Leisure time physical activity and the 16-year risks of mortality from coronary heart disease and all-causes in the Multiple Risk Factor Intervention Trial (MRFIT)

Left ventricular mass normalization in child and adolescent athletes must account for sex differences

Background

To assess left ventricular hypertrophy, actual left ventricular mass (LVM) normalized for body size has to be compared to the LVM normative data. However, only some published normative echocardiographic data have been produced separately for girls and boys; numerous normative data for the pediatric population are not sex-specific. Thus, this study aimed to assess whether the LVM normative data should be developed separately for girls and boys practicing sports.

Methods

Left ventricular mass was computed for 331 girls and 490 boys, 5–19 years old, based on echocardiography. The effect of sex on the relationship between LVM and body size was evaluated using a linear regression model. Seven sets of the LVM normative data were developed, using different methodologies, to test concordance between sex-specific and non-specific normative data. Every set consisted of normative data that was sex-specific and non-specific. Upon these normative data, for every study participant, seven pairs of LVM z-scores were calculated based on her/his actual LVM. Each pair consisted of z-scores computed based on sex-specific and non-specific normative data from the same set.

Results

The regression lines fitted to the data points corresponding to LVM of boys had a higher slope than of girls, indicating that sex affects the relationship between LVM and body size. The mean differences between the paired LVM z-scores differed significantly from 0. The percentage of discordant indications, depending on the normalization method, ranged from 66.7% to 100% in girls and from 35.4% to 50% in boys. Application of the LVM normative data that were not sex-specific made relative LVM underestimated in girls and overestimated in boys.

Conclusion

The LVM normative data should be developed separately for girls and boys practicing sports. Application of normative data that are not sex-specific results in an underestimation of relative LVM in girls and overestimation in boys.

Exercise and Cardioprotection: A Natural Defense Against Lethal Myocardial Ischemia-Reperfusion Injury and Potential Guide to Cardiovascular Prophylaxis

Similar to ischemic preconditioning, high-intensity exercise has been shown to decrease infarct size following myocardial infarction. In this article, we review the literature on beneficial effects of exercise, exercise requirements for cardioprotection, common methods utilized in laboratories to study this phenomenon, and discuss possible mechanisms for exercise-mediated cardioprotection.

The Effects of Exercise and Physical Activity on Weight Loss and Maintenance

Obesity represents a major health problem in the United States and is associated with increased prevalence of cardiovascular (CV) disease risk factors. Physical activity (PA) and exercise training (ET) are associated with reduced CV risk, improved cardiometabolic risk factors, and facilitated weight loss through creating a negative energy balance. Clinicians need to counsel overweight and obese patients on how much PA/ET is needed to promote weight loss and weight loss maintenance. This will help establish realistic expectations and maximize improvements in CV risk factors. Although the minimum guidelines for aerobic PA (150 min of moderate or 75 min of vigorous physical activity per week) can improve CV health, these levels are generally inadequate for clinically significant weight loss or weight maintenance without caloric restriction. The purpose of this review is to evaluate the role of ET to promote clinically significant weight loss and promote weight maintenance. In particular, we will evaluate the likelihood of weight loss from ET programs composed of aerobic training only, resistance training only and programs that combine diet and ET. We will also explore the role of PA in promoting short-term and long-term weight maintenance.

Relationship between baseline physical activity assessed by pedometer count and new-onset diabetes in the NAVIGATOR trial

OBJECTIVE

Physical activity is related to clinical outcomes, even after adjusting for body mass, but is rarely assessed in randomized clinical trials.

RESEARCH DESIGN AND METHODS

We conducted an observational analysis of data from the Nateglinide and Valsartan in Impaired Glucose Tolerance Outcomes Research trial, in which a total of 9306 people from 40 countries with impaired glucose tolerance and either cardiovascular disease or cardiovascular risk factors were randomized to receive nateglinide or placebo, in a 2-by-2 factorial design with valsartan or placebo. All were asked to also participate in a detailed lifestyle modification programme and followed-up for a median of 6.4 years with progression to diabetes as a co-primary end point. Seven-day ambulatory activity was assessed at baseline using research-grade pedometers. We assessed whether the baseline amount of physical activity was related to subsequent development of diabetes in individuals with impaired glucose tolerance.

RESULTS

Pedometer data were obtained on 7118 participants and 35.0% developed diabetes. In an unadjusted analysis each 2000-step increment in the average number of daily steps, up to 10 000, was associated with a 5.5% lower risk of progression to diabetes (HR 0.95, 95%CI 0.92 to 0.97), with >6% relative risk reduction after adjustment.

CONCLUSIONS

Physical activity should be measured objectively in pharmacologic trials as it is a significant but underappreciated contributor to diabetes outcomes. It should be a regular part of clinical practice as well.

Sex-specific effects of leisure-time physical activity on cause-specific mortality in NHANES III

Associations between leisure time physical activity (LTPA) and all-cause mortality seem quite strong, however, less is known about the association of LTPA and cause-specific mortality. To examine this association data from the Third National Health and Nutrition Examination Survey (NHANES III), including 15,307 individuals of the non-institutionalized civilian United States population, were used. Data were collected from 1988 to 1994 with a mortality follow-up until 2006. LTPA was assessed during home interviews in which participants specified their LTPA and the performed frequency during the past month. Cox proportional hazards regression models were applied to analyze the risk of cause-specific mortality regarding LTPA. Hazard ratios (HRs) and 95% confidence intervals (CIs) were computed. An inverse association of LTPA with CVD mortality was observed for men and women combined for irregular (HR 0.66; 95% CI 0.51-0.85), and for regular activity (HR 0.58; 95% CI 0.47-0.72). An inverse association of LTPA with CVD mortality was observed only in women for irregular (HR 0.64; 95% CI 0.49-0.84) and for regular activity (HR 0.55; 95% CI 0.43-0.72). In men, no significant associations were seen. For mortality caused by respiratory diseases, a decreased mortality was also observed in the combined group (men and women) but after separating according to sex a decreased mortality was only observed in women. No statistically significant association of LTPA with cancer mortality was observed. Our data support an inverse association between LTPA and CVD and respiratory disease mortality in women, but not in men, and no associations with cancer.

