Wendell C. Taylor

Age and gender differences in objectively measured physical activity in youth.

PURPOSE The purpose of this study was to evaluate age and gender differences in objectively measured physical activity (PA) in a population-based sample of students in grades 1-12. METHODS Participants (185 male, 190 female) wore a CSA 7164 accelerometer for 7 consecutive days. To examine age-related trends, students were grouped as follows: grades 1-3 (N = 90), grades 4-6 (N = 91), grades 7-9 (N = 96), and grades 10-12 (N = 92). Bouts of PA and minutes spent in moderate-to-vigorous PA (MVPA) and vigorous PA (VPA) were examined. RESULTS Daily MVPA and VPA exhibited a significant inverse relationship with grade level, with the largest differences occurring between grades 1-3 and 4-6. Boys were more active than girls; however, for overall PA, the magnitudes of the gender differences were modest. Participation in continuous 20-min bouts of PA was low to nonexistent. CONCLUSION Our results support the notion that PA declines rapidly during childhood and adolescence and that accelerometers are feasible alternatives to self-report methods in moderately sized population-level surveillance studies.

Using objective physical activity measures with youth: How many days of monitoring are needed?

PURPOSE The purpose of this study was to establish the minimal number of days of monitoring required for accelerometers to assess usual physical activity in children. METHODS A total of 381 students (189 M, 192 F) wore a CSA 7164 uniaxial accelerometer for seven consecutive days. To examine age-related trends students were grouped as follows: Group I: grades 1-3 (N = 92); Group II: grades 4-6 (N = 98); Group III: grades 7-9 (N = 97); Group IV: grades 10-12 (N = 94). Average daily time spent in moderate-to-vigorous physical activity (MVPA) was calculated from minute-by-minute activity counts using the regression equation developed by Freedson et al. (1997). RESULTS Compared with adolescents in grades 7 to 12, children in grades 1 to 6 exhibited less day-to-day variability in MVPA behavior. Spearman-Brown analyses indicated that between 4 and 5 d of monitoring would be necessary to a achieve a reliability of 0.80 in children, and between 8 and 9 d of monitoring would be necessary to achieve a reliability of 0.80 in adolescents. Within all grade levels, the 7-d monitoring protocol produced acceptable estimates of daily participation in MVPA (R = 0.76 (0.71-0.81) to 0.87 (0.84-0.90)). Compared with weekdays, children exhibited significantly higher levels of MVPA on weekends, whereas adolescents exhibited significantly lower levels of MVPA on weekends. Principal components analysis revealed two distinct time components for MVPA during the day for children (early morning, rest of the day), and three distinct time components for MVPA during the day for adolescents (morning, afternoon, early evening). CONCLUSIONS These results indicate that a 7-d monitoring protocol provides reliable estimates of usual physical activity behavior in children and adolescents and accounts for potentially important differences in weekend versus weekday activity behavior as well as differences in activity patterns within a given day.

Compliance with physical activity guidelines: Prevalence in a population of children and youth

PURPOSE To use objective monitoring of physical activity to determine the percentages of children and youth in a population that met physical activity guidelines. METHODS A total of 375 students in grades 1-12 wore an accelerometer (CSA 7164) for seven consecutive days. Bouts of continuous activity and accumulation of minutes spent in physical activity at various intensities were calculated to determine how many students met three physical activity guidelines. RESULTS Over 90% of students met Healthy People 2010, Objective 22.6 and nearly 70% met the United Kingdom Expert Consensus Group guideline, both of which recommend daily accumulation of moderate physical activity. Less than 3% met Healthy People 2010, Objective 22.7, which calls for bouts of continuous vigorous physical activity. For the United Kingdom Expert Consensus Group guideline, compliance decreased markedly with age, but gender differences were not statistically significant. CONCLUSIONS Prevalence estimates for compliance with national physical activity guidelines varied markedly for the three guidelines examined. Objective monitoring of physical activity in youth appears to be feasible and may provide more accurate prevalence rates than self-report measures.

Correlates of physical activity in a national sample of girls and boys in grades 4 through 12.

Psychological, biological, social, and physical environmental variables were examined for their association with physical activity of young people. A national sample of 1,504 parents and children in Grades 4-12 were interviewed by telephone. Twenty-two potential determinants were assessed along with an 11-item child physical activity index (alpha = .76). Hierarchical multiple regressions were conducted separately for 6 age-sex subgroups. Percentage of variance explained ranged from 18% for boys in Grades 4-6 to 59% for girls in Grades 10-12. Three variables had strong and consistent associations with the child physical activity index that generalized across subgroups: use of afternoon time for sports and physical activity, enjoyment of physical education, and family support for physical activity. These 3 variables should be targeted for change to promote physical activity in all groups of young people.

Childhood and adolescent physical activity patterns and adult physical activity

PURPOSE A major research priority is the influence of childhood and adolescent physical activity patterns on adult physical activity. The research in this area is inconsistent. Therefore, the purpose of this study was to evaluate the relationships among specific components of physical activity during childhood and adolescence and exercise habits in adulthood. METHODS We analyzed preteen and teenage experiences, individual and team sports, and several psychosocial variables. One hundred and five male volunteers completed questionnaires about their current (estimated energy expenditure (EE)) and historic physical activity and a treadmill stress test. RESULTS Based on correlations and regression analyses, without and with controlling for potentially confounding variables (treadmill run time and sum of skinfolds), the frequency of being forced to exercise and the frequency of being encouraged to exercise during the preteen years were inversely related to adult physical activity. Being forced to exercise during the preteen years was more related to participation in individual sports than to participation in team sports or both individual and team sports. CONCLUSIONS Being forced to exercise during childhood may have potentially negative consequences for later activity. The findings indicate that experiences related to participation in activity during childhood and adolescence may influence adult physical activity. The implications of our findings are discussed and future research is recommended.

