Diane J. Catellier

Calibration of two objective measures of physical activity for children

Abstract A calibration study was conducted to determine the threshold counts for two commonly used accelerometers, the ActiGraph and the Actical, to classify activities by intensity in children 5 to 8 years of age. Thirty-three children wore both accelerometers and a COSMED portable metabolic system during 15 min of rest and then performed up to nine different activities for 7 min each, on two separate days in the laboratory. Oxygen consumption was measured on a breath-by-breath basis, and accelerometer data were collected in 15-s epochs. Using receiver operating characteristic curve (ROC) analysis, cutpoints that maximised both sensitivity and specificity were determined for sedentary, moderate and vigorous activities. For both accelerometers, discrimination of sedentary behaviour was almost perfect, with the area under the ROC curve at or exceeding 0.98. For both the ActiGraph and Actical, the discrimination of moderate (0.85 and 0.86, respectively) and vigorous activity (0.83 and 0.86, respectively) was acceptable, but not as precise as for sedentary behaviour. This calibration study, using indirect calorimetry, suggests that the two accelerometers can be used to distinguish differing levels of physical activity intensity as well as inactivity among children 5 to 8 years of age.

Defining Accelerometer Thresholds for Activity Intensities in Adolescent Girls

Implications for Muscle Lipid Metabolism and An accumulation of intramuscular lipid has been reported with obesity and linked with insulin resistance. The purpose of this paper is to discuss: 1) mechanisms that may be responsible for intramuscular lipid accumulation with obesity, and 2) the effects of common interventions (weight loss or exercise) for obesity on skeletal muscle lipid metabolism and intramuscular lipid content. Data suggest that the skeletal muscle of morbidly obese humans is characterized by the preferential partitioning of lipid toward storage rather than oxidation. This phenotype may, in part, contribute to increased lipid deposition in both muscle and adipose tissue, and promote the development of morbid obesity and insulin resistance. Weight loss intervention decreases intramuscular lipid content, which may contribute to improved insulin action. On the other hand, exercise training improves insulin action and increases fatty acid oxidation in the skeletal muscle of obese/morbidly obese individuals. In summary, the accumulation of intramuscular lipid appears to be detrimental in terms of inducing insulin resistance; however, the accumulation of lipid can be reversed with weight loss. The mechanism(s) by which exercise enhances insulin action remains to be determined.INTRODUCTION/PURPOSE The Talk Test has been shown to be well correlated with the ventilatory threshold, with accepted guidelines for exercise prescription, and with the ischemic threshold. As such, it appears to be a valuable although quite simple method of exercise prescription. In this study, we evaluate the consistency of the Talk Test by comparing responses during different modes of exercise. METHODS Healthy volunteers (N = 16) performed incremental exercise, on both treadmill and cycle ergometer. Trials were performed with respiratory gas exchange and while performing the Talk Test. Comparisons were made regarding the correspondence of the last positive, equivocal, and first negative stages of the Talk Test with ventilatory threshold. RESULTS The %VO2peak, %VO2 reserve, %HRpeak, and %HR reserve at ventilatory threshold on treadmill versus cycle ergometer (77%, 75%. 