your drawings seem to establish pretty well the force of the pose.
I suggest you should take more importance to the legs since they don't seem to distribute the weight of the person you are drawing, one suggestion is to draw one vertical line from a man's torso and then distribute both feets in equal distance from that line, in case the weight is on one foot draw it in the center of that line. One more thing, don't draw each muscle yet, each curve is supposed to be based on the previous curve and give it fluidity, your approach was more building them based on memory and it disrupts the dynamysm of the drawing.
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