Acute Effects of Focal Vibration on Posterior Shoulder Tightness and Tissue Stiffness in Overhead Athletes

Condition(s) studied

Investigational drug(s) / intervention(s)

Focal Vibration: A standardized single-session focal vibration intervention applied to the posterior shoulder muscles using fixed vibration parameters. The protocol is designed to evaluate the immediate effects of focal vibration on posterior shoulder tightness and related shoulder functions in overhead athletes and includes a sham-controlled comparison to distinguish treatment effects from placebo.

Sham Focal Vibration: The sham focal vibration intervention is performed using the same device, application duration, and application site as the active intervention. However, the device is configured not to deliver therapeutic vibration. This approach is intended to maintain participant blinding and to determine whether the observed effects are attributable to focal vibration rather than placebo effects.

Study summary

This study aims to investigate the acute effects of focal vibration on posterior shoulder tightness, posterior shoulder muscle stiffness, and glenohumeral range of motion in overhead athletes. A total of 36 overhead athletes aged 18-25 years who have regularly participated in overhead sports for at least four years will be included. Participants will be randomly allocated to either the focal vibration group or the sham control group using block randomization. All outcome assessments will be performed immediately before and immediately after a single intervention session.

The primary outcome measure is posterior shoulder tightness, assessed using the Horizontal Adduction Test. Secondary outcome measures include posterior shoulder muscle stiffness, assessed using the IndentoPRO digital tissue indentometer, and passive glenohumeral internal and external rotation range of motion, measured using the GYKO inertial sensor.

The primary research question is whether focal vibration has an acute effect on posterior shoulder tightness, muscle stiffness, and glenohumeral range of motion in overhead athletes. It is hypothesized that participants receiving focal vibration will demonstrate greater reductions in posterior shoulder tightness and muscle stiffness, as well as greater improvements in glenohumeral range of motion, compared with those receiving the sham intervention.

Eligibility

Primary outcome measure(s)

• Posterior Shoulder Tightness (Horizontal Adduction Test) — Immediately before and immediately after a single intervention session
  Posterior shoulder tightness will be assessed using the Horizontal Adduction Test. Participants will lie in the supine position while the scapula is stabilized by the examiner. The shoulder will be passively moved into horizontal adduction until the first point of scapular movement is detected. The horizontal adduction angle will be measured using a digital inclinometer. Lower values indicate greater posterior shoulder tightness, whereas higher values indicate improved shoulder flexibility.

Trial sites (1)

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