Energetic and Cognitive Demands of Treading Water: Effects of Technique and Expertise

Being able to tread water effectively can improve the likelihood of survival following accidental immersion. People tread water in various ways, ranging from rudimentary 'doggy-paddle' to more elaborate techniques like the eggbeater, but little is known about the energetic and cognitive requirements of treading wa-ter. We therefore aimed to measure the demands of treading wa-ter techniques for people of different experience levels. Three cohorts, comprising 21 adult water treading experts (water polo players), 15 intermediate swimmers and 16 inexperienced swim-mers, treaded water for 3 min each using four different tech-niques while cognitive and energetic economy measures were taken. For inexperienced swimmers, the flutter kick and breast-stroke patterns produced the lowest self-reported physical and task load (rating of perceived exertion, NASA task load index), while cognitive (probe reaction time), cardiac (heart rate) and metabolic (oxygen consumption) load did not differ between techniques. In contrast, for expert water treaders, both breast-stroke and eggbeater patterns produced lower cognitive, cardiac and metabolic loads. For intermediate swimmers, breaststroke resulted in the lowest cardiac and metabolic loads, as well as self-reported task load. Probe reaction time was highest while performing the eggbeater technique, indicating that this tech-nique was challenging to coordinate and cognitively demanding. While the energetic demands of antiphase kicking patterns (such as eggbeater in experts or flutter kick in beginners) may be sim-ilarly low, the symmetric coordination of upright breaststroke may explain why this pattern's cognitive economy was favour-able for all groups. As the eggbeater can be challenging to per -form for many people, an upright breaststroke technique is an adequate alternative to adopt in survival situations.