Dana L. Wolff

Estimated energy expenditures for school-based policies and active living

BACKGROUND Despite overwhelming evidence of the health benefits of physical activity, most American youth are not meeting the 60 minutes per day recommendation for moderate- to vigorous-intensity physical activity (MVPA). Policy changes have the potential to bring about substantial increases in physical activity in youth, within school and community settings. PURPOSE The purpose of this study was to quantify the increase in energy expenditure for school-based policies and built environment changes. METHODS Scientific literature reviews were consulted, and more than 300 published studies (1995-2011) in English were identified based on titles and abstracts. After an initial screening, 85 articles were included. Study quality was assessed, and the impact of various strategies for increasing physical activity in youth was estimated from objective measurements/direct observation. RESULTS Within school settings, the average minutes of MVPA gained per school day for studies in each intervention category were as follows: mandatory physical education (23 minutes); classroom activity breaks (19 minutes); afterschool activity programs (10 minutes); standardized physical education curricula (6 minutes more than traditional physical education); modified playgrounds (6 minutes); and modified recess (5 minutes more than traditional recess). Within community settings, significant MVPA was associated with active commuting (16 minutes) and park renovations (12 minutes), but proximity to parks had a small effect (1 minute). No conclusions could be drawn regarding joint-use agreements, because of a lack of studies quantifying their impact on energy expenditure. CONCLUSIONS Of the various policies and built environment changes examined, the largest effects were seen with mandatory physical education, classroom activity breaks, and active commuting to school. Policymakers can use this information along with estimates of the cost, feasibility, and population reach, to identify the best options for increasing physical activity in youth.

Accelerometer-based physical activity: total volume per day and standardized measures.

The use of accelerometers in physical activity (PA) research has increased exponentially over the past 20 yr. The first commercially available accelerometer for assessing PA, the Caltrac, was worn on the waist and estimated PA energy expenditure in kilocalories. Around 1995, the emphasis shifted to measuring minutes of moderate-to-vigorous PA (MVPA), especially for bouts of 10 min or longer. Recent studies, however, show that light-intensity PA and intermittent (nonbout) MVPA also have important health benefits. The total volume of PA performed is an important variable because it takes the frequency, intensity, and duration of activity bouts and condenses them down into a single metric. The total volume of PA is appropriate for many research applications and can enhance comparisons between studies. In the future, machine learning algorithms will provide improved accuracy for activity type recognition and estimation of PA energy expenditure. However, in the current landscape of objectively measured PA, total activity counts per day (TAC/d) is a proxy for the total volume of PA. TAC/d percentiles for age- and gender-specific groups have been developed from the National Health and Nutrition Examination Survey ActiGraph data (2003-2006), providing a novel way to assess PA. The use of TAC/d or standardized units of acceleration could harmonize PA across studies. TAC/d should be viewed as an additional metric, not intended to replace other metrics (e.g., sedentary time, light-intensity PA, moderate PA, and vigorous PA) that may also be related to health. As future refinements to wearable monitors occur, researchers should continue to consider metrics that reflect the total volume of PA in addition to existing PA metrics.

The Relationships between Weather-Related Factors and Daily Outdoor Physical Activity Counts on an Urban Greenway

The purpose of this study was to examine relationships between weather and outdoor physical activity (PA). An online weather source was used to obtain daily max temperature [DMT], precipitation, and wind speed. An infra-red trail counter provided data on daily trail use along a greenway, over a 2-year period. Multiple regression analysis was used to examine associations between PA and weather, while controlling for day of the week and month of the year. The overall regression model explained 77.0% of the variance in daily PA (p < 0.001). DMT (b = 10.5), max temp-squared (b = −4.0), precipitation (b = −70.0), and max wind speed (b = 1.9) contributed significantly. Conclusion: Aggregated daily data can detect relationships between weather and outdoor PA.

Coordinated and Aerobic Exercise do not Improve Attention in Graduate Students

Acute coordinative exercise, represented by various sports skills requiring bilateral use of hands or feet, has been shown to improve attention in school age children in a classroom setting. The purpose of this investigation was to determine if acute aerobic and coordinative exercise improves attention in graduate students in the same setting. Twenty- eight students (19 Women, 9 men; Age=24±1 years; BMI=22.9±0.6) enrolled in a graduate education program completed 3 sessions, each separated by 7 d. Immediately before a 1 h classroom lecture, subjects completed either 15 m of quiet sitting, aerobic exercise (walking), or coordinative exercise. Coordinative exercise consisted of a sequence of bilateral activities requiring gross and fine motor movement using balls of various sizes and types. Prior to and immediately after the lecture, subjects completed the d2 Test of attention. Subjects did not exercise or drink caffeine prior to participation. Heart rate was similar during aerobic and coordinative exercise. The total number of items processed (TN) and concentration performance (CP) increased from immediately post exercise to post-lecture in all conditions. The number of errors following coordinative exercise before the lecture was greater than the other conditions. The results of this investigation suggest that aerobic and coordinative exercise do not influence attention in graduate students.