A move you can do in water aerobics to work out your hamstrings is the hamstring curl. I can do these, um usually in the classes I use the weights to do these. What you want to do is put the weights behind your knees. OK, so you're here, and you just want to pump up and down. Normally this is done in the deep end and you should wear a belt to keep afloat or have a noodle. You can tread with your arms but it's gonna be a little difficult. So you're here. And I usually combine this move with another move that I do. Your legs are going in a jumping jack motion. So I usually do about a minute of hamstring curls and then a minute of jumping jack legs. OK, and that way you can mix it up and you can get a more intense workout. So that's hamstring curls. A good set of weights will help you achieve a good exercise with the the hamstrings.