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.