D. S. Ward

Correlates of objectively measured physical activity in preadolescent youth.

OBJECTIVE The purpose of this study was to identify the psychosocial and environmental correlates of objectively measured physical activity behavior in a diverse sample of sixth-grade students. DESIGN Cross-sectional. PARTICIPANTS AND SETTINGS One hundred ninety-eight sixth-grade students from 4 public middle schools in Columbia, South Carolina. The study group was 52.0% female, 55.1% African-American, with a mean age of 11.4 +/- 0.6 years. MAIN OUTCOME MEASURES Time spent in moderate physical activity (MPA) and vigorous physical activity (VPA) was assessed using a uniaxial accelerometer (CSA WAM 7164) (Computer Science and Applications Inc., Shalimar, FL). Determinant variables included: age, gender, race/ethnicity (demographic); physical activity self-efficacy, social norms related to physical activity, and beliefs regarding physical activity outcomes (psychosocial); and perceived physical activity habits of parents and peers, involvement in community physical activity organizations, involvement in community-based sports programs, access to fitness/sporting equipment at home, and self-reported hours spent watching television or playing video games (environmental). RESULTS For boys, physical activity self-efficacy, social norms related to physical activity, and involvement in community physical activity organizations were salient predictors of MPA and VPA. Among girls, only physical activity self-efficacy emerged as a clear predictor of objectively measured physical activity. CONCLUSIONS These findings are consistent with previous studies using self-reported physical activity and suggest that interventions to increase physical activity in preadolescent youth should endeavor to boost physical activity self-efficacy by offering a wide selection of enjoyable, developmentally-appropriate physical activity options.

Correlates of physical activity behavior in rural youth.

The purpose of this study was to identify correlates of physical activity behavior in a sample of rural, predominantly African American youth. Three hundred sixty-one fifth-grade students from two rural counties in South Carolina (69% African American, median age = 11 years) completed a questionnaire designed to measure beliefs and social influences regarding physical activity, physical activity self-efficacy, perceived physical activity habits of family members and friends, and access to exercise and fitness equipment at home. After school physical activity and television watching were assessed using the Previous Day Physical Activity Recall (PDPAR). Students were classified as physically active according to a moderate physical activity standard: two or more 30-min blocks at an intensity of 3 METs (metabolic equivalents) or greater, and a vigorous physical activity standard: one or more 30-min blocks at an intensity of 6 METs or greater. According to the moderate physical activity standard, 34.9% of students were classified as low-active. Multivariate analysis revealed age, gender, television watching, and exercise equipment at home to be significant correlates of low activity status. According to the vigorous physical activity standard, 32.1% of the students were classified as low-active. Multivariate analysis revealed age, gender, television watching, and self-efficacy with respect to seeking support for physical activity to be significant correlates of low activity status. In summary, gender and the amount of television watching were found to be the most important correlates of physical activity in rural, predominantly African American youth.

Exaggerated blood pressure response to dynamic exercise and risk of future hypertension

This study examined the association between an exaggerated blood pressure response to treadmill exercise and the risk of developing hypertension. Subjects were healthy normotensive men (n = 5386) who had a baseline graded maximal exercise test between 1971 and 1982, and completed a mailed follow-up questionnaire. At follow-up in 1986, cases (n = 151) reported physician diagnosed hypertension and controls (n = 201) reported normotension. Those who had developed hypertension at follow-up were more likely to have had an exaggerated blood pressure response to exercise (OR = 2.4, 1.4-4.3). In multiple logistic regression analysis an exaggerated response was significantly associated (OR = 3.0, 1.5-6.1) with future hypertension after controlling for sitting systolic and diastolic blood pressure, weight change from age 21 to follow-up, entry age, family history of hypertension, body mass index, treadmill time, alcohol consumption, and years of follow-up. These results suggest that an exaggerated blood pressure response to exercise is independently associated with increased risk of future hypertension, and therefore, may be an important factor in determining hypertension risk.