Social Determinants of Physical Activity Among Adult Asian-Americans: Results from a Population-Based Survey in California

The objective of this study was to evaluate the key social determinants of physical activity among six Asian-American subgroups using public access 2007 California Health Interview Survey data. Physical activity was defined as meeting the American College of Sports Medicine recommendation of 450 metabolic equivalent-minutes per week. Factors positively associated with meeting physical activity recommendations included being bilingual among Chinese and Vietnamese, and increasing age for Chinese only. On the other hand, being middle aged, currently married, and low neighborhood safety were significantly associated with lower odds of meeting physical activity recommendations, as were being female for Japanese and Koreans, and living above the poverty level for Vietnamese. Such results highlight the heterogeneity among Asian-Americans and need for health messages targeted at specific subgroups. Additionally, the role of built environment, particularly in areas with high Filipino residents, should be a public health priority for increasing physical activity outcomes.

Impact of Exercise Programs on Hospital Readmission Following Hospitalization for Heart Failure: A Systematic Review

Given persistently high 30-day readmission rates among patients hospitalized for heart failure, there is an ongoing need to identify new interventions to reduce readmissions. Although exercise programs can improve outcomes among ambulatory heart failure patients, it is not clear whether this benefit extends to reducing readmissions following heart failure hospitalization. We therefore conducted a systematic review of the literature to identify randomized controlled trials examining the impact of exercise programs on hospital readmissions among patients recently hospitalized for heart failure. We searched Ovid MEDLINE, EMBASE, and the Wiley Cochrane Library for studies that fulfilled pre-defined criteria, including that the exercise program pre-specify activity type and exercise frequency, duration, and intensity. Exercise interventions could occur at any location including within the hospital, at an outpatient facility, or at home. Among 1213 unique publications identified, only one study fulfilled inclusion criteria. This study was a single-site randomized controlled trial that consisted of a 12-week exercise program in a cohort of 105 patients with a principal diagnosis of HF at a metropolitan hospital in Australia. This study revealed a reduction in 12-month all-cause and cardiovascular-related hospitalization rates. However, inferences were limited by its single-site study design, small sample size, premature termination, and high risk for selection, performance, and detection bias. As no studies have built upon the findings of this study, it remains unknown whether exercise programs can improve readmission rates among patients recently hospitalized for heart failure, a significant gap in the literature.

Social Cognitive Theory in Diabetes Exercise Research: An Integrative Literature Review

PURPOSE

This integrative review critically examined the literature on diabetes research using Social Cognitive Theory (SCT) to determine its predictive ability in explaining exercise behavior and to identify key interventions that enhance exercise initiation and maintenance.

METHODS

Literature published between 1985 and 2002 was searched using the following keywords: SCT, self-efficacy, diabetes mellitus, non-insulin-dependent diabetes mellitus, insulin-dependent diabetes mellitus, physical activity, and exercise. The databases searched were CINAHL, Medline, and PsychInfo. Of the 38 articles retrieved from databases, 13 were reviewed.

RESULTS

A statistically significant relationship between self-efficacy and exercise behavior was found in correlational studies. Results from the predictive study support the predictability of self-efficacy for exercise behavior. Mixed results were found for the predictive ability of outcome expectancies for exercise behavior. Self-efficacy was predictive of exercise initiation and maintenance over time. The evidence for successful interventions to increase self-efficacy and exercise behavior over time was inconclusive.

CONCLUSIONS

To better understand exercise behavior and to develop effective exercise interventions, a microanalytic, theory-driven approach to studying exercise behavior is needed. Several suggestions are offered to strengthen exercise self-efficacy.

Calcium handling proteins: structure, function, and modulation by exercise

Heart failure is a serious public health issue with a growing prevalence, and it is related with the aging of the population. Hypertension is identified as the main precursor of left ventricular hypertrophy and therefore can lead to diastolic dysfunction and heart failure. Scientific studies have confirmed the beneficial effects of the physical exercise by reducing the blood pressure and improving the functional status of the heart in hypertension. Several proteins are involved in the mobilization of calcium during the coupling excitation-contraction process in the heart among those are sarcoplasmic reticulum Ca(2+)-ATPase, phospholamban, calsequestrin, sodium-calcium exchanger, L-type calcium's channel, and ryanodine receptors. Our goal is to address the beneficial effects of exercise on the calcium handling proteins in a heart with hypertension.

Relationship between lower extremity muscle strength and all-cause mortality in Japanese patients undergoing dialysis

BACKGROUND

Skeletal muscle wasting is common and insidious in patients who are undergoing hemodialysis. However, the association between lower extremity muscle strength and all-cause mortality remains unclear in this population.

OBJECTIVE

The purpose of this study was to investigate the prognostic significance of lower extremity muscle strength on 7-year survival in a cohort of patients who were clinically stable and undergoing hemodialysis.

DESIGN

A prospective cohort study was conducted.

METHODS

A total of 190 Japanese outpatients who were undergoing maintenance hemodialysis 3 times per week at a hemodialysis center were followed for up to 7 years. Lower extremity muscle strength was evaluated using a handheld dynamometer at the time of patient enrollment in the study. Muscle strength data were divided by dry weight and expressed as a percentage. A Cox proportional hazards regression model was used to assess the contribution of lower extremity muscle strength to all-cause mortality.

RESULTS

The median age (25th and 75th percentiles) of this study population was 64 years (57 and 72 years), 53.2% of the patients were women, and the time on hemodialysis was 39.0 months (15.9 and 110.5 months) at baseline. During a median follow-up of 36.0 months, there were 30 deaths. With a multivariate Cox model, the hazard ratio in the group with a knee extensor strength of <40% was 2.73 (95% confidence interval=1.14-6.52) compared with that in the ≥40% group.

LIMITATIONS

This was a small-scale observational study, and the mechanisms underlying the higher mortality risk in patients with poor muscle strength undergoing hemodialysis than in other patients undergoing hemodialysis remain to be elucidated.

CONCLUSIONS

Decreased lower extremity muscle strength was strongly associated with increased mortality risk in patients undergoing hemodialysis.

