Access to pedestrian roads, daily activities, and physical performance of adolescents

An alternative design for small-scale school health experiments: does daily walking produce benefits in physical performance of school children?

BACKGROUND

The mainstream randomized clinical trial is not always feasible in a school setting. There might be practical and ethical issues that make dividing school classes into an intervention and a control group impossible or undesirable, and there is a need to explore the validity of alternative designs and analyses.

METHODS

An alternative to a randomized clinical trial in a physical performance experiment at a school is introduced and evaluated. The before-intervention data are utilized as control data for the intervention data in addition to adjust for pre-intervention differences. The strict class year structure of school data makes this possible. In a rural school in inland Norway, all school children joined the project of walking in a rugged terrain outside school for 20 min every school day during one school year. Measurements of low back static endurance, hamstrings flexibility, standing balance and cardiovascular fitness were made before and after the intervention. As intervention and 'aging' were confounded, the special use of the pre-intervention data, 'age-adjusted', is proposed to solve this issue. A comparison with having an independent control group is performed.

RESULTS

The alternative analysing method is judged to yield valid results without having an independent control group. The age-adjusted analyses showed 11% increase in low back static endurance, 8% increase in hamstrings flexibility, 69% increase in balance and 6-13% increase in cardiovascular fitness. The effects were largest among those children who had the lowest performances before the intervention.

CONCLUSION

The introduced statistical methods display that, in a school population, evaluations from an experiment can be made without an independent control group. A 20-min walk during school time for 1 year seemed to improve physical performance.

Walking and Bicycling to School: A Review

Walking and bicycling (active commuting) to school has been proposed as a strategy for increasing youth physical activity and decreasing the prevalence of overweight. Citations for this review were retrieved through PubMed, Transport, ERIC, and ISI database searches using relevant keywords (1975 to March 2007), government and organization Web sites, and bibliographic citations. This review presents (1) prevalence estimates for active commuting to school; (2) the correlates of active commuting to school, presented using a new conceptual framework; (3) the associations between active commuting to school and health (ie, physical activity, weight status, environmental); and (4) a summary of the findings and recommendations for further research. Considerable heterogeneity exists among the reviewed studies for sample size and demographics, the methods used to measure active commuting, and the definition used to identify a positive case (active commuter). In general, active commuting to school is much less prevalent in the United States compared with European countries. A wide range of correlates of active commuting to school have been studied (individual to policy level). Active commuters tend to be more active than nonactive commuters, although no difference in weight status was observed in most studies. More research is needed to corroborate these findings and build on the knowledge base so that effective walk-to-school interventions can be implemented independently or as part of other health promotion efforts, including physician counseling for physical activity.

Truncus endurance, hip and ankle mobility and aerobic fitness in 15-year-old Norwegian adolescents in 1968 and 1997

This study compared the physical performance of adolescents in 1997 and 1968. The material included 1329 15-year-old Norwegian adolescents in Akershus county in Norway in 1968, and 1105 15-year-old adolescents in the same region in 1997. The investigations were supervised by the same conductor on both occasions, and used identical physical tests. The test battery included dynamic endurance of abdominal and low back muscles, hip flexion, ankle dorsiflexion and aerobic fitness. Compared with 1968, low back extension endurance in 1997 was almost 10% lower in both genders, the endurance of the abdominal muscles was 4.8% poorer among boys and 8.1% higher among girls and the ratio between abdominal and low back extension endurance was 11.8% higher among boys and 26.4% higher in girls. Compared with 1968, hip flexion in 1997 was 8.3% higher in girls, while ankle dorsiflexion and aerobic fitness in boys were 15% and 13.4% poorer, and 4.8% poorer and 2.5% higher in girls, respectively. The data indicate a general decline during one generation in physical performance among boys, a decline in low back endurance, truncus balance and ankle mobility among girls and in a higher abdominal endurance among girls.

