Effect of the spacing of backpack shoulder straps on cervical muscle activity, acromion and scapular position, and upper trapezius pain

Analytical parameters to check association between load carriage system and bag packs-influenced musculoskeletal complications among school going students: a scoping review

PURPOSE

This study aimed to investigate the correlation between load-carriage systems and backpacks on musculoskeletal complications among school-going students. Additionally, the purpose was to identify research gaps and provide recommendations for future research.

METHODS

To conduct this study, we conducted a thorough search of five databases for literature published between January 2010 and December 2022. Our focus was on original published articles that reported musculoskeletal complications using analytical parameters or outcome measures among school-going students. Two reviewers independently extracted data for eligibility. The studies selected for the analysis focused on musculoskeletal complications and the outcome measures to report these complications.

RESULTS

A total of 3541 titles were screened; of which, 18 observational studies were included. The musculoskeletal complications identified in these studies included lower back, shoulder, and neck pain and disturbed posture. Overall, the quality of the reporting in these studies was deemed satisfactory.

CONCLUSION

Our analysis revealed that pain and postural abnormalities were the most frequently reported complications. Hence, we recommend that future studies incorporate multiple evaluations rather than concentrating on a single symptom.

Upward pulling plus exercise improves scapulocostal pain and scapular position

[Purpose] To investigate the effect of upward pulling combined with shoulder retraction (upward pulling plus exercise) on scapulocostal pain and scapular position. [Subject and Methods] A 22-year-old woman with severe pain in the right and left scapulocostal areas. The horizontal distance from the inferior angle to the spinal process was measured. The tester assessed scapulocostal pain after stretching and massage. The tester assessed pain after upward pulling plus exercise. [Results] Left and right scapulocostal pain reduced to 2/10 after the upward pulling plus exercise. The horizontal distance from the inferior angle to the spinal process also decreased. [Conclusion] Upward pulling plus exercise might be recommended as a primary therapeutic approach to treat scapulocostal pain or scapulocostal syndrome.

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

[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.

Effects of a low-center-of-gravity backpack on the trunk stability of mountaineers while ascending and descending

[Purpose] This study developed a backpack with a low center of gravity (LCG) and investigated the effects of the LCG backpack on the trunk stability of mountaineers while ascending and descending. [Subjects and Methods] Ten males aged 20–32 years were recruited. The subjects ascended and descended a road with an inclination of 30 degrees wearing the standard or LCG backpack, and trunk acceleration was measured using a tri-axial accelerometer. [Results] The anterior-posterior (AP) and medial-lateral (ML) trunk acceleration while ascending and descending with the LCG backpack were significantly lower than those with the standard backpack. [Conclusion] The results suggest that the LCG backpack could prevent falling injuries during mountaineering and mountain-related activities.

The effects of bag style on muscle activity of the trapezius, erector spinae and latissimus dorsi during walking in female university students

Back pain is common in adolescents which has been associated with carrying a bag. However, there is little research examining the effects of bag style in female adolescents. The aim of the study was to investigate the effects of different bag conditions on muscle activity of the trapezius, erector spinae and latissimus dorsi muscles in female university students during walking. Twelve female university students walked on a treadmill for 5 minutes at 1.1 m/s during five conditions; control, 1 strapped rucksack, 2 strapped rucksack, ipsilateral shoulder strap and contralateral shoulder strap, each containing 10% bodyweight. Electromyography for the trapezius, erector spinae and latissimus dorsi was recorded for the last 30 s of each condition. Two-way ANOVA and paired t-tests were used to identify differences between right and left muscles and between bag conditions. Results showed that muscle activity of the left trapezius was significantly higher than the right trapezius during the 1 strap rucksack condition. For the left trapezius, the 2 strapped rucksack and the control condition had significantly lower muscle activity compared to the 1 strapped rucksack and the ipsilateral shoulder strap. For the left erector spinae muscle, there was significantly greater muscle activity when wearing the contralateral shoulder strap compared to the control. For the right erector spinae, significantly lower muscle activity was observed when wearing the 2 strapped rucksack compared to the ipsilateral shoulder strap and contralateral shoulder strap. There were no significant differences in muscle activity of the latissimus dorsi muscles between any of the bag conditions. These findings suggest that a two strapped rucksack should be used when carrying loads to reduce spinal muscle activity which may, in turn, reduce reports of back pain in female adolescents.

Influence of Wearing a Brassiere on Pain and EMG Activity of the Upper Trapezius in Women with Upper Trapezius Region Pain

[Purpose] This study examined the effect of wearing a brassiere on upper trapezius (UT) region pain and EMG activity during arm elevation by women. [Subjects and Methods] Fourteen healthy women were recruited. Surface EMG data were collected from the UT muscles during arm elevation. Pressure pain in the UT region was measured using a baseline dolorimeter. [Results] The EMG activity of the UT increased significantly when a brassiere was worn compared to without. UT region pain showed no significant difference between with and without wearing a brassiere. [Conclusion] This suggests that wearing a brassiere increases the muscle activation of the UT in women.