Emerging technologies for assessing physical activity behaviors in space and time

Precise measurement of physical activity is important for health research, providing a better understanding of activity location, type, duration, and intensity. This article describes a novel suite of tools to measure and analyze physical activity behaviors in spatial epidemiology research. We use individual-level, high-resolution, objective data collected in a space-time framework to investigate built and social environment influences on activity. First, we collect data with accelerometers, global positioning system units, and smartphone-based digital travel and photo diaries to overcome many limitations inherent in self-reported data. Behaviors are measured continuously over the full spectrum of environmental exposures in daily life, instead of focusing exclusively on the home neighborhood. Second, data streams are integrated using common timestamps into a single data structure, the "LifeLog." A graphic interface tool, "LifeLog View," enables simultaneous visualization of all LifeLog data streams. Finally, we use geographic information system SmartMap rasters to measure spatially continuous environmental variables to capture exposures at the same spatial and temporal scale as in the LifeLog. These technologies enable precise measurement of behaviors in their spatial and temporal settings but also generate very large datasets; we discuss current limitations and promising methods for processing and analyzing such large datasets. Finally, we provide applications of these methods in spatially oriented research, including a natural experiment to evaluate the effects of new transportation infrastructure on activity levels, and a study of neighborhood environmental effects on activity using twins as quasi-causal controls to overcome self-selection and reverse causation problems. In summary, the integrative characteristics of large datasets contained in LifeLogs and SmartMaps hold great promise for advancing spatial epidemiologic research to promote healthy behaviors.

Habitual physical activity measured by accelerometer and survival in maintenance hemodialysis patients

BACKGROUND AND OBJECTIVES

The association between mortality and physical activity based on self-report questionnaire in hemodialysis patients has been reported previously. However, because self-report is a subjective assessment, evaluating true physical activity is difficult. This study investigated the prognostic significance of habitual physical activity on 7-year survival in a cohort of clinically stable and adequately dialyzed patients.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

A total of 202 Japanese outpatients who were undergoing maintenance hemodialysis three times per week at the hemodialysis center of Sagami Junkanki Clinic (Japan) from October 2002 to February 2012 were followed for up to 7 years. Physical activity was evaluated using an accelerometer at study entry and is expressed as the amount of time a patient engaged in physical activity on nondialysis days. Cox proportional hazard regression was used to assess the contribution of habitual physical activity to all-cause mortality.

RESULTS

The median patient age was 64 (25th, 75th percentiles, 57, 72) years, 52.0% of the patients were women, and the median time on hemodialysis was 40.0 (25th, 75th percentiles, 16.8, 119.3) months at baseline. During a median follow-up of 45 months, 34 patients died. On multivariable analysis, the hazard ratio for all-cause mortality per 10 min/d increase in physical activity was 0.78 (95% confidence interval, 0.66-0.92; P=0.002).

CONCLUSIONS

Engaging in habitual physical activity among outpatients undergoing maintenance hemodialysis was associated with decreased mortality risk.

Cardiovascular benefits of exercise

Regular physical activity during leisure time has been shown to be associated with better health outcomes. The American Heart Association, the Centers for Disease Control and Prevention and the American College of Sports Medicine all recommend regular physical activity of moderate intensity for the prevention and complementary treatment of several diseases. The therapeutic role of exercise in maintaining good health and treating diseases is not new. The benefits of physical activity date back to Susruta, a 600 BC physician in India, who prescribed exercise to patients. Hippocrates (460–377 BC) wrote “in order to remain healthy, the entire day should be devoted exclusively to ways and means of increasing one’s strength and staying healthy, and the best way to do so is through physical exercise.” Plato (427–347 BC) referred to medicine as a sister art to physical exercise while the noted ancient Greek physician Galen (129–217 AD) penned several essays on aerobic fitness and strengthening muscles. This article briefly reviews the beneficial effects of physical activity on cardiovascular diseases.

Assessment of leisure-time physical activity for the prediction of inflammatory status and cardiometabolic profile

OBJECTIVES

Associations of leisure-time physical activity (LTPA), commuting and total physical activity with inflammatory markers, insulin resistance and metabolic profile in individuals at high cardiometabolic risk were investigated.

DESIGN

This was a cross-sectional study.

METHODS

A total of 193 prediabetic adults were compared according to physical activity levels measured by the international physical activity questionnaire; p for trend and logistic regression was employed.

RESULTS

The most active subset showed lower BMI and abdominal circumference, reaching significance only for LTPA (p for trend=0.02). Lipid profile improved with increased physical activity levels. Interleukin-6 decreased with increased total physical activity and LTPA (p for trend=0.02 and 0.03, respectively), while adiponectin increased in more active subsets for LTPA (p for trend=0.03). Elevation in adjusted OR for hypercholesterolemia was significant for lower LTPA durations (p for trend=0.04). High apolipoprotein B/apolipoprotein A ratio was inversely associated with LTPA, commuting and total physical activity. Increase in adjusted OR for insulin resistance was found from the highest to the lowest category of LTPA (p for trend=0.04) but significance disappeared after adjustments for BMI and energy intake. No association of increased C-reactive protein with physical activity domains was observed.

CONCLUSIONS

In general, the associations of LTPA, but not commuting or total physical activity, with markers of cardiometabolic risk reinforces the importance of initiatives to increase this domain in programs for the prevention of lifestyle-related diseases.

Dose response between physical activity and risk of coronary heart disease: a meta-analysis

BACKGROUND

No reviews have quantified the specific amounts of physical activity required for lower risks of coronary heart disease when assessing the dose-response relation. Instead, previous reviews have used qualitative estimates such as low, moderate, and high physical activity.

