A Randomized Controlled Trial of an Exercise Maintenance Intervention in Men and Women After Cardiac Rehabilitation (ECO-PCR Trial).

BACKGROUND: Exercise maintenance interventions are needed for cardiac rehabilitation (CR) graduates to maintain moderate and vigorous-intensity physical activity (MVPA). We tested an exercise facilitator intervention (EFI) to promote exercise maintenance compared with usual care (UC) separately in men and women. METHODS: This was a 3-site, randomized (1:1), parallel-group, superiority trial (ECO-PCR). CR graduates were stratified by site and sex and randomly allocated (concealed). EFI participants received a face-to-face introductory session, 5 small-group counseling teleconferences, and 3 personal calls from a trained facilitator over 50 weeks. In-person assessments were undertaken at baseline and 26 and 52 weeks after randomization. The primary outcome was weekly minutes of MVPA, measured by accelerometer. Secondary outcomes were exercise capacity, risk factors, quality of life, and enrollment in community-based exercise programs. Effects were tested with the use of linear mixed models. RESULTS: A total of 449 CR graduates (135 women, 314 men) were randomised (n = 226 EFI, n = 223 UC). In the intention-to-treat analysis for men and for women, there were no significant effects for treatment or time on MVPA. In a planned secondary analysis that considered only those adherent to EFI (completed ≥ 66% of sessions; per-protocol), bouted MVPA (ie, in sustained bouts of ≥ 10 min) was higher in women in the EFI group (mean = 132.6 ± 135.2 min/wk at 52 weeks) compared with UC (111.8 ± 113.1; P = 0.013). Regarding secondary outcomes, in women, a treatment group main effect was observed for blood pressure (P = 0.011) and exercise capacity (P = 0.019; both per-protocol) favouring EFI; no other differences were observed. CONCLUSIONS: In this trial of CR completers, an EFI showed promise for women, but was ineffective in men.

Data-Driven Audiogram Classification for Mobile Audiometry.

Recent mobile and automated audiometry technologies have allowed for the democratization of hearing healthcare and enables non-experts to deliver hearing tests. The problem remains that a large number of such users are not trained to interpret audiograms. In this work, we outline the development of a data-driven audiogram classification system designed specifically for the purpose of concisely describing audiograms. More specifically, we present how a training dataset was assembled and the development of the classification system leveraging supervised learning techniques. We show that three practicing audiologists had high intra- and inter-rater agreement over audiogram classification tasks pertaining to audiogram configuration, symmetry and severity. The system proposed here achieves a performance comparable to the state of the art, but is significantly more flexible. Altogether, this work lays a solid foundation for future work aiming to apply machine learning techniques to audiology for audiogram interpretation.

Adult validation of a self-administered tablet audiometer.

BACKGROUND: There is evidence to suggest that rates of hearing loss are increasing more rapidly than the capacity of traditional audiometry resources for screening. A novel innovation in tablet, self-administered portable audiometry has been proposed as a solution to this discordance. The primary objective of this study was to validate a tablet audiometer with adult patients in a clinical setting. Secondarily, word recognition with a tablet audiometer was compared against conventional audiometry. METHODS: Three distinct prospective adult cohorts underwent testing. In group 1 and group 2 testing with the automated tablet audiometer was compared to standard sound booth audiometry. In Group 1, participants' pure tone thresholds were measured with an automated tablet audiometer in a quiet clinic exam room. In Group 2, participants completed monosyllabic word recognition testing using the NU-6 word lists. In Group 3, internal reliability was tested by having participants perform two automated tablet audiometric evaluation in sequence. RESULTS: Group 1 included 40 patients mean age was 54.7 ± 18.4 years old and 60% female; Group 2 included 44 participants mean age was 55.2 ± 14.8 years old and 68.2% female; Group 3 included 40 participants with mean age of 39.4 + 15.9 years old and 60.5% female. In Group 1, compared to standard audiometry, 95.7% (95% CI: 92.6-98.9%) of thresholds were within 10 dB. In Group 2, comparing word recognition results, 96.2% (95% CI: 89.5-98.7%) were clinically equivalent and within a critical difference range. In Group 3, One-way Intraclass Correlation for agreement for the both left- and right-ear pure tone average was 0.98. The mean difference between repeat assessments was 0 (SD = 2.1) in the left ear, and 0.1 (SD = 1.1) in the right ear. CONCLUSION: Puretone audiometry and word recognition testing appears valid when performed by non-healthcare experts using a tablet audiometer outside a sound booth in a quiet environment. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02761798. Registered April, 2016 < https://clinicaltrials.gov/ct2/show/NCT02761798>.

