The influence of shoulder position during multi-joint exercises in the relative scapular muscles activity in symptomatic and asymptomatic conditions

Article type: Research Article

Authors: Melo, Ana S.C.^{a; b; c; d} | Vilas-Boas, João P.^{e; f} | Cruz, Eduardo B.^{g; h} | Macedo, Rui M.ⁱ | e Ferreira, Sílvia B.^j | Sousa, Andreia S.^{k; *}

Affiliations: [a] Center for Rehabilitation Research – Human Movement System (Re)habilitation Area, Department of Physiotherapy, School of Health, Polytechnic of Porto, Porto, Portugal | [b] Research Centre in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal | [c] Porto Biomechanics Laboratory, Porto, Portugal | [d] Center for Interdisciplinary Applied Research in Health, Health School of the Setubal Polytechnic Institute, Campus do IPS Estefanilha, Setúbal, Portugal | [e] Centre of Research, Education, Innovation and Intervention in Sport (CIFI2D), Faculty of Sport, University of Porto, Porto, Portugal | [f] Porto Biomechanics Laboratory (LABIOMEP), University of Porto, Porto, Portugal | [g] Department of Physiotherapy, Escola Superior de Saúde, Instituto Politécnico de Setúbal, Campus do IPS Estefanilha, Setúbal, Portugal | [h] Comprehensive Health Research Center (CHRC), Universidade Nova de Lisboa, Lisbon, Portugal | [i] Department of Physiotherapy, Center for Rehabilitation Research – Human Movement System (Re)habilitation Area, School of Health, Polytechnic of Porto, Porto, Portugal | [j] School of Health, Polytechnic of Porto, Porto, Portugal | [k] Department of Physiotherapy, Center for Rehabilitation Research – Human Movement System (Re)habilitation Area, School of Health, Polytechnic of Porto, Porto, Portugal

Correspondence: [*] Corresponding author: Andreia S. Sousa, Department of Physiotherapy, Center for Rehabilitation Research – Human Movement System (Re)habilitation Area, School of Health, Polytechnic of Porto, Porto, Portugal. E-mails: [email protected] or [email protected]

Abstract: BACKGROUND: Scapular muscles changes, as increased upper trapezius activity and decreased middle and lower trapezius and serratus anterior muscle activity, have been demonstrated in shoulder pain specific or non-specific conditions. Shoulder external rotation exercises have been recommended to improve scapular activity in shoulder pain. OBJECTIVE: To evaluate the relative scapular muscles activity during multi-joint exercises combining shoulder external rotation, trunk rotation and scapular squeeze. METHODS: Forty-one participants with and without shoulder pain were assessed in a cross-sectional study. They performed isometric multi-joint exercises at 0∘ and 90∘ of shoulder abduction with and without support. The relative activity of upper, middle, and lower trapezius and serratus anterior (upper/middle and lower portions) was measured through electromyography. The scapular muscular balance was assessed by the ratio between relative activity of the upper trapezius and the other muscles.

DOI: 10.3233/BMR-220056

Journal: Journal of Back and Musculoskeletal Rehabilitation, vol. Pre-press, no. Pre-press, pp. 1-11, 2023