a three city survey study of relationship between back pack usage, weight and back pain.

1. Backpacks and
Back pain
Many children today are coming home with backpacks laden with several books,
notebooks, calculators and school supplies, often bent over under the strain of
carrying it all. Some students end up carrying bags that are equal to 30 percent of
their body weight, according to some studies. In the mini-project for our course on
Field Methods and Research Writing, we conducted a cross-sectional study to
determine the relation between the weight of schoolbags, backpack usage and the
incidence of back pains.
Submitted by
Narendran. A (HS07H016)
Neha B. Joseph (HS07H017)
Shivraj Singh Negi (HS07H022)

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ABSTRACT
This study surveyed the prevalence of back pain in school students and examined its
association with backpack usage – the type of backpack, backpack load, time spent
carrying the load. 76.35% of the students surveyed reported back pain validated by
significant bodily pain in neck, shoulders, upper and lower back, visits to the doctor
and reduced physical activity. Backpack usage (p<0.05) was independently
associated with back pain. The weight of the backpack was the most dominant
component of ‘backpack usage’.
Objective To determine the relation between backpack usage and back
pain in school children.
Study Design A cross sectional study
Method A total of 150 students, ranging from ages 10 to 18 years,
participated by completing a self-administered questionnaire
about their health, nutrition, activities, and backpack use. Each
student's body weight, height, and backpack weight were
measured.
Result 76.35 % of the students surveyed reported back pain validated
by significant bodily pain in neck, shoulders, upper and lower
back, visits to the doctor and reduced physical activity.
Backpack usage (p<0.05) was independently associated with
back pain.
Conclusion The use of backpacks during the school day and backpack
weights are independently associated with back pain.

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INTRODUCTION
Back pain (defined as pain in the neck,
shoulders, upper and lower back)
among adolescents is an important
concern. Studies like Harreby’s in 1995
have linked adolescent back pain to
adult back strain. Excessive load-bearing
for long periods on immature spines
could put children at increased risk of
future back problems in adulthood. Hence it is necessary to determine the exact
cause of back pain to take preventive measures so that future health disorders can
be reduced in both children and adults. Weight of backpacks has been commonly
understood as the most dominant factor causing back pain in adolescents. However,
some studies have linked back pain to furniture comfort in schools (Mohd Azuan K.
et al.) and physical activity of the child. In this survey we are attempting to ascertain
if backpacks are still the greatest determinant of back pain.
Total back pack use can be defined only when factors like the type of backpack used,
mode of carriage and duration of carriage are included. In 2008, a study conducted
by Haselgrove looked at components of backpack usage other than weight of
backpacks like method of transport to school and duration of carriage that can also
cause back pain. We attempt to proceed along the same lines as Haselgrove. Our
survey looks at various components of backpack usage (type and style of backpack
used, the mode of carriage, duration of backpack carriage (time taken to and fro
from school), mode of transport as well as the load of the backpack) and aims to
determine the relation between backpacks usage and back pain.
Our research question is
 Is backpack usage (1. type and style of backpack used, 2. the mode of
carriage, 3. duration of backpack carriage (time taken to and fro from
school), 4. mode of transport and 5. weight of the backpack) independently
associated with back pain (pain in neck, shoulders, upper and lower back)?
LITERATURE REVIEW
Research in the field of spinal pain among adolescents is vast. Several studies have
tried to establish causal relations between back pain and nutrition, physical activity,
psychological conditions, body posture etc. (Cardon, 2004). The reason why this field

