Kinematic Analysis of Synchronized Skaters During the Off-Ice Execution of Spiral and Spin Tasks.

The primary objective of the present study was to examine differences and associations in joint angles and segmental swings during the off-ice execution of one static (spiral) and one dynamic (spin) sport-specific balance task and to determine whether motor control strategies differ when participants perform the tasks on their dominant and nondominant legs. Junior synchronized skaters (n = 15, age = 16.3 ± 1.5 years, years of practice: 9.8 ± 2.8 years, 10 females) performed spiral and spin tasks three times with 60 s of rest allowed between each trial. Participants' movements were captured using an optical-based motion capture (MoCap) system that utilized 39 skin-attached retro-reflective markers. Our results indicate no differences in synchronized skaters' kinematic features when the spiral task is performed on their dominant versus nondominant leg (p > 0.05). However, the results of Spearman's correlation analyses suggest different motor control strategies between the various body segments during right- versus left-leg task execution. In addition, participants produced a larger swing with their left versus right arm, regardless of whether the spiral task was performed on the dominant (39.97 ± 10.32 vs. 30.22 ± 7.80, p < 0.001) or the nondominant (52.88 ± 13.65 vs. 37.12 ± 9.59, p < 0.001) leg. Lastly, the association between the knee angle of the supporting leg and the swing of the head (ρ = -0.54; p = 0.038) suggests that the greater the knee angle of the support leg during the spins, the less compensatory head swing was needed during the task.