Publications
Effects of a Lumbar Support Cushion in a Backpack on Postural Alignment and Skeletal Muscle Mechanical Properties: A Repeated-Measures Trial in Healthy Adults
Authors: Ju-Yeon Jung 1, Jin-Hwa Jung 2, Hwi-Young Cho 3, Ji-Eun Baek 3, Hye Rim Suh 4
Affiliations:
- Institute of Human Convergence Health Science, Gachon University, Incheon 21936, Republic of Korea
- Department of Occupational Therapy, Semyung University, Jecheon 27136, Republic of Korea
- Department of Physical Therapy, College of Health Science, Gachon University, Incheon 21936, Republic of Korea
- Department of Physical Therapy, Division of Health Science, Baekseok University, Cheonan 31065, Republic of Korea
Journal: Journal of Clinical Medicine - October 2026, Volume 15, Issue 20, Article no. 7900 (DOI: 10.3390/jcm15207900)
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Field & Applications:
- Product development
- Musculoskeletal health
- Balance / Postural control
Background/Objectives: Backpacks are widely used for carrying loads; however, posteriorly positioned loads can shift the body’s center of mass, promote forward trunk and head compensation, and increase neck and shoulder muscle loading. This study examined the effects of a detachable lumbar support cushion at loads equivalent to 10%, 15%, and 20% of the body weight.
Methods: Twenty-eight healthy adult men completed repeated-measures trials of backpacks without or with lumbar support cushions. The craniovertebral angle (CVA), forward trunk lean (FTL), pelvic tilt angle (PTA), upper trapezius, sternocleidomastoid (SCM) tone, and stiffness were assessed. The trial registration was completed by the Clinical Research Information Service of the Republic of Korea (KCT0012211).
Results: Most variables changed significantly as the load increased, with the largest changes occurring up to 15% and limited additional changes between 15% and 20%. The cushion did not significantly affect CVA or FTL but increased PTA and reduced SCM tone.
Conclusions: A detachable lumbar support cushion may modify the PTA and was associated with lower SCM tone during backpack carriage.
Keywords: backpack, detachable lumbar support cushion, postural alignment, muscle tone, muscle stiffness
This study investigated the effects of a detachable backpack lumbar support cushion on postural alignment and the mechanical properties of the neck and shoulder muscles across different backpack loads. The use of the lumbar support cushion was associated with greater PTA. In the exploratory analysis of the 10% and 15% body weight conditions, a greater increase in UT stiffness was observed in the WoL condition than in the WL condition. SCM tone was also generally higher in the WoL condition than in the WL condition. These findings suggest that the lumbar support cushion may influence the postural responses and the mechanical properties of the neck and shoulder muscles during backpack carriage. One possible explanation is that changes in the PTA associated with lumbar support may alter compensatory postural responses in the upper body; however, this mechanism remains hypothetical because thoracic kyphosis and muscle activity were not directly measured in this study. Overall, a detachable lumbar support cushion may provide a practical means for modifying postural responses during backpack carriage.