Scapula-focused exercises with or without biofeedback increase corticospinal excitability in recreational overhead athletes with shoulder impingement.

Abstract

Individuals with shoulder impingement syndrome (SIS) exhibit changed corticospinal excitability, scapular kinematics, and scapular muscle activation patterns. To restore the scapular kinematics and muscle activation patterns in individuals with SIS, treatment protocols usually include scapula-focused exercises, such as scapular orientation training and strength training. To investigate whether these two types of scapular exercise can reverse the changed corticospinal excitability of recreational overhead athletes with SIS. Randomized Controlled Clinical Trial. University laboratory. Forty-one recreational overhead athletes with SIS (n=20 in the scapular orientation group with age= 26.45±4.13 years; height= 171.85±7.88 cm; mass= 66.70±10.68 kg; n=21 in the strengthening group with age= 26.43±5.55 years; height= 171.62±5.87 cm; mass= 68.67±10.18 kg). Both groups performed a 30-minute training protocol consisting of three exercises to strengthen the lower trapezius and serratus anterior muscles without overactivating the upper trapezius. Participants in the scapular orientation group were instructed to consciously activate their scapular muscles with electromyographic biofeedback and cues, whereas the strengthening group did not have biofeedback or cues for scapular motion. Corticospinal excitability was assessed using transcranial magnetic stimulation. Scapular kinematics and muscle activation during arm elevation were also measured. After the training, both groups demonstrated a significant increase in motor evoked potentials in lower trapezius (P=0.004) and significant increases in scapular upward rotation (P=0.032), lower trapezius activation (P<0.001), and serratus anterior activation (P<0.001) during arm elevation. Moreover, the scapular orientation group showed higher lower trapezius activation levels during arm elevation following the training, compared with the strengthening group (P=0.028). With or without biofeedback and cues, scapula-focused exercises improved scapular control and increased corticospinal excitability. Adding biofeedback and cues for scapular control during exercise helped facilitate greater lower trapezius activation, and thus, feedback and cues are recommended during scapula-focused training.