I have really stuck on this exercise.
I can do 25 reps at once of this exercise. I can do 17 pull-ups in a bar (shoulder-wide grip). I can even do a clumsy rope climb:
but it is still impossible for me to progress and do 5 sets of 15 repetitions of ground rows, with the pace of the video (and also doing the mobility exercise at the same time). I could do it if I would rest 1 more minute between reps but this is a no-no.
Why is this happening? Is it because some muscle which is required from this exercise is really untrained? Is it an endurance issue?