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Biomedical subjects

T L McKenzie

Publications and source records attributed to T L McKenzie.

At least 19 recordsLinked to original sources
PubMed2001

Parental provision of transportation for adolescent physical activity.

BACKGROUND: Physical activity (PA) is important to adolescents' health. Parent transportation to activity locations is a practical strategy for increasing youth PA that has rarely been examined. DESIGN: Cross-sectional surveys of students and parents. SETTING/PARTICIPANTS: Ethnically diverse students (N=1678; 712 boys, 966 girls; M age=13.0 years) from 24 middle schools (grades six to eight) and their parents completed surveys (response rate=72%). MAIN OUTCOME MEASURES: Frequency of parents transporting adolescents to PA locations was studied in relation to adolescents' reported participation in PA during the previous week and their involvement in sports and activity lessons during the past year. RESULTS: Parents transported adolescents to PA locations 2.13 times per week, with boys being transported more often than girls (p=0.03). Ethnic/racial differences in frequency of transport were evidenced (p=0.002). Parent transportation for PA significantly contributed to girls' total PA (p=0.001) and their participation in sports/activity lessons (p=0.001). Transportation contributed marginally (p=0.06) to boys' total PA, but significantly to their participation in sports/activity lessons (p=0.001). CONCLUSIONS: Parent provision of transportation to activity locations is associated with out-of-school PA in a diverse adolescent population. This variable should be targeted for intervention.

Adolescent↗
PubMed2001

Effects of the CATCH physical education intervention: teacher type and lesson location.

BACKGROUND: Substantial differences exist in how and where physical education (PE) is conducted in elementary schools throughout the United States. Few effectiveness studies of large-scale interventions to improve PE have been reported. DESIGN: Multicenter randomized trial. SETTING/ PARTICIPANTS: The Child and Adolescent Trial for Cardiovascular Health (CATCH) was implemented in PE classes in 96 schools (56 intervention, 40 control) in four study centers: California, Louisiana, Minnesota, and Texas. INTERVENTION: The 2.5-year PE intervention consisted of professional development sessions, curricula, and follow-up consultations. MAIN OUTCOME MEASURES: Intervention effects on student physical activity and lesson context in PE were examined by teacher type (PE specialists and classroom teachers) and lesson location (indoors and outdoors). RESULTS: Differential effects by teacher type and lesson location were evidenced for both physical activity and lesson context. Observations of 2016 lessons showed that intervention schools provided more moderate-to-vigorous physical activity (p=0.002) and vigorous physical activity (p=0.02) than controls. Classroom teachers improved physical activity relatively more than PE specialists, but PE specialists still provided longer lessons and more physical activity. Classroom teachers increased lesson length (p=0.02) and time for physical fitness (p=0.03). CONCLUSIONS: The intervention improved PE of both specialists' and classroom teachers' lessons. States and districts should ensure that the most qualified staff teaches PE. Interventions need to be tailored to meet local needs and conditions, including teacher type and location of lessons.

Analysis of Variance↗
PubMed2001

Physical activity assessment options within the context of the Canadian Physical Activity, Fitness, and Lifestyle Appraisal.

The Canadian Physical Activity, Fitness, and Lifestyle Appraisal (CPAFLA) is a standardized battery of tests that is commonly used to assess asymptomatic individuals. This paper reviews evidence concerning the reliability, validity, and utility of the procedure currently used to assess habitual physical activity in the CPAFLA and surveys available physical activity assessment options. Special considerations related to age, gender, ethnicity, seasonal variations, and within-week variance are discussed. The potential assessment options are discussed with consideration given to the logistical and pragmatic constraints inherent in the CPAFLA. New technologies for future assessment of physical activity are briefly presented and recommendations for future research forwarded.

Canada↗
PubMed2001

Changes and tracking of physical activity across seven years in Mexican-American and European-American mothers.

Longitudinal changes in physical activity among 129 Mexican-American (mean age 30.8; SD = 5.6) and 97 European-American (mean age 31.2; SD = 5.4) women were studied. Two physical activity recall interviews were administered at baseline and 7 years later. At baseline, European-American women reported more vigorous leisure activity (p < .005) than Mexican-Americans, and Mexican-Americans reported more moderate work activity (p < .02) than European-Americans. Virtually all components of physical activity increased significantly over the 7 years. Pearson tracking correlations for total energy expenditure were about r = 0.30. The finding that both groups increased physical activity overtime was unexpected and was unrelated to a reduction in the number of preschool children in the homes over time.

Adult↗
PubMed2001

The association of school environments with youth physical activity.

