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Effect of scapular protraction and retraction on isometric shoulder elevation strength
Jay Smith1, Brian R Kotajarvi, Denny J Padgett
1Department of Physical Medicine and Rehabilitation, Mayo Clinic Motion Analysis Laboratory, 200 First Street SW, Rochester, MN 55905, USA.
Objectives:
To examine the effect of scapular protraction (SP) and scapular retraction (SR) on isometric shoulder elevation strength measured in the sagittal plane and to test the hypothesis that strength would be significantly reduced when tested in the SP position relative to the neutral resting scapular position (SN).
Design:
Prospective before-after trial.
Setting:
Multidisciplinary sports medicine center.
Participants:
Ten healthy volunteers (5 men, 5 women) ages 26 to 43 years recruited from the Mayo Clinic, Rochester, MN.
Interventions:
Subjects completed 3 maximal isometric shoulder elevation contractions at 90 degrees of sagittal plane elevation in the SN, SP, and SR positions. The order of scapular positions was varied to minimize fatigue effects. Mean isometric strength values were compared by using Student t tests.
Main Outcome Measures:
Isometric shoulder elevation strength for the 3 scapular positions.
Results:
Isometric strength was significantly lower for the SP position compared with the SN position (8.5 +/- 3.4 kg vs 11.1 +/- 4.0 kg, P <.0005) and for the SR position relative to the SN position (7.8 +/- 3.3 kg vs 11.1 +/- 4.0 kg, P <.00003). Strength values did not differ between the SP and SR positions (P =.38).
Conclusions:
Movement of the scapula into a protracted or retracted position results in a statistically significant reduction in isometric shoulder elevation strength as measured in this study. Further research is warranted to examine the relationship between scapular position and shoulder muscle function.