Backgroundm: Scapulohumeral rhythm (SHR) has been established as the kinematic hallmark indicating
motion of the shoulder joint. Numerous studies have investigated the effect of different factors on SHR. The
purpose of the present study was to determine the scapular upward rotation and scapulohumeral rhythm ratio
among frontal, sagittal, and scapular planes in different humeral abduction angles.
Materials and Methods: In the curremnt experimental study, conducted at the University of Kurdistan in
2018, 35 healthy male individuals participated. Two inclinometers were used to measure humeral abduction
and scapular upward rotation in scapular rest position, 45°, 90°, and 135° shoulder abduction in frontal,
sagittal, and scapular planes. Participants performed humeral abduction with dominant shoulder in different
planes. The scapular motility rhythm was calculated from the distribution of glenohumeral abduction rate
on the upper scapular rotation from the rest position of the scapula to 45, 90 and 135 degrees of shoulder
abduction at different levels.
Results: No significant difference was found in scapular upward rotation (p=0.07) and scapulohumeral
rhythm (p=0.48) among frontal, sagittal, and scapular planes in 45° humeral abduction, but the scapula had
more upward rotation in 90° humeral abduction in frontal plane compared with sagittal plane (p<0.05). Also,
the scapula had more upward rotation in 135° humeral abduction in frontal plane compared with scapular
and sagittal planes (p<0.05). On the other hand, findings showed that scapulohumaral rhythm ratio from
scapular rest position to 45°, 90°, and 135° humeral abduction in frontal plane was less compared with that
of sagittal and scapular planes (p<0.05). On the other hand, findings showed that scapulohumaral rhythm
ratio from scapular rest position to 90° humeral abduction in sagittal plane was more as compared with
frontal plane while scapulohumaral rhythm ratio from scapular rest position to 135° humeral abduction in
sagittal plane was more than those of the two other planes (p<0.05).
Conclusion: It seems that there are significant differences in scapular upward rotation and scapulohumaral
rhythm ratio among frontal, sagittal, and scapular planes. These findings can be useful in clinical assessments
and future studies.