OBJECTIVES: This study assessed the association of school environmental characteristics with student physical activity on campus. METHODS: Physical activity areas (n = 137) at 24 public middle schools were assessed for area type, size, and improvements (e.g., basketball courts). Student physical activity and the presence of equipment and supervision were directly observed before school, after lunch, and after school. RESULTS: Environmental characteristics explained 42% of the variance in the proportion of girls who were physically active and 59% of the variance for boys. CONCLUSIONS: School environments with high levels of supervision and improvements stimulated girls and boys to be more physically active.

Adolescent↗
PubMed2000

Leisure-time physical activity in school environments: an observational study using SOPLAY.

BACKGROUND: Schools provide settings for physical activity (PA), but objective tools for measuring PA are lacking. We assessed an instrument to directly observe group PA and measured the leisure-time PA of adolescents throughout the school day. METHODS: Leisure-time PA was studied by direct observation in 24 middle schools in Southern California using SOPLAY (System for Observing Play and Leisure Activity in Youth). SOPLAY uses momentary time sampling to record the activity of each individual as sedentary, walking, or very active. RESULTS: The largest proportion of students visited activity areas at lunch time (19.5%), followed by before (4. 1%) and after school (2.1%). More boys than girls visited activity areas before school (33.4 vs 7.7) and at lunch time (148.8 vs 36.7). Boys in areas engaged in more moderate to vigorous PA than girls before school (59.6 vs 40%) and at lunch time (67.7 vs 51.7%). CONCLUSIONS: Few students use opportunities to be physically active during lesiure time at school. Policies and environmental manipulations (e.g., supervision, equipment, structured programs) are needed to attract more adolescents, especially girls, to existing activity areas. The feasibility of SOPLAY for measuring group PA was established.

Adolescent↗
PubMed2000

Physical activity behavior change: issues in adoption and maintenance.

The many benefits of participation in regular moderate- or vigorous-intensity physical activity are well established, yet more than 60% of the population is sedentary or insufficiently active. Published studies have revealed that behavior modification and cognitive-behavior modification can be successfully used to assist patients, healthy adults, and youth in the adoption of physically active lifestyles. However, few studies with adults and youth have examined the maintenance of physical activity behavior beyond 6 months of adoption of this behavior. Maintenance of physical activity is critically important because ongoing participation in the behavior is necessary to sustain health benefits. Knowledge of effective intervention strategies for long-term maintenance of physical activity is at an early stage. The authors provide a summary of what is known about the maintenance of physical activity behavior in adults and youth and how physical activity behavior relates to other health behaviors such as smoking, as well as recommendations for research on physical activity behavior change and maintenance.

Adolescent↗
PubMed2000

Student activity levels, lesson context, and teacher behavior during middle school physical education.

There is little research on students' engagement in physical activity in middle school physical education (PE). We observed student activity, lesson context, and teacher behavior in 430 PE lessons taught by 126 teachers in 24 schools. Variables were analyzed by mixed-model nested analyses of covariance. Boys were more active than girls overall and during skill drills, game play, and free play. Student activity varied by lesson context, with fitness activities producing the most activity. Class size was negatively associated with student activity. Daily PE contributed a weekly total of 25 min of vigorous activity and 83 min of moderate-to-vigorous activity--much less than national objectives. Results suggest that numerous opportunities exist for increasing student physical activity during middle school PE.

Adolescent↗
PubMed1999

Predictors of change in children's physical activity over 20 months. Variations by gender and level of adiposity.

BACKGROUND: Physical activity declines during childhood and determinants of this decline are poorly understood. The purpose of this prospective study was to examine modifiable psychological and social correlates of physical activity change over 20 months. SUBJECTS: 370 girls and 362 boys in public schools, studied through the 4th and 5th grades. MEASURES: A physical activity index was computed from child reports, parent reports, and objective activity monitoring. Predictor variables were assessed by child and parent surveys. RESULTS: In multiple regressions, after adjustments for demographic variables, psychological variables explained 4% of the variance in boys' physical activity change, parent variables explained 8%, and interactions with skinfolds explained 3%, for a total of 15% (unadjusted). Regarding change in girls' physical activity, psychological variables explained 3%, parent variables explained 1.5%, and interactions with skinfold explained 1.5%, for a total of 6% explained variance (unadjusted). There were differences in predictors among children with high and low levels of body fat. CONCLUSIONS: Children's preferences for physical activity and frequency of parents transporting children to activity locations explained significant proportions of variance for girls and boys. The results support a dynamic model of the determinants of children's physical activity, but most of the variance was left unexplained.

