People are faced with various forms of load carrying and its consequences in
their daily life. Most occupations also expose people to the problems resulting
from load carriage. One of the most common forms of load carrying is making
use of backpacks. Students of various education levels use bags or backpacks
for carrying their books and other education instruments (Legg
and Cruz, 2004).
Studies have shown that more than 50% of the students carry very heavy school
bags. Also, 55% of the students carry loads which weigh more than the allowed
limit (10-15% of the body weight) to school which may damage the vertebral column
and cause musculoskeletal pains (Iyer, 2001).
Nowadays, a large number of individuals suffer from spinal pain which is one
of the most common reasons for visiting the physicians. Students also experience
spinal pains quite early mainly due to using heavy school bags (Legg
and Cruz, 2004; Grimer, 1996).
Studies have revealed a significant relationship between the backpack weight
and body posture. For instance, in case the students use school bags which weigh
more than 10-15% of their body weight, a forward head posture is created in
order to compensate (Weir, 2002). Ideally, a school
bag or backpack should not weigh more than 10% of the individuals weight
and is better to be carried on both shoulders (Whittfield
et al., 2005).
Carrying school bags (handbags or backpacks) not only creates some musculoskeletal
as well as postural problems, but it also affects the lung mechanics and the
respiratory volume. Besides, it has been shown that carrying loads close to
the trunk can affect the pulmonary function (Weir, 2002;
Siambanes et al., 2004). Of course, the rate
of effects is various at different ages. Between 12 and 14 years of age (middle
school), humans vertebral column is continuously growing and any kind
of stress to the vertebral column presents as pain and discomfort (Leboeuf-Yde
and Kyvik, 1998).
Up to now, the effect of carrying heavy bags on the adolescents natural
growth has not been proved. Studies have been conducted on the relationship
between heavy school bags and educational failure, lack of motivation, lack
of learning, and absenteeism; however, no definite results have been obtained
(Ko and Kim, 2013).
Moreover, several studies have been performed on the physiological and biomechanical
effects of carrying backpacks on the musculoskeletal system and human body.
These studies have investigated various factors related to carrying backpacks
or school bags. Most of the studies have shown the backpack weight as the main
factor causing undesirable effects on human body, particularly when the backpack
or school bag weighs more than 15-20% of the body weight. Length of carriage
and design of the school bag were also among the factors which attracted the
researchers attention (Weir, 2002, Stuempfle
et al., 2004; Mazzocca et al., 2005;
Liu, 2007; Devroey et al.,
According to what was mentioned above, it is necessary to conduct studies on
this issue on Iranian students in order to clarify various dimensions of carrying
heavy bags. The results of such studies can be used to plan and execute programs
for changing the authorities,
parents, and students
attitude toward carrying heavy bags and prevent pain as well as musculoskeletal
problems among the children and adolescents.
MATERIALS AND METHODS
Subjects: In the present descriptive-analytical, cross-sectional study,
the samples were selected through cluster sampling. First, Shiraz districts
were defined as categories and each school was considered as a cluster. Then,
random sampling was performed for selecting the clusters and all the students
of each school were entered into the study.
The study was conducted on 12-15 year old middle school students. This group
was selected because of their sensitive body growth. In addition, they use school
bags more than the following levels and, at the same time, have more capability
for completing the questionnaires compared to the primary school students.
Study protocol: The study data were collected through a researcher-made
questionnaire whose validity had been confirmed. This questionnaire included
both open-ended and close-ended questions classified in 5 categories of demographic
information, history of the students
diseases, information about the students
activities, and features of the school bag and its carrying mode. The ratio
of the bag weight to the body weight (kg) was also calculated in 3 different
Statistical analysis: Finally, the data were entered into the SPSS statistical
software (v. 11.5) and analyzed through descriptive and analytical statistical
methods. Chi-square was used to determine the independence of two qualitative
variables, while one-way and two-way ANOVA were used for comparing the quantitative
According to the results, 54.1% (424) of the participants were female, while
45.9% (360) were male and 16 questionnaires were excluded from the study due
to the distortion of the answers to the main questions. Considering the educational
districts, 24.6, 18.8, 30.4, and 26.2% of the students were from the first,
second, third, and fourth educational districts, respectively. Moreover, 33.7,
33.8, and 32.4% of the students were studying in the first, second, and third
grades of middle school, respectively.
The study results showed that 20.3, 33.6, 14.2, and 31.9% of the students carried
their bags for less than 10 min, between 10 and 20 min, between 20 and 30 min,
and more than 30 min, respectively. In addition, 10.8% of the subjects never,
42.3% rarely, 32.3% mostly, and 14.5% always felt a kind of pain due to carrying
their bags. Furthermore, 18.8, 21.3, 26.3 and 33.6% of the participants watched
TV or used computer for less than an hour, between 1 and 2 h, between 2 and
3 h, and more than 3 h, respectively. Besides, 60.5% of the students used benches,
while 39.5% used chairs.
