Kelly R. Evenson

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.

Reducing delay in seeking treatment by patients with acute coronary syndrome and stroke: A scientific statement from the American Heart Association Council on Cardiovascular Nursing and Stroke Council

Patient delay in seeking treatment for acute coronary syndrome and stroke symptoms is the major factor limiting delivery of definitive treatment in these conditions. Despite decades of research and public education campaigns aimed at decreasing patient delay times, most patients still do not seek treatment in a timely manner. In this scientific statement, we summarize the evidence that (1) demonstrates the benefits of early treatment, (2) describes the extent of the problem of patient delay, (3) identifies the factors related to patient delay in seeking timely treatment, and (4) reveals the inadequacies of our current approaches to decreasing patient delay. Finally, we offer suggestions for clinical practice and future research.

Obesity prevalence and the local food environment

Disparities in access to healthy foods have been identified particularly in the United States. Fewer studies have measured the effects these disparities have on diet-related health outcomes. This study measured the association between the presence of food establishments and obesity among 1295 adults living in the southern region of the United States. The prevalence of obesity was lower in areas that had supermarkets and higher in area with small grocery stores or fast food restaurants. Our findings are consistent with other studies showing that types of food stores and restaurants influence food choices and, subsequently, diet-related health outcomes.

Exploring associations between physical activity and perceived and objective measures of the built environment.

The built environment may be responsible for making nonmotorized transportation inconvenient, resulting in declines in physical activity. However, few studies have assessed both the perceived and objectively measured environment in association with physical activity outcomes. The purpose of this study was to describe the associations between perceptions and objective measures of the built environment and their associations with leisure, walking, and transportation activity. Perception of the environment was assessed from responses to 1,270 telephone surveys conducted in Forsyth County, NC and Jackson, MS from January to July 2003. Participants were asked if high-speed cars, heavy traffic, and lack of crosswalks or sidewalks were problems in their neighborhood or barriers to physical activity. They were also asked if there are places to walk to instead of driving in their neighborhood. Speed, volume, and street connectivity were assessed using Geographic Information Systems (GIS) for both study areas. Locations of crashes were measured using GIS for the NC study area as well. Objective and perceived measures of the built environment were in poor agreement as calculated by kappa coefficients. Few associations were found between any of the physical activity outcomes and perception of speed, volume, or presence of sidewalks as problems in the neighborhood or as barriers to physical activity in regression analyses. Associations between perceptions of having places to walk to and presence of crosswalks differed between study sites. Several associations were found between objective measures of traffic volume, traffic speed, and crashes with leisure, walking, and transportation activity in Forsyth County, NC; however, in Jackson, MS, only traffic volume was associated with any of the physical activity outcomes. When both objective and perceived measures of the built environment were combined into the same model, we observed independent associations with physical activity; thus, we feel that evaluating both objective and perceived measures of the built environment may be necessary when examining the relationship between the built environment and physical activity.

Neighborhood environment, access to places for activity, and leisure-time physical activity in a diverse North Carolina population

Purpose. To examine associations between perceived neighborhood characteristics, access to places for activity, and leisure-time physical activity. Design. Cross-sectional telephone survey. Setting. Cabarrus, Henderson, Pitt, Robeson, Surry, and Wake counties in North Carolina. Subjects. Population-based sample of 1796 adults at least 18 years of age residing in the six counties. Measures. The 133-item questionnaire assessed self-reported leisure-time physical activity and perceptions of neighborhood characteristics (sidewalks, trails, heavy traffic, streetlights, unattended dogs, and safety from crime) and general access to places for physical activity. Results. Trails, streetlights, and access to places were positively associated with engaging in any leisure activity: unadjusted odds ratio (OR) (95% confidence interval [CI]); 1.62 (1.09–2.41), 1.57 (1.14–2.17), and 2.94 (1.91–4.52), respectively. Trails and access to places were positively associated with engaging in the recommended amount of leisure activity: 1.49 (1.00–2.22), and 2.28 (1.30–4.00), respectively). In multivariable logistic regression modeling including environmental factors and demographics, access to places was associated with any activity (2.23 [1.44–3.44]) and recommended activity (2.15 [1.23–3.77]), and trails were associated with recommended activity (1.51 [1.00–2.28]). Conclusion. Certain neighborhood characteristics, particularly trails, and access to places for physical activity may be associated with leisure activity levels. In this study, perceived neighborhood environmental factors and access to places for physical activity were strongly associated with race, education, and income.

