Question

Joints may be prepared for vigorous physical activity through:

-Stretching
-Muscular strength
-Muscular endurance
-Cardio workouts

Answer 1

I think the answer is stretching. It is good to stretch the muscles before you do a intense workout. You must prepare your muscles and get it started. Do the workout easy and slowly for your body to get use to then once you have enough energy then kick up to either medium to hard to intense workout. 

Answer 2

Joints may be prepared for vigorous physical activity through stretching. Because stretching preps the joints for vigorous workouts.

I hope this helps!