According to the study findings, 62.6, 16 and 21.3% of the students used backpacks,
handbags, and shoulder bags, respectively. In addition, 31% of the students
carried their bags on both shoulders, while 69% carried them on one side. Among
the students who used backpacks, 48.9, 40.4 and 10.6% carried them on both shoulders,
the right shoulder, and the left shoulder, respectively. Regarding those who
made use of handbags or shoulder bags, 68.02% used the right side, while 31.98%
used the left side.
Overall, 80.6% (632) of the students mentioned that their feeling of pain was
related to carrying school bags. Among these students, 40.8% stated that they
felt pain when they carried the bags, while 32% said that they felt pain when
they put the bags down. Also, 27.2% mentioned that they always felt this pain.
The mean weight of school bags was compared between the two sexes. According
to the results, the mean weight of the girls
and boys bags was 3.67 and 3.88
kg, respectively and the difference was statistically significant ( P = 0.001)
|| Information about the students weight, height, and
|| Relationship between the type of school bags and musculoskeletal
The results also revealed a significant relationship between musculoskeletal
pains and sex (P = 0.042). In fact, 86.3% of the girls and 81% of the boys reported
pain. The relationship between the type of school bags and musculoskeletal pains
are given in Table 2.
Moreover, a statistically significant relationship was observed between musculoskeletal
pains and educational districts of Shiraz (P=0.037). The highest and lowest
rates of pain were reported by the first district and second district students,
respectively (90.2% vs. 80.3%). However, no significant relationship was found
between the type of tables used in the classrooms and total musculoskeletal
The results of the present study showed that 62.6% of the students used backpacks.
In addition, 31% of the students carried their bags on both shoulders, while
69% carried them on one side. Among the students who used backpacks, 48.1, 40.2
and 11.7% carried them on both shoulders, the right shoulder, and the left shoulder,
In the study by Chow et al. (2007), 83% of
the students used backpacks and 59.3% used single strap backpacks. Puckree
et al. (2004) also conducted a study in South Africa and showed that
69% of the students used backpacks 40% of whom made use of double strap backpacks.
In the same line, Moore et al. (2007) performed
a study in England and reported that 81% of the students used backpacks. The
results of the present study showed that similar to other countries, Iranian
students also mostly made use of backpacks.
According to the results, the highest prevalence of musculoskeletal pains was
detected in the shoulders followed by waist, neck, back, knees, feet, ankles,
hands, wrists, and thighs while the lowest rate was related to the elbows. In
the study by Brackley et al. (2009), the prevalence
of shoulder pain, knee pain, and waist pain was reported as 36.9, 26.7 and 20.8%,
respectively. Puckree et al. (2004) also conducted
a similar study in South Africa and reported the prevalence of musculoskeletal
pains among the students to be 86.9%. In the same line, Van
Gent et al. (2003) performed a research and reported the prevalence
of musculoskeletal pains to be 43.6% for neck and shoulders and 46.5% for waist,
which is in agreement with the findings of the current study.
In this study, 80.6% (632) of the students stated that neck pain was related
to carrying school bags. In a similar study which was conducted by Cottalorda
et al. (2003) on middle school students, 59% of the subjects believed
musculoskeletal pains to be related to carrying bags or backpacks.
The results of the present study revealed a significant difference between
the two sexes regarding the mean weight of school bags (p<0.001). The mean
weight of the boys school bags (3.88 kg) was higher than that of the girls
bags (3.67 kg). This is consistent with the studies performed by Van
Gent et al. (2003), Bettany-Saltikov et al,
2008) and might be due to the fact that because of being stronger and having
stronger muscle tissues, boys are able to carry more loads.
The study results also revealed a significant relationship between musculoskeletal
pains and sex (P=0.042). Girl students felt more musculoskeletal pains in comparison
to boys which might be due to their weaker and more sensitive muscle tissues
and, consequently, their improper spinal alignment and disturbance in the function
of their inter-vertebral discs which act like a bumper. This troubles their
posture and, according to the specialists, improper posture causes musculoskeletal
pains later in life. In addition, lack of physical activity makes the girls
more susceptible to postural problems. Cottalorda et
al. (2003) also mentioned the girls to be more susceptible to musculoskeletal
pains; such a way that 80% of the girls and 63% of the boys had such pains.
Also, they reported a significant relationship between sex and musculoskeletal
pains, which is in agreement with the findings of the current study.
The present study also investigated the relationship between BMI and musculoskeletal
pains in at least one body point; however, no significant relationship was observed.
Similarly, Merati et al. (2001) investigated
the students anthropometric features and found no relationships between
their BMI and musculoskeletal problems.
The allowed school bag weight is believed to be 0.07% of ones
body weight. In addition, using a backpack is preferred in case it is carried
on both shoulders. Otherwise, using a handbag has fewer consequences. Students
are recommended not to carry bags for more than 20 minutes a day. Also, in case
they use handbags or shoulder bags, they had better use them alternatively on
The present study was extracted from M.Sc. thesis financially supported by
the Research Vice-chancellor of Shiraz University of Medical Sciences, Shiraz,
Iran (89-5366). Hereby, the authors would like to thank the department of education
of Fars Province and Shiraz.