If a muscle is already at about 80 of its resting length it cannot be stimulated to contract any more because?

When a muscle is at about 80% of its resting length, it is said to be at its optimal length. This is because the muscle fibers are able to generate the most force when they are at this length. If the muscle is stretched beyond its optimal length, the force generated by the muscle fibers decreases. This is because the muscle fibers are not able to contract as effectively when they are stretched.

Additionally, when a muscle is stretched beyond its optimal length, it is more likely to be damaged. This is because the muscle fibers are more likely to tear when they are stretched. Therefore, it is important to avoid stretching muscles beyond their optimal length.