... One of the problems is that some of the studies involve passive CWI [46,47,52,54,56,58,61,[63][64][65]71,72,76,77,81,85,[96][97][98], while others deal with active CWI [42,45,50,55,57,62,[66][67][68][73][74][75]79,82,[86][87][88][89][90][93][94][95]. Many of the research studies were based on cold adapted winter swimmers [41,67,68,71,75,77,82,85,86,[88][89][90]94,95]. Other investigations on the beneficial effects of regular CWI were performed on subjects with no previous experience [46,47,52,54,[56][57][58][63][64][65]69,70,[72][73][74]76,81,87,92,93]. ...