COMPARISON OF THE SHOULDER GIRDLE KINEMATICS DURING WHEELCHAIR SITTING AND STANDING TENNIS SERVING MOTION

M. Yoshimi¹, N. Maeda¹, M. Komiya¹, S. Tsutsumi¹, T. Abekura¹, Y. Urabe¹

¹Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan

Background: Wheelchair tennis is a para-sport played sitting on a wheelchair. A previous study reported that shoulder joint injuries occur more frequently in wheelchair tennis players than able-bodied players and are most likely to occur from maximum shoulder external rotation to ball impact during the serving motion (Martin et al., 2014). This is thought to be partly due to changes in the shoulder girdle kinematics resulting from restricted movement of the lower limb and trunk caused by wheelchair sitting. However, it is unclear what differences in scapular and glenohumeral joint motion occur in the wheelchair sitting and standing positions. If this difference in movement can be clarified, it might help prevent injuries in the serving motion of wheelchair tennis players.

Purpose: The aim of this study was to investigate the kinematics differences of the shoulder girdle during the tennis serving motion between wheelchair sitting and standing positions.

Methods: Twenty-one able-bodied male collegiate tennis players (age: 20.9 ± 1.4 y.o.; height: 170.4 ± 4.0 cm; weight: 59.6 ± 6.0 kg, tennis playing experience: 6.7 ± 2.7 years) were included in this study. Nineteen people were right-handed players, and two people were left-handed players. They performed flat tennis serves with maximum effort in two conditions: Wheelchair sitting and Standing. An electromagnetic tracking device (Liberty, Polhemus Inc.) was used to record the kinematic data of the scapular (external rotation, upward rotation, posterior tilt) and glenohumeral joint (horizontal adduction, elevation, external rotation) during cocking phase (arm elevation to maximum shoulder external rotation). Comparison between the wheelchair sitting and standing was performed using the paired t-test or Wilcoxon signed-rank test. The significance level was set at p<0.05.

Results: The scapular external rotation displacement of Wheelchair sitting was less than Standing (Wheelchair sitting: -3.6 ± 10.6°, Standing: 3.6 ± 9.3°, p<0.01) and the scapular posterior tilt displacement of Wheelchair sitting was less than Standing (Wheelchair sitting: 8.5 ± 5.4°, Standing: 11.1 ± 7.7°, p<0.05). In the glenohumeral joint, external rotation displacement was decreased in the Wheelchair sitting (Wheelchair sitting: 58.1 ± 22.7°, Standing: 65.3 ± 29.3°, p<0.05).

Conclusions: The scapular motion during the serving motion in the wheelchair sitting position showed a decrease in external rotation and posterior tilt compared to the standing position. Shoulder external rotation involves not only glenohumeral external rotation, but also scapular external rotation, upward rotation, posterior tilt, and mobility of the thoracic spine (Miyashita et al., 2010). It is considered that the decreased mobility of the thoracic spine associated with the wheelchair sitting prevented scapular external rotation and posterior tilt movement during the serving motion, and as a result, glenohumeral external rotation movement was also restricted.

Implications: The results showed that scapular external rotation and posterior tilt were particularly restricted during the serving motion in wheelchair sitting compared to the standing position. It is suggested that improving the mobility of the scapular may be important in preventing injury in wheelchair tennis.

Funding acknowledgements: We have no funding acknowledgement in this study.

Keywords:
Wheelchair tennis
Kinematic analysis
Shoulder girdle

Topics:
Sport & sports injuries
Musculoskeletal: upper limb

Did this work require ethics approval? Yes

Institution: Hiroshima University

Committee: Ethical Committee for Epidemiology

Ethics number: E-1952