California↗
PubMed1999

Effects of health-related physical education on academic achievement: project SPARK.

The effects of a 2-year health-related school physical education program on standardized academic achievement scores was assessed in 759 children who completed Metropolitan Achievement Tests before and after the program. Schools were randomly assigned to condition: (a) Specialists taught the Sports, Play, and Active Recreation for Kids curriculum; (b) classroom teachers were trained to implement the curriculum; and (c) controls continued their usual programs. The Trained Teacher condition was superior to Control on Language, Reading, and Basic Battery. The Specialist condition was superior to Control on Reading, but inferior on Language. Despite devoting twice as many minutes per week to physical education as Controls, the health-related physical education program did not interfere with academic achievement. Health-related physical education may have favorable effects on students' academic achievement.

California↗
PubMed1999

Correlations among physical activity and eating behaviors in 4- to 7-year-old Anglo- and Mexican-American children.

Physical activity and dietary behaviors are often correlated in adults and adolescents. This association was examined in 351 Anglo- and Mexican-American children between the ages of 4 and 7 years. Behaviors were assessed by structured observations and interviews at home and school. Observed physical activity was significantly correlated with energy intake (r = .43), but was unrelated to the percentage of calories from total fat or saturated fat. Thus, interventions with young children to improve dietary behavior or physical activity should not be expected to automatically lead to changes in the other.

Child↗
PubMed1998

Determinants of dietary intake in a sample of white and Mexican-American children.

OBJECTIVE: To assess the influence of several potential psychosocial determinants on children's eating behavior. PARTICIPANTS: Three hundred fifty-one Mexican-American and non-Hispanic white children (mean age = 4.4 years old at baseline) participated in the San Diego Study of Children's Activity and Nutrition for up to 2.5 years. METHODS: Child's eating behavior was described by 3 dependent variables: total energy, percentage energy from fat, and sodium intake per 1,000 kcal. Dietary information was collected 4 days a year using a 24-hour food intake record, which was a combination of direct observation and interviews with food preparers. The 35 predictor variables from child, parental, demographic, and environmental domains were collected by behavioral observation, interviewer-administered questionnaires, and physical measurements. STATISTICAL ANALYSES: Bivariate and regression analyses via mixed linear models were performed. RESULTS: Variables from the children's domain (such as skinfold thickness and weight) had the strongest associations with energy intake; parental variables (such as fat avoidance behavior and prompts to increase children's food intake) were associated with child's percentage energy from fat and sodium intake. In regression analyses, parsimonious subsets of variables accounted for 46% of variance in energy intake (3 variables), 40% of the variance in percentage of energy from fat (4 variables), and 44% of variance in sodium intake per 1,000 kcal energy (1 variable) in between-subject variance components. CONCLUSIONS: Fat and sodium intake of children may be improved by improving parents' nutrition habits and by having parents encourage children to eat a healthful diet. Few modifiable correlates of children's energy intake were identified.

California↗
PubMed1998

Effects of physical activity interventions in youth. Review and synthesis.

INTRODUCTION: Physical inactivity has been identified as an important public health concern for youth. School and community settings can be important infrastructures for promoting physical activity (PA). This paper reviews studies of physical activity in school and community settings among preschool through college-aged persons to determine characteristics and effects of interventions. Studies in progress are included. METHODS: Studies from 1980 to 1997 testing physical activity interventions in schools and community settings were identified by computerized search methods and reference lists of published reviews. Studies needed to have used a quantitative assessment of PA, used a comparison or control group, included participants who were preschool through college age, and be conducted in the United States or foreign school or community settings. Significance of effects was examined overall and for various types of interventions. RESULTS: Twenty-two school-based studies were reviewed, 14 completed and 8 in progress. Three studies were in countries other than the United States. The 8 studies in progress were all in the United States. Only 7 community studies were reviewed, all in the United States. Four studies were in progress. Several community studies involved a high percentage of African-American or Hispanic youth and their families. Studies showing the best results used randomized designs, valid and reliable measurements, and more extensive interventions. Some follow-up results showed PA was sustained after interventions ended. CONCLUSIONS: The collection of school and community studies is limited for several age groups with none below third grade and only three at college age. There are few community studies. The most is known about upper-elementary-age-students, including the first multicenter randomized trial to report significant results for increasing moderate to vigorous physical activity (MVPA) in physical education (PE) and increase vigorous PA outside of school. A number of older study designs were weak and assessments less than optimal, but studies in progress are stronger. Special attention is needed for girls, middle schools, and community settings for all youth. More objective assessments are needed for measuring PA outside of school and in younger children, since they cannot provide reliable self-report.

