Heart rate recovery
Heart rate increases with high levels of activity and, with the termination of activity, returns to normal resting heart rate. Measuring the heart rate (pulse) for the first 30 seconds after exercise, then multiplying by two, gives number of beats per minute or bpm. HHR varies with fitness, and is gender and age specific, but an expected rate of recovery can be anticipated according to these variables.
Failure to follow the expected HRR for gender and age indicates that the individual may be seriously fatigued or have a high core temperature. This test is an effective way to measure if a person is at risk of heat stroke.
Dehydration can also be detected using HRR. The heart rate normally increases when moving from a sitting to a standing position. If the heart rate increases by more than 20 bpm then the person is very likely to be dehydrated.