Effects of carrying a backpack in an asymmetrical manner on the asymmetries of the trunk and parameters defining lateral flexion of the spine

Risk Factors Involved in Postural Disorders in Children and Adolescents

Postural disorders in children and adolescents have an increasing incidence. The aim of this study was to identify the type of postural defects in school-age and preschool children, as well as the external risk factors determined by an inadequate lifestyle. The research included 134 children aged between 5 and 18 years, in whom postural defects were identified. The project involved an examination of the children's body posture, a survey of the parents to determine the children's lifestyle, blood tests, and spinal X-rays. A significant percentage (76%) of the children included in the study were underweight. The examination of postural defects in the students revealed scoliosis in 21% of the patients, kyphosis in 7.5%, and lordosis in 1.5%, while 70% of the patients presented an association between at least two postural defects. As far as risk factors are concerned, we identified the presence of rickets sequelae in 70% of the patients, the presence of pectus excavatum in 43% of the patients, genu varum in 15%, and flat foot in 12%. Additionally, 90% of the children had an incorrect posture at the desk, while 42% incorrectly carried their backpack on one shoulder only. In terms of diet quality, associations between an inadequate diet and postural disorders were found for kyphosis, scoliosis, and other deformities. In conclusion, postural abnormalities in children have an increased incidence from an early age and are a result of the change in lifestyle in recent years, represented by sedentarism, a lack of physical activity, the excessive use of electronic devices, stress, and an inadequate diet.

Comparison of muscle activity in school students while carrying backpacks and trolley bags

BACKGROUND

Trolley bags have gained popularity among students, but there is limited research comparing them to backpack-style school bags.

OBJECTIVE

This study aimed to compare how carrying a backpack versus a trolley bag affects the activity of trunk and lower limb muscles in secondary school students.

METHODS

Electromyographic activity was measured in 25 students (13.4±1.1 years) as they walked on level ground and up/down stairs while carrying both types of bags. The activity of the gastrocnemius, tibialis anterior, semitendinosus, rectus femoris, lumbar erector spinae, and rectus abdominis muscles was assessed on both the dominant and non-dominant sides.

RESULTS

The study found significantly reduced muscle activation in most of the targeted muscles when walking on level ground with the trolley bag and when going up/down stairs with the backpack.

CONCLUSIONS

Lifting a trolley bag depends on the slope of the walking surface and is more efficient on level ground, while carrying a backpack is more efficient when going up and down stairs. Since it is not practical to switch bags when encountering stairs in schools, a bag with a mixed model design incorporating features of both trolley and backpack may be more beneficial and practical for students to use. Students, parents, and teachers should be aware of the injury risks associated with carrying different types of bags.

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

(1) Background: the effects of load carriage packs on human gait biomechanics, physiology and metabolism depend on the weight carried, the design of the pack and its interaction with the user. (2) Methods: An extensive search in the PubMed database was performed to find all the relevant articles using the following keywords: backpack, rucksack, backpack ergonomy and sports backpack; 60 articles were included. (3) Results and significance: Double pack (DP) and T-pack (TP) designs are recommended solutions for school children, compared with backpacks (BP). For soldiers and hikers, a backpack remains the best compromise. A hip belt is recommended for BPs as well as for the back of DPs. Shorter and stiffer shoulder straps combined with a higher and tighter load placement on the back provide the best combination in terms of balance, muscle activation and energy expenditure. It is, therefore, possible to determine guidelines for designing the optimal load carriage system, depending on the application. (4) Conclusions: based on the available evidence, DP and TP are advantageous in terms of posture. DP is better than conventional BPs in terms of balance and muscle activation, but has the disadvantage of limited visibility, thermal sensation and obstructed ventilation. In general, it is desirable not to exceed 40% of body mass (BM).

Ergonomic factors of school bags and their adaptation to the weight of students

BACKGROUND

Students use a school bag to carry their school supplies which may not have the required standards and ergonomic factors.

OBJECTIVE

This study was aimed to examine the ergonomic factors of schoolbags and their adaptation to the weight of elementary school students.

METHODS

This cross-sectional study was carried out on 721 primary schoolchildren. To collecting data a checklist, which its final version was approved by the experts, was designed by researchers. Data were analyzed by using SPSS ver. 22 and Chi-square test, One-Way ANOVA, and univariate and multivariate logistic regression models.

