When yousquat, for example, your glutes help distribute and share theload placed on your lower body with other muscles, like yourquads and hamstrings. If your glutes are weak, in other words,other muscles have to compensate

The soleus initiates slow contractions, while the gastroc initiates fast contractions. (Cordo et al., 1982)

The medial and lateral heads of gastroc function differently from one another; the medial head works much harder than the lateral head to eccentrically resist knee extension.

your power is initiated by the larger, stronger muscle groups in the central part of your body, whereas the smaller muscles of your extremities are used in fine movements and coordination (i.e., skills)

Well, as you descend into the bottom of the squat or lunge (in hip flexion and knee flexion), the rectus femoris is trying to lengthen at the knee but shorten at the hip, and ends up staying roughly the same length. Then as you ascend (performing hip extension and knee extension), the muscle is trying to shorten at the knee but lengthen at the hip, and again ends up staying about the same length. (3)