Date Available


Year of Publication


Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation


Health Sciences


Rehabilitation Sciences

First Advisor

Timothy L. Uhl

Second Advisor

Arthur J. Nitz


The role rehabilitation plays in the management of patients with lateral epicondylalgia (LE) remains elusive secondary to high recurrence rates. Addressing scapular muscle deficits may be important in the rehabilitation of patients with LE. However, it is unknown if scapular muscle impairments exist in a working population of patients with LE. The purpose of this dissertation was to assess scapular muscle strength and endurance in a working population of patients with LE.

Clinical scapular muscle assessment tools are limited in their ability to isolate specific muscles. Rehabilitative ultrasound imaging (RUSI) is a potentially useful tool but few studies have investigated its utility. Absolute muscle thickness measurements were obtained on healthy individuals for the lower trapezius (LT) and serratus anterior (SA) under three conditions (arm at rest, arm elevated with a low load, arm elevated with a high load). For both the LT and SA, a significant distinction could be made in muscle thickness between rest and a loaded condition but not between the two load conditions. Furthermore, excellent reliability was demonstrated for both muscles.

It is unknown whether arm dominance plays a role in scapular muscle assessments. Therefore, healthy individuals between the ages of 30 and 65 were recruited to compare the effect of arm dominance on scapular muscle strength, endurance, and change in thickness measured by RUSI. Results indicate that arm dominance does significantly affect some measures of scapular muscle strength and endurance. However, the differences between the dominant and non-dominant limbs were not beyond measurement error.

Scapular muscle strength, endurance, and change in muscle thickness of the LT and SA were assessed in 28 patients presenting with signs and symptoms consistent with LE. LT strength, SA strength, middle trapezius strength, endurance, and change in SA thickness were significantly less in patients with LE compared to matched controls. SA and LT strength were significantly less in the involved limb compared to the uninvolved limb in patients with LE. The results suggest that assessing scapular muscle endurance as well as LT and SA strength is indicated when evaluating patients with LE, and the results should be compared to normative data.