Self-selected exercise intensity of habitual walkers

This study assessed self-selected exercise intensity of habitual walkers. Twenty-nine healthy adults (22 females, 7 males; age (mean +/- SD) = 34.9 +/- 8.6 yr) performed a typical exercise walk while walking speed was measured by an unseen observer. On a subsequent occasion, the subjects walked at the same pace on a treadmill while several variables related to exercise intensity were measured. The mean self-selected walking pace was 1.78 +/- 0.19 m.s-1. Mean percents of VO2max and HRmax elicited by the treadmill exercise were 52 +/- 11% and 70 +/- 9%, respectively. Mean MET level was 5.2 +/- 1.2, and ratings of perceived exertion (RPE) averaged 10.9 +/- 1.6. Based on reported frequency and duration of walking, weekly energy expenditure in exercise walking was estimated to be 1127 +/- 783 kcal.wk-1. These data suggest that the self-selected exercise intensity of healthy, habitual exercise walkers meets the American College Sports Medicines recommendation for improvement of cardiorespiratory fitness. These data further suggest that, in this population, the average weekly energy expended through walking reaches a level associated with improvements in health and longevity.

A study of factors associated with weight change in women who attempt smoking cessation

This study investigated behavioral and attitudinal relationships over a 12-week time period in 48 women enrolled in a commercial smoking cessation program who were categorized as non-recidivists (NR), early recidivists (ER) and late recidivists (LR) to cigarette smoking. NR had significantly higher weight gains (F = 6.70), significantly higher levels of physical activity (F = 6.42), and significantly less concern of postsmoking cessation weight gain (F = 5.08) than either two groups of recidivists, (p less than or equal to .05). Other findings, although not significant, were that NR exhibited lower caloric intake and more frequent snacking behaviors than either ER or LR. These results indicate an overall stronger commitment to more positive health behaviors in the NR than those who returned to cigarette smoking.

Weekly variability in total body water using 2H2O dilution in college-age males

The variability in measuring total body water (TBW) using deuterium oxide (2H2O) dilution has not been extensively tested. The purpose of this study was to determine the variability of weekly measurements of TBW utilizing the 2H2O dilution technique in 10 males and to determine the amount of biological versus technical variability using a generalizability ANOVA (GENOVA). Ten male subjects aged 21-32 yr were tested on four separate occasions for body weight (BW), underwater weight (UwWt), and TBW. BW remained quite stable across the four sessions with a 0.7% coefficient of variation (CV). Both UwWt and TBW had a CV of 4% across the four sessions. No differences were found between TBW estimates from plasma, saliva, or urine. GENOVA analysis determined that 25-50% of the total variability in measuring TBW was attributed to the sample analysis/separation procedures. Four percent of the TBW in these subjects was 1.8 l. This technique would therefore not be expected to detect changes less than 0.9 l (50% of 1.8 l). The estimates of %FAT from TBW were lower but not significantly different from UwWt. Blood, urine, and saliva were able to produce similarly repeatable measures of TBW.

Differential Effects of Three Teachers Over a Unit of Instruction

The purpose of this study was to describe the effects of three teachers on psychomotor, affective, and cognitive outcomes over a 15-lesson volleyball unit. Three intact middle school physical education classes were used. Pre- and posttests were administered for the overhead set, forearm pass, and serve psychomotor skills. A semantic differential test with four affective dimensions and a written test on the rules, strategies, and mechanics of volleyball were also administered pre- and posttest. Data on instructional characteristics were obtained using academic learning time (ALT-PE); observation system for content development (OSCD-PE), and a content analysis of lessons. The following were key aspects of the results: (a) Teachers differed in their approaches to the content of the unit more than in the characteristics of their instruction as determined through observational data; (b) teachers differed in respect to the psychomotor skills for which they were able to produce statistically significant student ...

Weight control and calorie expenditure: Thermogenic effects of pre-prandial and post-prandial exercise

The thermogenic effects of pre- and postprandial exercise was examined in seven lean active females. Energy expenditure was measured for 3 h via open circuit indirect calorimetry after four separate treatments: Exercise Only (25 min treadmill run at 60% VO2 max), Meal Only (910 kcal mixed meal), Exercise-Meal and Meal-Exercise. The thermogenic response to the Exercise-Meal treatment was similar to the Meal Only treatment. However, the Meal-Exercise treatment resulted in a greater energy expenditure than the Meal Only and Exercise-Meal treatments. The Exercise Only treatment showed the lowest thermogenic response. These data suggest that exercise following a meal would be more beneficial than exercise before a meal in increasing and maintaining an elevated energy expenditure.