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is so popular probably lies in the fact that spinal pain in adolescent years has been
associated with several potential health consequences in adult years including back
strain, altered gait, bad posture etc. Establishing a cause for this spinal pain would
definitely make it easier to take preventive measures.
Most of these studies have provided definitive results. Although there are some
studies which link back pain to furniture comfort in schools (Mohd Azuan K.), most
studies have linked back pain to weight of schoolbags. J. Whittfield has established
that Musculoskeletal symptoms are multi-factorial in origin; the carriage of heavy
schoolbags is a dominant contributory factor (J. Whittfield et al.,2005). A study
conducted by Sheir-Neiss brings about a p=0.0001 association between load of
backpacks and back pain (Sheir-Neiss et al., 2003). Haselgrove has shown that even
perceived school bag load among schoolchildren can lead to back pain. (Haselgrove
et al., 2008). T. Puckree has gone further along the same line of thinking and
established that the type of bag used by school kids is the most dominant factor
contributing to back pain among adolescents(T. Puckree et al., 2004) Haselgrove has
also looked at other factors like method of transport to school and duration of
carriage that can cause back pain.( Haselgrove et al., 2008)
This study was designed along the same lines. It looks at various components of
backpack usage (type and style of backpack used, the mode of carriage, duration of
backpack carriage (time taken to and fro from school), mode of transport as well as
the load of the backpack) and aims to determine if backpack usage is independently
associated to back pain.
METHODOLOGY
Design
A cross-sectional study design was adopted to conduct the research.
Participants
A total of 150 students in the age group 10-15 years participated in the survey. The
participants were chosen from the two states of Tamil Nadu and Uttarakhand. No
exclusion criteria were applied to the participants in the study.
Data Collection
Data was collected through a household survey. Participants were asked to fill in
questionnaires with questions regarding their backpack use, nutrition, health
problems, body posture, awareness levels about back pain and its causes, etc. Each
student’s body weight, height, and backpack weight were measured using scales that

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the researcher carried to each household. And it was only after each participant had
given informed consent to participation in the survey that the questionnaire was
handed out to him/her. A pilot study was conducted in order to test the viability of
the survey methods. The effect of this pilot study was notable. It led to a relaxation
of the conditions required to define a person as ‘suffering from back pain’.
The questionnaire was made up of 29 multiple-choice questions, both open-ended
and closed-ended. The questions covered areas like socio-economic status of the
students’ households, nutritional aspects, sleeping/sitting posture, physical ailments,
and student’s awareness about the harmful effects of heavy backpack usage.
Questions testing the prevalence of back pain were taken from a previously
validated questionnaire (Standardised Nordic questionnaires for the analysis of
musculoskeletal symptoms - I. Kuorinka, B. Jonsson, A. Kilbom, H. Vinterberg, F.
Biering-Sorensen, G. Andersson and K. Jorgensen -- Applied Ergonomics 1987).
Questions dealing with the other factors that can cause back pain were taken from
reliable questionnaires from previously conducted researches listed in the section
‘Literature Review’. The questionnaire was prepared keeping in mind the Indian
context. For instance, factors like smoking/drinking that might have caused back pain
were excluded keeping in mind the cultural norms of Indian children in the age group
10-15.
Definition of Variables
The two primary variables in our survey are backpacks and back pain. Previous
surveys in this area have focused solely on the weight of the backpack to determine
the incidence of back pain. We, however, have used a broader definition of
‘backpack usage’ and taken into account other components of backpack usage like
the type and style of backpack used, the mode of carriage, duration of backpack
carriage (time taken to and fro from school), mode of transport as well as the load of
the backpack.
A child was classified as having back pain if one or more of the following were
reported during the preceding month: pain in at least 2 of the following body parts –
neck, shoulders, upper back, lower back, a visit to a doctor for back pain, or
exemption from any leisure activities or sports because of neck or back pain.
Data Analysis
Descriptive Statistics were used to examine the usage of backpacks and the
prevalence of back pain. Relationships between the use and load of school bags were
examined using simple two variable regression in Excel.

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Regression Statistics
Multiple R 0.11872536
R Square 0.014095711
Adjusted R
Square 0.007388879
Standard Error 3.02550826
Observations 149
The population regression model is: y = β1 + β2 x1 + u
It is assumed that the error u is independent with constant variance (homoskedastic)
We wish to estimate the regression line: y = b1 + b2 x1
The standard error here refers to the estimated standard deviation of the error term
u. It is sometimes called the standard error of the regression. It equals sqrt(SSE/(n-
k)). It is not to be confused with the standard error of y itself (from descriptive
statistics) or with the standard errors of the regression coefficients given below.
ANOVA
df SS MS F Significance F
Regression 1 19.23828053 19.23828 2.101694 0.149266148
Residual 147 1345.593934 9.1537
Total 148 1364.832215
The column labelled F gives the overall F-test of H0: β1 = 0 and β2 = 0 versus Ha: at
least one of β1 and β2 does not equal zero.
F = [Regression SS/(k-1)] / [Residual SS/(n-k)] = [19.23828053/1] / [1345.593934/147]
= 2.101694
The regression output of most interest is the following table of coefficients and
associated output:
Coefficients Standard Error t Stat P-value Lower 95% Upper 95%
Intercept 5.112372401 0.784345694 6.518009 1.06861E-09 3.56232234 6.662422463
14.28571429 -0.093205244 0.064291797 -1.44972 0.149266148 -0.220260833 0.033850345
Let βj denote the population coefficient of the jth regressor (intercept, back pack
weight and back pain)
Then
 Column "Coefficients" gives the least squares estimates of βj.
 Column "Standard error" gives the standard errors (i.e. the estimated
standard deviation) of the least squares estimates bj of βj.