Public parks and physical activity among adolescent girls

OBJECTIVES

Physical activity may be constrained or facilitated by local environments. The availability of neighborhood facilities for physical activity may be particularly relevant for youth, who are unable to drive and whose activity is often limited to the immediate distance they are able to walk or bicycle. Several studies have shown that proximity to recreational facilities and parks is one of the most important predictors of physical activity. Because the United States already has an extensive infrastructure of parks, with 70% of adults indicating that they live within walking distance of a park or playground, parks may be a potential venue for increasing physical activity. This might be particularly important for adolescent girls, whose physical activity levels decline substantially as they go through puberty. The goal of this study was to examine the association between park proximity, park type, and park features and physical activity in adolescent girls.

PATIENTS AND METHODS

This was a cross-sectional study using baseline data from the Trial of Activity for Adolescent Girls. It included 1556 grade 6 girls who were randomly selected from 6 middle schools in each of the following 6 field site areas: Washington, DC, and Baltimore, Maryland; Columbia, South Carolina; Minneapolis, Minnesota; New Orleans, Louisiana; Tucson, Arizona; and San Diego, California. Girls wore accelerometers for 6 days to measure metabolic equivalent-weighted moderate-to-vigorous physical activity, a measure accounting for the volume and intensity of activity. Metabolic equivalent-weighted moderate-to-vigorous physical activity was calculated for the hours outside of school time using 2 different cutpoints, activity levels > or = 3.0 metabolic equivalents and > or = 4.6 metabolic equivalents, the latter indicating activity at the intensity of a brisk walk or higher. We mapped all of the parks within 1 mile of each girl's home. Trained staff used a checklist to document the presence of facilities and amenities at each park, including passive amenities, such as drinking fountains, restrooms, and areas with shade, as well as active amenities like basketball courts, multipurpose fields, playgrounds, and tennis courts.

RESULTS

Mean nonschool metabolic equivalent-weighted moderate/vigorous physical activity, using the 4.6 metabolic equivalent cutoff, was 611.1 minutes (range: 49.7-4718.6 metabolic equivalent minutes per 6 days) and 1704.8 metabolic equivalent minutes per 6 days (range: 276.2-5792.6 metabolic equivalent minutes per 6 days) when using the 3.0 metabolic equivalent cutpoint. Many girls had multiple parks within a 1-mile radius of their homes: 57% had > or = 1 type of park, the majority being neighborhood or community parks; 42% had between 1 and 3 parks, 37% had > or = 4 parks, and 14% had > or = 8 parks. The type, number, and specific parks features were associated with girls' nonschool metabolic equivalent-weighted moderate/vigorous physical activity. At the 4.6 metabolic equivalent cutpoint, higher levels of nonschool metabolic equivalent-weighted moderate/vigorous physical activity were associated with both neighborhood and community parks (22 metabolic equivalent minutes) and miniparks (40 metabolic equivalent minutes). Each park, regardless of type, in the half-mile around each girl's home was associated with an increase in nonschool metabolic equivalent-weighted moderate/vigorous physical activity by 2.8% or 17.2 nonschool minutes of metabolic equivalent-weighted moderate/vigorous physical activity per 6 days. Beyond a half-mile, each park increased nonschool metabolic equivalent-weighted moderate/vigorous physical activity by 1.1% or 6.7 metabolic equivalent minutes per 6 days. For the average girl with 3.5 parks within a 1-mile radius of home, the presence of parks accounted for 36.5 extra nonschool metabolic equivalent minutes per 6 days, approximately 6% of total nonschool metabolic equivalent-weighted moderate/vigorous physical activity. Using the 3.0 metabolic equivalent cutpoint, this sums to an additional 68 metabolic equivalent minutes of nonschool metabolic equivalent-weighted moderate/vigorous physical activity over 6 days, or 4% of the total. The most common amenities in the parks were playgrounds, multipurpose fields, and picnic areas. Slightly more than one third of girls lived within a half-mile of a park with a basketball court, and > 20% had access to walking paths and tennis courts in their local park. Higher levels of nonschool metabolic equivalent-weighted moderate/vigorous physical activity per 6 days were associated with walking paths (13 metabolic equivalent minutes), running tracks (82 metabolic equivalent minutes), playgrounds (28 metabolic equivalent minutes), and basketball courts (30 metabolic equivalent minutes). Parks with streetlights and floodlights were also associated with an increase of 18 and 22 minutes of nonschool metabolic equivalent-weighted moderate/vigorous physical activity, respectively. With the 3.0 metabolic equivalent cutoff for metabolic equivalent-weighted moderate/vigorous physical activity, additional nonschool metabolic equivalent minutes more than doubled when girls had miniparks (92 metabolic equivalent minutes), natural resource areas (36 metabolic equivalent minutes), walking paths (59 metabolic equivalent minutes), and running tracks (208 metabolic equivalent minutes) within a half-mile of their homes. Skateboard areas and special-use parks were negatively associated with nonschool metabolic equivalent-weighted moderate/vigorous physical activity in adolescent girls.

