THE ACUTE EFFECTS OF VIBRATION STIMULI TRAINING ON SENSORIMOTOR CONTROL OF THE SHOULDER COMPLEX

S. Kotoshiba¹, Y. Urabe¹, M. Morikawa¹, M. Yoshimi¹, N. Maeda¹

Background: Shoulder functional stability requires an exquisite balance of active and passive forces by the muscle and joint structures and is regulated by the sensorimotor control system of the shoulder (Myers et al., 2008). The sensorimotor control is expressed as static and dynamic stability and allow evaluating in detail by measuring the associated muscle activity. Whole-body vibration (WBV) improves neuromuscular performance by inducing involuntary reflexive contractions via the tonic vibration reflex (Mester et al., 1999). In previous study, WBV enhanced both shoulder muscle function and proprioception; however, the impact of vibration on the sensorimotor control of the shoulder joint remains unclear.

Purpose: To investigate the acute effect of vibration stimuli on muscle function and sensorimotor control of the shoulder joint.

Methods: Fifteen healthy male university subjects participated in this study. Each participant performed the exercise in a modified push-up position with partial weight-bearing with and without vibration stimuli. Their hands shoulder-width apart, elbows extended, were pressed firmly against the middle of the vibration platform. The vibration protocol included 6 sets of 30 s with a rest of 30 s between sets. Main outcome measures were:
1) the center of pressure velocity over 30 s in the push-up position with their hands on the force platform as the upper limb static stability test,
2) Upper Quarter Y Balance Test (UQYBT) score as the upper limb dynamic stability test, and
3) electromyography data of the upper limb during UQYBT pre- and post-exercise.
We determined the effects of the intervention on all the outcome measures using 2-way repeated-measures analysis of variance (ANOVA) with the conditions (vibration, control) as a between-participants factor and time (pre-exercise, post-exercise) as a within-participants factor. The significance level was set at 5%.

Results: Vibration condition resulted in a higher increase in the UQYBT score (all directions) (P<0.01) and infraspinatus, serratus anterior, and lower trapezius muscle activity (P<0.05) between pre- and post-exercise than the control condition. The stabilometric parameters were no significant interaction between condition and time.

Conclusion(s): This is the first study to examine the effect of vibration stimuli on the sensorimotor control of the shoulder joint in young healthy men. Our results indicate that exercise with vibration stimuli more effectively increased muscle activity in the rotator cuff muscle and scapular stability muscle and improved the dynamic stability of the upper limb than exercise without vibration stimuli. Vibration stimuli could maximize training gains while limiting injury risk for athletes. Our findings could guide the development of rehabilitation programs for patients with shoulder instability.

Implications: In clinical practice, our results confirmed that rehabilitation of the sensorimotor control system, including proprioception, and neuromuscular rehabilitation exercises should be performed when rehabilitating the shoulder. Patients with shoulder instability and pain can be efficiently rehabilitated using closed kinetic chain and plyometric exercises with vibration stimuli.

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

Keywords: vibration stimuli, sensorimotor control, shoulder stability

Topic: Musculoskeletal: upper limb

Did this work require ethics approval? Yes

Institution: Hiroshima University

Committee: Hiroshima University

Ethics number: No. E-2038