Hepatitis C Testing, Status and Treatment among Marginalized People Who Use Drugs in an Inner City Setting: An Observational Cohort Study.

BACKGROUND: Chronic hepatitis C virus (HCV) infection is common among people who inject drugs (PWID) and is associated with morbidity and premature death. Although HCV can be cured, treatment may be inaccessible. We studied HCV testing, status and treatment among marginalized people who use drugs in Ottawa, Canada, a setting with universal insurance coverage for physician services. METHODS: We analyzed data from the Participatory Research in Ottawa: Understanding Drugs study, a cross-sectional, peer-administered survey of people who use drugs from 2012 to 2013. We linked responses to population-based health administrative databases and used multivariable Poisson regression to identify factors independently associated with self-reported HCV testing, self-reported positive HCV status, and database-determined engagement in HCV treatment. RESULTS: Among 663 participants, 562 (84.8%) reported testing for HCV and 258 (45.9%) reported HCV-positive status. In multivariable analysis, HCV-positive status was associated with female gender (RR 1.27; 95%CI 1.04 to 1.55), advancing age (RR 1.03/year; 95%CI 1.02 to 1.04), receiving disability payments (RR 1.42; 95%CI 1.06 to 1.91), injecting drugs (RR 5.11; 95%CI 2.64 to 9.91), ever injecting with a used needle (RR 1.30; 95%CI 1.12 to 1.52), and ever having taken methadone (RR 1.26; 95%CI 1.05 to 1.52). Of HCV positive participants, 196 (76%) were engaged in primary care but only 23 (8.9%) had received HCV therapy. Conclusions/Importance: Although HCV testing and positive status rates are high among PWID in our study, few have received HCV treatment. Innovative initiatives to increase access to HCV treatment for PWID are urgently needed.

Impact of health care reform on enrolment of immigrants in primary care in Ontario, Canada.

OBJECTIVES: In 2003, Ontario introduced a patient enrolment system as part of health care reforms, aimed at enhancing primary health care services, but it is unclear whether immigrants have benefited from this health care reform. Therefore, we studied whether this reform changed the extent of immigrants' enrolment in primary care services in Ontario between 2003 and 2012. METHODS: This is a population-based retrospective cohort study, in which a closed cohort of 9231840 Ontario residents between 1985 and 2003 was created, using linked health administrative and immigration databases. Levels of enrolment for traditional and more comprehensive capitation-based practice between 2003 and 2012 were compared by immigrant status. Logistic regression modelling was used to assess the odds of enrolment on primary care practices. RESULTS: Overall enrolment in primary care practices increased gradually after 2004, until 2012, when two-thirds of the cohort (67%) were enrolled. The immigrants' enrolment level remained consistently lower than that of long-term residents over the study period. By 2012, enrolment of immigrants in capitation-based models was significantly lower (17.3% versus 25.4%). In particular, enrolment in Family Health Teams, considered the most comprehensive care model, was considerably lower in immigrants compared with long-term residents (5.6% versus 18.0%; OR = 0.40, 95% CI: 0.40 to 0.41). CONCLUSIONS: Immigrant enrolment rates in new comprehensive primary care models were consistently lower than among long-term residents. This has implication on equitable primary care access for immigrant populations.

Assessing Timely Presentation to Care Among People Diagnosed with HIV During Hospital Admission: A Population-Based Study in Ontario, Canada.

