Cardio-respiratory adjustments and cost of locomotion in school children during backpack walking (the Italian Backpack Study)

Examining the Backpack Weight Relative to Students' Body Weight Among Urban and Rural Schoolchildren: A Cross-Sectional Study

Background Schoolbags or backpacks have been an essential part of the education system for a long time. However, a hefty backpack causes the child to arch the back excessively or bend their head and trunk forward to withstand the weight of the schoolbag. If the student carries the backpack on one shoulder, he/she bends to the opposite side to compensate for the extra weight, which may damage the shoulders and spine. Considering these factors, the main aim of this study was to investigate the percentage of backpack weight in proportion to the student's body weight regarding the new guidelines among urban and rural schoolchildren aged 12 to 15 years in Bangalore, Karnataka. Methodology In southern India, over a year, a cross-sectional study was conducted with 500 students who voluntarily participated after providing written consent. They completed a questionnaire, underwent vital and anthropometric measurements, and had their weights measured, including the weights of their backpacks. Sample bags were inspected to determine contributing weight factors and evaluate adherence to timetables. Results The average weight carried by children of all ages was 6.53 kg, averaging 13.53% of their body weight. Among males, the percentage carrying backpacks weighing over 10% of their body weight was 80.9%, while among females, it was 85.7%. Of all the males carrying bags weighing more than 10% of their body weight, 67.7% attended government schools, while 32.3% attended private schools. Among females studying in government schools, 63.6% carried backpacks weighing more than 10% of their body weight, while among those in private schools, 36.4% carried bags exceeding that weight. Conclusions The study concluded that despite regulations being implemented on backpack weight for children, a significant number still carry bags exceeding 10% of their body weight among both urban and rural school children. This could elevate pressure on neck and back muscles, leading to excessive fatigue and potential damage to the skeletal system, ultimately contributing to spinal deformities.

The effect of vertical load placement on metabolic rate during loaded walking in humans

We examined the effects of vertical load placement on the metabolic cost of walking. Twelve healthy participants walked on a treadmill with 13.8 and 23.4 kg loads in both high and low vertical positions. Metabolic rate was measured using respirometry. While load position had no effect on the net metabolic rate for the 13.8 kg load, the net metabolic rate with the 23.4 kg load was significantly reduced by 4.3% in the high vertical load position compared to the low vertical load position. Loads carried higher on the trunk were also associated with increased forward trunk lean that reduced the load gravitational moment arm in the sagittal plane suggesting that reduction of fore-aft upper body torques is an energy-saving mechanism during loaded walking. Practitioner Summary: Load placement within a backpack affects the biomechanics of load carriage. We experimentally tested the metabolic cost of high and low load placement during walking and found the high position to be less costly with large loads. Loading high may be the optimal technique for carrying heavy backpacks.

Risk Factors for Low Back Pain in Childhood and Adolescence: A Systematic Review

OBJECTIVES

To identify factors associated with low back pain (LBP) in children and adolescents.

MATERIALS AND METHODS

A systematic review was conducted (Prospero CRD42016038186). Observational studies analyzing LBP risk factors among participants aged between 9 and 16 were searched for in 13 electronic databases and 8 specialized journals until March 31, 2016, with no language restrictions. In addition, references in the identified studies were manually tracked. All identified studies that included ≥50 participants aged 9 to 16, were reviewed. Their methodological quality was assessed by 2 reviewers separately, using validated tools, which scored, from worst to best, 0 to 100 for cross-sectional and 0 to 12 for cohort studies. A sensitivity analysis only included studies that had adjusted for confounders, had ≥500 participants, and had a methodological score of ≥50%.

RESULTS

A total of 5142 citations were screened and 61 studies, including 137,877 participants from 5 continents, were reviewed. Their mean (range) methodological scores were 74.56 (50 to 100) for cross-sectional studies and 7.36 (5 to 9) for cohort studies. The studies had assessed 35 demographic, clinical, biological, family, psychological, ergonomic, and lifestyle risk factors. The mean (range) prevalence of LBP ranged between 15.25% (3.20 to 57.00) for point prevalence and 38.98% (11.60 to 85.56) for lifetime prevalence. Results on the association between LBP and risk factors were inconsistent. In the sensitivity analysis, "older age" and "participation in competitive sports" showed a consistent association with LBP.

