When I use the phrase "be more aggressive" to an athlete, generally I mean they need to be quicker, more explosive in their movements. In many cases, the athletes are hesitant to go as hard as they can due to fear of injury, or lack of knowledge or confidence in the skill.
Other times though, that lack of explosive power is not a lack a psychological constraint, but instead a physical constraint. Muscular Power is the result of muscular strength AND the speed in which a muscle can be contracted.
To test and see if the issue is psychological or physiological, I generally have an athlete do a few straight jumps with an arm swing. If the athlete has a high straight jump, with correct movement patterns, I know that he issue is individual and will try breaking down the skill and teach it in a different way, perhaps give visual demonstrations for visual learners, or specific drills for kinesthetic learners.
However, I see that the athlete does not do the straight jump with correct movement patterns, or does have good movement patterns but does not go anywhere, I know I need to work on strength and coordination with that cheerleader.
I hope this helps!
-Coach Matt
Full-Out: Cheer & Fitness