METHODS AND RESULTS

We performed an aggregate data meta-analysis of epidemiological studies investigating physical activity and primary prevention of CHD. We included prospective cohort studies published in English since 1995. After reviewing 3194 abstracts, we included 33 studies. We used random-effects generalized least squares spline models for trend estimation to derive pooled dose-response estimates. Among the 33 studies, 9 allowed quantitative estimates of leisure-time physical activity. Individuals who engaged in the equivalent of 150 min/wk of moderate-intensity leisure-time physical activity (minimum amount, 2008 U.S. federal guidelines) had a 14% lower coronary heart disease risk (relative risk, 0.86; 95% confidence interval, 0.77 to 0.96) compared with those reporting no leisure-time physical activity. Those engaging in the equivalent of 300 min/wk of moderate-intensity leisure-time physical activity (2008 U.S. federal guidelines for additional benefits) had a 20% (relative risk, 0.80; 95% confidence interval, 0.74 to 0.88) lower risk. At higher levels of physical activity, relative risks were modestly lower. People who were physically active at levels lower than the minimum recommended amount also had significantly lower risk of coronary heart disease. There was a significant interaction by sex (P=0.03); the association was stronger among women than men.

CONCLUSIONS

These findings provide quantitative data supporting US physical activity guidelines that stipulate that "some physical activity is better than none" and "additional benefits occur with more physical activity."

No Time to ‘Weight’: The Link between Obesity and Stroke in Women

The obesity epidemic in the USA threatens the gains that have been made in the prevention and treatment of stroke. Both obesity and stroke disproportionately affect women more than men. Understanding the effect of obesity on stroke risk in women may be a useful stepping stone to reducing the burden of stroke in this vulnerable population. This article reviews the association between stroke and general obesity, abdominal obesity and metabolic syndrome in women. All three factors have been shown to independently increase stroke risk in women.

Physical activity recommendations and cardiovascular disease risk factors in young Hispanic women

Despite the benefits associated with regular physical activity, there is little epidemiological evidence to support positive health outcomes when meeting physical activity guidelines in high-risk ethnic groups, such as Hispanic women. We compared cardiovascular disease risk factors between young Hispanic women who meet and those who do not meet current physical activity guidelines. Height, weight, waist circumference, and blood pressure were measured in 60 Hispanic women aged 20-39 years. Lipids, C-reactive protein, insulin, and glucose were assessed. Body composition and cardiovascular fitness were assessed by BodPod and maximal oxygen uptake (VO₂(max)) respectively. Participants wore an accelerometer and average minutes (assessed in 10-min bouts) spent in light, moderate, and hard daily activity for weekdays and weekends was determined. Seventy percent of participants did not meet the recommended physical activity guidelines, whereas 30% did so. Following current physical activity guidelines was associated with significantly lower mean cholesterol (mean ± s: 4.2 ± 0.8 vs. 4.7 ± 0.9 mmol · l⁻¹) and triglycerides (0.7 ± 0.3 vs. 1.1 ± 0.6 mmol · l⁻¹), and higher fat-free mass (43.3 ± 3.8 vs. 40.2 ± 5.1 kg) and relative (40.4 ± 7.6 vs. 35.6 ± 7.0 ml · kg⁻¹ · min⁻¹) and absolute (2.5 ± 0.3 vs. 2.1 ± 0.4 litres · min⁻¹) VO₂(max) (P < 0.05). These findings suggest an improved health status in women who meet versus those who did not meet current physical activity guidelines.

Sedentary behavior and depression among adults: a review

BACKGROUND

Physically inactive lifestyles and sedentary behaviors (SB) are key contributors to ill health. Although the association between SB (e.g., watching TV/using the computer) and physical health has been well documented, increasing research has focused on the possible link between SB and mental health (e.g., depression).

PURPOSE

This review aims to investigate the effect of SB on the risk of depression in adults.

METHOD

A systematic search for original research articles investigating associations between SB and depression in adults was performed using the several electronic data bases.

RESULTS

A total of seven observational and four intervention studies were included in this review. All observational studies found positive associations between SB and risk of depression, while intervention studies showed contradictory results.

CONCLUSION

Evidence for the relationship between SB and risk of depression in adults is limited by methodological weaknesses. However, on balance, this review suggests that SB is associated with an increased risk of depression. Further studies are needed assessing different types of SB and depression; the interrelationship between physical activity, SB, and depression; causal links between SB and depression; and intervention strategies aimed at reducing SB and their effects on risk of depression.

Accuracy of a novel multi-sensor board for measuring physical activity and energy expenditure

The ability to relate physical activity to health depends on accurate measurement. Yet, none of the available methods are fully satisfactory due to several factors. This study examined the accuracy of a multi-sensor board (MSB) that infers activity types (sitting, standing, walking, stair climbing, and running) and estimates energy expenditure in 57 adults (32 females) 39.2 ± 13.5 years. In the laboratory, subjects walked and ran on a treadmill over a select range of speeds and grades for 3 min each (six stages in random order) while connected to a stationary calorimeter, preceded and followed by brief sitting and standing. On a different day, subjects completed scripted activities in the field connected to a portable calorimeter. The MSB was attached to a strap at the right hip. Subjects repeated one condition (randomly selected) on the third day. Accuracy of inferred activities compared with recorded activities (correctly identified activities/total activities × 100) was 97 and 84% in the laboratory and field, respectively. Absolute accuracy of energy expenditure [100 - absolute value (kilocalories MSB - kilocalories calorimeter/kilocalories calorimeter) × 100] was 89 and 76% in the laboratory and field, the later being different (P < 0.05) from the calorimeter. Test-retest reliability for energy expenditure was significant in both settings (P < 0.0001; r = 0.97). In general, the MSB provides accurate measures of activity type in laboratory and field settings and energy expenditure during treadmill walking and running although the device underestimates energy expenditure in the field.

Physical activity and risk of cardiovascular disease events: inflammatory and metabolic mechanisms

PURPOSE

The biological mechanisms through which physical activity lowers the risk of cardiovascular disease (CVD) are incompletely understood. We examined the extent to which inflammatory/hemostatic factors (C-reactive protein and fibrinogen), metabolic factors (adiposity, total cholesterol, and HDL cholesterol), and hypertension mediate the association between physical activity and risk of CVD events.

METHODS

Data were collected from a nationally representative sample of 7881 men and women that were linked to a patient-based database of CVD hospital admissions and deaths up to September 2006.

