Forwards-backwards hand velocity induced by the upper trunk rotation in front crawl strokes and its association with the stroke frequency

ABSTRACT

The aim of this study was to determine the contribution of the upper trunk rotation consisting of roll-pitch-yaw to hand velocity in the forwards-backwards direction during front crawl strokes and to investigate the association of forwards-backwards hand velocity induced by the upper trunk rotation with stroke frequencies. Fifteen skilled swimmers with retro-reflective markers performed front crawl strokes in a swimming pool where a motion capture system was set. Forwards-backwards hand velocity solely induced by the upper trunk rotation was determined during the performance. In the pull and push phases, 28% and 19% of the backward hand velocity was induced by the upper trunk rotation, respectively, while 19% of the forward hand velocity resulted from the upper trunk rotation in the recovery phase. The upper trunk rotation contributed to the forwards-backwards velocity as much as the elbow joint and was the second primary source of backward hand velocity in the pull phase. The forwards-backwards hand velocity created by the upper trunk rotation was associated with the stroke frequencies (r = 0.56, p < 0.05). The forwards-backwards hand velocity induced by the upper trunk would influence hand propulsion and stroke frequency so that a swimmer and coach should consider this performance-enhancing variable.

KEYWORDS:

• Upper trunk contribution
• upper extremity rotation
• roll-pitch-yaw

Acknowledgments

The authors are grateful to Dr Yasushi Ikuta, Osaka Kyoiku University, and Dr Hiroshi Ichikawa, Niigata University of Health and Welfare, for supporting the measurements in the present study and to Mr Flex Chia, Republic Polytechnic, for providing artwork and to Republic Polytechnic for financially supporting this research. This work was supported by MEXT KAKENHI under Grant 26750301.

Disclosure statement

The authors have no conflict of interest to the manuscript entitled “Back-and-forth hand velocity induced by the upper trunk rotation in front crawl strokes and its association with the stroke frequency”.

Additional information

Funding

This work was supported by the MEXT KAKENHI [26750301].