Biomedical subjects
Publications and source records attributed to Thomas L McKenzie.
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OBJECTIVE: To prospectively examine potential benefits of active commuting to school on measures of weight status and physical activity in a sample of youth. RESEARCH METHODS AND PROCEDURES: A cohort of students from seven elementary schools was measured four times--in the fall and spring of fourth grade (N = 1083) and fifth grade (N = 924). Participants were classified as active (walking, biking, or skateboarding to school almost every day for baseline analyses or at least 2 d/wk for analyses of consistent active commuting) or non-active commuters to school. Accelerometers were used to measure physical activity. Height, weight, and skinfolds were objectively assessed. RESULTS: Boys who actively commuted to school had lower BMI (p < 0.01) and skinfolds (p < 0.05) than non-active commuters to school in the fourth grade. Active commuting to school over 2 years was not associated with BMI change or overweight status. DISCUSSION: Walking and cycling to school may contribute to preventing excessive weight gain, or leaner children may walk or cycle to school.
The Trial of Activity for Adolescent Girls (TAAG) is a randomized, multicenter field trial in middle schools that aims to reduce the decline of physical activity in adolescent girls. To inform the development of the TAAG intervention, two phases of formative research are conducted to gain information on school structure and environment and on the conduct of physical education classes. Principals and designated staff at 64 eligible middle schools were interviewed using the School Survey during Phase 1. The following year (Phase 2), physical education department heads of the 36 schools selected into TAAG were interviewed. Responses were examined to design a standardized, multicomponent physical activity intervention for six regions of the United States. This article describes the contribution of formative research to the development of the physical education intervention component and summarizes the alignment of current school policies and practices with national and state standards.
Formative research is used to inform intervention development, but the processes of transmitting results to intervention planners and incorporating information into intervention designs are not well documented. The authors describe how formative research results from the Trial of Activity for Adolescent Girls (TAAG) were transferred to planners to guide intervention development. Methods included providing oral and written reports, prioritizing recommendations, and cross-checking recommendations with intervention objectives and implementation strategies. Formative work influenced the intervention in many ways. For example, results indicated that middle schools offered only coeducational physical education and health education classes, so the TAAG intervention was designed to be appropriate for both sexes, and intervention strategies were developed to directly address girls' stated preferences (e.g., enjoyable activities, opportunity to socialize) and barriers (e.g., lack of skills, fear of injury) for physical activity. The challenges of using formative research for intervention development are discussed.
PURPOSE: To assess girls' physical activity (PA) in middle school physical education (PE) as it relates to field site, lesson context and location, teacher gender, and class composition. METHODS: We observed girls' PA levels, lesson contexts, and activity promotion by teachers in 431 lessons in 36 schools from six field sites participating in the Trial of Activity for Adolescent Girls. Interobserver reliabilities exceeded 90% for all three categories. Data were analyzed using mixed-model ANOVA with controls for clustering effects by field site and school. RESULTS: Mean lesson length was 37.3 (+/-9.4) min. Time (13.9+/-7.0 min) and proportion of lessons (37.9+/-18.5%) spent in moderate to vigorous PA (MVPA), and time (4.8+/-4.2 min) and proportion of lessons (13.1+/-11.7%) in vigorous PA (VPA) differed by field site (P<0.004). Lesson time for instructional contexts differed by field site, with overall proportions as follows: game play (27.3%), management (26.1%), fitness activities (19.7%), skill drills (12.1%), knowledge (10.6%), and free play (4.4%). Coed classes were 7.9 min longer than girls-only classes (P=0.03). Although 27 s shorter, outdoor lessons were more intense (MVPA%=45.7 vs 33.7% of lesson, P<0.001) and provided 4.0 more MVPA minutes (P<0.001). MVPA, VPA, and lesson contexts did not differ by teacher gender. There was little direct promotion of PA by teachers during lessons. CONCLUSIONS: Substantial variation in the conduct of PE exists. Proportion of lesson time girls spent accruing MVPA (i.e., 37.9%) fell short of the Healthy People 2010 objective of 50%. Numerous possibilities exist for improving girls' PA in PE.
