Effect of backpack shoulder straps length on cervical posture and upper trapezius pressure pain threshold

Abstract

[Purpose] This study was performed to investigate the effect of the length of backpack shoulder straps on upper trapezius muscle pain threshold and craniovertebral angle. [Subjects and Methods] There were 25 participants, with ages from 15 to 23 years old. Upper trapezius pain threshold and craniovertebral angle were measured for all subjects without the backpack then re-measured after walking on a treadmill for 15 min under 2 conditions: 1) wearing a backpack with short straps; and 2) wearing a backpack with long straps. [Results] there was a significant reduction in upper trapezius pain threshold and craniovertebral angle while carrying a backpack with long shoulder straps, compared to use of a backpack with short shoulder straps or no backpack. [Conclusion] A backpack with short straps is less harmful than a backpack with long straps. This result should be considered in ergonomic design of backpacks to reduce the incidence of various physiological and biomechanical disorders.

Prevalence and Factors Associated with Musculoskeletal Pain among Secondary School Students

“…In this study, the length of straps does not associate with pains measured similar to research by Yoon (2014). Similarly, another study shows that the straps length does have an effect on upper trapezius pain threshold in shoulders (Abdelraouf et al, 2016). There is a lack of literature on the proper length and level of backpack shoulder straps.…”

Impact of Backpacks on Ergonomics: Biomechanical and Physiological Effects: A Narrative Review

“…Strap length has been reported to have significant effects on head and neck posture: in particular, BPs with a weight of 15% BM and long shoulder straps result in a significant reduction in the cranial spine, both compared to shorter straps and in the unloaded condition [ 27 ].…”

“…Regarding the influence of design, no significant differences in shoulder comfort were found between FP and BP at a load of 10 to 15% BM [ 26 ], but the strap length has been reported to exert significant effects on shoulder pain: specifically, in BPs weighing 15% BM were observed to have significantly higher discomfort with longer shoulder straps compared to shorter ones [ 27 ].…”

“…To optimize the interaction with the pack, the use of a hip belt, and non-flexible, shorter shoulder straps would be beneficial in terms of both kinematics and comfort, as well as a more vertical load distribution [ 27 , 32 , 33 , 68 ]. Furthermore, in children, it is desirable not to exceed 10% BM considering the total load.…”

Development and testing of auxetic shoulder straps for sport backpacks

“…It is well known that the weight of a backpack acts directly on the back via the shoulder straps, which can lead to discomfort, especially at pressure points such as the shoulder and collarbone. Scientific literature suggests that this pressure could be alleviated by wider straps that better distribute the pressure in this area 3 . Extensive research has investigated the discomfort and muscle fatigue resulting from improper load distribution on the human back [4][5][6][7] .…”