Holy crap you make it feel like its easy.
I got hard time in making good proportion
 

dr. manhattan ? 

Thanks a lot!

I see! And I understand.

By the way, 8 heads is idealized proportions. Most real adult men are 7-7.5 heads tall. Many art instruction books don't make that distinction, so I figured I'd mention it. You are, of course, welcome to use whatever proportions suit your work.

I haven't read all this text, but the intention was study the muscles and create something like caricatures. I know that proportions are not right; the normal size for an adult is 8 heads, and his height is about 6. Anyway, thanks for writing this message and i'll read it and take note for the next time. :) Oh, and i'll change its name. xD

Since you titled this an anatomy study, I'm going to assume you were going for realistic, perhaps idealized anatomy here. The proportions are unusual for an adult human.

The legs are too short. The torso and arms seem proportioned okay (perhaps a bit wide, but not implausibly so), so I think just lengthening the legs would do the trick. A handy factoid to keep in mind is that the pubic mound will be roughly halfway up the body (if you measure from heel to the top of the head), perhaps a little bit below the halfway point, often stylised as being slightly above the halfway point. You have it way below the halfway point.

From the legs being too short, you're getting a few other issues, such as  the feet being on the small side, and the muscles looking cramped in there, because each muscle isn't getting the space it should be getting.

Speaking of the muscles - you did a good job conveying the form of the torso and arms, but it looks like on the legs you focused too much on showing the individual muscles, to the detriment of the legs as a whole. That is, the overall forms of the legs do not read very well, because you overdefined the muscles. It also looks like you have indents where the knees should be. Unless a character is extremely heavily muscled, the knee will tend to be a bump, not an indent.

The neck looks a bit thin to be attached to those muscular shoulders. It's not impossible, but it looks quite odd. People with developed trapezius muscles tend to have the other neck muscles also be developed, which makes for a thicker neck. People with very developed trapezius muscles will sometimes have the appearance of no neck at all, because it gets swallowed up, if you will, by the surrounding muscles, making a very smooth transition from the shoulders to the head.