 1 degree to an oral thermometer, raising an oral temperature reading from 98.6 to 99.6 F, is actually fitting.