When I talk about loosening up, the lines quality (to me) is very precise and clean. When you look at the definition of a gesture line, they "allow the artist to capture a subject's movement, form, and character". I think you are definitely capturing the form in the exercises but because of how clean and precise those lines are, the images seem more static. Uploading an example of what I mean by messy from another artist that more matches how I tend to work. If you do try to change up what you're doing, I don't recommend trying to do all of your drawings in the new way. Just try a couple a day and see how it feels.
Don't take my word as gospel. I know everyone learns differently, so do what you need to do to understand the human body. This may even come naturally the more you practice or as you get to the anatomy classes.
Hope this clarifies a bit, sorry my reply was so vague!