89%, and 84% vs 67%, 64%, 82%, and 74%) were not significantly different than the equivocal stage of the Talk Test (83%, 82%, 86%, and 80% vs 73%, 70%, 87%, and 81%). The VO2 at ventilatory threshold and the last positive, equivocal and negative stages of the Talk Test were well correlated during treadmill and cycle ergometer exercise. CONCLUSIONS The results support the hypothesis that the Talk Test approximates ventilatory threshold on both treadmill and cycle. At the point where speech first became difficult, exercise intensity was almost exactly equivalent to ventilatory threshold. When speech was not comfortable, exercise intensity was consistently above ventilatory threshold. These results suggest that the Talk Test may be a highly consistent method of exercise prescription.INTRODUCTION Obesity and weight gain are negative prognostic factors for breast cancer survival. Physical activity (PA) prevents weight gain and may decrease obesity. Little information exists on PA levels among cancer survivors. We assessed PA, including the proportion of breast cancer survivors engaging in recommended levels, by categories of adiposity, age, disease stage, and ethnicity in 806 women with stage 0-IIIA breast cancer participating in the Health, Eating, Activity, and Lifestyle Study. METHODS Black, non-Hispanic white, and Hispanic breast cancer survivors were recruited into the study through Surveillance Epidemiology End Results registries in New Mexico, Western Washington, and Los Angeles County, CA. Types of sports and household activities and their frequency and duration within the third yr after diagnosis were assessed during an in-person interview. RESULTS Thirty-two percent of breast cancer survivors participated in recommended levels of PA defined as 150 min x wk(-1) of moderate- to vigorous-intensity sports/recreational PA. When moderate-intensity household and gardening activities were included in the definition, 73% met the recommended level of PA. Fewer obese breast cancer survivors met the recommendation than overweight and lean breast cancer survivors (P < 0.05). Fewer black breast cancer survivors met the recommendation compared with non-Hispanic white and Hispanic breast cancer survivors (P < 0.05). CONCLUSIONS Most of the breast cancer survivors were not meeting the PA recommendations proposed for the general adult population. Efforts to encourage and facilitate PA among these women would be an important tool to decrease obesity, prevent postdiagnosis weight gain, and improve breast cancer prognosis.PURPOSE To derive a regression equation that estimates metabolic equivalent (MET) from accelerometer counts, and to define thresholds of accelerometer counts that can be used to delineate sedentary, light, moderate, and vigorous activity in adolescent girls. METHODS Seventy-four healthy 8th grade girls, age 13 - 14 yr, were recruited from urban areas of Baltimore, MD, Minneapolis/St. Paul, MN, and Columbia, SC, to participate in the study. Accelerometer and oxygen consumption (.-)VO(2)) data for 10 activities that varied in intensity from sedentary (e.g., TV watching) to vigorous (e.g., running) were collected. While performing these activities, the girls wore two accelerometers, a heart rate monitor and a Cosmed K4b2 portable metabolic unit for measurement of (.-)VO(2). A random-coefficients model was used to estimate the relationship between accelerometer counts and (.-)VO(2). Activity thresholds were defined by minimizing the false positive and false negative classifications. RESULTS The activities provided a wide range in (.-)VO(2) (3 - 36 mL x kg x min) with a correspondingly wide range in accelerometer counts (1- 3928 counts x 30 s). The regression line for MET score versus counts was MET = 2.01 +/- 0.00171 (counts x 30 s) (mixed model R = 0.84, SEE = 1.36). A threshold of 1500 counts x 30 s defined the lower end of the moderate intensity (approximately 4.6 METs) range of physical activity. That cutpoint distinguished between slow and brisk walking, and gave the lowest number of false positive and false negative classifications. The threshold ranges for sedentary, light, moderate, and vigorous physical activity were found to be 0 - 50, 51- 1499, 1500 - 2600, and >2600 counts x 30 s, respectively. CONCLUSION The developed equation and these activity thresholds can be used for prediction of MET score from accelerometer counts and participation in various intensities of physical activity in adolescent girls.

Long-Term Effects of Cholesterol Lowering and Angiotensin-Converting Enzyme Inhibition on Coronary Atherosclerosis: The Simvastatin/Enalapril Coronary Atherosclerosis Trial (SCAT)

