Abstract
BACKGROUND: Although strength exercises for shoulder girdle protraction (SGP) have been emphasized in subjects with scapular winging, few experimental studies have SGP strength measured this function in this cohort.
OBJECTIVE: To compare SGP strength and performance of the upper quarter closed-kinetic-chain in healthy subjects and patients with scapular winging.
METHODS: Twenty-six men (13 patients with scapular winging, 13 controls) exerted maximal isometric SGP force against a force-measurement device while the upper quarter Y-balance test was conducted to examine the performance of the upper quarter closed-kinetic-chain using a Y-balance kit.
RESULTS: The SGP strength in the patient group was significantly lower than that of the control group (p=0.001) while the scores on the Y-balance did not differ between the groups. The correlation between strength and motion of the upper limb during performance of upper quarter closed-kinetic-chain was relatively low (r=0.394, p=0.046). A sensitivity analysis has indicated that based on the extreme values of the patient group (the maximal individual SGP strength score) and the control group (the minimal individual strength score), 4 of the patients and 8 of the healthy participants, would have been categorized as uninvolved (false negatives) and involved (false positives), respectively. However based on the mean SGP strength score, only one patient crossed into the control subjects distribution while none of the control subject have crossed into the patients distribution.
CONCLUSIONS: These findings indicate that although scapular winging may be associated with SGP weakness, particularly in cases where the isometric force is less than 130 N. However, great care has to be taken in interpretation of findings while further research should be encouraged.