Acute effect of flexible bar exercise on scapulothoracic muscles activation, on isometric shoulder abduction force and proprioception of the shoulder of individuals with and without subacromial pain syndrome

Background: There is currently no evidence about the effects of neuromuscular facilitation after the use of a flexible bar on scapulothoracic muscle activity in individuals with subacromial pain syndrome. The study aimed to assess the acute effect of flexible bar exercise and subjective fatigue on scapulothoracic muscle activity, shoulder proprioception, and shoulder abduction force of subjects with and without symptoms of subacromial pain syndrome. Method: Fifty subjects with subacromial pain syndrome and 50 asymptomatic subjects were recruited. A short-term flexible bar exercise was performed to assess the vibratory stimulus effects on scapulothoracic muscle activity, shoulder proprioception, and shoulder abduction force, and the same exercise was performed on a long-term basis to assess the effects of subjective fatigue. The activities of the serratus anterior and three portions of the trapezius muscle were investigated using surface electromyography during arm elevation. The active joint position sense error was assessed to determine shoulder proprioception using a laser pointer. A hand-held dynamometer was used to assess isometric shoulder abduction force. Findings: No significant intra-group differences were found in scapulothoracic muscle activity, as well as in active joint position sense error and isometric shoulder abduction force in either group (p > 0.05). Interpretation: The acute effects of flexible bar exercise and subjective fatigue were unable to influence scapulothoracic muscle activation, shoulder joint position sense, and isometric shoulder abduction force in subacromial pain syndrome.