InsideHook: How Your Exercise as a Teenager Impacts Your Longevity.
That sucks since I was a skinny non athletic teen
The critical issue here I think is contained in the following:
Even in walk-happy Japan, exercise rates tend to decline with age. But “inculcating” an exercise habit in adolescence (to borrow a phrase from Tamura) increases the chance that one will keep moving into their middle-age and retirement years.
As long as one is relatively healthy/functional and willing to make exercise into a routine that persists throughout the remainder of life, I would argue that sarcopenia can be readily avoided.