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 Column "t Stat" gives the computed t-statistic for H0: βj = 0 against Ha: βj ≠ 0.
This is the coefficient divided by the standard error. It is compared to a t with (n-k)
degrees of freedom where here n = 18 and k = 3.
 Column "P-value" gives the p-value for test of H0: βj = 0 against Ha: βj ≠ 0..
This equals the Pr{|t| > t-Stat}where t is a t-distributed random variable with n-k
degrees of freedom and t-Stat is the computed value of the t-statistic given in the
previous column.
 Columns "Lower 95%" and "Upper 95%" values define a 95% confidence
interval for βj.
A simple summary of the above output is that the fitted line is
y = 5.112372401 + 0.093205244*x2
95% confidence interval for slope coefficient β2 is from Excel output (0.220260833,
0.033850345).
Consider test H0: β1 = 0 against Ha: β1 ≠ 0 at significance level α = .05.
Using the p-value approach
From the output p-value = 0.00000000106.
Reject the null hypothesis at level .05 since the p-value is < 0.05.
RESULTS
All 150 respondents correctly filled out all the questions in the questionnaires. The
mean age of the respondents was 13 years. Almost all respondents carried
backpacks over two shoulders. School bus and Taxi/Auto were the two most popular
modes of transport (52.7%). Around 72% of schoolchildren reported carrying their
schoolbags for over 20 minutes daily. Most respondents agreed to slouching forward
or tilting sideways while carrying their schoolbags. On the average, the backpack
loads represented 11.75% of student body weights.
Around 76 % of the respondents reported the prevalence of back pain. More females
(82.2 %) than males (67.6%) reported the prevalence of back pain. Most (48%)
respondents suffered from pain in 2 or more parts in the spinal area. Around 16.8%
respondents reported that they suffered from spinal pain for over 8-30 days in the
last two months. Almost 32.4 % had suffered in the past week.
Other factors also seem to have played a role in causing back pain.
Nutrition (β1= 5.562254945; β2= -0.295046615 )
T.V viewing and Physical activity (β1= 3.521834661; β2= 0.176496842 )
Sleeping/sitting posture (β1= 3.748191569; β2= 0.062713062)
Awareness about back pain and its causes (β1= 4.75821308 ; β2= -0.423426466)

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Results of the survey:
Use and Load of the
Bag Male Female Total
(n=71) (n=79) (n=150)
Use of School bag
(Duration Of carriage)
min
<10 minutes 1 1 2
10-20 minutes 17 23 40
20-30 minutes 39 27 66
30-40 minutes 6 15 21
40-50 minutes 3 6 9
50-60 minutes 2 5 7
>=60 minutes 1 2 3
Method of carriage Male Female Total
Both Shoulders 63 78 141
One Shoulder 6 1 7
Method of transport to
school Male Female Total
School Bus 17 27 44
Car 7 14 21
Cycle 14 7 21
Walk 4 3 7
Taxi/Auto 19 15 34
Rickshaw 1 4 5
Public Transport (Train/Bus) 7 9 16
Load of school bag Male Female Total
<2 kgs 0 0 0
2-3 kgs 0 5 5
3-4 kgs 19 25 44
4-5 kgs 23 29 52
5-6 kgs 14 15 29
6-7 kgs 12 3 15
>7kgs 1 2 3
School bag use: The most significant factors associated with back pain were related
to back pack usage, and interestingly, the level of awareness. These factors have
higher r value associated with them compared to other factors like nutrition and
socio-economic background. Among the various components of backpack usage,
back pack weight had the highest associated r values with low p values. Back pain
was reported less in respondents carrying backpacks for less than 10 minutes daily.

