Is there an immediate effect on pectoralis minor length after performing a prone scapular retraction exercise using typical sets and repetitions in pain-free participants?

Introduction: Pectoralis Minor (PM) length shortening may contribute to faulty scapular. kinematics and result in shoulder pathology.

Purpose: of the Study: To evaluate if a prone scapular retraction exercise will demonstrate an immediate lengthening of the pectoralis minor (PM) in healthy participants.

Methods: 50 healthy participants were measured to determine the length of their PM. The participants then performed three sets of 10 repetitions of a prone scapular retraction exercise. Next, the participants had their PM length measured again to see if there was an immediate change in PM length.

Results: PM length was not found to significantly lengthen immediately after the prone scapular retraction exercise. The mean PM length increased by 0.243 cm after the exercise but this was less than the MDC of 0.63 cm so the difference does not represent a real alteration in PM length.

Discussion: The hypothesis was that due to the theory of reciprocal inhibition, the PM would increase in length after the exercise. This study does not support this hypothesis. This study suggests that to improve PM length the PM needs to be subjected to more time at a lengthened position than what was afforded by our exercise.

Conclusion: This study demonstrated that three sets of 10 repetitions of a prone scapular retraction exercise did not significantly change the PM length. If this exercise is being implemented to increase the PM length it should be used after a stretch of the PM.