Alternative methods for measuring scapular muscles protraction and retraction maximal isometric forces.

Area of Science:

• Biomechanics
• Musculoskeletal research
• Sports medicine

Background:

• Scapular stabilizing muscles are crucial, yet quantitative strength measurements are limited.
• Few studies assess isometric or concentric forces of these muscles.
• Reliable objective measures for scapular protraction/retraction strength, especially without glenohumeral joint involvement, are scarce.

Purpose of the Study:

• To evaluate the reliability of four novel methods for measuring maximal isometric strength.
• To assess scapular protraction and retraction muscle strength.
• To determine reliability with and without glenohumeral (GH) joint participation.

Main Methods:

• Thirty healthy females (22-26 years) participated.
• An Isobex® stationary tension dynamometer measured maximal isometric force (kg).
• Each method was tested across three sessions on nonconsecutive days, with three randomized trials per session.

Main Results:

• High intrasession (ICC2,3: 0.95-0.98) and intersession (ICC3,3: 0.94-0.96) reliability was observed.
• Protraction and retraction testing showed significant relationships (r=0.92 and r=0.93, respectively).
• Good agreement was found for protraction methods, but weaker agreement for retraction methods.

Conclusions:

• Four new methods offer reliable options for measuring scapular protraction/retraction isometric strength.
• These methods are suitable for young, healthy females.
• The findings provide objective tools for assessing scapular muscle function, with or without GH joint involvement.