DISCUSSION

Future studies should focus on muscle characteristics, the relationship between body and backpack weights, duration of carrying the backpack, characteristics of sport practice, and which are the factors associated with specifically chronic pain.

Effect of backpack carrying on forced vital capacity in cystic fibrosis: A randomized crossover-controlled trial

BACKGROUND

Backpack carrying impacts lung function in healthy children but the effect in children with cystic fibrosis (CF) is unknown.

METHODS

Three backpack positions were tested: no backpack (NB), a 12.5% body-weight backpack carried bilaterally (BB) or unilaterally (UB), at rest and during a 10 minute walk. Primary outcome was forced vital capacity (FVC). Secondary outcomes included comparison of cardio-respiratory variables within and between groups.

RESULTS

Nine children with CF (13.3±2.6 years; FEV1 66±22%) and 18 healthy children (13.8±1.8 years; FEV1 107±30%) were included. FVC was reduced with UB compared to NB (68.5±23.3% vs 72.1±24.3%, p = 0.024) in children with CF. FEV1, MIP and MEP decreased more with UB in children with CF than in healthy peers. Increases in VO2, VCO2 and minute ventilation with UB were greater in the CF group during walking.

CONCLUSIONS

Unilateral backpack wearing affects FVC in children with CF and requires greater cardio-respiratory adjustments compared to healthy peers.

Comparison of Perceived Backpack Comfort Using Two Rating Scales

Students' current use of backpacks to carry heavy loads of school material has promoted concern about musculoskeletal discomfort and postural problems. The purpose of this study was (a) to compare ratings of perceived comfort between subjects' personal backpacks and an experimental backpack and (b) to compare the data from two comfort rating scales. College-aged students ( N = 19) in a random ordered, cross-over design rated their personal, traditional backpacks and experimental backpacks for perceived neck, shoulder, back, and overall comfort on a 100-mm Visual Analog Scale and on an Anatomical Illustration Rating Scale. Analysis indicated no significant difference in comfort ratings of backpacks on Visual Analog Scale but, on the Anatomical Illustration Rating Scale the experimental backpack was significantly ( p<.05) more comfortable for the back. Further comparisons of backpacks, based on median splits of subjects' weight, height, and body mass index, indicated that body size is related to comfort ratings of backpacks. Special features of the experimental backpack may have contributed to greater comfort in selected areas based on body proportion. Subjective rating systems are not equally sensitive in distinguishing comfort. While backpacks with unique features may improve comfort, manufacturers should consider the size of the users in developing backpack designs.

Investigation of the relationship between carrying school bags (handbags and backpacks) and the prevalence of musculoskeletal pains among 12-15 year old students in Shiraz

Inappropriate school bags put students at risk of musculoskeletal problems and early fatigue. Heavy bags can change the body posture and the musculoskeletal system must react appropriately in order to compensate for this stress. It is recommended that the weight of a school bag must not be more than 10% of the student's body weight and the weight must be placed on both shoulders. The present study aimed to identify the risk factors associated with musculoskeletal disorders by comparing the prevalence of musculoskeletal pains among the students. The present descriptive, cross-sectional study was conducted in different educational districts of Shiraz. The study samples were selected using cluster sampling method. In this study, 800 students marked their painful areas on body maps and the SPSS statistical software (v. 11.5) was used to analyze the data. The results showed that among the students who used backpacks, 48.9% carried the weight on both shoulders, 40.4% carried the weight on their right shoulders, and 10.6% used their left shoulders. Besides, 68.02% of the students carrying handbags often used their right shoulders, while 31.98% used their left shoulders. The study results showed that similar to other countries, Iranian students also mostly made use of backpacks. Moreover, the musculoskeletal pains were most prevalent in the shoulders, which is in line with many other studies conducted on the issue.

