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Completed

NCT Number: NCT07000773

Trapezius Muscle Activation During Bilateral Scapular Retraction and Shoulder External Rotation Under Kinetic Chain and Unstable Surface Conditions

This study aims to investigate the effects of performing the Bilateral Scapular Retraction with Shoulder External Rotation (BSR-SER) exercise under kinetic chain involvement and unstable surface conditions on trapezius muscle activation. Surface electromyography (EMG) will be used to assess the activity levels of the upper, middle, and lower trapezius muscles. The goal is to determine whether integrating kinetic chain elements and instability can optimize muscle activation patterns in healthy individuals during a commonly used scapular rehabilitation exercise.

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Key information

Conditions

Healthy Volunteers

Age range

18 year–35 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Gazi University

Ankara, Çankaya, Turkey (Türkiye)

About this study

Maintaining muscular balance among the scapular stabilizers is crucial for optimal shoulder function. The Bilateral Scapular Retraction with Shoulder External Rotation (BSR-SER) exercise is frequently used in clinical rehabilitation to activate the lower trapezius while minimizing upper trapezius activity. Although this exercise is widely practiced, the effects of performing it under kinetic chain conditions (such as squat and lunge positions) and on an unstable surface have not been thoroughly explored.

This study will examine how adding kinetic chain involvement and instability influences the electromyographic activity of the upper trapezius (UT), middle trapezius (MT), and lower trapezius (LT) muscles during the BSR-SER exercise. Twenty healthy participants will perform the exercise in various lower extremity positions (standing, squat, lunge) and on both stable and unstable surfaces using a BOSU® ball. EMG data will be collected using a wireless surface EMG system and analyzed in terms of percentage of maximal voluntary isometric contraction (%MVIC).

The results of this study may provide valuable insights into the optimization of scapular stabilization exercises and guide clinicians in designing more effective shoulder rehabilitation programs by incorporating kinetic chain principles and unstable surfaces.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age between 18 and 35 years
  • Body Mass Index (BMI) less than 30 kg/m²

Exclusion criteria

  • Engaging in more than 6 hours per week of overhead sports or upper extremity strength training
  • History of surgery in the spine, lower extremities, or upper extremities
  • Experiencing pain in these regions within the past 6 weeks
  • Having a rheumatologic, systemic, or metabolic disease

Treatment and study plan

Bilateral Scapular Retraction with Shoulder External Rotation (BSR-SER) Exercise

Behavioral

Participants perform the Bilateral Scapular Retraction with Shoulder External Rotation (BSR-SER) exercise using a resistance band. The exercise is conducted under various conditions including stable and unstable surfaces (using BOSU® balance trainer) and in three different lower limb positions: standing, lunge, and squat. Each condition is randomized, and participants complete all conditions in a crossover design. The intervention aims to evaluate trapezius muscle activation patterns during these exercises using surface electromyography (EMG).

Primary outcomes

  1. Upper Trapezius Muscle Activation

    Time frame: Day 1 (during the exercise session)

    Surface electromyography (EMG) will measure the muscle activation level of the upper trapezius during the stationary phase of the BSR-SER exercise under various conditions. The activation will be normalized as a percentage of maximal voluntary isometric contraction (%MVIC).

  2. Middle Trapezius Muscle Activation

    Time frame: Day 1 (during the exercise session)

    Surface EMG will measure the muscle activation level of the middle trapezius muscle during the stationary phase of the BSR-SER exercise under different surface and lower limb position conditions. Activation levels will be expressed as %MVIC.

  3. Lower Trapezius Muscle Activation

    Time frame: Day 1 (during the exercise session)

    Surface EMG will measure the muscle activation of the lower trapezius during the stationary phase of the BSR-SER exercise. Muscle activity will be normalized to %MVIC.

  4. Muscle Activation Ratios

    Time frame: Day 1 (during the exercise session)

    Ratios of muscle activation between the upper, middle, and lower trapezius muscles will be calculated to assess balance of muscle recruitment during exercise.

Sponsors and collaborators

Lead sponsor

Recep Tayyip Erdogan University

Other

Collaborators

  • Gazi University

Registry information

Official study title

Trapezius Activation During Bilateral Scapular Retraction With Shoulder External Rotation: The Incorporation of Knetic Chain and Unstable Surface

Acronym: BSR-SER

Important dates

Study start
2022
Primary completion
2022
Study completion
2024
First posted
Jun 3, 2025
Registry last updated
Jun 3, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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