Affiliations: Department of Occupational Therapy, College of
Alternative Medicine, Jeonju University, Jeonju, Korea | Department of Physical Therapy, College of Biomedical
Science and Engineering, Inje University, Gimhae, Korea
Note: [] Corresponding author: Won-gyu Yoo, Department of Physical Therapy, College of Biomedical Science and Engineering, Inje University, 607 Obangdong, Gimhae 621–749 Gyeongsangnam-do, Korea. Tel.: +82 55 320 3994; Fax: +82 55 329 1678; E-mail: won7y@inje.ac.kr
Abstract: BACKGROUND: Several risk factors for upper-extremity muscle injuries
are known, including repetitive and continuous-flow assembly work. However, no
study has investigated the changes in the cervical flexion-relaxation ratio
(FRR) and scapular position after continuous detailed assembly work. OBJECTIVE: This study investigated the changes in the cervical FRR, trapezius
muscle pain, and acromion and scapular positions after continuous detailed
assembly work. METHODS: Fifteen male workers were recruited. The cervical
FRR, pressure-pain threshold (PPT) of the upper and middle trapezius muscle,
and acromion and scapular positions were measured in all subjects once before
and once after detailed assembly work. RESULTS: The cervical FRR after detailed assembly work was significantly decreased compared with that before
detailed assembly work. The PPT of the upper and middle trapezius muscle after
detailed assembly work was significantly decreased compared with that before
detailed assembly work. The acromion angle after detailed assembly work was
significantly decreased compared with that before detailed assembly work. The
scapular inferior distance after detailed assembly was significantly increased
compared with that before detailed assembly work. CONCLUSIONS: Our findings suggest that detailed assembly work may cause the absence of FRR,
upper trapezius and middle trapezius pain, and scapular malalignment associated
with a potential risk of neck and shoulder pain.
