Paul D. Loprinzi

Comparison of accelerometer cut points for predicting activity intensity in youth.

UNLABELLED The absence of comparative validity studies has prevented researchers from reaching consensus regarding the application of intensity-related accelerometer cut points for children and adolescents. PURPOSE This study aimed to evaluate the classification accuracy of five sets of independently developed ActiGraph cut points using energy expenditure, measured by indirect calorimetry, as a criterion reference standard. METHODS A total of 206 participants between the ages of 5 and 15 yr completed 12 standardized activity trials. Trials consisted of sedentary activities (lying down, writing, computer game), lifestyle activities (sweeping, laundry, throw and catch, aerobics, basketball), and ambulatory activities (comfortable walk, brisk walk, brisk treadmill walk, running). During each trial, participants wore an ActiGraph GT1M, and V˙O2 was measured breath-by-breath using the Oxycon Mobile portable metabolic system. Physical activity intensity was estimated using five independently developed cut points: Freedson/Trost (FT), Puyau (PU), Treuth (TR), Mattocks (MT), and Evenson (EV). Classification accuracy was evaluated via weighted κ statistics and area under the receiver operating characteristic curve (ROC-AUC). RESULTS Across all four intensity levels, the EV (κ=0.68) and FT (κ=0.66) cut points exhibited significantly better agreement than TR (κ=0.62), MT (κ=0.54), and PU (κ=0.36). The EV and FT cut points exhibited significantly better classification accuracy for moderate- to vigorous-intensity physical activity (ROC-AUC=0.90) than TR, PU, or MT cut points (ROC-AUC=0.77-0.85). Only the EV cut points provided acceptable classification accuracy for all four levels of physical activity intensity and performed well among children of all ages. The widely applied sedentary cut point of 100 counts per minute exhibited excellent classification accuracy (ROC-AUC=0.90). CONCLUSIONS On the basis of these findings, we recommend that researchers use the EV ActiGraph cut points to estimate time spent in sedentary, light-, moderate-, and vigorous-intensity activity in children and adolescents.

Physical activity and the brain: A review of this dynamic, bi-directional relationship

The brain plays a major role in regulating physical activity behavior and exercise performance. Regular physical activity may also play a key role in the prevention and treatment of various neurological conditions, such as Parkinsons disease, Alzheimers disease, depression, and cognitive function. This implies that not only does the brain (or the nervous system) regulate aspects of physical activity, but also that physical activity may potentially influence brain-related function and outcomes. This review details this bi-directional relationship and addresses its implications for improving physical activity, exercise performance, and brain-related function and outcomes.

Parental Influences on Physical Activity Behavior in Children and Adolescents: A Brief Review:

Understanding the social and environmental factors that influence physical activity is important in the development of effective interventions to increase physical activity behavior in children and adolescents. One factor that has received considerable research attention is the influence of parenting practices and behaviors on child physical activity. This review evaluated 103 studies that examined the influence of parental physical activity, parental support for child physical activity, parenting style, and family cohesion on child and adolescent activity behavior. Results showed that parental support was consistently positively and significantly associated with child activity. With respect to the association between parent and child physical activity, there was little evidence of association. Although the evidence linking parenting style and family cohesion with child physical activity was nonsupportive, too few studies have examined these relationships to draw firm conclusions. Priorities for future research and implications for health care professionals are discussed.

Benefits and environmental determinants of physical activity in children and adolescents.

In this review, we identify the health benefits associated with physical activity (PA); address the physical activity and sedentary guidelines issued by public health scientists as well as children’s compliance to these guidelines; discuss the importance of motor skill acquisition during early childhood; and identify different settings that contribute to physical activity participation and strategies for improving PA in these settings. Results show that regular participation in PA during childhood has numerous immediate benefits, including positive changes in adiposity, skeletal health, psychological health, and cardiorespiratory fitness. Additionally, motor skill development during early childhood may have immediate health benefits as well as long-lasting effects in adulthood. Furthermore, the benefits of PA during childhood also appear to positively influence adult health outcomes, such as increased bone mineral density. Key environmental settings that have been shown to influence children’s PA behavior include child care, active commuting to and from school, school recess, school physical education, after-school programs, churches, medical settings, and the home environment. Recommendations for practitioners and researchers are discussed.

Measuring Children's Physical Activity and Sedentary Behaviors

The high prevalence of overweight and obesity among children necessitates the need to promote physical activity and reduce sedentary behaviors in children. Consequently, there is a need to be able to reliably and accurately measure physical activity and sedentary behaviors in children. Unfortunately, there is no one measurement tool that captures physical activity and sedentary behaviors perfectly. When choosing a measurement tool to assess physical activity and sedentary behavior, researchers and practitioners must be aware of the strengths and limitations of each measurement. To assist researchers and practitioners in choosing the appropriate measurement tool for the desired study, we overviewed the most common methods currently being used to measure physical activity and sedentary behavior in children, noting the strengths and limitations of each instrument.

Dose-response association of moderate-to-vigorous physical activity with cardiovascular biomarkers and all-cause mortality: Considerations by individual sports, exercise and recreational physical activities.

