Question

Explain why exercise programs must increase in difficulty and duration over time to remain effective.

Answer 1

They must increase in difficulty and duration over time to be more effective, because the harder and longer something is, your pushing yourself to do it, and you eventually get used to it.

Answer 2

its because your body gets used to your exercise over time and it becomes less and less effective, and you body begins to think its easy. That is why it is important to challenge yourself and go above your limits.