I did picture Tarzan as extremely muscular and large. I don't regard this as "muscle-bound" since the concept of being muscle-bound is silly. Bodybuilders do not lose any range of movement for normal activities. Scratching one's back may be impossible, but most athletic movements are not hindered at all by bodybuilding.
All NFL teams do it regularly. So do most other athletes. Even golfers are getting into it.
Although I did have initially, some inclination to regard Tarzan as more gymnast like because of his arboreal, I ultimately rejected this, because of his massive strength and fighting ability. Quick is nice, but size and strength rule the roost when it comes to fighting. That's why they have so many weight divisions in competitive fighting.
Tarzan is subject to the same principles of genetic strength and muscle size as is all mankind, no matter what his upbringing. Although strength is not absolutely dependent on size, they are very strongly corrrelated, and massive strength always means massive muscle size.
Tarzan's physical feats, battles, savagery, strength, etc. are so pervasive throughtout the books that I ultimately had to reject the slimmer, gynmast Tarzan for the massive muscled carnivore.
As we have learned more about weight training; and its benefits, and when we see the physiques on professional football players, who are very fast; professional and olympic wrestlers; professional boxers, etc., my own conception has been strengthened in my own mind as the most realistic, even considering the arboreal feats. I think few persons would regard the ape-man as being less than 200 pounds. If a 200 lb guy could sail through the middle terrace, so could a 260 pound one.
It wouldn't surprise me if ERB and/or readers who read these books at an earlier period than did I would regard Tarzan as less massive, since few bodybuilders or athletes had developed physiques anywhere near what is seen today. I discovered Tarzan in the 1960's, and modern super-bodybulders were getting going at that time. To me, the ape-man had to be physically comparable to superior to these weak, civilized creatures; and not just because of his maturation.
Tarak