Bear Size ~

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@brotherbear

In other words, post-prime brown bears (most likely all bears) can continue to gain muscle mass and maximum force without much muscle volume due to them being able to gain dense slow-twitch Ib fibers much easier, again, due to higher ERL levels.

Prime brown bears are able to gain muscle volume, but not as a fast rate as muscle mass or maximum force, that's why they look so huge and bulk at lower weights. At equal sizes/dimensions, the post-prime brown bear would most likely be much MUCH heavier than the prime brown bear due to, again, denser Ib fibres.

Fast-twitch fibers (IIa/x and IIb fibers) are larger in volume at the same mass than slow-twitch fibers (Ia and Ib fibers), and they produce the most change in force within the shortest time, not the absolute most force. IIa fibers contract forces very fast within the first second of activation, and IIb fibers, being even larger in volume within the same mass as IIa fibers, contact the same forces at an average speed 40% faster than IIa fibers.

Slow-twitch fibers actually have two functions: one for endurance/stamina, and one for a gradual contraction of brute force. Ia fibers are the former and Ib fibers are the latter. Ia fibers contract at maximum force depending on how many of those fibers the person has (hence, why a great marathon runner's muscles ache after a 2-hour marathon, and why a sprinter's muscles ache after about 40 seconds, if accounting for the same cardiovascular/respiratory endurance levels and weight: they each have an individual percentage of these Ia fibers.) Usually, the maximum force of Ia endurance-type fibers is 20% of the force displayed in either IIa/x or IIb fibers. Reply