BackgroundThis long-term, multicenter, randomized, double-blind, placebo-controlled, 2×2 factorial, angiographic trial evaluated the effects of cholesterol lowering and angiotensin-converting enzyme inhibition on coronary atherosclerosis in normocholesterolemic patients. Methods and ResultsThere were a total of 460 patients: 230 received simvastatin and 230, a simvastatin placebo, and 229 received enalapril and 231, an enalapril placebo (some subjects received both drugs and some received a double placebo). Mean baseline measurements were as follows: cholesterol level, 5.20 mmol/L; triglyceride level, 1.82 mmol/L; HDL, 0.99 mmol/L; and LDL, 3.36 mmol/L. Average follow-up was 47.8 months. Changes in quantitative coronary angiographic measures between simvastatin and placebo, respectively, were as follows: mean diameters, −0.07 versus −0.14 mm (P =0.004); minimum diameters, −0.09 versus −0.16 mm (P =0.0001); and percent diameter stenosis, 1.67% versus 3.83% (P =0.0003). These benefits were not observed in patients on enalapril when compared with placebo. No additional benefits were seen in the group receiving both drugs. Simvastatin patients had less need for percutaneous transluminal coronary angioplasty (8 versus 21 events;P =0.020), and fewer enalapril patients experienced the combined end point of death/myocardial infarction/stroke (16 versus 30;P =0.043) than their respective placebo patients. ConclusionsThis trial extends the observation of the beneficial angiographic effects of lipid-lowering therapy to normocholesterolemic patients. The implications of the neutral angiographic effects of angiotensin-converting enzyme inhibition are uncertain, but they deserve further investigation in light of the positive clinical benefits suggested here and seen elsewhere.

Promoting Physical Activity in Middle School Girls Trial of Activity for Adolescent Girls

BACKGROUND Physical activity is important for weight control and good health; however, activity levels decline in the adolescent years, particularly in girls. DESIGN Group randomized controlled trial. SETTING/PARTICIPANTS Middle school girls with English-speaking skills and no conditions to prevent participation in physical activity in 36 schools in six geographically diverse areas of the United States. Random, cross-sectional samples were drawn within schools: 6th graders in 2003 (n=1721) and 8th graders in 2005 (n=3504) and 2006 (n=3502). INTERVENTION A 2-year study-directed intervention (fall 2003 to spring 2005) targeted schools, community agencies, and girls to increase opportunities, support, and incentives for increased physical activity. Components included programs linking schools and community agencies, physical education, health education, and social marketing. A third-year intervention used school and community personnel to direct intervention activities. MAIN OUTCOME MEASURES The primary outcome, daily MET-weighted minutes of moderate-to-vigorous physical activity (MET-weighted MVPA), was assessed using accelerometry. Percent body fat was assessed using anthropometry. RESULTS After the staff-directed intervention (pre-stated primary outcome), there were no differences (mean= -0.4, 95% CI= -8.2 to 7.4) in adjusted MET-weighted MVPA between 8th-grade girls in schools assigned to intervention or control. Following the Program Champion-directed intervention, girls in intervention schools were more physically active than girls in control schools (mean difference 10.9 MET-weighted minutes of MVPA, 95% CI=0.52-21.2). This difference is about 1.6 minutes of daily MVPA or 80 kcal per week. There were no differences in fitness or percent body fat at either 8th-grade timepoint. CONCLUSION A school-based, community-linked intervention modestly improved physical activity in girls.

Adverse Behavioral and Emotional Outcomes from Child Abuse and Witnessed Violence

This article examines mental health outcomes of children who have witnessed violence in their social environment and/or have been physically abused. Participants (n = 167) come from a longitudinal study on child maltreatment. Outcomes—including depression, anger, and anxiety—are measured by the Child Behavior Checklist and the Trauma Symptom Checklist for Children. The authors used adjusted multivariate analyses to test the statistical significance of associations. The majority of children were female (57%) and non-White (64%). One third had been physically victimized; 46% had witnessed moderate-high levels of violence. Results confirm that children are negatively affected by victimization and violence they witness in their homes and neighborhoods. Victimization was a significant predictor of child aggression and depression; witnessed violence was found to be a significant predictor of aggression, depression, anger, and anxiety. Implications will be discussed.

Fourteen-year longitudinal study of vascular risk factors, APOE genotype, and cognition: The ARIC MRI Study

Strokes, vascular risk factors, and apolipoprotein E (APOE) genotype are associated with cognitive decline in the elderly, but definitive evidence that these affect cognition as early as middle age is limited.