Timely presentation to care for people newly diagnosed with HIV is critical to optimize health outcomes and reduce onward HIV transmission. Studies describing presentation to care following diagnosis during a hospital admission are lacking. We sought to assess the timeliness of presentation to care and to identify factors associated with delayed presentation. We conducted a population-level study using health administrative databases. Participants were all individuals older than 16 and newly diagnosed with HIV during hospital admission in Ontario, Canada, between April 1, 2007 and March 31, 2015. We used modified Poisson regression models to derive relative risk ratios for the association between sociodemographic and clinical variables and the presentation to out-patient HIV care by 90 days following hospital discharge. Among 372 patients who received a primary HIV diagnosis in hospital, 83.6% presented to care by 90 days. Following multivariable analysis, we did not find associations between patient sociodemographic or clinical characteristics and presentation to care by 90 days. In a secondary analysis of 483 patients diagnosed during hospitalization but for whom HIV was not recorded as the principal reason for admission, 73.1% presented to care by 90 days. Following multivariable adjustment, we found immigrants from countries with generalized HIV epidemics (RR 1.265, 95% CI 1.133-1.413) were more likely to present to care, whereas timely presentation was less likely for people with a mental health diagnosis (RR 0.817, 95% CI 0.742-0.898) and women (RR 0.748, 95% CI 0.559-1.001). Future work should evaluate mechanisms to facilitate presentation to care among these populations.

A cohort study examining emergency department visits and hospital admissions among people who use drugs in Ottawa, Canada.

BACKGROUND: The health of people who use drugs (PWUD) is characterized by multimorbidity and chronicity of health conditions, necessitating an understanding of their health care utilization. The objective of this study was to evaluate emergency department (ED) visits and hospital admissions among a cohort of PWUD. METHODS: We used a retrospective observational design between 2012 and 2013. The population was a marginalized cohort of PWUD (the PROUD study) for whom survey data was linked (n = 663) to provincial health administrative data housed at the Institute for Clinical Evaluative Sciences. We constructed a 5:1 comparison group matched by age, sex, income quintile, and region. The main outcomes were defined as having two or more ED visits, or one or more hospital admissions, in the year prior to survey completion. We used multivariable logistic regression analyses to identify factors associated with these outcomes. RESULTS: Compared to the matched cohort, PWUD had higher rates of ED visits (rate ratio [RR] 7.0; 95% confidence interval [95% CI] 6.5-7.6) and hospitalization (RR 7.7; 95% CI 5.9-10.0). After adjustment, factors predicting more ED visits were receiving disability (adjusted odds ratio [AOR] 3.0; 95% CI 1.7-5.5) or income assistance (AOR 2.7; 95% CI 1.5-5.0), injection drug use (AOR 2.1; 95% CI 1.3-3.4), incarceration within 12 months (AOR 1.6; 95% CI 1.1-2.4), mental health comorbidity (AOR 2.1; 95% CI 1.4-3.1), and a suicide attempt within 12 months (AOR 2.1; 95% CI 1.1-3.4). Receiving methadone (AOR 0.5; 95% CI 0.3-0.9) and having a regular family physician (AOR 0.5; 95% CI 0.2-0.9) were associated with lower odds of having more ED visits. Factors associated with more hospital admissions included Aboriginal identity (AOR 2.4; 95% CI 1.4-4.1), receiving disability (AOR 2.4; 95% CI 1.1-5.4), non-injection drug use (opioids and non-opioids) (AOR 2.2; 95% CI 1.1-4.4), comorbid HIV (AOR 2.4; 95% CI 1.2-5.6), mental health comorbidity (AOR 2.4; 95% CI 1.3-4.2), and unstable housing (AOR 1.9; 95% CI 1.0-3.4); there were no protective factors for hospitalization. CONCLUSIONS: Improved post-incarceration support, housing services, and access to integrated primary care services including opioid replacement therapy may be effective interventions to decrease acute care use among PWUD, including targeted approaches for people receiving social assistance or with mental health concerns.

Practice facilitation for improving cardiovascular care: secondary evaluation of a stepped wedge cluster randomized controlled trial using population-based administrative data.