Refined food addiction: a classic substance use disorder.

Overeating in industrial societies is a significant problem, linked to an increasing incidence of overweight and obesity, and the resultant adverse health consequences. We advance the hypothesis that a possible explanation for overeating is that processed foods with high concentrations of sugar and other refined sweeteners, refined carbohydrates, fat, salt, and caffeine are addictive substances. Therefore, many people lose control over their ability to regulate their consumption of such foods. The loss of control over these foods could account for the global epidemic of obesity and other metabolic disorders. We assert that overeating can be described as an addiction to refined foods that conforms to the DSM-IV criteria for substance use disorders. To examine the hypothesis, we relied on experience with self-identified refined foods addicts, as well as critical reading of the literature on obesity, eating behavior, and drug addiction. Reports by self-identified food addicts illustrate behaviors that conform to the 7 DSM-IV criteria for substance use disorders. The literature also supports use of the DSM-IV criteria to describe overeating as a substance use disorder. The observational and empirical data strengthen the hypothesis that certain refined food consumption behaviors meet the criteria for substance use disorders, not unlike tobacco and alcohol. This hypothesis could lead to a new diagnostic category, as well as therapeutic approaches to changing overeating behaviors.

Disparities in Physical Activity and Sedentary Behaviors Among US Children and Adolescents: Prevalence, Correlates, and Intervention Implications

Regular physical activity is important for health benefits among youth, but disparities exist. This paper describes disparities in physical activity participation and sedentary behaviors among youth in the United States, provides intervention implications, and offers recommendations for future research focused on reducing disparities related to levels of physical activity. Secondary analysis of national accelerometer data showed that achievement of recommended levels of physical activity ranged across subgroups from 2% to 61%. Mean hours per day spent in sedentary behavior ranged from 5.5 to 8.5. The largest disparities were by gender and age. An improved understanding of correlates may inform the design of interventions to increase physical activity in targeted subgroups. Additional theoretically based research is needed to elucidate which factors contributing to physical activity disparities are amenable to change via intervention. To eliminate health disparities, changes in policies that have an impact on physical activity may be necessary to promote physical activity among high-risk youth.

PHYSICAL ACTIVITY INTERVENTIONS IN LOW-INCOME, ETHNIC MINORITY, AND POPULATIONS WITH DISABILITY

BACKGROUND Low-income, racial and ethnic minority, and populations with disabilities are more likely to be sedentary than the general population. Increasing physical activity in these groups is an important public health challenge. This report summarizes interventions that have targeted populations at risk for inactivity. METHODS Computer and manual searches were performed to identify manuscripts published from 1983 to 1997. Interventions conducted in these populations in which physical activity was part of the intervention, and activity or cardiorespiratory fitness were outcome measures, were included in the review. RESULTS Fourteen studies were identified. Most studies used pre-post or quasi-experimental designs. Common intervention features for the ten studies that included ethnic minority groups were community advisory panels, community needs assessments, and community members delivering the intervention. Eight studies reported a theoretical framework that guided the intervention. Increased physical activity was documented in two studies. Post-intervention follow-up was conducted in two studies; both reported no significant findings. Only four studies for people with disabilities were found; all four reported post-intervention physical activity change. CONCLUSION Much work remains to develop effective interventions for these populations. Research that involves the community at all steps in the design and implementation of the intervention shows greatest promise for promoting behavior change. Future intervention studies should include: (1) rigorous experimental designs; (2) theoretically based interventions; and (3) validated assessment instruments to detect physical activity change.

Community-based participatory research to prevent substance abuse and HIV/AIDS in African-American adolescents

Adolescence is a time for exploration and risk-taking; in todays urban environment, with the twin threats of substance abuse and HIV/AIDS, the stakes are particularly high. This paper describes a community-based participatory research project to design, implement, and evaluate a faith-based substance abuse and HIV/AIDS prevention program for African-American adolescents. A coalition of university-based investigators and African-American church member stakeholders collaborated on all aspects of Project BRIDGE, the 3-year intervention to reduce substance abuse and HIV/AIDS in African-American adolescents. Our results support the use of community-based participatory research to create desirable change in this setting. Adolescents who participated in Project BRIDGE reported significantly less marijuana and other drug use and more fear of AIDS than a comparison group. Project BRIDGE has been designated an official ministry of the church and the program has been extended to others in the larger metropolitan community. The church now has a well-trained volunteer staff. University faculty developed skills in negotiating with community-based settings. The coalition remains strong with plans for continued collaborative activities.

Neighborhood characteristics favorable to outdoor physical activity: Disparities by socioeconomic and racial/ethnic composition

This paper uses a socioecological framework to investigate socioeconomic and racial/ethnic disparities in neighborhood characteristics that are associated with outdoor physical activity. We surveyed 632 parents of 5th graders about perceptions of their neighborhood social processes and collected systematic observations of the physical environment on their block-face of residence. Higher poverty neighborhoods and non-White neighborhoods have better accessibility; however, they are less safe, less comfortable, and less pleasurable for outdoor physical activity, and have less favorable social processes. Interventions to reduce disparities in physical activity should address not only the physical environment, but also social processes favorable to physical activity.