Cerebral MRI findings and cognitive functioning The Atherosclerosis Risk in Communities Study

Objective: To examine the association between prevalent cerebral abnormalities identified on MRI and cognitive functioning in a predominantly middle-aged, population-based study cohort. Methods: Cerebral MRI was performed on 1,538 individuals (aged 55 to 72) from the Atherosclerosis Risk in Communities (ARIC) cohort, with no history of stroke or TIA, at study sites in Forsyth County, NC, and Jackson, MS. White matter hyperintensities (WMHs), ventricular size, and sulcal size were graded by trained neuroradiologists on a semiquantitative, 10-point scale. Cognitive functioning was assessed using the Delayed Word Recall Test (DWRT), Digit Symbol Substitution Test (DSST), and Word Fluency Test (WFT). Results: High ventricular grade was independently associated with significantly lower scores on the DWRT and DSST and greater risk (odds ratio [OR] 2.32, 95% confidence interval [CI] 1.51 to 3.56) of impaired scores (i.e., ≤10th percentile) on the DWRT. High sulcal grade was associated with a modest decrement in scores on the DWRT. The presence of coexisting high grade WMHs and silent infarcts was independently associated with lower scores on all cognitive tests and greater risk of impaired functioning on the DSST (OR 2.91, 95% CI: 1.23 to 6.89) and WFT (OR 2.28, 95% CI 1.03 to 5.08). The presence of two or more high-grade abnormalities was associated with increased risk of impaired functioning on all cognitive tests (DWRT: OR 2.23, 95% CI 1.40 to 3.55; DSST: OR 2.06, 95% CI 1.13 to 3.76; WFT: OR 2.07, 95% CI 1.23 to 3.49) independent of multiple covariates and silent infarcts. Conclusion: Common changes in brain morphology are associated with diminished cognitive functioning in middle-aged and young-elderly individuals.

Weekend and Weekday Patterns of Physical Activity in Overweight and Normal‐weight Adolescent Girls

Objective: To describe the patterns (specifically comparing weekdays and weekends classified by intensities) of physical activity (PA) measured by accelerometry in adolescent girls.

Psychosocial treatment within sex by ethnicity subgroups in the Enhancing Recovery in Coronary Heart Disease clinical trial.

Objective: Intervening in depression and/or low perceived social support within 28 days after myocardial infarction (MI) in the Enhancing Recovery in Coronary Heart Disease (ENRICHD) clinical trial did not increase event-free survival. The purpose of the present investigation was to conduct post hoc analyses on sex and ethnic minority subgroups to assess whether any treatment subgroup is at reduced or increased risk of greater morbidity/mortality. Methods: The 2481 patients with MI (973 white men, 424 minority men, 674 white women, 410 minority women) who had major or minor depression and/or low perceived social support were randomly allocated to usual medical care or cognitive behavior therapy. Total mortality or recurrent nonfatal MI (ENRICHD primary endpoint) and cardiac mortality or recurrent nonfatal MI (secondary endpoint) were analyzed as composite endpoints by group for time to first event using Cox proportional hazards regression. Results: There was a trend in the direction of treatment efficacy for white men for the primary endpoint (hazard ratio [HR], 0.80; 95% confidence interval, 0.61–1.05; p = .10) and a significant (p < .006, Bonferroni corrected) effect for the secondary endpoint (HR, 0.63; 95% CI, 0.46–0.87; p = .004). In contrast, the HRs for each of the other three subgroups were nonsignificant. The magnitude of differences in treatment effects between white men and the other subgroups remained significant for the secondary endpoint (p =.04) after adjustment for age, education, living alone, antidepressant use, comorbidity score, cardiac catheterization, ejection fraction, history of hypertension, and major depression. Conclusions: White men, but not other subgroups, may have benefited from the ENRICHD intervention, suggesting that future studies need to attend to issues of treatment design and delivery that may have prevented benefit among sex and ethnic subgroups other than white men.

Genome-wide association studies of cerebral white matter lesion burden

White matter hyperintensities (WMHs) detectable by magnetic resonance imaging are part of the spectrum of vascular injury associated with aging of the brain and are thought to reflect ischemic damage to the small deep cerebral vessels. WMHs are associated with an increased risk of cognitive and motor dysfunction, dementia, depression, and stroke. Despite a significant heritability, few genetic loci influencing WMH burden have been identified.