The utility of heart rate and minute ventilation as predictors of whole-body metabolic rate during occupational simulations involving load carriage

The utility of cardiac and ventilatory predictors of metabolic rate derived under temperate and heated laboratory conditions was evaluated during three fire-fighting simulations (70-mm hose drag, Hazmat recovery, bushfire hose drag; N = 16 per simulation). The limits of agreement for cardiac (temperate: - 0.54 to 1.77; heated: - 1.39 to 0.80 l min(- 1)) and ventilatory surrogates (temperate: - 0.19 to 1.27; heated: - 0.26 to 1.16 l min(- 1)) revealed an over-estimation of oxygen consumption that exceeded the acceptable limits required by occupational physiologists (N = 25; ± 0.24 l min(- 1)). Although ventilatory predictions offered superior precision during low-intensity work (P < 0.05), a cardiac prediction was superior during more demanding work (P < 0.05). Deriving those equations under heated conditions failed to improve precision, with the exception of the cardiac surrogate during low-intensity work (P < 0.05). These observations imply that individualised prediction curves are necessary for valid estimations of metabolic demand in the field.

Trunk muscular strength in pre-pubertal children with and without back pain

OBJECTIVE

While in adulthood there is no proven relationship between back pain and trunk muscle strength, in pre-pubertal subjects this topic has been poorly studied. The aim of the study was to evaluate isometric and isokinetic trunk muscle strength in children with or without previous back pain.

METHODS

The recent occurrence of back pain (last 6 months) among 144 children (77 males, 67 females, age 11.9 +/- 0.3 years) was assessed using a questionnaire. Extensor and flexor trunk muscle strength was measured through isometric and isokinetic (60, 90, 120 degrees/s) tests. Peak torque (PT), PT angle, PT flexor/PT extensor ratio and intra-session coefficient of variation (COV) were determined.

RESULTS

Flexor and extensor muscle PT, but not PT angle, were significantly higher in males than in females, irrespective of back pain occurrence. PT flexor/PT extensor ratio at 90 degrees angular velocities increased significantly only in males with back pain, compared with males without back pain. The COV trend was similar for flexor and extensor muscles.

CONCLUSIONS

Isometric and isokinetic trunk muscle strength probably play a minor role in back pain occurrence in children. The isokinetic testing velocity may be important in determining trunk strength differences between children with and without back pain.

Development of a compendium of energy expenditures for youth

BACKGROUND

This paper presents a Compendium of Energy Expenditures for use in scoring physical activity questionnaires and estimating energy expenditure levels in youth.

METHOD/RESULTS

Modeled after the adult Compendium of Physical Activities, the Compendium of Energy Expenditures for Youth contains a list of over 200 activities commonly performed by youth and their associated MET intensity levels. A review of existing data collected on the energy cost of youth performing activities was undertaken and incorporated into the compendium. About 35% of the activity MET levels were derived from energy cost data measured in youth and the remaining MET levels estimated from the adult compendium.

CONCLUSION

The Compendium of Energy Expenditures for Youth is useful to researchers and practitioners interested in identifying physical activity and energy expenditure values in children and adolescents in a variety of settings.

Study on the relationship between backpack use and back and neck pain among adolescents

A descriptive correlation study was conducted in Hobbs, New Mexico, USA, to find the relationship between backpack use and back and neck pain among adolescent boys and girls. A higher percentage of girls than boys rated their pain as being moderate to extremely strong. The correlation between pain and backpack weight per body mass index among girls was positive and significant, but negative and non-significant among boys. The correlation between pain and backpack weight was positive and non-significant among both boys and girls. The correlation between pain and each of the variables of backpack weight per body weight, backpack weight per height, and backpack weight per body surface area was negative and non-significant among boys, but positive and non-significant among girls. Gender-based research studies with additional variables and safe backpack use education in schools are recommended.