RESULTS

A total of 226 incident CVD events (64 fatal) occurred over an average follow-up of 7.2 yr. The risk of CVD decreased in relation to physical activity groups according to current recommendations (at least 30 min of moderate activity five times per week or vigorous activity three times per week). The lowest risks for CVD were seen in participants meeting the recommendations through undertaking vigorous activity (hazard ratio = 0.47, 95% CI = 0.22-0.99), although being physically active below the guidelines also conferred protection (hazard ratio = 0.57, 0.42-0.77). Biological risk factors collectively explained between 39.4% and 22.6% of the cardioprotective effects of moderate and vigorous physical activity, respectively. Inflammation and hypertension tended to explain the largest proportion of variance.

CONCLUSIONS

Participation in any physical activity, irrespective of meeting current guidelines, was associated with a lower risk of CVD. The inverse association between physical activity and CVD risk is partly mediated by biological risk factors.

Non-vigorous physical activity and all-cause mortality: systematic review and meta-analysis of cohort studies

BACKGROUND

Although previous studies have found physical activity to be associated with lower mortality, the dose-response relationship remains unclear. In this systematic review and meta-analysis we quantify the dose-response relationship of non-vigorous physical activity and all-cause mortality.

METHODS

We aimed to include all cohort studies in adult populations with a sample size of more than 10 000 participants that estimated the effect of different levels of light or moderate physical activity on all-cause mortality. We searched Medline, Embase, Cochrane (DARE), Web of Science and Global Health (June 2009). We used dose-response meta-regression models to estimate the relation between non-vigorous physical activity and mortality.

RESULTS

We identified 22 studies that met our inclusion criteria, containing 977 925 (334 738 men and 643 187 women) people. There was considerable variation between the studies in their categorization of physical activity and adjustment for potential confounders. We found that 2.5 h/week (equivalent to 30 min daily of moderate intensity activity on 5 days a week) compared with no activity was associated with a reduction in mortality risk of 19% [95% confidence interval (CI) 15-24], while 7 h/week of moderate activity compared with no activity reduced the mortality risk by 24% (95% CI 19-29). We found a smaller effect in studies that looked at walking alone.

CONCLUSION

Being physically active reduces the risk of all-cause mortality. The largest benefit was found from moving from no activity to low levels of activity, but even at high levels of activity benefits accrue from additional activity.

Smoking and atherosclerotic cardiovascular disease: part III: functional biomarkers influenced by smoking

Smoking cigarettes induces rapidly occurring and reversible functional changes in the cardiovascular system, which precede morphologic changes. These functional changes are also related to atherosclerotic disease development and thus may qualify as prognostic parameters in chronic smokers. As opposed to smoking-induced morphologic changes functional alterations occur and revert within minutes, thus, allowing for the detection of smoking-induced effects on the cardiovascular system within minutes following exposure to mainstream smoke. Some alterations represent 'direct' changes (e.g., endothelial function), others reflect changes in a different organ system (e.g., the autonomous nervous system influencing heart rate variability), while some represent the sum of alterations in many organs and systems (e.g., exercise performance influenced by the autonomous nervous and by endothelial and cardiac function). Since a specific functional parameter usually changes with at least one or several others, caution should be exercised when trying to establish a direct cause relationship between the alteration of a single parameter and a clinical outcome.

A systematic review of the evidence for Canada's Physical Activity Guidelines for Adults

This systematic review examines critically the scientific basis for Canada's Physical Activity Guide for Healthy Active Living for adults. Particular reference is given to the dose-response relationship between physical activity and premature all-cause mortality and seven chronic diseases (cardiovascular disease, stroke, hypertension, colon cancer, breast cancer, type 2 diabetes (diabetes mellitus) and osteoporosis). The strength of the relationship between physical activity and specific health outcomes is evaluated critically. Literature was obtained through searching electronic databases (e.g., MEDLINE, EMBASE), cross-referencing, and through the authors' knowledge of the area. For inclusion in our systematic review articles must have at least 3 levels of physical activity and the concomitant risk for each chronic disease. The quality of included studies was appraised using a modified Downs and Black tool. Through this search we identified a total of 254 articles that met the eligibility criteria related to premature all-cause mortality (N = 70), cardiovascular disease (N = 49), stroke (N = 25), hypertension (N = 12), colon cancer (N = 33), breast cancer (N = 43), type 2 diabetes (N = 20), and osteoporosis (N = 2). Overall, the current literature supports clearly the dose-response relationship between physical activity and the seven chronic conditions identified. Moreover, higher levels of physical activity reduce the risk for premature all-cause mortality. The current Canadian guidelines appear to be appropriate to reduce the risk for the seven chronic conditions identified above and all-cause mortality.

Cardiovascular risk factors for incident hypertension in the prehypertensive population

OBJECTIVES

The aim of this study was to investigate the effect of changes in cardiovascular disease (CVD) risk factors on progression from prehypertension (PreHTN) to hypertension (HTN) using an 8-yr prospective Korean Cancer Prevention Study (KCPS) by the National Health Insurance Corporation (NHIC) in Korea.

METHODS

A total of 16,229 subjects, aged 30 to 54, with new onset preHTN at baseline (1994-1996) in a biennial national medical exam were selected and followed up till 2004 at 2-yr intervals. All subjects underwent a biennial health examination including biochemical measurements and behavior. The log-rank test was performed to assess the relationship between changes in CVD risk factors and progression to HTN. The Cox proportional hazard model was used to identify factors influencing progression to HTN.

RESULTS

With regards the progression rate in men, ex-smokers (42.9%), abstainers (37.5%), and regular exercisers (37.6%) showed a slower progression rate than continuous smokers (49.5%) and continuous drinkers (50.9%). In women, those who participated in regular exercise (22.6%) had a lower rate of progression than continuous non-exercisers (36.1%). According to the results of the Cox proportional hazard model, improvements in smoking (hazard ratio [HR], 0.756), drinking (HR, 0.669), regular exercise (HR, 0.653), body mass index (HR, 0.715), and total cholesterol (HR, 0.788) played a protective role in progression to HTN in men, while in women, participating in regular exercise (HR, 0.534) was beneficial.

CONCLUSION

Improvements in CVD-related behaviors diminished the progression rate of HTN. This study suggests that individuals with PreHTN should be targeted for specific health behavioral intervention to prevent the progression of HTN.

