Muscular growth and genetic limit

Question

Many people go by the belief that people have a genetic limit for how much muscle they can build in a lifetime and the closer they get to the limit the slower they gain muscle.

I wanna know what logical argument and thought process created this idea since there seems to be no scientific evidence that can be found.

What seems more logical is that if someone grew from a 5×5 the first year, the next year, way more volume might be needed to replicate the ‘newbie’ gains. And as years go by, the volume requirement goes up higher. There the limit is physical age and mental toughness, not genes.

Answer 1

One's muscle potential appears to be limited by one's body frame. People with small bone structures aren't able to build as much muscle as people with really large bone structures. In experiments measuring top athletes muscle to bone ratio, they all seemed to have gone up to a certain point and just... stopped. As noted:

“One bookcase that is four inches wider than another will weigh only slightly more. But fill both cases with books and suddenly the little bit of extra width on the broader bookcase translates to a considerable amount of weight. Such is the case with the human skeleton.

“In measurements of thousands of elite athletes from soccer to weight lifting, judo, rugby, and more, Holway has found that each kilogram (2.2 pounds) of bone supports a maximum of five kilograms (11 pounds) of muscle. Five-to-one, then, is a general limit of the human muscle bookcase. The limit for women is closer to 4.1 to 1.

“Holway experimented on himself, spending years in heavy weight training with a diet high in protein and supplemented by creatine. But as he closed in on five-to-one, inhaling more steaks and shakes only added fat, not muscle.”

This seems to indicate that one way to build a massive amount of muscle is to grow your bones (Drink your milk kids!). Of course weightlifting will increase the density of your bones to some degree, but the overall size seems to be pretty much set in stone. We reach peak bone mass in our late teens and early twenties. After that there isn't any known way to dramatically increase bone mass like we can increase muscle mass.

Answer 2

Interesting question.

Big muscle is kind of cost for the body. It obvious that, when not used it shrinks. When new stimulus appears body adopts by building muscle. Then, somehow like in business there is time for cost optimisation...

Hormones, food plays role here, but still, that is more about levels, not limits. We are not fishes, so our body is not growing whole life. Longer muscles brings more space, so potentially the limit is higher, but still we are only humans :)

To be a bit more precise. Fast twitch fibers require energy to stay relaxed. That is a bit of simplification, however after death muscles twitch, and that is due to lack of active relaxing. Even if not precise - it shows that there are costs, not only while exercising, but at while sleeping as well. So I would expect that the cost can be so high that stops any grow.

Long running constant progress has some problems. First our body optimises to deal with training. Age has influence on hormones, and them on muscle building regeneration. Our joints are not made of steel, so constant grow brings stress also there. On the other hand - our body tries to deal with training with minimal effort, removing all not needed cells...

Hope I've helped.