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Don W. Morgan

A growing body of literature has confirmed the health benefits of regular physical activity in school-aged youth. However, less systematic attention has been directed toward establishing activity profiles and evaluating the impact of community-based interventions designed to increase physical activity and reduce sedentary behavior in preschool children. In this paper, current findings are reviewed to determine whether preschoolers are achieving sufficient levels of structured and unstructured physical activity and to identify potential correlates of activity and sedentary behavior in the young child. In addition, promotion of physical activity among preschool-aged children in selected community settings is discussed and future research initiatives are highlighted. Given current trends in the overweight and obesity status of children aged two to five years, efforts aimed at increasing physical activity levels and documenting gains in health-related fitness and movement skillfulness in this pediatric population should be accelerated.

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Kristin S. Ondrak and Don W. Morgan

The influence of height, body mass, daily physical activity (DPA), and dietary calcium intake (DCI) on bone mineral density (BMD) and content (BMC) was evaluated in 33 four-year-old girls. Results indicated that body mass was significantly correlated with and predictive of BMD and BMC at all sites except the femoral neck BMD. DPA and height also explained a significant proportion of the variance in femoral neck BMD and BMC of the lumbar spine and total body. DCI was not related to or predictive of BMD or BMC at any bone site. These findings highlight the importance of engaging in daily weight-bearing physical activity to promote bone health in young girls.

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Elizabeth A. Holbrook, Minsoo Kang and Don W. Morgan

As a first step toward the development of adapted physical activity (PA) programs for adults with visual impairment (VI), the purpose of this study was to determine the time frame needed to reliably estimate weekly PA in adults with VI. Thirty-three adults with VI completed 7 days of pedometer-based PA assessment. Generalizability theory analyses were conducted to quantify sources of variance within the PA estimate and determine the appropriate number of days of PA monitoring needed for the total sample and for participants with mild-to-moderate and severe VI. A single-facet, crossed design was employed including participants and days. Participants and days correspondingly accounted for 33–55% and 0–3% of the total variance in PA. While a reliable account of PA was obtained for the total sample over a 6-day period, shorter (4-day) and longer (9-day) periods were required for persons with mild-to-moderate and severe VI, respectively.

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Gary S. Krahenbuhl, Robert P. Pangrazi, William J. Stone, Don W. Morgan and Tracy Williams

Untrained 6- to 8-year-old children (N = 80) served as subjects in a cross sectional study of the fractional utilization of maximal aerobic power during submaximal running. Using the open-circuit method, the absolute oxygen demands of submaximal running were found to increase with age. When expressed relative to body weight, oxygen demands of submaximal running showed no statistically significant changes over the 3-year span. VO2max increased 36.2%, which was proportionally greater than the percentage increase for either body weight (28.4%) or the absolute oxygen demands of submaximal running (22.9%). Thus, during the span of years studied there was a significant reduction in the fractional utilization of maximal aerobic power required to run at a fixed submaximal speed.

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Brandi M. Eveland-Sayers, Richard S. Farley, Dana K. Fuller, Don W. Morgan and Jennifer L. Caputo

Background:

The benefits of physical fitness are widely acknowledged and extend across many domains of wellness. The association between fitness and academic achievement, however, remains to be clarified, especially in young children. Therefore, the purpose of this study was to examine the relationship between fitness and academic achievement in elementary school children.

Methods:

Data were collected from 134 third-, fourth-, and fifth-grade children. One-mile run time, body mass index, curl-up, and sit-and-reach data were collected from physical education instructors in Middle Tennessee. The percentage of questions answered correctly for the mathematics and reading/language arts sections of the Terra-Nova achievement test was taken as a measure of academic achievement.

Results:

A negative association (P < .01) was noted between 1-mile run times and mathematics scores (r = –.28), whereas a positive relationship (P < .05) was observed between muscular fitness and mathematics scores (r = .20). Relative to sex differences, inverse relationships (P < .05) were observed between 1-mile run times and reading/language arts and mathematics scores in girls (r = –.31 and –.36, respectively), but no significant associations were evident in boys.

Conclusions:

Results from this study support a link between specific components of physical fitness and academic achievement in elementary school children.

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Saori I. Braun, Youngdeok Kim, Amy E. Jetton, Minsoo Kang and Don W. Morgan

The purpose of this study was to determine if bone health at the femoral neck (FN) and lumbar spine (LS) can be predicted from objectively-measured sedentary behavior and physical activity data in postmenopausal women. Waist-mounted ActiGraph GT1M and GT3X devices were used to quantify levels of sedentary and moderate-to-vigorous intensity behavior during a 7-day period in 44 older females. Bone health (normal and osteopenia/osteoporosis) of FN and LS was derived from T scores generated using dual energy x-ray absorptiometry. Binomial logistic regression analysis indicated that sedentary time and number of breaks in sedentary behavior were significant predictors of osteopenia/osteoporosis at the FN, but not at the LS. Adherence to physical activity guidelines was not a significant predictor of bone health at the FN or LS. Our findings suggest that more frequent interruptions in sedentary behavior are associated with improved bone health in postmenopausal women.

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Don W. Morgan, Wayland Tseh, Jennifer L. Caputo, Ian S. Craig, Daniel J. Keefer and Philip E. Martin

The purpose of this study was to quantify running economy (RE) during level treadmill running in 6-year-old children and to identify the potentially mediating effects of resting oxygen uptake and body fat percentage on sex differences in RE. Resting oxygen uptake (VO2), body fat, and RE at 5 mph were quantified in 15 boys and 20 girls following 30 min of treadmill accommodation. While absolute VO2 and mass-related values of gross and net VO2 were significantly higher in boys compared to girls, gross VO2 expressed relative to fat-free mass was not different between sexes. These results indicate that 6-year-old girls exhibit better RE compared to 6-year-old boys when VO2 is expressed as a function of total body mass. This sex difference in VO2 may reflect an increase in aerobic energy demands associated with the presence of a greater muscle mass in boys.