(1.School of Swimming,Beijing Sports University,Beijing 100084,China;2.National Demonstration Center for Experimental Sports Science Education,School of Physical Education,South China Normal University,Guangzhou 510006,China;3.School of Leisure Sports and Tourism,Beijing Sports University,Beijing 100084,China) Abstract: The purpose of this study was to examine the difference of maximum power (Pmax) or maximum velocity (vmax) in underwater dolphin kick (UDK) between sex or body position, and investigate the relationship between Pmax and vmax for UDK as well as exploring whether these two factors moderated the relationship between Pmax - vmax in UDK. Forty-night elite swimmers voluntarily participated in the research (29 male swimmers, age: 20.7±3.2 year; height: 1.83±0.05 m, weight: 78.1±8.6kg; 20 female swimmers, age: 19.6±1.7year; height: 1.71±0.04 m, weight: 61.6±6.2 kg). The subjects were required to participate in testing for Pmax and vmax in two kinds of body position including prone and supine, respectively. Using multiple linear mixed-effect models to evaluate the moderation of sex or body position on the relationship between Pmax and vmax for UDK. The results showed that: Males’ vmax and Pmax were significantly higher than females (vmax: P<0.01, ES=0.93; Pmax:P<0.01, ES=1.40); no significant difference found in body position(P=0.448, ES=0.05) between the prone and supine, but UDK’s Pmax in the supine was significantly higher than in the prone (P<0.01, ES=0.25). The association between Pmax and vmax for UDK was not adjusted by the effect of sex or the effect of body position. The conclusion was that the difference of Pmax and vmax of UDK in gender or body position may not moderate the relationship between Pmax and vmax for UDK, and the coaches and the athletes do not need to make a training program for UDK based on sex or body position when these two factors was not moderated the relationship between Pmax and vmax for UDK. Key words: sports biomechanics;underwater dolphin kick;maximum velocity;maximum power |