Systematic review of the validity and reliability of consumer-wearable activity trackers

BackgroundConsumer-wearable activity trackers are electronic devices used for monitoring fitness- and other health-related metrics. The purpose of this systematic review was to summarize the evidence for validity and reliability of popular consumer-wearable activity trackers (Fitbit and Jawbone) and their ability to estimate steps, distance, physical activity, energy expenditure, and sleep.MethodsSearches included only full-length English language studies published in PubMed, Embase, SPORTDiscus, and Google Scholar through July 31, 2015. Two people reviewed and abstracted each included study.ResultsIn total, 22 studies were included in the review (20 on adults, 2 on youth). For laboratory-based studies using step counting or accelerometer steps, the correlation with tracker-assessed steps was high for both Fitbit and Jawbone (Pearson or intraclass correlation coefficients (CC) > =0.80). Only one study assessed distance for the Fitbit, finding an over-estimate at slower speeds and under-estimate at faster speeds. Two field-based studies compared accelerometry-assessed physical activity to the trackers, with one study finding higher correlation (Spearman CC 0.86, Fitbit) while another study found a wide range in correlation (intraclass CC 0.36–0.70, Fitbit and Jawbone). Using several different comparison measures (indirect and direct calorimetry, accelerometry, self-report), energy expenditure was more often under-estimated by either tracker. Total sleep time and sleep efficiency were over-estimated and wake after sleep onset was under-estimated comparing metrics from polysomnography to either tracker using a normal mode setting. No studies of intradevice reliability were found. Interdevice reliability was reported on seven studies using the Fitbit, but none for the Jawbone. Walking- and running-based Fitbit trials indicated consistently high interdevice reliability for steps (Pearson and intraclass CC 0.76–1.00), distance (intraclass CC 0.90–0.99), and energy expenditure (Pearson and intraclass CC 0.71–0.97). When wearing two Fitbits while sleeping, consistency between the devices was high.ConclusionThis systematic review indicated higher validity of steps, few studies on distance and physical activity, and lower validity for energy expenditure and sleep. The evidence reviewed indicated high interdevice reliability for steps, distance, energy expenditure, and sleep for certain Fitbit models. As new activity trackers and features are introduced to the market, documentation of the measurement properties can guide their use in research settings.

Determinants of Use of Emergency Medical Services in a Population With Stroke Symptoms: The Second Delay in Accessing Stroke Healthcare (DASH II) Study

Background and Purpose With the advent of time-dependent thrombolytic therapy for ischemic stroke, it has become increasingly important for stroke patients to arrive at the hospital quickly. This study investigates the association between the use of emergency medical services (EMS) and delay time among individuals with stroke symptoms and examines the predictors of EMS use. Methods The Second Delay in Accessing Stroke Healthcare Study (DASH II) was a prospective study of 617 individuals arriving at emergency departments in Denver, Colo, Chapel Hill, NC, and Greenville, SC, with stroke symptoms. Results EMS use was associated with decreased prehospital and in-hospital delay. Those who used EMS had a median prehospital delay time of 2.85 hours compared with 4.03 hours for those who did not use EMS (P =0.002). Older individuals were more likely to use EMS (odds ratio [OR] 1.21 for each 5-year increase, 95% CI 1.14 to 1.29), as were individuals who expressed a high sense of urgency about their symptoms (OR 1.69, 95% CI 1.09 to 2.62). Knowledge of stroke symptoms was not associated with increased EMS use (OR 0.63, 95% CI 0.40 to 0.98). Patients were more likely to use EMS if someone other than the patient first identified that there was a problem (OR 2.35, 95% CI 1.61 to 3.44). Conclusions Interventions aimed at increasing EMS use among stroke patients need to stress the urgency of stroke symptoms and the importance of calling 911 and need to be broad-based, encompassing not only those at high risk for stroke but also their friends and family.

