Kinematic and EMG data during underwater dolphin kick change while synchronizing with or without synchronization of kick frequency with the beat of a metronome

We investigated the effects of synchronizing kick frequency with the beat of a metronome on kinematic and electromyographic (EMG) parameters during the underwater dolphin kick as a pilot study related to the research that entitled “Effect of increased kick frequency on propelling efficiency and muscular co-activation during underwater dolphin kick” (Yamakawa et al., 2017) [1]. Seven collegiate female swimmers participated in this experiment. The participants conducted two underwater dolphin kick trials: swimming freely at maximum effort, and swimming while synchronizing the kick frequency of maximum effort with the beat of a metronome. The kinematic parameters during the underwater dolphin kick were calculated by 2-D motion analysis, and surface electromyographic measurements were taken from six muscles (rectus abdominis, erector spinae, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius). The results revealed no significant differences in the kinematic and EMG parameters between trials of the two swimming techniques. Therefore, the action of synchronizing the kick frequency with the beat of a metronome did not affect movement or muscle activity during the underwater dolphin kick in this experiment.


a b s t r a c t
We investigated the effects of synchronizing kick frequency with the beat of a metronome on kinematic and electromyographic (EMG) parameters during the underwater dolphin kick as a pilot study related to the research that entitled "Effect of increased kick frequency on propelling efficiency and muscular co-activation during underwater dolphin kick" (Yamakawa et al., 2017) [1]. Seven collegiate female swimmers participated in this experiment. The participants conducted two underwater dolphin kick trials: swimming freely at maximum effort, and swimming while synchronizing the kick frequency of maximum effort with the beat of a metronome. The kinematic parameters during the underwater dolphin kick were calculated by 2-D motion analysis, and surface electromyographic measurements were taken from six muscles (rectus abdominis, erector spinae, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius). The results revealed no significant differences in the kinematic and EMG parameters between trials of the two swimming techniques. Therefore, the action of

Value of the data
Data comparing kick frequency with or without synchronization to the beat of a metronome on kinematic and EMG parameters during the underwater dolphin kick are provided.
There were no significant differences in the kinematic or EMG parameters between two trials which consisted of swimming freely at maximum effort and swimming while synchronizing the kick frequency of maximum effort with the beat of a metronome.
Synchronizing kick frequency with the beat of a metronome does not affect movement or muscle activity during the underwater dolphin kick.

Data
We provide a dataset showing differences in the kinematic and EMG parameters between two underwater dolphin kick trials: swimming freely at maximum effort (Maximum effort) and swimming while synchronizing the kick frequency of maximum effort with the beat of a metronome (Synchronized 100% frequency). No significant differences between the two trials were detected in any kinematic or EMG parameters (Tables 1 and 2 below).

Experimental design, materials and methods
Seven collegiate female swimmers (mean 7standard deviation (SD): age, 19.0 70.6 years; height, 1.64 70.05 m; weight, 56.7 73.3 kg) participated in this experiment. The experimental trials consisted of 15 m underwater dolphin kick swimming. Firstly, the participants swam freely using the underwater dolphin kick at maximum effort. Secondly, they swam using the underwater dolphin kick while synchronizing the kick frequency of their maximum effort with the beat of a metronome. A rest interval of at least five minutes was set between the two trials. For 2-D motion analysis, video of the sagittal movement was recorded by two cameras at a 100 Hz sampling rate. To evaluate muscle activity, the surface EMG of six muscles (rectus abdominis, erector spinae, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius) were measured using a wireless recorder with an 8-channel EMG logger (Biolog2, S&ME Inc., Japan). From all the collected data, the kinematic and EMG parameters were calculated according to the method described by Yamakawa et al. [1]. All data are reported as the mean and standard deviation (Mean 7SD). Statistical analyses were conducted using BellCurve for Excel (SSRI Inc., Tokyo, Japan). The normality of all data was confirmed using the Shapiro-Wilk test. A paired t-test was used to compare the kinematic and EMG parameter data between the two conditions. The statistical significance level was set at 5% in this work (P o0.05).

Transparency document. Supplementary material
Transparency document associated with this article can be found in the online version at http://dx. doi.org/10.1016/j.dib.2017.07.027.