Muscle Memory?

The old mind/body dichotomy is now under serious threat. It's long been known that the brain and the body's immune system 'talk' to eachother. It's also been argued, for decades, that exercise has major benefits for mental health. Devi Sridhar (University of Edinburgh) has recently detailed some of the supposed benefits of 'myokine' release (https://www.theguardian.com/commentisfree/2023/may/04/exercise-mental-health-hope-molecules-mood-strength). Myokines are short polypeptides (sequences of amino acids), released into the blood stream when muscles contract. These small chemicals cross the blood-brain barrier (a mechanism that keeps out larger molecules), where they can act as antidepressants. Elevating the myokines appears to improve mood; make our capacities for both learning and performing motor activity better, as well as protect the brain from some of the negative consequences of the aging process. Myokines are even said to improve metabolism, reduce inflammation and increase muscle strength. Short polypeptides as easy to manufacture. So they may well be synthesised to replace some of the traditional antidepressants. Such compounds would, of course, have to be given by injection. If given orally, they would be broken down into their constituent amino acids. Exercise, of course, doesn't just change myokine levels. It also releases mood-altering neurotransmitters (like serotonin and dopamine), as well as a family of pain-relieving endorphins (peptides with opiate-like actions). Actual exercise, may still the best way of helping to maintain mental health for most folk?