The role of collective efficacy in exercise adherence: a qualitative study of spousal support and type 2 diabetes management

Adhering to increased exercise is often reported as one of the greatest challenges facing adults living with diabetes, a perception shared by the married middle-aged and older adults living with diabetes who participated in this study. Understanding how that challenge can best be met is both research and program relevant. Drawing on the social cognitive theory and social support literature, this qualitative study explored the powerful couple relationship in Type 2 diabetes management. The overarching goal of this paper was to illuminate the potentially key role of collective efficacy in exercise adherence in order to develop and test interventions that provide more effective supports for adults living with diabetes. Analyses revealed three core themes used by the couples to describe their perceived beliefs: 'Collective support', 'Collective motivation' and 'Collective responsibility'. Our findings provide insights regarding how collective beliefs of spousal support may influence the adoption and maintenance of an exercise program. As health educators look for approaches to improve exercise adherence in diabetes management, it is important to understand how couples can be empowered to assume responsibility for their management.

Worksite Opportunities for Wellness (WOW): effects on cardiovascular disease risk factors after 1 year

OBJECTIVE

To evaluate the effectiveness of a worksite health promotion program on improving cardiovascular disease risk factors.

METHODS

In St Louis, Missouri from 2005 to 2006, 151 employees (134 F, 17 M, 81% overweight/obese) participated in a cohort-randomized trial comparing assessments + intervention (worksite A) with assessments only (worksite B) for 1 year. All participants received personal health reports containing their assessment results. The intervention was designed to promote physical activity and favorable dietary patterns using pedometers, healthy snack cart, WeightWatchers(R) meetings, group exercise classes, seminars, team competitions, and participation rewards. Outcomes included BMI, body composition, blood pressure, fitness, lipids, and Framingham 10-year coronary heart disease risk.

RESULTS

123 participants, aged 45+/-9 yr, with BMI 32.9+/-8.8 kg/m(2) completed 1 year. Improvements (P< or =0.05) were observed at both worksites for fitness, blood pressure, and total-, HDL-, and LDL-cholesterol. Additional improvements occurred at worksite A in BMI, fat mass, Framingham risk score, and prevalence of the metabolic syndrome; only the changes in BMI and fat mass were different between worksites.

CONCLUSION

A multi-faceted worksite intervention promoted favorable changes in cardiovascular disease risk factors, but many of the improvements were achieved with worksite health assessments and personalized health reports in the absence of an intervention.

Exercise and limitations in physical activity levels among new dialysis patients in the United States: an epidemiologic study

PURPOSE

Epidemiologic studies of physical activity among patients with end-stage renal disease (ESRD) are lacking. The aim of this study was to describe the patterns of physical activity among new dialysis patients in the United States.

METHODS

Multivariate logistic regression analyses examined associations of self-reported limitations in physical activity and exercise frequency with sociodemographic and clinical variables in 2,264 patients from Wave 2 of the Dialysis Morbidity and Mortality Study.

RESULTS

Overall, 56% of patients exercised less than once a week, 75% reported severe limitations in vigorous activities, whereas 42% had severe limitations in moderate physical activities. Fewer limitations in moderate or vigorous activities correlated positively with male gender (odds-ratio [OR] = 1.61), black race OR =1.49), Hispanic ethnicity (OR = 2.39), serum albumin (OR = 1.69 per 1 g/L higher), positive affect (OR = 2.33), peritoneal dialysis (OR = 1.90), and negatively with age (OR = 0.67), heart failure (OR = 0.75), peripheral vascular disease (OR = 0.69), malnutrition (OR = 0.67), and depression (OR = 0.39). Patients reporting fewer limitations in moderate or vigorous activities (OR = 1.35 and 1.28, respectively), or frequent visits with a dietitian (2 to 3 times per week vs. less) (OR = 1.21) in the pre-ESRD period exercised more frequently.

CONCLUSIONS

Limitations in physical activity are common among new ESRD patients and these, in part, are related to pre-existing cardiovascular disease, malnutrition, and mental health.

Association of physical activity with all-cause and cardiovascular mortality: a systematic review and meta-analysis

BACKGROUND

Over the past several decades, numerous large cohort studies have attempted to quantify the protective effect of physical activity on cardiovascular and all-cause mortality. The aim of the authors' review was to provide an up-to-date overview of the study results.

METHODS

In a systematic MEDLINE search conducted in May 2007, the authors included cohort studies that assessed the primary preventive impact of physical activity on all-cause and cardiovascular mortality. The authors reported risk reductions on the basis of comparison between the least active and the most active population subgroups, with the least active population subgroup as the reference group. Random-effect models were used for meta-analysis.

RESULTS

A total of 33 studies with 883,372 participants were included. Follow-up ranged from 4 years to over 20 years. The majority of studies reported significant risk reductions for physically active participants. Concerning cardiovascular mortality, physical activity was associated with a risk reduction of 35% (95% confidence interval, 30-40%). All-cause mortality was reduced by 33% (95% confidence interval, 28-37%). Studies that used patient questionnaires to assess physical activity reported lower risk reductions than studies that used more objective measures of fitness.

CONCLUSIONS

Physical activity is associated with a marked decrease in cardiovascular and all-cause mortality in both men and women, even after adjusting for other relevant risk factors.

Effects of different levels of cigarette smoke exposure on prognostic heart rate and rate--pressure-product parameters

Reduced cigarette smoke exposure in adult smokers switching from a conventional cigarette (CC) to a potential exposure-reduced electrically heated cigarette smoking system (EHCSS) and no smoking (NS) improved exercise performance. The effects of reduced smoke exposure on the prognostic parameters heart rate (HR) and rate-pressure-product (RPP) were investigated. A total of 18 male adult CC-smokers were randomized in a 3-period cross-over study to CC, EHCSS, or to NS for 3 days each before performing spiroergometry. Exposure parameters declined from CC to EHCSS and to NS. Resting HR and RPP increased from NS to EHCSS and to CC. Chronotropic response/HR recovery were more pronounced in NS than in EHCSS and CC. RPPmax was similar in NS and EHCSS and lowest during CC. Reduced tobacco smoke exposure for 3 days improved the prognostic parameters HR and RPP in an apparently dose-dependent manner.

