Summary

We introduce the most effective range of rotation of cuff exercise (CE). According to rotational range, CE was divided into inside CE (ICE) in which subjects performed rotational exercise within the neutral position at the side and outside CE (OCE) which meant rotational exercise outside it. Our study showed ICE made range of external rotation increased compared with that after OCE.

Abstract

Purpose

the purpose of this study is to introduce the most effective method of cuff exercises (CE) to get better results of range of motion of a shoulder and muscle power of rotator cuff.

Methods

Our subjects consisted of 8 healthy cases and 16 shoulders without any shoulder troubles, with a mean age of 26.8 years (22-36 years).
According to rotational range, CE was divided into the following two types: inside CE in which subjects performed rotational exercise only within the neutral position at the side (ICE) and outside CE which meant rotational exercise only outside it (OCE). Randomly, subjects were divided into the following two groups; ICE group in which all subjects performed the ICE and OCE group in which they performed the OCE.
Before and after each exercise, external rotation angle (ERA) and external rotation strength (ERS) at the side were measured using a Moby Z II manual muscle tester (SAKAI med). During each CE, subjects performed 30 rotational movements with no load.
ERS was measured three times, whose average was corrected by using body weight.
We examined whether subjects’ scapula was stabilized in each CE by evaluation of scapular winging during it.
Statistical examination was performed between ERA and ERS before and after each CE by using the paired t test. Statistically significant level was 0.05.

Results

In the ICE group, the results of ERA and ERS before and after ICE were 42.2+-6.0 degs and 1.26±0.39 N/kg, and 47.2+-7.5 degs and 1.34±0.41 N/kg, respectively. Both results of ERA and ERS were significantly increased after ICE (ERA: p=0.0002, ERS: p=0.0013).
Meanwhile in the OCE group, the results of ERA and ERS before and after OCE were 40.6+-7.7 degs and 1.04±0.17N/kg, and 39.7+-8.7 degs and 1.32±0.24 N/kg, respectively. Compared with the results of ERA and ERS before OCE, that of ERA was decreased (p=0.19) and that of ERS was increased after OCE with statistically significant difference (p=0.0027).
As to scapular stability in each exercise, in 14 of all shoulders (87.5%) scapular winging was observed during the OCE, while all subjects in the ICE group showed no scapular winging.

Discussion

As for the optimal rotation range in the CE, our results showed the ICE was superior to the OCE, because compared with the results of ERA and ERS before the ICE and OCE, both those of ERA and ERS were significantly increased after ICE, while in the OCE group, only the result of ERS was increased, but that of the ERA was clearly decreased after OCE. We thought that scapular winging during the CE would have a great influence on the effect of CE, especially as to the external rotation. In the ICE group, there were no shoulders which showed scapular winging during ICE. Our study indicated that it was greatly important to perform the CE within the appropriate range of rotation with scapula kept stabilized.