These are looking pretty good, but a common problem among your sculpts is that your final model looks just like your base mesh + high frequency detail. Don't skip to the highest resolution and start painting in veins and all that if the fundamental forms of the muscles aren't there yet.

Try to work iteratively, subdivide, sculpt, subdivide, sculpt, etc. It's just too fluid and mushy - but no worries, it's an easy fix and most people do it when they first start sculpting.