BACKGROUND: Practice facilitation (PF), a multifaceted approach in which facilitators (external health care professionals) help family physicians to improve their adoption of best practices, has been highly successful. Improved Delivery of Cardiovascular Care (IDOCC) was an innovative PF trial designed to improve evidence-based care for people who have, or are at risk of, cardiovascular disease (CVD). The intervention was found to be ineffective as assessed by a patient-level composite score based on chart reviews from a subsample of patients (N = 5292). Here, we used population-based administrative data to examine IDOCC's effect on CVD-related hospitalizations. METHODS: IDOCC used a pragmatic, stepped wedge cluster randomized controlled design involving primary care providers recruited across Eastern Ontario, Canada. IDOCC's effect on CVD-related hospitalizations was assessed in the 2 years of active intervention and post-intervention years. Marginal and mixed-effects regression analyses were used to account for the study design and to control for patient, physician, and practice characteristics. Secondary and subgroup analyses investigated robustness. RESULTS: Our sample included 262,996 patient/year observations representing 54,085 unique patients who had, or were at risk of, CVD, from 70 practices. There was a strong decreasing secular trend in CVD-related hospitalizations but no statistically significant effect of IDOCC. Relative to patients in the control condition, patients in the intervention condition were estimated to have 4 % lower odds of CVD-related hospitalizations (adjOR = 0.96, 99 % CI 0.83 to 1.11). The nonsignificant result persisted across robustness analyses. CONCLUSIONS: Clinical outcomes from administrative databases were examined to form a more complete picture of the (in)effectiveness of a large-scale quality improvement intervention. IDOCC did not have a significant effect on CVD hospitalizations, suggesting that the results from the primary composite adherence score analysis were neither due to choice of outcome nor relatively short follow-up period. TRIAL REGISTRATION: ClinicalTrials.gov NCT00574808 , registered on 14 December 2007.

A Comparison of Accelerometer Cut-Points among Individuals with Coronary Artery Disease.

BACKGROUND: Accurate assessment of physical activity among coronary artery disease patients is important for assessing adherence to interventions. The study compared moderate-to-vigorous physical intensity activity and relationships with cardiometabolic health/fitness indicators using accelerometer cut-points developed for coronary artery disease patients versus those developed in younger and middle-aged adults. METHODS: A total of 231 adults with coronary artery disease wore an Actigraph GT3X accelerometer for ≥4 days (≥10 hours/day). Moderate-to-vigorous intensity physical activity between cut-points was compared using Bland-Altman analyses. Partial spearman correlations assessed relationships between moderate-to-vigorous intensity physical activity from each cut-point with markers of cardiometabolic health and fitness while controlling for age and sex. RESULTS: Average time spent in bouts of moderate-to-vigorous intensity physical activity using coronary artery disease cut-points was significantly higher than the young (mean difference: 13.0±12.8 minutes/day) or middle-aged (17.0±15.2 minutes/day) cut-points. Young and middle-aged cut-points were more strongly correlated with body mass index, waist circumference and systolic blood pressure, while coronary artery disease cut-points had stronger relationships with triglycerides, high-density and low-density lipoproteins. All were similarly correlated with measures of fitness. CONCLUSION: Researchers need to exert caution when deciding on which cut-points to apply to their population. Further work is needed to validate which cut-points provide a true reflection of moderate-to-vigorous intensity physical activity and to examine relationships among patients with varying fitness.

Healthy eating opinion survey for individuals at risk for cardiovascular disease.

OBJECTIVE: To develop and evaluate the validity and reliability of a questionnaire to measure intentions and beliefs about healthy eating in individuals at risk for coronary heart disease. METHOD: The Healthy Eating Opinion Survey was developed using the theory of planned behavior. An open-ended elicitation questionnaire was administered to 21 participants, and a 46-item questionnaire was developed for further testing. Test-retest reliability of each question on the survey was assessed by calculating the correlation coefficients between the responses over a 2- week period in 17 participants. Internal consistency was assessed using Cronbach's alpha, and factor analysis was used to assess the construct validity of the questionnaire in a sample of 388 participants. RESULTS: The responses to the elicitation questions were used to develop behavioral beliefs, normative beliefs, and control beliefs questions for the final questionnaire. Test-retest reliability ranged from 0.22-0.90, with the majority (89%) of correlations being moderate to strong. Internal consistency was good, with Cronbach's alpha ranging from 0.74-0.92. All intentions questions loaded onto a single factor; attitude questions loaded onto two factors; subjective norm questions loaded onto two factors; perceived behavioral control questions loaded onto one factor; behavioral beliefs questions loaded onto one factor; normative beliefs questions loaded onto one factor; and control beliefs questions loaded onto one factor. CONCLUSION: The questionnaire was found to be a reliable, valid questionnaire to assess beliefs and intentions toward eating a healthy diet in individuals at risk for coronary heart disease.

