Upper and lower trapezius muscle activity in subjects with subacromial impingement symptoms: is there imbalance and can taping change it?

OBJECTIVES: To investigate (i) whether subacromial impingement symptoms (SIS) were associated with upper and lower trapezius muscle imbalance and (ii) the effect of a scapula taping technique on upper and lower trapezius muscle activity.
DESIGN: Cross-sectional study with nested within-subject intervention.
SETTING: University research laboratory. PARTICIPANTS: Subjects who demonstrated SIS (n=16) on clinical testing and an age and gender matched group of asymptomatic subjects (n=32). MAIN OUTCOME MEASURES: Surface electromyography (EMG) to measure activity in the upper (UFT) and lower (LFT) fibres of trapezius during repeated humeral elevation in the scapular plane.
RESULTS: Symptomatic subjects demonstrated a significantly (95% CI 2.13 to 4.17, p=0.019) higher ratio of UFT:LFT activity than the asymptomatic subjects (95% CI 1.35 to 2.25). With tape in situ the symptomatic subjects demonstrated a significant (95% CI -8.6% to -17.3%, p<0.001) reduction in UFT activity but no significant (95% CI +2.8% to -17.5%, p=0.145) change in activity of LFT. No relationship (r=- 0.116, p=0.669) was found between the degree of underlying muscle imbalance and the reduction in UFT under the taped condition for the symptomatic group.
CONCLUSION: Subacromial impingement symptoms are associated with altered upper and lower trapezius muscle activity which can be partially addressed by the application of tape.