Final answer:
Power output required for an activity must equal the body's power production, and when production cannot meet the output demands, exercise intensity must be reduced. Power is the rate at which work is done, and the body's energy delivery determines its production for activities.
Step-by-step explanation:
The power output required for a given activity has to be matched by the actual power production for every activity from rest to maximal. The moment that power production fails to meet what is needed the person must reduce the intensity of the exercise.
In the context of physics and human physiology, power is defined as the rate at which work is done or energy is transferred. When we think about exercise, such as climbing stairs or sprinting, we're referring to the power output of the human body.
This output must be sufficient to meet the demands of the activity. During exercise, the body's energy stores and the ability to deliver energy efficiently determine the power production.
The relationship between energy (E), power (P), and time (t) is described by the formula E = Pt. Intense activities, like sprinting, require high power output, which can only be sustained for short durations due to the body's limited energy reserves.