Effect of an intervention to improve the cardiovascular health of family members of patients with coronary artery disease: a randomized trial.

BACKGROUND: Family members of patients with coronary artery disease (CAD) have higher risk of vascular events. We conducted a trial to determine if a family heart-health intervention could reduce their risk of CAD. METHODS: We assessed coronary risk factors and randomized 426 family members of patients with CAD to a family heart-health intervention (n = 211) or control (n = 215). The intervention included feedback about risk factors, assistance with goal setting and counselling from health educators for 12 months. Reports were sent to the primary care physicians of patients whose lipid levels and blood pressure exceeded threshold values. All participants received printed materials about smoking cessation, healthy eating, weight management and physical activity; the control group received only these materials. The main outcomes (ratio of total cholesterol to high-density lipoprotein [HDL] cholesterol; physical activity; fruit and vegetable consumption) were assessed at 3 and 12 months. We examined group and time effects using mixed models analyses with the baseline values as covariates. The secondary outcomes were plasma lipid levels (total cholesterol, low-density lipoprotein cholesterol, HDL cholesterol and triglycerides); glucose level; blood pressure; smoking status; waist circumference; body mass index; and the use of blood pressure, lipid-lowering and smoking cessation medications. RESULTS: We found no effect of the intervention on the ratio of total cholesterol to HDL cholesterol. However, participants in the intervention group reported consuming more fruit and vegetables (1.2 servings per day more after 3 mo and 0.8 servings at 12 mo; p < 0.001). There was a significant group by time interaction for physical activity (p = 0.03). At 3 months, those in the intervention group reported 65.8 more minutes of physical activity per week (95% confidence interval [CI] 47.0-84.7 min). At 12 months, participants in the intervention group reported 23.9 more minutes each week (95% CI 3.9-44.0 min). INTERPRETATION: A health educator-led heart-health intervention did not improve the ratio of total cholesterol to HDL cholesterol but did increase reported physical activity and fruit and vegetable consumption among family members of patients with CAD. Hospitalization of a spouse, sibling or parent is an opportunity to improve cardiovascular health among other family members. TRIAL REGISTRATION: clinicaltrials.gov, no NCT00552591.

The effects of chronic exercise training in individuals with permanent atrial fibrillation: a systematic review.

BACKGROUND: Atrial fibrillation, the most common sustained cardiac arrhythmia, is associated with significant morbidity and mortality. Chronic exercise training is a recognized form of treatment for those with many forms of heart disease. There might also be a role for exercise in the management of permanent atrial fibrillation; few studies have explored the effects of chronic exercise training in persons with this condition. The purpose of this study was to systematically evaluate and summarize the evidence surrounding the effects of chronic exercise training in persons with permanent atrial fibrillation. METHODS: A systematic and comprehensive literature review was undertaken of all English language literature. A total of 6 studies, 3 randomized controlled trials with a total of 118 participants, and 3 observational studies with a total of 93 participants, were identified. RESULTS: The literature suggests that short-term chronic exercise training of low, moderate, or vigorous intensity in adults with permanent atrial fibrillation significantly improved rate control, functional capacity, muscular strength and power, activities of daily living, and quality of life. The effect of short-term chronic exercise training on aerobic capacity in adults with permanent atrial fibrillation is conflicting. CONCLUSIONS: Chronic exercise training appears to play a promising role in the management of permanent atrial fibrillation. Future studies examining the effect of various forms of exercise training interventions in improving clinical outcomes and exercise tolerance in those with permanent atrial fibrillation are needed.

