Abstract
Introduction Power production is suggested to be an important factor in successful sports performance. Athletes develop their power through training force production and velocity. Force production is seen to be a determinant in several sports, however its role in the sport of judo and throwing techniques is relatively unknown. More specifically, its impact on the kuzushi phase of a judo throw and its relationship to pulling kuzushi has not been thoroughly investigated. Preliminary research appears to suggest a relationship between the timing of ground reaction forces (GRF) and pulling velocities, but the true nature is yet to be understood.
Purpose
The current study was conducted to compare the relationship between peak GRF and peak pulling velocities. Additionally, timing characteristics and pulling velocities were compared between advanced and novice judo players.
Methods
Fifteen judo players were recruited to be a tori, and one advanced judo player served as uke to receive all throws. Participants were outfitted with reflective markers placed throughout their bodies for kinematic measurements using eight high-speed infrared cameras. They were asked to stand opposite the uke, upon a surface, above two synchronized force plates. The tori was instructed to perform the ippon seoi-nage throw with maximal effort. For data analysis, the measured portion of each trial would begin when tori initiated a forward step, and ended when both feet came in contact following their turn. Peak resultant GRF (GRFR) and peak resultant wrist velocity (Vwrist) were analyzed for correlation. Linear mixed models were created determine the effects of height, gender, years of experience, and rank on the following variables: time to peak wrist velocity, GRFR, Vwrist, and uke’s peak resultant COM velocity (Vuke). For all models, significance was set at p < 0.05. Differences between the advanced and novice groups were determined using independent t-tests also set at p < 0.05.
Results
No significant correlation was found between GRFR and Vwrist (r = -0.08, p = 0.77). There were no significant differences between groups for time to peak wrist velocity (p = 0.97), Vwrist (p = 0.81), and Vuke (p = 0.66). The linear mixed models also determined there to be no significant effect on any variables (p > 0.05).
Conclusion
The role of force production during kuzushi in the ippon seoi-nage throw does not appear to be significant however future investigations should be conducted to observe possible influences on the tsukuri phase. In regard to pulling velocities and timing characteristics, lack of differences may suggest that the ippon seoi-nage throw can be performed in various ways, which may offer different explanations behind a skillful throw.