CONCLUSIONS

Adolescent girls who live near more parks, particularly near those with amenities that are conducive to walking and with active features, engage in more nonschool metabolic equivalent-weighted moderate/vigorous physical activity than those with fewer parks. Whether this is because of actual use of the parks or neighborhood choice could not be determined. Although the magnitude of the association between parks and additional minutes of metabolic equivalent-weighted moderate/vigorous physical activity was small for an individual, amounting to an average of 4%-6% of a girl's total nonschool metabolic equivalent-weighted moderate/vigorous physical activity, it is likely to have a large population-level association. Because of the potential population level impact, the use of parks to promote physical activity should be further studied.

Personal, family, social, and environmental correlates of active commuting to school

BACKGROUND

Active commuting to school may be an important opportunity for children to accumulate adequate physical activity for improved cardiovascular risk factors, enhanced bone health, and psychosocial well-being. The purpose of this study was to examine personal, family, social, and environmental correlates of active commuting to school among children.

METHODS

Cross-sectional study of 235 children aged 5 to 6 years and 677 children aged 10 to 12 years from 19 elementary schools in Melbourne, Australia. Self-administered questionnaires were completed by parents, and the older children. The shortest possible routes to school were examined using a geographic information system.

RESULTS

Among both age groups, negative correlates of active commuting to school included parental perception of few other children in the neighborhood and no lights or crossings for their child to use, and an objectively assessed busy road barrier en route to school. In younger children, an objectively assessed steep incline en route to school was negatively associated with walking or cycling to school. Good connectivity en route to school was negatively associated with walking or cycling to school among older children. Among both age groups, children were more likely to actively commute to school if their route was <800 meters. There were no associations with perceived energy levels or enjoyment of physical activity, weight status, or family factors.

CONCLUSIONS

For children, creating child-friendly communities and providing skills to safely negotiate the environment may be important. Environmental correlates of active transport in children and adults may differ and warrant further investigation.

Associations between activities and low back pain in adolescents

The aim of this cross-sectional study was to explore associations between self-reported leisure activities and low back pain (LBP). The material included all adolescents in eighth and ninth grade in two geographical areas in the school year 1996-1997. Eighty-eight adolescents participated (mean age 14.7 years), making the response rate 84%. LBP during the preceding year was reported by 57%. Sixty-six percent reported physical activity 3 times weekly or more. The median time spent on television or computer was 15 h. In multivariate analyses, LBP was inversely associated with time spent on physical activity, in particular with regular walking or bicycling. LBP was associated with the use of television or computer more than 15 h weekly, but not with the time spent reading. The results confirm studies showing inverse associations between walking and LBP. Future research should involve prospective studies of the potential effects of walking or bicycling and other specific activities on LBP.

Epidemiology of low back pain in children and adolescents

It has been estimated that over 80% of the population will report low back pain (LBP) at some point in life, and each year 7% of the adult population consult their GP with symptoms. Prevalence increases with age, reaching a peak during the sixth decade of life. Until recently little was known about LBP at young ages. Clinically it was perceived to be uncommon-with few children consulting because of LBP in primary care. Large prospective epidemiological studies have shown that, in those free of LBP at baseline, the best predictor of future onset is a previous history of LBP. Therefore, to understand the epidemiology of LBP, and what predisposes someone to a trajectory of LBP in adult life, it is important to examine the condition at young ages, to determine factors responsible for onset of initial episodes, and to examine whether LBP in childhood is related to symptoms in adulthood.

