Butt muscle in free and back, relaxed or not?

Lie on your stomach and ask someone to watch you lift your left leg, and then your right leg, straight up just a little. They should be able to see if you are using your lower back or your butt to initiate the lifts. I did that for a chiropractor at a swim meet and he told me I was using my lower back to lift my legs, not my butt, and that this was hurting my back. He gave me butt-strengthening exercises. So yes, I think using your butt for kicking is a good idea. The main exercise: lie on your stomach, both legs bent so calves are at 90 degrees to floor. Clench your butt and lift your legs (keep thighs pretty much parallel to floor, except to the extent you lift them slightly), one at a time, alternating, maybe 15 times one leg, 15 times the other, toward the ceiling. You'll feel it the next day. No awareness of this while swimming, but I think once the exercises get your muscles used to engaging this way you'll have a better kick and a stronger back.

Lie on your stomach and ask someone to watch you lift your left leg, and then your right leg, straight up just a little. They should be able to see if you are using your lower back or your butt to initiate the lifts. I did that for a chiropractor at a swim meet and he told me I was using my lower back to lift my legs, not my butt, and that this was hurting my back. He gave me butt-strengthening exercises. So yes, I think using your butt for kicking is a good idea. The main exercise: lie on your stomach, both legs bent so calves are at 90 degrees to floor. Clench your butt and lift your legs (keep thighs pretty much parallel to floor, except to the extent you lift them slightly), one at a time, alternating, maybe 15 times one leg, 15 times the other, toward the ceiling. You'll feel it the next day. No awareness of this while swimming, but I think once the exercises get your muscles used to engaging this way you'll have a better kick and a stronger back.