Effects of external stabilization on infraspinatus activity and shoulder external rotation strength during the wiper exercise in individuals with and without scapular dyskinesis.

BACKGROUND

The wiper exercise is an effective movement for selectively activating the infraspinatus (IsP) muscle. Weakness in this muscle may contribute to shoulder hypermobility and joint subluxation.

METHODS

Thirty participants were recruited, and individuals with and without scapular dyskinesis (SD) were identified using the dynamic SD test. IsP muscle activity and strength were measured during the wiper exercise. A 2 × 3 mixed-measures ANOVA was conducted to examine differences in IsP activity and shoulder external rotation strength across three fixation conditions (no fixation, NF vs fixation on pelvis, FP vs fixations on pelvis and thorax, FPT) in individuals with and without SD.

RESULTS

The FPT condition elicited significantly greater IsP muscle activity and external rotation strength compared to both the NF and FP conditions (p < .05), regardless of SD presence. No significant difference in muscle activity was observed between the NF and FP conditions (p > .05), although strength differed significantly (p < .05).

CONCLUSION

The FPT condition during the wiper exercise is recommended as a targeted intervention to improve IsP activity and external rotation strength in individuals both with and without SD.