RESULTS

In this study, about 90.1% of students used a backpack to carry their items and most students carried backpacks with a weight up to 10% of their body weight. In 43.5% of the students, waist width was appropriate with backpack width at the bottom, and in 96.6% shoulder width was appropriate with backpack width at the top. Multivariate logistic regression showed that girls in compared to boys were more likely tolerated ratio of backpack weight to body weight, and also had more likely proportion of waist width and the backpack width at the bottom. The grades of the first, second, and fourth used more heavy backpacks. Students who their mothers were employee compared to housewives, carried heavier backpacks and had more likely proportion of waist width and the backpack width at the bottom. As the mother's age increased, the proportion of waist width and the backpack width at the bottom is diminished.

CONCLUSION

The schoolbags weight of many students was more than the standard weight, and their schoolbags did not have the required standards. Educational interventions can increase the knowledge of students and parents about the ideal weight of a schoolbag and the criteria for choosing a proper school bag.

Effects of School Backpacks on Spine Biomechanics During Daily Activities: A Narrative Review of Literature

OBJECTIVE

The purpose of this narrative review is to summarize the effects of carrying school backpacks on spine and low-back biomechanics as a risk factor for low back pain in young individuals.

BACKGROUND

Backpacks constitute a considerable daily load for schoolchildren. Consistently, a large number of children attribute their low back pain experience to backpack use.

METHOD

A literature search was conducted using a combination of keywords related to the impact of carrying backpacks on lower back biomechanics. The references of each identified study were further investigated to identify additional studies.

RESULTS

Twenty-two studies met inclusion criteria. A total of 1,159 people aged 7 to 27 years were included in the studies. The added load of a backpack and the changes in spinal posture when carrying a backpack impose considerable demand on internal tissues and likely result in considerable spinal loads. The findings included results related to the effects of backpack weight and position on trunk kinematics and spine posture as well as trunk muscle activity during upright standing, walking, and ascending and descending stairs.

CONCLUSION

Backpack-induced changes in trunk kinematics for a given activity reflect alterations in mechanical demand of the activity on the lower back that should be balanced internally by the active and passive responses of lower back tissues. Although the reported alterations in trunk muscle activities and lumbar posture are indications of changes in the active and passive response of the lower back tissues, the resultant effects on spinal load, that is, an important causal factor for low back pain, remains to be investigated in the future. A knowledge of backpack-induced changes in spinal loads can inform design of interventions aimed at reduction of spinal load via improved backpack design or limitation on carrying duration.

APPLICATION

This narrative review is intended to serve as an educational article for students and trainees in ergonomics and occupational biomechanics.

One-shoulder carrying school backpack strongly affects gait swing phase and pelvic tilt: a case study

The use of backpacks is common to both adults and children and often leads to the onset of musculoskeletal discomforts. Although a large number of studies have focused on the optimal load for children schoolbags, there is no general consensus. Here we report a 13-yr old girl case study, showing the impact of weight and wearing the school backpack on gait parameters. The variation of gait parameters and pelvis angles in different conditions were studied: without backpack (CTRL), or with backpack at 10% Body Weight (10BW), 15% BW (15BW) and 20% BW (20BW), carried “on both shoulders” (2S), “on one shoulder” (1S), or “with one hand” (1H). Swing phase was comparably modified by 2S/20BW and 1S/10BW conditions, suggesting that a lower backpack weight was sufficient to induce gait alterations when carried in asymmetrical conditions. Pelvic tilt, which was preserved by a two-shoulders distributed 10% BW load (2S/10BW), was strongly reduced in asymmetrical condition (1S/10BW), suggesting that a low weight carried on a single shoulder generates postural modifications including reduction of pelvic tilting, which is known to be associated to low back pain.