Influence of carrying heavy loads on soldiers' posture, movements and gait

Military personnel are required to carry heavy loads whilst marching; this load carriage represents a substantial component of training and combat. Studies in the literature mainly concentrate on physiological effects, with few biomechanical studies of military load carriage systems (LCS). This study examines changes in gait and posture caused by increasing load carriage in military LCS. The four conditions used during this study were control (including rifle, boots and helmet carriage, totalling 8 kg), webbing (weighing 8 kg), backpack (24 kg) and a light antitank weapon (LAW; 10 kg), resulting in an incremental increase in load carried from 8, 16, 40 to 50 kg. A total of 20 male soldiers were evaluated in the sagittal plane using a 3-D motion analysis system. Measurements of ankle, knee, femur, trunk and craniovertebral angles and spatiotemporal parameters were made during self-paced walking. Results showed spatiotemporal changes were unrelated to angular changes, perhaps a consequence of military training. Knee and femur ranges of motion (control, 21.1 degrees +/- 3.0 and 33.9 degrees +/- 7.1 respectively) increased (p < 0.05) with load (LAW, 25.5 degrees +/- 2.3 and 37.8 degrees +/- 1.5 respectively). The trunk flexed significantly further forward, confirming results from previous studies. In addition, the craniovertebral angle decreased (p < 0.001) indicating a more forward position of the head with load. It is concluded that the head functions in concert with the trunk to counterbalance load. The higher muscular tensions necessary to sustain these changes have been associated with injury, muscle strain and joint problems.

The energetic costs of trunk and distal-limb loading during walking and running in guinea fowl Numida meleagris: I. Organismal metabolism and biomechanics

We examined the energetic cost of loading the trunk or distal portion of the leg in walking and running guinea fowl (Numida meleagris). These different loading regimes were designed to separately influence the energy use by muscles used during the stance and swing phases of the stride. Metabolic rate, estimated from oxygen consumption, was measured while birds locomoted on a motorized treadmill at speeds from 0.5 to 2.0 m s-1, either unloaded, or with a mass equivalent to 23% of their body mass carried on their backs, or with masses equal to approximately 2.5% of their body mass attached to each tarsometatarsal segment. In separate experiments, we also measured the duration of stance and swing in unloaded, trunk-loaded, or limb-loaded birds. In the unloaded and limb-loaded birds, we also calculated the mechanical energy of the tarsometatarsal segment throughout the stride. Trunk and limb loads caused similar increases in metabolic rate. During trunk loading, the net metabolic rate (gross metabolic rate-resting metabolic rate) increased by 17% above the unloaded value across all speeds. This percentage increase is less than has been found in most studies of humans and other mammals. The economical load carriage of guinea fowl is consistent with predictions based on the relative cost of the stance and swing phases of the stride in this species. However, the available comparative data and considerations of the factors that determine the cost of carrying extra mass lead us to the conclusion that the cost of load carrying is unlikely to be a reliable indicator of the distribution of energy use in stance and swing. Both loading regimes caused small changes in the swing and/or stance durations, but these changes were less than 10%. Loading the tarsometatarsal segment increased its segmental energy by 4.1 times and the segmental mechanical power averaged over the stride by 3.8 times. The increases in metabolism associated with limb loading appear to be linked to the increases in mechanical power. The delta efficiency (change in mechanical power divided by the change in metabolic power) of producing this power increased from 11% in walking to approximately 25% in running. Although tarsometatarsal loading was designed to increase the mechanical energy during swing phase, 40% of the increase in segmental energy occurred during late stance. Thus, the increased energy demand of distal limb loading in guinea fowl is predicted to cause increases in energy use by both stance- and swing-phase muscles.

The effect of backpack load on the gait of normal adolescent girls

Concerns regarding the effects of load carriage have led to recommendations that backpacks be limited to 10?-?15% of body weight, based on significant changes in physical performance. However, gait responses to backpack loads are not entirely consistent and there is a particular lack of data regarding load-bearing gait in adolescent females. Gait patterns of 22 normal adolescent girls were recorded at backpack loads of 0, 7.5, 10.0, 12.5 and 15.0% body weight. Temporal-distance, ground reaction force and joint kinematic, moment and power parameters were analysed by repeated measures ANOVA with factors of backpack load and side (left or right). Walking speed and cadence decreased significantly with increasing backpack load, while double support time increased. Kinematic changes were most marked at the proximal joints, with a decreased pelvic motion but a significant increase in the hip sagittal plane motion. Increased moments and power at the hip, knee and ankle showed increasing demand with backpack load. Parameters showed different responses to increasing load, and those that suggested a critical load indicated this to be approximately 10% body weight. While this may be due to a change in gait due to increased demand, further work is required to verify this and also to examine the cumulative effects of backpack load on the musculoskeletal system, which may be more appropriate in determining recommended load limits.

