Can Physical Activity Moderate Relationships between School Related Stress and HealthComplaints among Japanese Elementary School Children?
Minoru Takakura1, Minoru Kobayashi2, Masaya Miyagi3 Hisamitu Kobashigawa2
and Atsushi Kurihara4
Faculty of Medicine, University of the Ryukyus, Okinawa, Japan1, Faculty of Education,
University of the Ryukyus, Okinawa, Japan2, Okinawa Prefectural College of Nursing,
Okinawa, Japan3, and Faculty of Culture and Education, Saga University, Saga, Japan4
Keywords: exercise, buffering effects, subjective symptoms
Introduction
In Japan, it is compulsory for all children from ages 6 to 15 years to attend elementaryand junior high schools. As school children spend their time in school almost all day, theirperceptions of school environments are associated with not only their academic performances
but also with their physical and psychological well-being. In particular, school-related stresses,
such as pressure from schoolwork and high academic demands, have been designated as
primary sources of somatic and psychological complaints (Takakura & Sakihara, 2001;
Torsheim & Wold, 2001). As greater frequency of subjective health complaints among school
children are associated with their absence from school and poor academic achievement,
effective school health promotion programs that address students' health concerns need to bedeveloped.
Previous studies with adults suggested that physical activities have positive
influences on people's health outcomes such as mortality, morbidity, somatic and mental healthproblems, and physical fitness. Among young people, however, low to moderate associations
between physical activity levels and health outcomes have been shown (Sallis & Owen, 1999).
For example, a study of Japanese school children demonstrated that physical activity level was
significantly but weakly associated with stress responses (r=-.18, p<.01) (Uechi, Takenaka &Oka, 2000).
Past research also indicated that physical activity may have a buffering effect on
health outcomes in the sense that physical activity acts as a moderator in the association
between stress and health outcomes. Haugland, Wold & Torsheim (2003) showed that among
Norwegian 15-year-olds there were positive relationships between the levels of school-related
stress and the frequency of health complaints, and interactions between school-related stressand physical activity on health complaints, suggesting that school-related stress was moreclosely related to health complaints for adolescents who reported low levels of physical activity.
Norris, Carroll & Cochrane (1992) also showed that high intensity exercise program for
10-week training period moderated the association between perceived stress and healthoutcomes among secondary school students.
However, these previous studies were carried out exclusively on adolescentpopulations. To our knowledge, no studies have attempted to examine a moderator effect ofphysical activity on the association between stress and health outcomes among Japaneseelementary school children. Moreover, few studies have examined if practices such as eating
breakfast, having enough sleep, watching TV, and playing PC games can moderate theassociation between stress and health outcomes among them.
This study aims to examine whether subjective health complaints are associated withschool-related stress and physical activity among Japanese 6th grade school children and to
determine the influence of physical activity on the relation of school-related stress to healthcomplaints. In addition, other health practices were examined as moderators of the association
between stress and health complaints.

