I use they for surfing . it do work you out more and you do get tire more use they but that be only in the first 2 or 3 week . you do have to be careful because you can injury you shoulder if you try to use they with all you strength all the time . when I go out there without they I do feel stronger . they do not help to keep you warm , but they do not make you that much colder either , so there you go . - Chris