I don't understand why you would have to feel heavier, i think you would feel lighter, especially if CNS firing improves
If you suddenly lose mass, then yeah.
So what do you think about the Squat Dr. guy, 200 lbs squatting 600+, while still developing forces at a high rate (he sprinted as well and reported fast times, believing it or not is another thing). His body seriously thinks he is "heavy" when he is developing such forces? Of course there are countless other examples of people like this, such as many football players, sprinters (maurice greene, chambers (who has a huge vert, huge squat, and a lot of muscle mass).
If I move to Jupiter for 3 months, then come back here, I should feel lighter, not heavier despite gains in muscle mass. If I go on a spaceship flight to the moon, and lose bone/muscle mass, i will be lighter, but feel heavier.
If I jump around on a trampoline for a while, I feel heavier even though I perceived myself to be lighter while on the trampoline. After a set of 3 of squat jumps, I feel lighter, despite feeling heavier with a lot of weight on my back.
Which systems coordinate these 'feelings' is my real question.
I see the analogy of higher muscle mass compared to an engine, but it seems like you're comparing the CNS to that engine with is not analogous, it should be the heart you're talking about, and the CNS the driver of the car. If your strength, especially explosive strength keeps increasing, how can the muscle mass be considered a burden? Furthermore if we are performing explosive strength training the tendons are hypertrophying as well and this results in further strength gains so the discussino should not just include muscle.