It is how hard you are working while performing the activity

It is how long you are doing the activity.

It is what type of activity you are doing.

This principle states that the only way to gain health benefit through physical activity involvement is to place a higher demand on the body to exert more effort than it normally does.

This principle explains that the level of the intensity of your exercise should be increased gradually.

A principle that the body will adapt specifically to the workload it experienced. It implies that improvements in fitness level will be limited to the activities that one is performing.

A principle that states that no two persons are the same and that their rate of adaptation to the same workload differs.

It indicates that disuse or inactivity results in loss of benefits achieved in overloading.