Evaluation of Novel High-Density EMG Feedback Parameters on the Spatial Distribution of Trapezius Muscle Activity

Each year, 17.9% of adults working in a computer-dominated work environment develop an episode of chronic neck and shoulder pain. An effective treatment method for chronic pain is postural correction through therapist. The understanding of the relation between cervicoscapular posture and trapezius muscle activity is not fully understood because the anatomy of the scapula is not accessible for direct observation. Until recently, the spatial distribution of trapezius muscle activity could not be measured due to the limitation in size of detection zone in traditional bipolar electrodes. The primary goal of postural correction when treating cases of chronic neck and shoulder pain is to shift the distribution of trapezius muscle activity inferior. However, treatment methods of chronic musculoskeletal diseases are often inefficient due to the inability of the participant to permanently alter posture and activation patterns. The first goal of this project was to determine the relation between cervicoscapular posture and the distribution of trapezius muscle activity. To accomplish this, cervicoscapular posture and trapezius muscle activity were recorded while participants adopted three unique shoulder postures. Because scapular position cannot be measured ex vivo, the position of the acromion process relative to C7 was used as a surrogate.