Low-back pain in adolescents is associated with poor hip mobility and high body mass index

The objective of this cross-sectional study was to investigate whether body mass index (BMI) and hip mobility are associated with low-back pain (LBP) in adolescents. The study population included all adolescents in 8th and 9th grades in a rural and in an urban area in Eastern Norway. Eighty-eight adolescents participated (mean age 14.7 years), making the response rate 84%. LBP was assessed by a questionnaire answered in the classrooms as pain/discomfort in the low back during the preceding year. Body height and weight were measured, and BMI was calculated. Hip mobility was measured as active movements by a goniometer. The level of significance was set to P< or =0.05. In bivariate analysis for the whole group, LBP was associated positively with a higher than mean BMI, while LBP among boys was associated with a less than mean hip flexion, internal rotation, and hamstrings flexibility. In multiple regression analyses, adjusting for gender and well-being, LBP was associated with a higher than mean BMI, a less than mean hamstrings flexibility, and a less than mean hip flexion. The results suggest further prospective research to investigate whether poor hip mobility and high BMI may predict juvenile LBP.

Active or passive journeys and low back pain in adolescents

The objective of this cross-sectional study was to study associations between low back pain (LBP) and modes of transport to school and leisure activities among adolescents. The study population included all adolescents in eighth and ninth grade in two geographic areas in eastern Norway. Eighty-eight adolescents participated (mean age 14.7 years), making the response rate 84%. Data concerning active (walking/bicycling) and passive (bus/car) journeys were obtained from lists and maps from local authorities, and from the pupils, using a questionnaire that also included LBP, activities and wellbeing. Distance walked/bicycled to school was slightly shorter among those reporting LBP in bivariate analyses. Walking/bicycling more than 8 km weekly to regular activities was inversely associated with LBP in multivariate analysis (OR 0.3; 95% confidence interval 0.1-1.0). No associations were found between passive journeys and LBP. The results raise the question for future research of whether lack of active transport may be one cause behind the increase in juvenile LBP.

The significance of high lumbar mobility and low lumbar strength for current and future low back pain in adolescents

STUDY DESIGN

This study comprised a cross-sectional part and a prospective part.

OBJECTIVE

To study whether low lumbar extension strength, high lumbar mobility, and high mobility-extension strength ratios are related to current and future low back pain in adolescents.

SUMMARY OF BACKGROUND DATA

Knowledge is sparse about the significance of lumbar mobility and strength for low back pain in adolescents.

METHODS

The study population included all the adolescents in the eighth and ninth grades of a rural municipality (n = 44) and in an urban area (n = 61) during the 1996-1997 school year. At baseline, 88 adolescents (mean age, 14.7 years) participated in the study, giving a response rate of 84%. Low back pain was assessed by questionnaire as pain or discomfort in the low back during the preceding year. Sagittal lumbar mobility was tested by Schober's modified technique, and lumbar strength as static endurance extension strength. The follow-up part was conducted 3 years later, which included 98% of the adolescents.

RESULTS

By bivariate and multivariate analyses in the cross-sectional part of the study, low back pain was found to be highly associated with low lumbar extension strength (P = 0.004-0.02), and high lumbar mobility-extension strength ratios (P = 0.005-0.04). Baseline low lumbar extension strength and high lumbar sagittal mobility-extension strength ratios (P = 0.03 and P = 0.02, respectively) predicted low back pain at follow-up assessment in multivariate analyses when control was used for gender, previous low back pain, physical activity, and well-being. No associations were found between plain sagittal mobility and low back pain.

CONCLUSION

The study findings support theories suggesting insufficient strength and stability in the low back as important factors for both concurrent and future low back pain in adolescents.