Correlates of Physical Activity among Women from Diverse Racial/Ethnic Groups

OBJECTIVE Women have lower rates of participation in leisure time physical activity than men and have been studied to a lesser extent than men. Because physical activity plays a vital role in overall health, it is important to identify factors than can help increase physical activity rates for women. METHODS Defining and understanding correlates of physical activity is critical for at-risk populations and for planning effective interventions. This paper reviews research conducted in the past two decades on correlates of physical activity in women. An ecological model with an added physical environment component was used to organize the correlates. Studies conducted among adult white, black, American Indian, Asian, and Hispanic women are included. A total of 91 studies were reviewed. Many studies included white women, fewer studies included black and Hispanic women, and even fewer included American Indian women, and only 3 studies included Asian women. RESULTS The correlates most studied are sociodemographic variables, with nonwhite race, lower educational levels, and older age most consistently associated with lower levels of physical activity. Few studies focused on environmental and policy correlates. Social support was an overwhelmingly positive determinant of physical activity for all groups of women. CONCLUSIONS Based on these findings, we recommend that future research include more diverse groups of women and evaluate modifiable factors, such as psychological, interpersonal, and environmental correlates. Future research also should include more intervention and longitudinal studies.

A systematic review of fast food access studies.

The frequent consumption of energy‐dense fast food is associated with increased body mass index. This systematic review aims to examine the methodology and current evidence on fast food access and its associations with outcomes. Six databases were searched using terms relating to fast food. Only peer‐reviewed studies published in English during a 10‐year period, with data collection and analysis regarding fast food access were included. Forty articles met the aforementioned criteria. Nearly half of the studies (n = 16) used their own set of features to define fast food. Studies predominantly examined the relationship between fast food access and socioeconomic factors (n = 21) and 76% indicated fast food restaurants were more prevalent in low‐income areas compared with middle‐ to higher‐income areas. Ten of 12 studies found fast food restaurants were more prevalent in areas with higher concentrations of ethnic minority groups in comparison with Caucasians. Six adult studies found higher body mass index was associated with living in areas with increased exposure to fast food; four studies, however, did not find associations. Further work is needed to understand if and how fast food access impacts dietary intake and health outcomes; and if fast food access has disparate socioeconomic, race/ethnicity and age associations.

Physical Activity as a Preventative Factor for Frailty: The Health, Aging, and Body Composition Study

BACKGROUND It is unclear if physical activity (PA) can prevent or reverse frailty. We examined different doses and types of PA and their association with the onset and severity of frailty. METHODS Health, Aging and Body Composition (Health ABC) study participants (N = 2,964) were followed for 5 years, with frailty defined as a gait speed of less than 0.60 m/s and/or inability to rise from a chair without using ones arms. Individuals with one impairment were considered moderately frail and those with both severely frail. We examined PA doses of volume and intensity, activity types (eg, lifestyle vs exercise activities), and their associations with incident frailty and transition to severe frailty in those who became frail. RESULTS Adjusted models indicated that sedentary individuals had significantly increased odds of developing frailty compared with the exercise active group (adjusted odds ratio [OR] = 1.45; 95% confidence interval [CI]: 1.04-2.01), whereas the lifestyle active did not. Number of diagnoses was the strongest predictor of incident frailty. In those who became frail during follow-up (n = 410), there was evidence that the sedentary (adjusted OR = 2.80; 95% CI: 0.98-8.02) and lifestyle active (adjusted OR = 2.81; 95% CI: 1.22-6.43) groups were more likely to have worsening frailty over time. CONCLUSIONS Despite the strong relationship seen between comorbid conditions and onset of frailty, this observational study suggests that participation in self-selected exercise activities is independently associated with delaying the onset and the progression of frailty. Regular exercise should be further examined as a potential factor in frailty prevention for older adults.