Are children's backpack weight limits enough? A critical review of the relevant literature

STUDY DESIGN

Literature review.

OBJECTIVE

To examine the epidemiologic, physiologic, and biomechanical literature that has contributed to the suggested weight limit of 10 to 15% body weight for children's backpacks.

SUMMARY OF BACKGROUND DATA

The majority of children use a backpack to transport their belongings to and from school on a daily basis; however, controversy exists over the safety of backpack use and backpack loads.

METHODS

A thorough review of the literature was completed to examine the appropriateness of the suggested weight limits and to determine future areas of research needed to increase the safety of children's backpacks.

RESULTS

Epidemiologic, physiologic, and biomechanical data support the suggested weight limit of 10% to 15% body weight. CONCLUSIONS.: Based on the current literature, the value of 10% to 15% body weight is a justified weight limit; however, further research is required to determine the association between backpack use and injury and how the factors of load, backpack design, and personal characteristics, such as physical fitness, interact and influence the adaptations required when carrying a backpack.

Patterns of active transport in 11-12 year old Australian children

OBJECTIVES

To describe the habitual transport patterns of 11 to 12-year-old children in Australia, to determine the personal and environmental factors associated with active transport (AT), and to quantify how much AT contributes to overall daily energy expenditure (EE).

METHODS

The participants in this study were 136 children aged 11-12 year olds from eight randomly chosen primary schools in Adelaide, South Australia. Each child recalled their trips on two school days and a non-school day. Mass and stature were measured, and children completed a computerised activity recall and a neighbourhood satisfaction questionnaire. Trips were categorised according to their destination, child and parent dissatisfaction with the neighbourhood, and the gender, socio-economic status (SES), BMI and activity levels of the children undertaking them. These categories, along with the distance to the destination, were used as independent variables in a logistic regression model, with trip mode (passive versus active) as the dependent variable.

RESULTS

Children made an average of 1.0 active trips per day, with a median trip length of 0.63 km, while the median total distance covered actively per child per day was 0.61 km. Twenty-six per cent of children did no AT over the three days, and 67% did no AT on a weekend day. Distance was by far the strongest predictor of the likelihood that a trip would be active. Trips made by girls were less likely to be active compared with boys. Trips to the shops were less likely to be active than trips to school. Children's AT accounted for 1.3% of their daily EE.

CONCLUSIONS AND IMPLICATIONS

The active transport levels of children were very low. Interventions should focus on making neighbourhoods safer and more accessible to children and should promote bicycle use.

Low back pain prevention's effects in schoolchildren. What is the evidence?

Given the high prevalence rates of back pain, as early as in childhood, there has been a call for early preventive interventions. To determine which interventions are used to prevent back problems in schoolchildren, as well as what the evidence is for their utility, the literature was searched to locate all investigations that used subjects under the age of 18 and not seeking treatment. Included investigations were specifically designed as an intervention for low back pain (LBP) prevention. Additionally, a literature search was performed for modifiable risk factors for LBP in schoolchildren. The literature-update search was performed within the scope of the "COST Action B13" of the European Commission, approved for the development of European guidelines for the management of LBP. It was concluded that intervention studies in schoolchildren focusing on back-pain prevention are promising but too limited to formulate evidence-based guidelines. On the other hand, since the literature shows that back-pain reports about schoolchildren are mainly associated with psychosocial factors, the scope for LBP prevention in schoolchildren may be limited. However, schoolchildren are receptive to back-care-related knowledge and postural habits, which may play a preventive role for back pain in adulthood. Further studies with a follow-up into adulthood are needed to evaluate the long-term effect of early interventions and the possible detrimental effect of spinal loading at young age.