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.
Dissemination and sustainability of evidence-based physical education programs (PE) has been studied rarely. The sustainability of a health-related PE program (SPARK) was independently evaluated in 111 elementary schools in 7 states. Surveys were mailed to schools that had received SPARK curriculum books, training and follow-up (response rate = 47%). Up to 80% of schools that adopted SPARK PE reported sustained use up to 4 years later. Schools using SPARK had more frequent PE classes. Sustained use was related to support from the principal, not previously having a standard PE program, having adequate equipment, and teachers being physically active. Program sustainability was similar in advantaged and disadvantaged schools. Evidence-based PE programs can be sustained up to 4 years.
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This descriptive study explored the potential for public parks and recreation centers as intervention sites for promoting physical activity among youth. Directors (55% women) of 44 recreation centers in San Diego County completed a survey of their centers' physical activity programming for youths ages 3 to 17 years (response rate = 60%). On an average weekday, 373 (SD = 782) youths participated in physical activity at a center. More boys attended than girls (p <.05). Some centers sponsored after-school programs at elementary (41%) and middle (11%) schools but not at high schools (0%). Primary barriers to providing physical activity programs were inadequate staffing (54%), funding (39%), and facilities (32%). Girls and low-income youth were identified as the most difficult populations to reach. Directors reported considerable interest in collaborating on interventions to improve youth activity programs. Public parks and recreation centers are understudied settings with the potential for substantial involvement in efforts to promote youth physical activity.
PURPOSE: School physical education (PE) is highly recommended as a means of promoting physical activity, and randomized studies of health-related PE interventions in middle schools have not been reported. We developed, implemented, and assessed an intervention to increase physical activity during middle-school PE classes. METHODS: Twenty-four middle schools (approximately 25,000 students, 45% nonwhite) in Southern California participated in a randomized trial. Schools were assigned to intervention (N = 12) or control (N = 12) conditions, and school was the unit of analysis. A major component of the intervention was a 2-yr PE program, which consisted of curricular materials, staff development, and on-site follow-up. Control schools continued usual programs. Student activity and lesson context were observed in 1849 PE lessons using a validated instrument during baseline and intervention years 1 and 2. RESULTS: The intervention significantly (P = 0.02) improved student moderate to vigorous physical activity (MVPA) in PE, by approximately 3 min per lesson. Effects were cumulative; by year 2 intervention schools increased MVPA by 18%. Effect sizes were greater for boys (d = 0.98; large) than girls (d = 0.68; medium). CONCLUSIONS: A standardized program increased MVPA in middle schools without requiring an increase in frequency or duration of PE lessons. Program components were well received by teachers and have the potential for generalization to other schools. Additional strategies may be needed for girls.
BACKGROUND: Our objective was to evaluate the effects of environmental, policy, and social marketing interventions on physical activity and fat intake of middle school students on campus. DESIGN: Twenty-four middle schools were randomly assigned to intervention or control conditions. Baseline measures were collected in spring 1997, and interventions were conducted during the 1997-1998 and 1998-1999 school years SETTING/PARTICIPATION: The schools had mean enrollments of 1109, with 44.5% nonwhite students. Over 2 years, physical activity interventions were designed to increase physical activity in physical education classes and throughout the school day. Nutrition interventions were designed to provide and market low-fat foods at all school food sources, including cafeteria breakfasts and lunches, a la carte sources, school stores, and bag lunches. School staff and students were engaged in policy change efforts, but there was no classroom health education. MAIN OUTCOMES MEASURES: Primary outcomes were measured by direct observation and existing records. RESULTS: Randomized regression models (N =24 schools) revealed a significant intervention effect for physical activity for the total group (p <0.009) and boys (p <0.001), but not girls (p <0.40). The intervention was not effective for total fat (p <0.91) or saturated fat (p <0.79). Survey data indicated that the interventions reduced reported body mass index for boys (p <0.05). CONCLUSIONS: Environmental and policy interventions were effective in increasing physical activity at school among boys but not girls. The interventions were not effective in reducing fat intake at school. School environmental and policy interventions have the potential to improve health behavior of the student population, but barriers to full implementation need to be better understood and overcome.