Method

Procedures and Subjects
Classroom teachers conducted a self-administered questionnaire survey in aclassroom setting in May and July 2002. The study sample consisted of 1,978 students in 6th
grade (ages 11-12) at 25 public elementary schools throughout Okinawa, Japan. Schools werechosen based on the size of the student population in school districts and willingness of school
administrators to participate in the study. A total of 1,573 students had complete data and wereused for statistical analyses (51.2% boys and 48.8% girls).
Measures
The questionnaires mainly consisted of items adapted from the 1997/1998 HealthBehaviour in School-aged Children Study (HBSC) by the World Health Organization (Currie,1998). The questionnaires were translated into Japanese by a research team that included abilingual speaker and they were reviewed for reliability and validity.
Health complaints were measured by the HBSC symptom checklist that included theitems headache, abdominal pain, backache, feeling low, irritability, nervousness, sleeping
difficulties, and dizziness. Students reported on a 5-point scale if each symptom wasexperienced seldom or never, about once every month, about once every week, more than oncea week, or most days. Cronbach’s alpha coefficient was .73. The logarithm of the scale score
was used because of its skewed distribution. School-related stress was measured by one item:‘How pressured do you feel by the schoolwork you have to do?’ The item was rated on a
4-point scale ranging from ‘not at all’ to ‘a lot’.
Physical activity was measured by frequency and duration questions The frequency
question asked students ‘Outside school hours: How often do you usually exercise in your freetime, so much that you get out of breath or sweat?’ The response categories were: ‘Once amonth or less’, ‘Once a week’, ‘2-3 times a week’, ‘4-6 times a week’, and ‘Every day’. Theduration question asked students ‘Outside school hours: How many hours do you usually
exercise in your free time, so much that you get out of breath or sweat?’ The response
categories were: ‘None’, ‘About half an hour per week’, ‘About 1 hour per week’, ‘About 2-3hours per week’, ‘About 4-6 hours per week’, and ‘About 7 hours per week’. The responses
were re-categorized to create a dichotomous summary measure. Students who reported beingactive ‘2-3 times a week’ or more and ‘about 1 hour per week’ or more were classified as active.
Students who reported being active for ‘once a week’ or less or ‘half an hour per week’ or lesswere classified as inadequately active (Booth, Okely, Chey & Bauman, 2001).
In addition, practice variables including eating breakfast, having enough sleep,watching TV, and playing PC games were assessed.
ResultsThe descriptive analyses showed that boys were more likely to report healthcomplaints than girls (t= -6.07, p<.001). The levels of school-related stress among girls weresignificantly higher than those of boys ( 2=34.63, p<.001). Boys were more likely to report2
being physically active (76.3%) compared with girls (48.5%),=129.96, p<.001. Boys
2
played PC games for more hours than girls did ( =136.90, p<.001), while girls watched TV
for more hours than boys did ( 2=6.32, p=.012). No gender differences in the proportions ofstudents having enough sleep and eating breakfast were shown ( 2=.67, p=.41; 2=.74,p=.39).
As a result of analysis of variance, school-related stress showed a significant main
effect on health complaints among both boys and girls (F=11.78, p<.001; F=8.99, p<.001),
suggesting the relationship between high levels of school-related stress and high levels of

complaints. However, physical activity did not show a main effect on health complaints among
boys and girls (F=1.44, p=.23; F=.83, p=.36). In addition, there was no interaction between
school-related stress and physical activity on health complaints among boys and girls (F=1.36,p=.25; F=.61, p=.61). As for other health practices, among girls, having enough sleep, eating
breakfast, watching TV, and playing PC games showed significant main effects on healthcomplaints (p<.05). Among boys, eating breakfast and playing PC games showed a significant
main effect (p<.05). Students who slept for 7-8 hours, ate breakfast everyday, watched TV forless than 4 hours a day, or played PC games for less than 4 hours a week were less likely toreport health complaints. A series of analyses of variance for health practices also showedsignificant main effects of school-related stress (p<.05). However, there was no interaction
between school-related stress and each health practice on health complaints (p .05).
Conclusions
This study shows that, at least among Japanese 6th grade school children in Okinawa,physical activity was not associated with the levels of health complaints and the relationshipbetween school-related stress and health complaints. In other words, physical activity in thisage group had no direct and buffering effects on health outcomes. The findings of this study
were not consistent with previous studies of adolescent populations seeking to determine if
physical activity could influence health outcomes and the relationship between stress level andhealth outcomes. A possible explanation could be that the impacts of school-related stress orother health practices surpass that of physical activity on health complaints. Indeed,school-related stress and health practices had significant main effects on health complaints inthis age group. Our earlier cross-sectional studies revealed that physical activity was strongly
associated with physical fitness level and also high level of physical fitness decreased healthcomplaints. Therefore, it will be necessary to conduct a prospective study to confirm causal
linkages between physical activity, physical fitness, and health outcomes among elementary
school children.
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