First image seems to lack a bit of luster. It lacks contrast on the face as if the skin was overexposed a bit then taken back in post processing. I bet it's something you can fix though with a bit of curves.
Very nice montage. One thought, the weight in her right hand bleeds into the black background making it look small. Fitness folks probably don't want to look like they use tiny weights so it may be worth photoshopping that back a bit.
Nice images but I think it would have more effective visual balance as triptych if the left image was centered in its frame, the center image was a bit smaller and not so cramped looking, and the in the right frame you used an image of her facing left towards the center so when the eye scans left-to-right it stops rather than following her gaze out of the frame.