Cartable et pathologie rachidienne

Back pain has become a real public health concern both for adults and children. In general, patients complain of moderate pain. While the topic was long ignored by the scientific community, the number of publications has increased over the last three Years. We reviewed the literature to separate real evidence from speculations. Recognized risk factors for spinal pain are: female gender, poor general status, family history of back pain, particular psychological patterns, time spent sitting watching television, history of spinal trauma, intense physical activity, practicing competition sports, and age (more frequent in adolescents than children). Several recent papers have drawn attention to the role of the weight of the school backpack in children, particularly when its weight exceeds 20% of the child's body weight. Many children carry heavy backpacks which for some may weigh 30% to 40% of their body weight. Several groups have estimated that the maximum should be 10% of the body weight. It appears that time spent carrying the backpack as well as its weight is an important factor favoring back pain. Backpacks can injury the head or face, as well as the hands, the elbow, the wrist, the shoulder, the foot and the ankle. Back trauma is observed as the sixth most common injury. The 'weak point' is the shoulder and not the back. A poorly positioned backpack can modify posture and gait. Carrying the backpack with two shoulder straps affects posture and gait less than carrying it on one shoulder. The posture of the spine changes when the weight of the backpack increases. This is probably one of the reasons why many parents who consult believe that there is a relationship between the weight of the backpack and scoliosis or kyphosis, observed in many of their children. It is proven that adolescents who suffer from back pain will probably have chronic back pain as adults, but there is not evidence to our knowledge demonstrating a relationship between the development of spinal deviation and the weight of the backpack. Recent studies have been conducted to design backpacks allowing a better weight distribution and comfort. This type of backpack appears to have a limited benefit. Furthermore, the question of mode must not be ignored for children and adolescents. Backpacks with one sack in front and one in back certainly provide better weight distribution but are they acceptable for children and adolescents?

The association of backpack use and back pain in adolescents

STUDY DESIGN

A cross-sectional study comprising the first phase of an ongoing, longitudinal prospective study was conducted.

OBJECTIVE

To investigate the relation between backpack use and back pain in adolescents.

SUMMARY OF BACKGROUND DATA

The prevalence of nonspecific back pain increases dramatically during adolescence from less than 10% in the pre-teen-age years up to 50% in 15- to 16-year-olds. There is widespread concern that heavy backpacks carried by adolescents contribute to the development of back pain.

METHODS

A total of 1126 children, ages 12 to 18 years, participated by completing a questionnaire about their health, activities, and backpack use. Each child's body weight, height, and backpack weight were measured. A child was classified as having back pain if one or more of the following were reported during the preceding month: neck or back pain that had interfered with school or leisure, neck or back pain with a severity rating of 2 or more on a scale 0 to 10, a visit to a physician or therapist for neck or back pain, or exemption from physical education or sports because of neck or back pain.

RESULTS

Of 1122 backpack users, 74.4% were classified as having back pain, validated by significantly poorer general health, more limited physical functioning, and more bodily pain. As compared with no or low use of backpacks at school, heavy use (odds ratio, 1.98; P < 0.0001) was independently associated with back pain. Female gender and larger body mass index also were significantly associated with back pain. As compared with adolescents who had no back pain, adolescents with back pain carried significantly heavier backpacks that represented a significantly greater percentage of their body weights.

CONCLUSION

The use of backpacks during the school day and backpack weights are independently associated with back pain.

Backpacks in children

Back pain and deformity are common in adolescents. There has been extensive discussion in the lay literature as to the potential for back pain and spinal deformity with backpack use. The scientific literature on this subject is sparse but is increasing. Epidemiologic studies have identified risk factors associated with back pain in adolescents and daily use of a heavy backpack may be important. A book bag weighing more than 15% to 20% of a child's weight is associated with back pain, and improper use of the backpack can result in changes of posture and gait. There is no evidence that structural spinal deformity can result from backpack use. Children who experience back pain are at increased risk of having back pain as adults. The economic impact may be significant, because back pain is a major cause of disability in adults. The current authors review the available scientific literature and comments on this public health issue.