The effects of a loaded rucksack and weighted vest on metabolic cost and stride frequency in female adults

This study evaluated the metabolic cost and stride frequency during exercise while wearing an evenly distributed weight vest in recreationally fit women. Nine healthy women performed a modified Balke treadmill test until volitional fatigue in one of three conditions; (1) unloaded (2) rucksack and (3) weighted vest. Wearing a weighted vest did not show improvement of V̇_O2peak, HR_peak, peak stride frequency or average stride frequency (all p ≥ 0.05). However, total time of exercise was significantly longer in the evenly distributed weight vest condition compared to the rucksack condition (p = 0.024) despite similar V̇_O2peak and HR_peak. These results may provide practical information when females in tactical populations are preparing for missions in which heavy loads must be carried. Practitioner summary: This study compared the effects of load carriage mode on metabolic cost and stride frequency during graded exercise in females. The weighted vest showed significantly longer exercise time despite similar V̇_O2peak and HR_peak. Development of standardised weight distribution mode may serve as an advantageous strategy for females in tactical settings. Abbreviations: HR: heart rate; V̇O2: oxygen uptake; RPE: rating of perceived exertion; V̇O2peak: peak oxygen uptake; HRpeak: peak heart rate.

Analysis of the Effect of Backpack Design with Reduced Load Moment Arm on Spinal Alignment

In this study, we designed a backpack that can reduce the moment arm of backpack load by placing the center of gravity of the backpack close to the axis of the spine. In order to investigate the effect of sagittal spinal alignment compared with the general backpack, we conducted the study using radiological images. The participants in this study were 18 adults (8 males and 10 females). The subjects participated in the experiment without carrying the backpack, wearing the normal backpack, and wearing a backpack designed to reduce the load moment arm by placing the center of gravity close to the body. Spinal alignment parameters were measured and analyzed using 3D radiography measurement software based on radiographic images taken under three conditions. The overall angle of lumbar lordosis, upper arc, lower arc, difference between pelvic incidence and lumbar lordosis, lower cervical lordosis, and sagittal vertical axis were measured. In the case of wearing the backpack rather than without the backpack, there was a significant difference in the overall angle of lumbar lordosis, lower arc, lower cervical spine angle, difference between pelvic incidence and lumbar lordosis, and sagittal vertical axis. In the case of wearing the backpack with reduced moment arm, the overall angle and lower arc of lumbar lordosis were significantly increased compared to those with the normal backpack. The difference between pelvic incidence and lumbar lordosis was significantly decreased. The results showed that a normal backpack caused imbalance of sagittal spinal alignment, and the backpack reducing the load moment arm by placing the backpack's center of gravity close to the vertebral joint played a positive role in reducing the change of lumbar alignment compared with the normal backpack.

The Effects of Force That Pushes Forward Lumbar Region on Sagittal Spinal Alignment When Wearing Backpack

The purpose of this study is to design a backpack to push the lumbar region forward and confirm the change in the sagittal plane of the spine using radiography when wearing the backpack to present an effective backpack wearing method that can help spinal alignment. Place the question addressed in a broad context and highlight the purpose of the study. A total of 14 adult volunteers participated in the study. The study was carried out on the subjects without carrying a backpack, with a general backpack, and with a backpack designed to push the lumbar region forward. We investigated cervical, thoracic, lumbar, and sacral alignment under these three conditions. Lumbar lordosis showed a significant decrease in the state of wearing a general backpack compared to the case without a backpack, and a significant increase in the state of wearing a backpack designed to push the lumbar region forward rather than a general backpack. In addition, the sacral slope was significantly increased when carrying the backpack designed to push the lumbar region forward, compared to carrying the general backpack. There was a significant correlation between the sacral and lumbar alignment change when wearing the backpack compared to the state without a backpack. The results of this study indicate that wearing a backpack designed to push the lumbar region forward may contribute to the recovery of lumbar lordosis that is reduced when wearing a general backpack. This may be due to an increase in the sacral slope corresponding to the inferior angle of lumbar spine.

Effects of backpack and double pack loads on postural stability

Measurement of postural stability is crucial for identifying predictors of performance, determining the efficacy of physical training and rehabilitation techniques and evaluating and preventing injuries, particularly for heavy load carriage in hikers, mountain search and rescue personnel and soldiers. This study investigated the effect of load distribution on postural stability in an upright stance using backpack and double pack loads under conflicting or impaired somatosensory, visual and vestibular conditions. The sensory organisation tests were conducted on 20 young adults before and after a 10-min level walking exercise. Young adults' ability to use inputs from somatosensory and visual systems to maintain postural stability was significantly reduced following a 10-min walking exercise with a heavy backpack (30% of body weight), whereas no significant changes were observed for double pack carriage. Thus, the distribution of heavy loads to the front and back provides superior balance control compared with back-only loading. Practitioner summary: This study investigated the effects of heavy (30% of body weight) load distribution on postural stability after a 10-min walking exercise. Backpack carriage significantly reduced postural stability, whereas there was no significant effect under double pack loads. Distribution of heavy loads on the front-and-back is desirable for superior balance control.