Adolescent↗
PubMed1998

Direct home observations of the prompting of physical activity in sedentary and active Mexican- and Anglo-American children.

Social interactions are important correlates of physical activity in children. Previous studies used global measures; the present study examined the influence of specific social interactions on immediate physical activity in children with data obtained from the Behaviors of Eating and Activity for Child Health: Evaluation System (BEACHES). The study examined parental and peer prompting of physical activity at home among 178 Mexican-American and 113 Anglo-American children at age 4 years and again at age 6.5 years. Most activity prompts came from adults interacting with children when they were sedentary. A reduction in the frequency of prompts from baseline to follow-up occurred in the prompter group (adult or child peer), gender, ethnicity, and preprompted activity level categories. Children's responses to these prompts showed that as they aged, they seemed to rely less on the interpersonal (especially adult) aspects of their environment for cues to be more active.

Adult↗
PubMed1998

Tracking of health-related fitness components in youth ages 9 to 12.

PURPOSE: The purpose of this study was to examine the tracking of multiple health-related fitness components in children from fourth to sixth grade. METHODS: A battery of fitness tests was used to measure 414 children (213 boys, 201 girls, mean = 9.48 yr, +/- 0.41) from three elementary schools in Southern California. Children were assessed during the fall and spring of each grade. Baseline scores were correlated (Spearman) with each subsequent time point. RESULTS: For boys 3-yr correlations of body mass index (BMI) (0.89), skinfold thickness (0.80), sit-and-reach test (0.67), and the pull-up test (0.66) indicated high levels of tracking. Mile run (0.56), sit-up test (0.46), and waist-to-hip ratio (0.30) tracked moderately. For girls BMI (0.83), sum of skinfolds (0.75), sit-and-reach test (0.72), and the pull-up test (0.63) tracked highly, while mile run (0.42), sit-up test (0.47), and waist-to-hip ratio (0.42) tracked moderately. CONCLUSIONS: Results suggest that relative rankings of BMI, skinfold thickness, and sit-and-reach test performance are more likely to track during early adolescence. Measures of cardiovascular fitness, muscular strength, and endurance and fat distribution may be less likely to track into adolescence, possibly because they are more influenced by changes in physical activity or because tracking may be reduced by measurement error.

Body Composition↗
PubMed1997

Factors parents use in selecting play spaces for young children.

BACKGROUND: The amount of time children spend in play spaces (ie, physical locations that are appropriate for children's physical activity) near their homes is correlated with their level of physical activity. OBJECTIVE: To examine factors used in parents' decisions about the selection of play spaces for their children. SUBJECTS: Parents (primarily mothers) of 178 Mexican American and 122 white children who were a mean age of 4.9 years old at the first measurement. MEASURES: In individual interviews, parents rated 24 factors on their importance in selecting for their children a play space that is away from their home or yard. Decision factors were rated from 1 (ie, not important at all) to 5 (ie, very important). RESULTS: The most important factors, with ratings ranging from 4.8 to 4.2, were safety and availability of toilets, drinking water, lighting, and shade. Mexican American parents rated 8 of 24 items significantly higher than did white parents, including lighted at night, organized activities, play supplies, and drinking water. White parents rated 5 of 24 items significantly higher than did Mexican American parents, including distance from home, cost of admission, and child's friends go there. The rated importance of 7 of 24 items increased during 1 year, including play supplies, drinking water, distance from home, and parents' friends or relatives go there. CONCLUSIONS: These results indicate that parents can identify factors they use in selecting places for their young children to play, and selection factors differ somewhat by ethnicity or socioeconomic status. Further studies are needed to determine whether improvements on the most important selection factors might be effective in increasing the use of play spaces by children and their parents. Clinicians may be able to use the most highly rated decision factors to help parents assess the acceptability of play spaces in their areas.

Adult↗
PubMed1997

Physical activity levels and prompts in young children at recess: a two-year study of a bi-ethnic sample.

We investigated physical activity and encouragement for activity in a bi-ethnic cohort during recess. Activity and associated interactions of 287 children were recorded at preschool and again 2.2 years later. Children expended nearly twice as much energy at preschool recess than at elementary recess. Activity levels declined as recess time elapsed. At preschool, European-American children engaged in more moderate to vigorous activity than Mexican-Americans. As participants moved to elementary school, teachers' prompts to be active decreased and prompts from peers increased. Boys and girls received similar amounts of activity prompts at preschool, but prompts to boys increased over time. The findings suggest that school environments could be altered to promote healthful physical activity among young children.

Age Factors↗