Activation of the trapezius muscle during varied forms of Kendall exercises

Kinney, Elissa; Wusthoff, Jodi; Zyck, Amy; Hatzel, Brian; Vaughn, Dan; Strickler, Tim; Glass, Stephen

doi:10.1016/j.ptsp.2007.11.001

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Volume 9, Issue 1 , Pages 3-8, February 2008

Activation of the trapezius muscle during varied forms of Kendall exercises

Elissa Kinney
- Department of Physical Therapy, Grand Valley State University, Allendale, MI, USA
Jodi Wusthoff
- Department of Physical Therapy, Grand Valley State University, Allendale, MI, USA
Amy Zyck
- Department of Physical Therapy, Grand Valley State University, Allendale, MI, USA
Brian Hatzel
- Department of Movement Science, Grand Valley State University, Allendale, MI 49401, USA
Dan Vaughn
- Department of Physical Therapy, Grand Valley State University, Allendale, MI, USA
Tim Strickler
- Department of Biomedical Sciences, Grand Valley State University, Allendale, MI, USA
Stephen Glass
- Department of Movement Science, Grand Valley State University, Allendale, MI 49401, USA
- Corresponding author. Tel.: +16163318126; fax: +16163318658.

Received 10 April 2007; received in revised form 5 October 2007; accepted 2 November 2007.

Abstract

The trapezius muscle plays a crucial role in maintaining proper shoulder mechanics and is often considered a source of weakness and dysfunction in patients.

Objectives

The purpose of this study was to investigate the activation patterns of the middle and lower trapezius during four prone horizontal abduction exercises of the glenohumeral joint (GHJ).

Methods

The muscle activation patterns of 19 female and 13 male volunteers were measured using surface EMG during horizontal arm abduction exercises commonly used in rehabilitative settings. Each subject performed 10 repetitions of horizontal abduction (ABD) at each position using only the weight of the arm. Function was assessed during shoulder horizontal abduction while positioned at: 75°, 90°, 125° and 160° of GHJ ABD. Electromyographic activity was collected during the concentric phase during each test repetition in the lower (LTRAP) and middle trapezius (MTRAP). A repeated measure ANOVA was performed followed by Bonferroni's post hoc test.

Results

The MTRAP had significantly greater recruitment at 90° and 125°, compared to 160°. Similarly, results for the lower trapezius indicated that recruitment at 90° and 125° was significantly greater than 160°.

Conclusion

Most significant muscle activation for the middle and lower trapezius occurred at 90° and 125° of GHJ ABD. For the clinician, training at 90° is easy to identify, and provides maximal activation, negating the need for multiple training angles.

Keywords: Electromyography, Shoulder rehabilitation, Arm abduction, Glenohumeral joint