Unique environmental effects on physical activity participation: a twin study

Background

The health benefits of regular physical activity are well established. However, the relative contribution of heritable and environmental factors to physical activity participation remains controversial. Using a cut-point of 60 minutes of total activity per week, data from the GenomEUtwin project revealed consistent genetic influence on physical activity participation in 37,051 twin pairs from seven countries. We hypothesized that the heritability of physical activity participation would be attenuated using the CDC/ACSM recommended minimum threshold of 150 minutes of moderate intensity activity per week.

Methods

Data were obtained from 1,389 twin pairs from the community-based University of Washington Twin Registry. Twin similarity in physical activity participation using both cut-points was analyzed using tetrachoric correlations and structural equation modeling in all same-sex pairs.

Results

Correlations were higher in monozygotic (r_MZ = 0.43, 95% CI = 0.33–0.54) than dizygotic pairs (r_DZ = 0.30, 95% CI = 0.12–0.47) using the 60 minute cut-point. However, differences were attenuated using the 150 minute standard (r_MZ = 0.30, 95% CI = 0.20–0.40; r_DZ = 0.25, 95% CI = 0.07–0.42). Using the lower cut-point, the best fitting model of twin resemblance only included additive genetics and unique environment, with a heritability of 45%. In contrast, using the higher threshold, the best fitting model included the common and unique environment, with the unique environment contributing 72% of the variance.

Conclusion

Unique environment factors provide the strongest influence on physical activity participation at levels recommended for health benefits.

Commuting physical activity is favourably associated with biological risk factors for cardiovascular disease

BACKGROUND

Little is known about the effects of commuting physical activity on biological cardiovascular risk factors although such knowledge may form an important basis for interventions aimed at reducing cardiovascular disease (CVD) by increasing physical activity. We examined the associations between commuting, leisure time and total physical activity and biological risk factors for CVD. Design A cross-sectional study of men and women, who participated in a health screening programme.

METHODS

The study population comprised persons aged 30-60 years from a population-based random sample, response rate 53% (n = 6,906). Weight, height, waist circumference and blood pressure were measured and blood samples were collected. Physical activity was assessed by a self-administered questionnaire.

RESULTS

Time spent on commuting, leisure time and total physical activity was positively associated with high-density lipoprotein cholesterol and negatively associated with low-density lipoprotein cholesterol, triglycerides, waist circumference and body mass index. Time spent on total physical activity was negatively associated with total cholesterol and diastolic blood pressure. Among men there was no relationship between time spent on physical activity and systolic blood pressure. Time spent on commuting physical activity and total physical activity was negatively associated with systolic blood pressure among women.

CONCLUSION

Commuting physical activity, independent of leisure time physical activity, was associated with a healthier level of most of the cardiovascular risk factors. An increase in commuting physical activity in the population may therefore reduce the incidence of CVD.

Intensive management of risk factors for accelerated atherosclerosis: the role of multiple interventions

Patients at high risk of vascular events can reduce their risk by 75% to 80% through a combination of lifestyle changes and medical therapy. These include smoking cessation, a Mediterranean diet, daily exercise, maintaining a fit weight, moderate consumption of alcohol, effective control of blood pressure and diabetes, intensive treatment with lipid-lowering drugs and antiplatelet agents, and perhaps treatment with vitamins to lower homocysteine. Much of this is achieved primarily by the patient; physicians need to become better at assisting their patients in making lifestyle changes. Effective control of treatment-resistant hypertension can be improved by individualizing medical therapy to the underlying cause, based on measurement of plasma renin and aldosterone. Measurement of carotid plaque may be useful by providing feedback on the success of therapy.

Effects of Levels of Cigarette Smoke Exposure on Symptom-Limited Spiroergometry

Previous investigations demonstrated reduced exposure to selected cigarette smoke constituents in adult smokers switching from conventional cigarettes (CC) to an electrically heated cigarette smoking system (EHCSS). This study investigated whether reduced exposure and no smoking (NS) would improve exercise performance. In a 3-period crossover study, 18 male adult smokers (age, 43.6+/-5.3 years) of CC were randomized to smoke CC (tar, 11 mg; nicotine, 0.8 mg; carbon monoxide, 11 mg), to use EHCSS (tar, 3 mg; nicotine, 0.2 mg; carbon monoxide, 0.4 mg [Federal Trade Commission method]), or to NS for 3 days before performing symptom-limited spiroergometry. NS and EHCSS vs CC resulted in less severe dyspnea (NS, 44.4% [P<.01 vs CC;] EHCSS, 50% [P=.03 vs CC;] CC, 88.9%), higher working capacity (NS, 2.92+/-0.4 W/kg [P=.06 vs CC;] ECHSS, 2.92+/-0.4 W/kg [P=.04 vs CC;] CC, 2.86+/-0.5 W/kg), higher peak oxygen uptake (NS, 2694+/-466 mL O(2)/min [P=.08 vs CC;] EHCSS, 2830+/-606 mL O(2)/min [P=.03 vs CC;] CC, 2682+/-492 mL O(2)/min), higher anaerobic threshold (NS, 1324+/-306 mL O(2)/min; EHCSS, 1396+/-312 mL O(2)/min [P=.03 vs CC;] CC, 1315+/-290 mL O(2)/min), and higher maximum rate-pressure product (NS, 30.1+/-2.7 x 10(3) mm Hg/min; EHCSS, 2.8 x 10(3) mm Hg/min [P<.01 vs CC;] CC, 30.7+/-29.2+/-3.6 x 10(3) mm Hg/min) indicating that reduced exposure from tobacco smoke and NS for 3 days may improve cardiovascular function as detected by symptom-limited spiroergometry.

Endurance training reduces circulating inflammatory markers in persons at risk of coronary events: Impact on plaque stabilization?

