- It allows fast glucose clearance from blood via both insulin and non-insulin glucose transport.
- It drives bone density by pure mechanical tension. More muscle = stronger bones/tendons to support them. The usual hip fracture/high mortality we see in elderly people follows the loss of muscle mass->loss of bone strength->bone breaks->fall pathway, not the more intuitive fall->bone break.
- It serves as "organ reserve". In case of injury or disease, your muscle mass will literally keep you alive. There are some interesting studies about muscle mass on admission to the ICU and mortality/morbidity. This is the extreme case, but you get the picture.
- Not per-se, but the neurological effort you put in your weight training sessions drive the secretion of Brain-derived neurotrophic factor (BDNF). BDNF improves existing neurons signaling and promotes the creation of new ones. As a side note, I have seen a huge improvement in my - properly diagnosed - ADHD child after putting him in a functional "lift heavy shit" exercise program.
