Cellular muscle size

Question

We know that individual muscles cells can either be fully active to their greatest potential or completely off, there's no such thing as partial activation.

We also know that strength training recruits more muscle fibers at a time depending on the force needed, that's why larger muscles are usually stronger, think glutes vs biceps.

Muscle growth usually happens by muscle cells getting bigger from being put under tension.

So my question is : Do big muscle cells output more force than small muscle cells or are they just more resistant to stress?

This is not related to other questions like ''how does muscle size relate to strength'' or ''are bigger muscles stronger'' because those questions are usually about the entire muscles, while this one is about the individual muscle cells and anyway most of the answers are just ''reps in the range of X build strength and reps in the range of X build muscle''.

Answer 1

Everything else being equal, sure, a myocyte (muscle cell) with more myofibrils (fibers) will be stronger than one that has less. But that's a really narrow statement that dodges the other elements of force production.

Just to start with some background:

A newborn baby has more muscle cells than a 30 year old pro body builder, it's the size of the myocytes (muscle cells) that increase.

As the myocyte increases, cellular components like myofibrils increase. Additionally, the cells contain more intracellular bodies such as mitochondria and house more glycogen. This is why trained muscles get bigger.

Greg's answer from 2011 does a good job of explaining why a big body builder can be weaker than a smaller strength athlete. The general deal is that there's more to force production than muscle size. Indeed, body builders aren't even trying for maximum recruitment at once (total strength, low rep range).

Your specific question however was:

Do big muscle cells output more force than small muscle cells or are they just more resistant to stress?

Maybe, but it's not really causal, since muscle cells don't create force, they're a component of an overall chain that creates force. Calcium uptake, ATP, total recruitment, and neural pathways are all involved as well. So big muscle cells with everything else wrong won't produce more force than smaller muscle cells.

I don't even necessarily understand your conclusion that they're more resistant to stress. What kind of stress? Muscles and connective tissue tend to be able to tolerate loads and ranges of motions they've been exposed to, and do a lesser job with anything else.