Neighbourhood walkability and physical activity among family members of people with heart disease who participated in a randomized controlled trial of a behavioural risk reduction intervention.

This study adds to the current literature investigating the relationship between individuals' physical activity (PA) and the built environment. Self-reported PA from a prospective behavioural risk reduction intervention was explored in the context of objectively measured Walk Score(®) and neighbourhood walkability in Ottawa, Canada. Participants in the intervention arm had significantly higher odds of meeting PA guidelines at 12-weeks compared to the standard care control group. This was not influenced by Walk Score(®) or walkability. This individual-level intervention was effective in assisting participants to overcome potential structural barriers presented by their neighbourhood to meet PA guidelines at 12-weeks.

Cardiac rehabilitation: beginning at the bedside.

PURPOSE: Despite well-documented positive benefits, cardiac rehabilitation (CR) is an underutilized resource for patients following a cardiac event or intervention. Bias in the CR referral process has led to programs designed to ensure that all eligible patients receive a referral. The purpose of the current investigation was to describe the implementation of a nurse-delivered automatic bedside referral process and to examine the effectiveness on referral and intake rates for CR. METHODS: In 2007, an automatic CR referral system was implemented at the University of Ottawa Heart Institute. A nurse-delivered automatic bedside referral process was implemented in 2008. A CR nurse screened all inpatient charts, discussed CR benefits and program options with patients, triaged the patient to the appropriate program, and facilitated booking of the CR intake appointment. Data were analyzed to determine the effectiveness of this approach. RESULTS: Only 15.5% to 19.7% of eligible patients participated in CR program prior to 2006. Implementation of an automatic referral process increased participation to 26.7%. The nurse-delivered bedside automatic referral process increased participation to 32.6%. The proportion of patients receiving CR referrals almost tripled following the implementation of the nurse-delivered referral process from 26.7% in 2003 to 79.0% in 2008. CONCLUSIONS: A nurse-delivered automatic bedside referral process had a positive impact on both referral and intake to CR. Future challenges for CR programs will be to ensure optimal participation in programs, while managing the growth associated with increased rates of involvement.

Influence of movement intensity and physical activity on adiposity in youth.

BACKGROUND: Despite the plethora of research examining the physical activity-adiposity relation in youth, questions remain regarding the ideal intensity. Therefore, the purpose of this study was to explore the independent effects of physical activity intensity and incidental movement on total and trunk adiposity. METHODS: The sample consisted of 1165 youth aged 8 to 17 years from the 2003-04 U.S. National Health and Nutrition Examination Survey. Physical activity (low, moderate, vigorous intensity) and incidental movement (activity level when not physically active) were measured using Actigraph accelerometers over 7 days. Total body and trunk fat were measured using dual-energy X-ray absorptiometry; age- and sex-specific percentile scores were calculated. RESULTS: Bivariate analyses revealed an inverse relation between total, low, moderate and vigorous intensity physical activity with total body and trunk fat. After consideration of the total volume of physical activity in the multivariate analyses, moderate-to-vigorous intensity physical activity remained significantly related to total and trunk fat. Participants with the highest (top 12.5%) moderate-to-vigorous intensity activity values had total fat percentile scores that were 34 points lower than participants with the lowest (bottom 25%) values. CONCLUSION: These results are consistent with public health guidelines which recommend that children and youth participate in moderate-to-vigorous intensity physical activity.

Knowledge, attitudes and behaviours related to dietary sodium among 35- to 50-year-old Ontario residents.

