The aim of this study was to compare shoulder muscle force and moment production during external rotation performed in the transverse and sagittal planes. An optimization model was used for estimating shoulder muscle force production of infraspinatus, teres minor, supraspinatus, anterior deltoid, middle deltoid and posterior deltoid muscles. The model uses as input data the external rotation moment, muscle moment arm magnitude, muscle physiologic cross-sectional area and muscle specific tension. The external rotation moment data were gathered from eight subjects in transverse and six subjects in sagittal plane using an isokinetic dynamometer. In the sagittal plane, all studied muscles presented larger estimated force in comparison with the transverse plane. The infraspinatus, teres minor, supraspinatus and posterior deltoid muscles presented larger moment in sagittal when compared with transverse plane. When prescribing shoulder rehabilitation exercises, therapists should bear in mind the described changes in muscle force production.
Marcelo Peduzzi de Castro (Corresponding Author) is with the School of Sports, University of Porto, Porto, and with the Polytechnic Institute of Porto, Portugal. Daniel Cury Ribeiro is with the School of Physiotherapy, University of Otago, Dunedin, Otago, New Zealand. Felipe de Camargo Forte is with Worcestershire Acute Hospitals, NHS Trust, Worcester, Worcestershire, United Kingdom. Joelly Mahnic de Toledo is with the Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. Roberto Costa Krug is with Physio from the Inside Out—Physiotherapy Post Grad Training, and with the Galway City Physiotherapy Clinic, Fort Lorenzo, Co Galway, Ireland. Jefferson Fagundes Loss is with the Exercise Research Laboratory, School of Physical Education, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.