PURPOSE: To understand how menopause changes woman's nervous system and muscles. We also want to see if hormone therapy, structured strength training exercise, or a combination of both can protect a woman's strength and physical function during this transition.

PURPOSE: To better understand the cause of muscle fatigue across the lifespan and in people with specific conditions. We also want to determine whether participating in an exercise training program can improve muscle fatigue.

PURPOSE: To understand the cause of muscle fatigue in people with type 2 diabetes and prediabetes.