BACKGROUND: Excessive consumption of dietary sodium is an important public health issue. Little is known about the knowledge, attitudes and behaviours related to sodium consumption among Canadians. OBJECTIVE: To examine knowledge, attitudes and behaviours related to sodium consumption among a sample of Canadians 35 to 50 years of age. METHODS: A random-digit-dial telephone survey was conducted among adults aged 35 to 50 years of age in two regions in Ontario. Logistic regression was used to examine the likelihood of having taken action in the past 30 days to reduce sodium consumption, and the likelihood that respondents were intending to reduce sodium in the next six months. RESULTS: A total of 3130 interviews were completed. The majority of respondents were aware of excessive sodium consumption as a health issue and reported that they were taking action to reduce their dietary sodium intake. A large proportion of respondents did not correctly identify many foods as being high in sodium and, consequently, may have incorrectly believed they were consuming healthy amounts of sodium. Respondents who believed sodium reduction was important were more likely to have taken action to reduce sodium within the previous 30 days. Respondents who self-identified as consuming too much sodium were less likely to have taken action. CONCLUSIONS: The findings of the present study suggest that in addition to policy changes designed to reduce the sodium content of foods, there is a need to address the low levels of knowledge surrounding sources of excessive sodium in popular Canadian foods, the importance of a reduced intake of sodium and the availability of lower-sodium alternatives.

Influence of bouts of physical activity on overweight in youth.

BACKGROUND: It is unknown whether bouts of physical activity confer benefits beyond the total volume of physical activity. It was hypothesize that bouts of physical activity would independently predict overweight in youth. METHODS: The sample included 2498 youth (aged 8-17 years) from the 2003-2004 and 2005-2006 cycles of the National Health and Nutrition Examination Survey. Analyses were conducted in 2008. Sporadic sessions (1-4 minutes) of moderate-to-vigorous physical activity (MVPA); short bouts (5-9 minutes) of MVPA; and medium-to-long bouts (>or=10 minutes) of MVPA were measured over 7 days using Actigraph accelerometers. BMI was used to classify participants as normal weight or overweight. Logistic regression was used to predict the relative odds of overweight according to total MVPA and bouts of MVPA. RESULTS: After controlling for the volume of MVPA, individuals in the highest quartile for total bouts of MVPA (short + medium-to-long bouts) were only 0.38 (95% CI=0.18, 0.80) times as likely to be overweight compared to the lowest quartile. After controlling for the volume of MVPA and the amount accumulated in short bouts, individuals in the highest quartile for medium-to-long bouts of MVPA were only 0.55 (95% CI=0.32, 0.95) times as likely to be overweight compared to the lowest quartile. CONCLUSIONS: Moderate-to-vigorous physical activity that took place in bouts conferred benefits on adiposity status that were independent of the total volume of MVPA in this large sample of youth.

Dose-response relation between physical activity and blood pressure in youth.

UNLABELLED: The dose-response relationship between physical activity (PA) and cardiovascular health in children and adolescents is unclear. Blood pressure (BP) is a practical and useful measure of cardiovascular health in youth. PURPOSE: This study aims to examine the dose-response relationship between objectively measured PA and BP in children and adolescents. METHODS: The sample included 1170 youth aged 8-17 yr from the 2003/04 U.S. National Health and Nutrition Examination Survey. PA was measured using Actigraph accelerometers (Ft. Walton Beach, FL, USA) over 7 d. Thresholds of 2000 and 3000 counts per minute were used to denote those minutes where the participants were engaged in total PA and moderate-to-vigorous intensity PA, respectively. BP was measured using standard procedures. Systolic and diastolic BP values were adjusted for age, height, and sex. Participants with adjusted BP values > or = 90th percentile were considered to have hypertension. Thirty-six fractional polynomial regression models were used to obtain the dose-response curve that best fit the relation between PA with systolic BP, diastolic BP, and hypertension. RESULTS: Inverse dose-response relations were observed between total and moderate-to-vigorous PA with systolic and diastolic BP. The slopes of the curves were modest indicating a minimal influence of PA on mean BP values. The likelihood of having hypertension decreased in a curvilinear manner with increasing minutes of PA. At 30 and 60 min.d of moderate-to-vigorous PA, the odd ratios (95% confidence intervals) for hypertension were 0.50 (0.28-0.64) and 0.38 (0.17-0.52), respectively, in comparison to no PA. CONCLUSIONS: A modest dose-response relation was observed between PA and mean systolic and diastolic BP values. PA did, however, have a strong gradient effect on BP when predicting hypertensive values. These results support the public health recommendation that children and youth accumulate at least 60 min of moderate-to-vigorous PA daily.