Inflammatory pathways are involved in destabilization of atherosclerotic plaques. We assessed the hypothesis that endurance training decreases circulating concentrations of inflammatory markers in persons with coronary artery disease (CAD) and cardiovascular risk factors (CVRFs). Thirty-two subjects with CAD and/or CVRFs joined a 12-week supervised endurance training. We found a significant decrease of the chemokines interleukin (IL)-8 (pre: 3.9+/-0.6, change: -1.2+/-0.4 pg/ml, -21%, p=0.002) and monocyte chemoattractant protein-1 (pre: 213+/-9, change: -20.4+/-8.2 pg/ml, -5%, p=0.03). Diabetes mellitus (DM) significantly influenced changes of IL-8 (p=0.002). IL-8 substantially dropped by 39% in diabetics. Moreover, matrix metalloproteinase-9 (MMP-9) highly significantly decreased in response to training (pre: 750+/-98, change: -278+/-77 ng/ml, -18%, p=0.005). Exercise-induced changes of MMP-9 were influenced by concomitant use of statins (p=0.038). We observed a particularly strong MMP-9 reduction of 44% in patients treated with statins. Acute phase reactants IL-6 (pre: 1.7+/-0.3, change: +0.25+/-0.7 pg/ml, +4%, p=0.58) and high sensitivity C-reactive protein (pre: 2.1+/-0.5, change: -0.25+/-0.4 mg/l, -9%, p=0.54) did not change in response to training. In conclusion, endurance training decreased circulating chemokines and MMP-9, which may in part explain its beneficial effect on coronary risk. Patients with DM or treated with statins because of hypercholesterolemia may particularly take advantage.

Different forms of physical activity and cardiovascular risk factors among 24???64-year-old men and women in Finland

BACKGROUND

There is convincing evidence that regular physical activity reduces risk factors for cardiovascular diseases (CVD) among men. However, only a few studies have been conducted among women. Most previous studies have focused on the effects of leisure-time physical activity on cardiovascular risk factors, without considering the impact of occupational or commuting physical activity.

DESIGN

Four independent cross-sectional surveys were carried out at 5-year intervals within the framework of the FINMONICA studies in 1982, 1987, 1992 and 1997.

METHODS

An independent random sample was drawn from the national population register for each survey. The samples were stratified by sex and 10-year age categories according to the WHO MONICA protocol. The survey consisted of a self-administered questionnaire.

RESULTS

Not only leisure-time physical activity, but also commuting activity was directly associated with high-density lipoprotein (HDL)-cholesterol and was inversely related to body mass index (BMI) and waist circumference among both men and women. High occupational physical activity was related to high HDL-cholesterol levels and high total serum cholesterol levels in both sexes and to lower BMI, waist circumference and diastolic blood pressure (DBP) in men. High leisure-time physical activity was associated with reduced DBP among both men and women, whereas high occupational physical activity was related to lower DBP only among men.

CONCLUSION

Not only leisure-time physical activity but also commuting activity is associated with reduced levels of some cardiovascular risk factors. All forms of physical activity should be promoted to reduce CVD in the population.

Association of physical activity with mortality in the US dialysis population

BACKGROUND

It is unclear whether the protective benefits of regular physical activity on mortality extend to patients with end-stage renal disease (ESRD). We tested this hypothesis in a national cohort of new patients with ESRD in the United States.

METHODS

Data for a subset of patients (n = 2,507; 62%) from the Dialysis Morbidity and Mortality Wave 2 study were used to explore the associations of exercise and limitations in physical activity with mortality.

RESULTS

Overall, 56% of patients exercised less than once a week, whereas the remainder reported more frequent physical activity; 2 to 3 times/wk in 18%, 4 to 5 times/wk in 6%, and daily exercise in 20%. Severe limitations in vigorous and moderate physical activities were reported by 75% and 42%, respectively. Mortality risks were greatest for those with severe limitations in either moderate (relative risk [RR], 1.72; 95% confidence interval [CI], 1.44 to 2.05) or vigorous physical activities (RR, 1.51; 95% CI, 1.20 to 1.90) compared with those reporting minimal or no limitations. Conversely, mortality risks were lower for patients who exercised 2 to 3 (RR, 0.74; 95% CI, 0.58 to 0.95) or 4 to 5 times/wk (RR, 0.70; 95% CI, 0.47 to 1.07), whereas no advantage was associated with daily exercise (RR, 1.06; 95% CI, 0.86 to 1.30).

CONCLUSION

Although limitations in physical activity are common among new patients with ESRD in the United States and correlate highly with increased mortality risk, this study shows an association of frequent exercise of up to 4 to 5 times/wk with improved survival. The surprising lack of association of daily exercise with increased survival deserves additional study.

Physical inactivity causes endothelial dysfunction in healthy young mice

OBJECTIVES

We sought to determine if physical inactivity affects endothelial function in young healthy individuals.

BACKGROUND

Recent studies have linked exercise training to increased bioavailability of vascular nitric oxide (NO) and to improved endothelial function in patients with cardiovascular disorders. The effects of physical inactivity on normal vascular endothelial function are not known.

METHODS

Healthy young male C57Bl/6 mice living in groups of five in large cages, where they were running, climbing, and fighting during their active cycle, were randomly assigned to stay there or to live alone in small cages where they were predominantly resting. After five and nine weeks citrate synthase activity (a measure of mitochondrial respiratory chain activity), heart weight/body weight ratio, vascular reactivity, and protein expression of endothelial nitric oxide synthase (eNOS) were assessed.

RESULTS

Singularized mice showed a reduction of citrate synthase activity (p < 0.05), of endothelium-dependent vasorelaxation (to 65 +/- 5% of control levels; p < 0.001), and of eNOS protein expression (to 53 +/- 8% of control levels; p < 0.01). In striking contrast, vascular responses to potassium chloride, phenylephrine, and the NO-donor racemic S-nitroso-N-acetylpenicillamine were unchanged. The alterations of vascular eNOS-activity were completely reversible when singularized mice underwent exercise. In mice living in groups, exercise showed only a small effect on aortic eNOS expression.

CONCLUSIONS

In young healthy individuals physical inactivity induces endothelial dysfunction, which is completely reversible by a short period of moderate exercise training. We suggest that physical inactivity, the so-called sedentary lifestyle, increases cardiovascular risk in young healthy individuals by inducing endothelial dysfunction.