Head-Out Water-Based Protocols to Assess Cardiorespiratory Fitness—Systematic Review

The aquatic environment offers cardiorespiratory training and testing options particularly for individuals unable to adequately train or test on land because of weight bearing, pain or disability concerns. No systematic review exists describing cardiorespiratory fitness protocols used in an aquatic environment. This review investigated the different head-out water-based protocols used to assess cardiorespiratory fitness. Our comprehensive, systematic review included 41 studies with each included paper methodological quality assessed using the statistical review of general papers checklist. Diverse protocols arose with three major categories identified: conducted in shallow water, deep water, and using special equipment. Thirty-seven articles presented data for peak/maximal oxygen consumption (VO(2peak)/VO(2max)). Twenty-eight of 37 studies predefined criteria for reaching a valid VO(2peak)/VO(2max) with shallow water exercise demonstrating 20.6 to 57.2 mL/kg/min; deep water running 20.32 to 48.4 mL/kg/min; and underwater treadmill and cycling 28.64 to 62.2 mL/kg/min. No single, accepted head-out water-based protocol for evaluating cardiorespiratory fitness arose. For clinical use three cardiorespiratory fitness testing concepts ensued: water temperature of 28–30 °C with difference of maximum 1 °C between testing participants and/or testing sessions; water depth adapted for participant aquatic experiences and abilities; and intensity increment of 10–15 metronome beats per minute.