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

Abstract

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.

Keywords: biomechanics; kinesiology; motor control; team sport; youth.

FIGURE 1

Experimental setup. (Panel A and B) 3D avatar of a representative subject during the spiral and spin tasks, respectively. (Panel C) Schematic illustration of the placement of the reflective markers for motion capture measurements. Adopted from (Pálya and Kiss 2018). Head markers: LHBD/RHBD, left/right posterior head; LHFD/RHFD, left/right anterior head. Torso markers: C7, cervical spine vertebra 7; CLAV, sternum xiphoid process; RBAK, right side of the back (not an exact location, only to aid with sides); STRN, sternum jugular notch; T10, thoracic spine vertebra 10. Upper extremity markers: LELB/RELB, left/right humerus lateral epicondyle; LFIN/RFIM, left/right hand second metacarpal; LFRM/RFRM left/right lower arm (not an exact location, only to aid with segments); LSHO/RSHO, left/right clavicle‐acromion joint; LUPA/RUPA, left upper arm (not an exact location, only to aid with segments); LWRA/RWRA, left/right radius styloid process; LWRB/RWRB, left/right ulna styloid process. Lower extremity markers: LANK/RANK, left/right lateral malleolus; LASI/RASI, left/right anterior superior iliac spine; LHEE/RHEE, left/right heel (bisection of the distal aspect of the posterior calcaneum); LKNE/RKNE, left/right knee (lateral epicondyle of the femur); LPSI/RPSI, left/right posterior superior iliac spine; LTHI/RTHI, left/right thigh (not an exact location, only to aid with sides); LTIB/RTIB, left/right shank (not an exact location, only to aid with sides); LTOE/RTOE, left/right toes (between the distal ends of the 1st and 2nd metatarsi).

FIGURE 2

Differences between the swings of the arms during the spiral task. Swing of participants' left versus right arm, regardless if the spiral task was performed on their dominant (Panel A) or the nondominant (Panel B) leg. The violin plots (transparent color) over the boxplots represent the data distribution. The boxplots show the median, the upper, and lower quartiles and the min and max values. Red error bars within the boxplots represent the 95% confidence interval (CI) around the mean (red dot). Each data point is an individual token: the horizontal jitter is not meaningful and is only used for visualization purposes. *** indicates differences between the left and right arms in both standing conditions (p < 0.001). The graphs were created using RStudio software (version 2023.12.0 + 369) (Team 2020).