Date of Award


Document Type

Scholarly Project

Degree Name

Doctor of Physical Therapy (DPT)


Physical Therapy

First Advisor

Susan H.N. Jeno


Electromyography; Muscle, Skeletal -- physiology; Range of Motion, Articular; Rotation; Spine; Superficial Back Muscles


Purpose/Hypothesis: Rotation of the spine is a common movement used for completing daily activities and participating in sports. As a contributing factor to back injuries, the performance of spine rotation is an important consideration for the rehabilitation and prevention of future back injury. Muscles involved in spine rotation have been researched, though limited findings exist for one of the largest back muscles: Latissimus Dorsi (LD). The LD muscle contributes to many movements of the trunk and limbs given its multiple attachment sites including the pelvis, scapula, ribs and humerus. Influence of the LD on spine rotation, however, has not been thoroughly researched. The purpose of this study was to increase understanding and compare muscle activity of LD during open and closed kinetic chain activities to other back muscles.

MaterialslMethods: Latissimus dorsi muscle activity was recorded using surface electrodes while subject performed left and right rotation in both standing and quadruped positions. Four spinal rotation test positions (standing rotation right/left, quadruped rotation right/left) were initiated by movement of the pelvis. Using Maximal Voluntary Contraction (MVC) to normalize muscle activity of the LD, findings were analyzed for significance at α=.05.

Results: In fixed positioning, the L LD activity was significantly greater than the L middle trapezius (MT) and L erector spinae (ES) during right rotation. In non-fixed positioning, the ES activity was significantly greater than the MT and LD for both right and left rotation and both right and left sides. No other significant differences were found in either positions.

Discussion/Conclusions: Our findings suggest the LD significantly contributes to fixed position contralateral spinal rotation when compared to MT and ES. In fixed positioning, the LD may be mechanically advantaged to contribute to spinal rotation, whereas in non-fixed positioning, the LD may be mechanically disadvantaged to contribute to spinal rotation compared to the ES.

Clinical Relevance: Our findings suggest clinicians should consider the LD as significant contributors to spinal rotation. Treatment of patients with back pain should involve thorough examination and specific interventions addressing LD strength and mobility.