Let’s say you can only build 5lbs of muscle per year (arbitrarily chosen number). Say 2lbs of that can go towards upper body and 3lbs can go towards lower body, if you stopped training lower body would the amount you can put towards your upper body increase to say - 3lbs?
Similarly, assuming an FFMI of 25 is the maximum natural limit, does that assume even distribution over your entire body? If someone never trained legs could they theoretically achieve an FFMI of 25 but just carry way more muscle in their upper body?
The question makes me think of bench only competitors. Are they stronger in bench than full body competitors because their bodies don’t have to spend as much muscle building allowance on lower body or is it just because they can dedicate more training time to bench?
Not really, as there appears to be a carrying capacity for muscle given a particular skeleton size. Since this doesn’t change, I don’t think the amount of muscle you can put on in a given year really changes- though this varies wildly.
I don’t assume FFMI of 25 is the max natural limit and I wouldn’t assume even distribution over the entire body either, as people will carry different amounts of muscle in different proportions.
Bench only competitors aren’t necessarily stronger than lifters who do full meets in the bench press, though this depends on the class, fed, and equipment. I’d assume any differences are related to genetics, opportunity, and resources dedicated to training.