This is a trivial question but I would like to have it answered anyway. Why are some of my muscles hard as a rock (like my chest), while other muscles (like my bicep) are a little softer? By hard or soft I mean that if I were to flex the muscle one would be completely rigid, while the other would show some elasticity. Is this any indicator of muscle twitch? (By the way, fat wouldnt be a reason for the 2 different states in my case.) Thanks in advance.
There may be several contributing factors, but a major one may be variances in INTRAMUSCULAR (NOT subcutaneous) fat amongst your various muscle groups. Hope that helps.