My research is on the effects of yoga (quite unusual research field). There is very little research on the hormonal effects of yoga (small studies shows increased GABA and decreased cortisol). This small indian study shows that oxytocin increased after yoga therapy
Oxytocine also boosts muscle generation and assists in healing
Higher oxytocin levels means that more muscle mass is maintained with older age and possibly performing yoga prevents this muscle loss. More research is definetely needed in this area.