Long-term maintenance effects of physical education (PE) curriculum and staff development programs have not been studied. The authors assessed the sustainability of the Child and Adolescent Trial for Cardiovascular Health (CATCH) PE intervention using direct observations of 1,904 PE lessons in former intervention and control schools in four U.S. states 5-years postintervention. Student physical activity levels, lesson contexts, and level of CATCH PE training of teachers were analyzed. Student energy expenditure levels and proportion of PE time in moderate-to-vigorous physical activity in intervention schools were maintained 5 years later, but vigorous activity declined sharply. Meanwhile, postintervention gains in former control schools, influenced by delayed program implementation and secular trends, resulted in a convergence of activity levels in intervention and control schools. Use of CATCH PE curricula was associated with increased levels of teacher training and school support for PE in both former intervention and control schools.
To test the effectiveness of the Child and Adolescent Trial for Cardiovascular Health (CATCH) program, a randomized trial was conducted in 96 elementary schools in four regions of the United States. Results from the original trial indicated a significant positive effect on the delivery of physical education (PE). All 56 former intervention schools (FI), 20 randomly selected former control schools (FC), and 12 newly selected unexposed control schools (UC) were assessed 5 years postintervention. Results indicate a strong secular trend of increasing moderate to vigorous physical activity (MVPA) in PE classes among both FC and UC schools. The FI schools surpassed the Healthy People 2010 goal for MVPA during PE lesson time (i.e., 50%), whereas the FC and UC schools came close to it. Barriers to implementing CATCH PE included insufficient training and lower importance of PE compared to other academic areas and indicate the need for in-service training.
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We assessed the relationship between young children's movement skills and their physical activity in early adolescence. Balance, agility, eye-hand coordination, and skinfold thicknesses in 207 Mexican American and Anglo American children (104 boys, 103 girls) were measured at ages 4, 5, and 6 years. Habitual physical activity was assessed at the age of 12 years by two interviewer-administered 7-day recalls. Ethnic differences in movement skills were not found. Young girls were better at jumping and balancing, and young boys were better at catching. Tracking of skills was low, and children's early childhood skills were not related to their physical activity 6 years later. Further studies involving additional movement skills and other populations are recommended to determine if enhanced movement skills in children promote subsequent physical activity.
This article assessed the effects of a video, "Dynamotion," on children's knowledge, self-efficacy, and attitude about physical activity and heart health. A quasi-experimental design was used; 12 classrooms (grades K-2) were assigned to intervention (N = 116) or comparison (N = 92) groups. Students completed a 9-item pre- and posttest; only the intervention group was exposed to the video, during which qualitative assessments were made. Repeated measures analyses were used to detect changes. Overall, the intervention group had greater gains in knowledge and self-efficacy than did the comparison group (p < 0.001), and they seemed to enjoy the video. The results suggest that exposure to a short, interactive, educational video may promote health among young children.
Increasing physical activity among youth represents a national health goal, and using volunteer activity providers at schools offers one possible solution. This paper describes results from a program to recruit volunteer physical activity providers in middle schools. Twenty-one volunteers provided 850 physical activity hours at seven schools, including 575 activity sessions and 7,186 student contacts. Volunteers who received incentives offered more minutes of activity, conducted more activity sessions, reached a greater number of students, and logged more student-minutes of physical activity than those who received none. Male volunteers provided more activity minutes than female volunteers, but females were marginally more successful in engaging female students. Results can help guide schools to more effectively increase student physical activity throughout the school day.