Answer:
When the muscle is completely contract.
Step-by-step explanation:
Remember the that maximum force of a muscle is when is completely contract. A characteristic of a muscle is that can contract and can relax in the opposite direction. In this way, when all the microfibers of the muscle are join together (they are contract) is when the maximum tissue force is applied.
With exercise the fibers of the muscles can grow or reproduce to strength the muscle.