We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
We have discussed the topic in the past. Muscle degradation occurs partly from disuse, but also from age. It ramps up in middle age. Low energy, feebleness, frailty, and bone fragility are the final results. The older you get, the more difficult it becomes to build and maintain muscle functioning so the ideal approach is to get on board before the deterioration becomes measurable.
From what is known now, only intense physical effort can delay it (ie heavy weights, sprints, maybe high-volume anaerobic calisthenics, and the like. Comfortable or aerobic exercise doesn't help). Many claim it can be reversed to some extent, and I think it can.
We will all experience a 10% decline in muscle mass between the ages of 25 and 50 and a further 45% shrinkage by our eighth decade – if we do nothing about it. To illustrate this decline by example, the biceps muscle of a newborn baby has around 500,000 fibres while that of an 80-year-old has a mere 300,000. As we age, we also produce less growth hormone, which leads to reduced levels of protein synthesis and, again, muscle atrophy. This is not the kind of acceleration needed by the veteran athlete in search of speed, as decreased muscle equates to reduced strength and power and less ‘oomph’ ...
That is from a somewhat grim article explaining physical performance and ageing, mainly focused on running but applicable to all physical activity. Yes, high-intensity exertion does raise levels of growth hormone, and that is good.
They also recommend supplemental creatine for middle-aged, and above, heavy daily exercisers. There is good evidence for its helpfulness. Especially for those over age 30, supplemental creatine (naturally found mostly in red meat and especially in rare red meat) permits a higher level of intensity of exertion for sprinting and weight-lifting, resulting in more muscle stress, resulting in stronger muscle repair (protein synthesis) during a recovery day or two.
Strength Training Helps to Stop Age Related Muscle Loss. Mind you, "training" means it is unpleasant and highly aversive for good reason: it's hateful, stressful work requiring delayed gratification, not recreation. Not for everybody (obviously).