Gender Differences in Energy Expenditure During Walking With Backpack and Double-Pack Loads

OBJECTIVE

To investigate gender differences in energy expenditure during walking with backpack and double-pack loads.

BACKGROUND

Studies have reported that energy expenditure during walking with double-pack loads is lower compared with backpack carriage. However, the effect of gender on energy expenditure while walking with these two load distribution systems has not been investigated.

METHOD

Thirty healthy young adults (15 female and 15 male participants) walked on a treadmill with backpack and double-pack loads weighing 30% of their body weight at a speed of 0.89 m/s for 10 min. The energy expenditure in terms of oxygen consumption (VO2) and respiratory exchange ratio (RER) were continuously monitored using a portable gas analyzer throughout each walking exercise. A mixed-design analysis of variance model was adopted to test the effects of gender, pack, and time on VO2 and RER.

RESULTS

No time effect was observed on VO2. However, significant gender, pack, and interaction effects were observed. The lowest VO2 was found in female participants under double-pack carriage. No significant gender or pack differences existed in RER. However, RER significantly and incrementally increased in time from the 4th through 6th, 8th, and 10th min.

CONCLUSION

This study revealed that heavy double-pack load carriage for healthy young female participants had significantly lower energy expenditure (normalized by the entire system weight, i.e., the participant's weight plus the weight of the pack) than that of the male participants in a 10-min walking exercise.

APPLICATION

The findings of this study indicated that healthy young female participants carried a heavy double-pack with less energy cost (normalized by the entire system weight, i.e., the participant's weight plus the weight of the pack) compared with their male counterparts during a 10-min walking exercise.

Trunk asymmetry is associated with dominance preference: results from a cross-sectional study of 1029 children

BACKGROUND

In some studies, an association has been reported between laterality of the curve in scoliotic adolescents and hand dominance; however, additional studies have to be performed to confirm these findings.

OBJECTIVE

The objective of this study is to evaluate the prevalence between trunk asymmetry and side dominance in hand, foot and visual laterality in adolescents.

METHODS

This was a cross-sectional study secondary analysis. In total, 1029 children (491 females) were enrolled from the Secondary School of Brescia, Italy, with a mean age of 12 (SD=0.9 years). All subjects underwent a screening program divided into three phases: Phase 1, collection of demographic and clinical characteristics; Phase 2, spine evaluation with a plumb line and Bunnell Scoliometer; and Phase 3, evaluation of side dominance of the eye, hand and foot with a 4-item survey.

RESULTS

Our data showed a prevalence of 0.43%, 1.01% and 0.87% for thoracic, thoracolumbar and lumbar curves, respectively, with a right-side dominance and a prevalence of 2.72%, 2.54% and 0.65% for thoracic, thoracolumbar and lumbar curves, respectively, with a left-side dominance.

CONCLUSION

The left-side dominance could have a prevalence on trunk asymmetry in thoracic and thoraco-lumbar curves. Our study suggests that the clinical evaluation of trunk asymmetry should be associated with the evaluation of laterality.

The association between backpack use and low back pain among pre-university students: A pilot study

Background

Individuals aged 30–60 years have a high possibility of experiencing low back pain. However, children and adolescents are not exempted from this problem. This study aimed to determine the relationship between backpack usage and the frequency of low back pain in pre-university students.

Methods

A total of 101 currently enrolled pre-university students were recruited for this cross-sectional study. They answered a questionnaire about their demographic details and their frequency of backpack usage. Their backpacks were weighed for four consecutive school days. The Roland–Morris Disability Questionnaire and Body Discomfort Chart were used to rate discomfort levels.

Results

The use and weight of a backpack were not significantly associated with low back pain, as indicated by the Roland–Morris Disability Questionnaire and Body Discomfort Chart (p > 0.05).

Conclusion

This study did not find an association between the use of a backpack and low back pain in Malaysian pre-university students.