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There was a linear trend noted between times taken to get to school with bag with
back pain felt. Duration of bag use and back pain have a low slope coefficient
(0.003904299).
Discussion
The findings from this study indicate that multiple factors are associated with back
pain but the most dominant one was the back pack weight. This is consistent with
findings by previous researches that have shown that back pack weight in excess of
10% of body weight significantly increases the risk of back pain.
The research also showed that females (82.2%) suffered more intense back pain than
males (67.6%). The cause of the higher prevalence of spinal pain amongst females is
unknown. Studies have shown that females have a lower pain tolerance which may
partially account for the increased back pain prevalence rates. Additionally females
have weaker upper body strength compared to males.
A limitation of this study is that backpack weight was measured on a single day of
the week. This may have been an incorrect estimate of the actual weight of the
schoolbag. Ideally, the correct estimate would be an average of the backpack weight
on all 5 days of the week. But due to methodological difficulties, the weight of the
bag on a single day of the week had to suffice as a measure. Another limitation of
this study is that it relied on self-administered questionnaires instead of medical
reports to make an estimate about the prevalence of back pain. When triggered by
so many questions regarding backpack usage and because of the preconceived
notion that heavy backpacks do cause back pain, the answers given by the
respondents may have well been an overestimate. Also, there might have been a
recall bias involved when the participants were asked to give an estimate of the
number of days on which they experienced back pain in the past 2 months. Another
limitation is that some factors like psychological conditions (depression, loneliness)
may have caused fatigue and tiredness, thereby translating into spinal pain, were left
out of the survey. The methodological difficulties of measuring psychological
conditions forced us to drop this factor out of consideration.
CONCLUSION
This study shows that there are various factors causing back pain among adolescents
– backpack usage, nutrition, physical activity, body posture while sitting/sleeping,
and awareness. Backpack usage; however seems to be the most dominant factor.

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Our objective was to find out the relation between backpack usage and back pain.
And we found that Backpack usage (p<0.05) was independently associated with back
pain, with weight of the backpack being the strongest component causing that back
pain. Despite the limitations involved in our survey, we believe that our research
objective has been achieved.
An important finding of this survey is that back pain has been highly associated with
weight of the backpack and also the low levels of awareness among parents, children
and schoolteachers about the causal relation between weight of the schoolbag and
back pain. The knowledge gained from the survey can be put into use by medical
practitioners and government agencies all over the world to set ceilings on the
weight carried by schoolchildren in their backpacks. This would go a long way in
reducing back pain in adolescents and more severe health problems in adulthood.
Some of the measures adopted could be to set a ceiling on the weight of every
schoolbag, buying an extra set of textbooks for home study so that the books used in
school could be stored in a locker on the school premises, encouraging the use of
padded double shoulder backpacks. The preventive measures are numerous. Proper
implementation is all that is necessary.

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REFERENCE
Low back pain prevention's effects in schoolchildren. What is the evidence?
Greet Cardon, F. Balague
Springer-Verlag 2004
Correlates of heavy backpack use by elementary school children
S.N. Forjuoha, J.A. Schuchmannb, B.L. Lanea
Public Health (2004)
Neck, Upper Back and Lower Back Pain and Associated Risk Factors among
Primary School Children
Mohd Azuan K., Zailina H., Shamsul B.M.T., Nurul Asyiqin M.A., Mohd Azhar M.N.
and Syazwan Aizat I.
Science Alert
Schoolbag weight and musculoskeletal symptoms in New Zealand secondary
schools
J. Whittfield, S.J. Legg,
and D.I. Hedderley
Applied Ergonomics, Volume 36, Issue 2, March 2005
School bag carriage and pain in school children
T. Puckree; SP Silal, J. Lin
Disability & Rehabilitation, Volume 26, Issue 1 January 2004
The Association of Backpack Use and Back Pain in Adolescents
Sheir-Neiss, Geraldine I. PhD; Kruse, Richard W. DO; Rahman, Tariq PhD; Jacobson,
Lisa P. ScD; Pelli, Jennifer A. MS
Spine, 1 May 2003
Standardised Nordic questionnaires for the analysis of musculoskeletal symptoms
I. Kuorinka, B. Jonsson, A. Kilbom, H. Vinterberg, F. Biering-S6rensen,
G. Andersson and K. Jorgensen
Applied Ergonomics 1987
Perceived school bag load, duration of carriage, and method of transport to school
are associated with spinal pain in adolescents: an observational study
Haselgrove, Clare; Straker, Leon; Smith, Anne; O'Sullivan, Peter; Perry, Mark; Sloan,
Nick
Australian Journal of Physiotherapy