Affiliations: [a] Department of Physical Therapy, The Graduate School, Inje University, Korea | [b] Department of Physical Therapy, College of Biomedical Science and Engineering, Inje University, Korea
Correspondence:
[*]
Corresponding author: Won-gyu Yoo, Department of Physical Therapy, College of Biomedical Science and Engineering, Inje University, 607 Obang-dong, Gimhae, Gyeongsangnam-do, 621-749, Korea. Tel.: +82 55 320 3994; Fax: +82 55 329 1678; E-mail:won7y@inje.ac.kr
Abstract:
BACKGROUND: Although overhead work is closely related to musculoskeletal
disorders, it is difficult to avoid these postures in daily working
conditions. In industrial tasks that require elevated arm postures above
shoulder height, flexibility in the location of the task is necessary. OBJECTIVE: This study investigated the sternocleidomastoid, upper trapezius,
lower trapezius, and anterior deltoid, serratus anterior muscle activities
during overhead work involving four different height and distance locations
performed by healthy adult participants. METHODS: Eighteen young male right-hand-dominant workers were recruited. The
right upper trapezius, lower trapezius, serratus anterior, anterior deltoid,
and sternocleidomastoid muscle activities were measured under for overhead
work condition (Location 1: overhead work with a height of 10 cm above the
head of each subject and distance of 15 cm, Location 2: overhead work with a
height of 10 cm above the head of each subject and distance of 30 cm,
Location 3: overhead work with a height of 20 cm above the head of each
subject and distance of 15 cm, Location 4: overhead work with a height of 20
cm above the head of each subject and distance of 30 cm). RESULTS: In Location 3, there was significantly higher neck extension range
of motion compared to Location 1, Location 2 and Location 4. In Location 1,
the activities of the upper trapezius, lower trapezius, serratus anterior,
anterior deltoid, and sternocleidomastoid muscles were significantly lower
than those in Location 3 (p < 0.05). In Location 2, the activities of the
upper trapezius, lower trapezius, serratus anterior, anterior deltoid, and
sternocleidomastoid muscles were significantly lower than those in Location
4 (p < 0.05). In Location 1, there were significantly lower upper trapezius,
lower trapezius, serratus anterior, and anterior deltoid muscle activities
than in Location 2 (p < 0.05). In Location 3, there were significantly lower
upper trapezius, lower trapezius, serratus anterior, and anterior deltoid
muscle activities than in Location 4 (p < 0.05). In Location 1, there was
significantly higher sternocleidomastoid muscle activity than in Location 2
(p < 0.05). Finally, In Location 3, there was significantly higher
sternocleidomastoid muscle activity than in Location 4 (p < 0.05). CONCLUSIONS: Overhead workers should engage in work that involves a low
height and near distance. Height appears to be a stronger risk factor than
distance in overhead work.
