What is the rationale for having the individual maintain a moderate isometric contraction of the upper arm and forearm musculature during the application of the elbow hyperextension taping techniques?

For the prevention of musculature.

Explanation:

The isometric contraction does not change the muscle length and joint angle remains constant. These are mainly done in the static positions.

The elbow hyperextension taping techniques, the individual maintain isometric contraction of upper arm. The main rationale is to prevent the musculature constriction by the tape techniques.