BACKGROUND Previous research demonstrates that moderate-to-vigorous physical activity (MVPA) is associated with reduced all-cause mortality risk. Our understanding of whether individual physical activities are associated with all-cause mortality is less understood. METHODS Data from the 1999-2006 NHANES were employed, with follow-up through 2011. 48 different individual physical activities (e.g., swimming, running, bicycling) were assessed, and total MVPA MET-min-month was calculated based on their responses to these 48 individual physical activities. RESULTS Greater engagement in MVPA was associated with more favorable cardiovascular biomarkers, particularly for men. Even after adjustment for total MVPA, different individual physical activities were associated with cardiovascular biomarkers across gender. When compared to those not meeting guidelines (0-1999 MVPA MET-min-month), a dose-response association between MVPA and mortality was observed, with those engaging in 5 times the guideline level having the lowest risk of all-cause mortality (45% reduced risk). There was no evidence of a harmful effect of very high MVPA (e.g., 20,000+ MVPA MET-min-month). CONCLUSIONS Engaging in MVPA even below the minimum recommendation was associated with survival benefits, and the greatest survival effects occurred at a dose of approximately 5 times the minimum recommendation. Although very high levels (e.g., 10 times the minimum recommendation) of self-reported MVPA did not demonstrate the greatest survival effects, high levels of physical activity did not appear to have harmful effects.

Exercise and Cognitive Function: A Randomized Controlled Trial Examining Acute Exercise and Free-Living Physical Activity and Sedentary Effects

OBJECTIVE To simultaneously examine the effects of acute exercise intensity and free-living physical activity and sedentary behavior on cognitive function in young, healthy adults. PATIENTS AND METHODS Using a counterbalanced, crossover, randomized controlled design, 87 young adults (mean age, 21.4 years) completed various cognitive assessments with and without an acute bout of exercise preceding the assessment. Participants were randomized into 1 of 4 groups to complete a 30-minute bout of acute exercise: control (no exercise), light intensity (40%-50% of predicted maximum heart rate [HR(max)]), moderate intensity (51%-70% of predicted HR(max)), or vigorous intensity (71%-85% of predicted HR(max)). Subjectively and objectively determined (accelerometry) physical activity and sedentary behavior were assessed to examine the association between these free-living behaviors and cognitive function. The study duration was August 26, 2013, to September 11, 2014. RESULTS Concentration-related cognition (mean ± SD Feature Match test score) was significantly higher after a 30-minute acute bout of moderate-intensity exercise (145.1±26.9) compared with cognitive assessment without exercise (121.3±19.2; P=.004). Furthermore, questionnaire-determined sedentary behavior was inversely associated with visual attention and task switching (Trail Making Test A score) (β=-0.23; P=.04). Last, estimated cardiorespiratory fitness (volume of maximum oxygen consumption) was positively associated with reasoning-related cognitive function (Odd One Out test score) (β=0.49; P=.05); when adding metabolic equivalent of task minutes per week to this model, the results were not significant (β=0.47; P=.07). CONCLUSION These findings provide some support for acute moderate-intensity exercise, sedentary behavior, and cardiorespiratory fitness being associated with executive functioning-related cognitive function in young, healthy adults.

Objectively measured physical activity and C-reactive protein: National Health and Nutrition Examination Survey 2003-2004

The association between physical activity (PA) and C‐reactive protein (CRP) is inconsistent, with nearly all studies using self‐report measures of PA. The purpose of this study was to examine the association between objectively measured PA and CRP in US adults and children. Adults (N=2912) and children (N=1643) with valid accelerometer data and CRP data were included in the analyses. Logistic regression analysis was used to assess the odds of meeting PA guidelines across CRP quartiles for children and among adults with low, average, and high CRP levels. For adults, after adjustments for age, gender, race, body mass index, smoking, diabetes, and high‐density lipoprotein cholesterol (HDL‐C), compared with those with low CRP levels, odds ratios were 0.59 (CI=0.45–0.77) and 0.46 (CI=0.28–0.76) for participants with average and high CRP levels, respectively. For children, after adjustments for age, gender, race, weight status, and HDL‐C, compared with those in CRP quartile 1, odds ratios were 0.96 (CI=0.5–1.84), 1.23 (CI=0.71–2.12), and 0.79 (CI=0.33–1.88) for participants in quartiles 2, 3, and 4, respectively. Objectively measured PA is inversely associated with CRP in adults, with PA not related to CRP in children.

Physical Activity, Self-Regulation, and Early Academic Achievement in Preschool Children.

Research Findings: The present study investigated whether active play during recess was associated with self-regulation and academic achievement in a prekindergarten sample. A total of 51 children in classes containing approximately half Head Start children were assessed on self-regulation, active play, and early academic achievement. Path analyses indicated that higher active play was associated with better self-regulation, which in turn was associated with higher scores on early reading and math assessments. Practice or Policy: Results point to the benefits of active play for promoting self-regulation and offer insight into possible interventions designed to promote self-regulation and academic achievement.

Physical Activity and the Risk of Breast Cancer Recurrence: A Literature Review

PURPOSE/OBJECTIVES To examine the association between physical activity and breast cancer mortality and recurrence, and to provide an overview of factors related to physical activity behavior in women with breast cancer. DATA SOURCES An extensive review of the epidemiologic literature on the effect of physical activity on breast cancer recurrence and mortality was conducted using PubMed up to December 2010, involving the following key words: physical activity, exercise, breast cancer, breast cancer recurrence, and breast cancer mortality. DATA SYNTHESIS For breast cancer recurrence and breast cancer-related mortality, studies were included if physical activity served as the independent variable and a measure of association was reported. To examine determinants of physical activity, studies were included if a hypothesized factor served as the independent variable and a measure of association was reported. CONCLUSIONS Of the six studies that examined the influence of physical activity on breast cancer mortality, four (67%) reported a protective effect (i.e., inverse association), two examined the influence of physical activity on breast cancer recurrence and reported a nonsignificant risk reduction. Few studies have examined factors that influence physical activity behavior in women with breast cancer, and findings suggest that psychosocial factors play an important role in influencing the activity patterns of breast cancer survivors. Future longitudinal studies are needed to confirm those findings. IMPLICATIONS FOR NURSING To prevent breast cancer recurrence and breast cancer-related mortality, nurses should encourage breast cancer survivors to engage in regular exercise.