A physical activity data collection unit includes one or more infrared sensors configured to provide an output indicative of a pulse rate of a user of the physical activity data collection unit, at least one temperature sensor configured to provide an output indicative of at least a body temperature of the user, and at least one accelerometer configured to provide an output indicative of movements of the user. The physical activity data collection unit can also include a microcontroller configured to determine a pulse rate, a body temperature, and movement characteristics of the user of the data collection unit based on outputs from the one or more infrared sensors, the at least one temperature sensor, and the at least one accelerometer; determine a physical exertion level of the user based on one or more of the pulse rate, the body temperature, or the movement characteristics of the user; and store, in a memory, data indicative of the physical exertion level during a time period during which the physical exertion level exceeds a predetermined threshold.