Association between self-reported leisure-time physical activity and measures of cardiorespiratory fitness in an elderly population

Reference values for estimated VO2max by two submaximal cycle tests: the Åstrand-test and the Ekblom-Bak test

AIMS

Submaximal tests estimating VO2max have inherent biases; hence, using VO2max estimations from the same test is essential for reducing this bias. This study aimed to establish sex- and age-specific reference values for estimated VO2max using the Åstrand-test (Å-test) and the Ekblom-Bak test (EB-test). We also assessed the effects of age, exercise level, and BMI on VO2max estimations.

METHODS

We included men and women (20-69 years) from the Swedish working population participating in Health Profile Assessments between 2010 and 2020. Excluding those on heart rate-affecting medicines and smokers, n = 263,374 for the Å-test and n = 95,043 for the EB-test were included. VO2max reference values were based on percentiles 10, 25, 40, 60, 75, and 90 for both sexes across 5-year age groups.

RESULTS

Estimated absolute and relative VO2max were for men 3.11 L/min and 36.9 mL/min/kg using the Å-test, and 3.58 L/min and 42.4 mL/min/kg using the EB-test. For women, estimated absolute and relative VO2max were 2.48 L/min and 36.6 mL/min/kg using the Å-test, and 2.41 L/min and 35.5 mL/min/kg using the EB-test. Higher age (negative), higher exercise level (positive), and higher BMI (negative) were associated with estimated VO2max using both tests. However, explained variance by exercise on estimated VO2max was low, 10% for the Å-test and 8% for the EB-test, and moderate for BMI, 23% and 29%.

CONCLUSION

We present reference values for estimated VO2max from two submaximal cycle tests. Age, exercise, and BMI influenced estimated VO2max. These references can be valuable in clinical evaluations using the same submaximal tests.

Association of Physical Activity With Maximal and Submaximal Tests of Exercise Capacity in Middle- and Older-Aged Adults

Although physical activity (PA) is an important determinant of exercise capacity, the association between these constructs is modest. The authors investigated the associations of self-reported and objectively measured PA with maximal and submaximal tests of exercise capacity. Participants aged ≥40 years (N = 413; 49.6% female) completed a PA questionnaire, wore a uniaxial accelerometer (5.2 ± 1.1 days), and performed maximal (cardiopulmonary exercise test [CPET]) and submaximal (long-distance corridor walk) tests with indirect calorimetry (oxygen consumption, V˙O2). Linear regression models were fitted to assess the variation in exercise capacity explained (partial eta squared, η2) by PA variables. Accelerometer-measured vigorous (η2 = 22% female; η2 = 16% male) and total PA (η2 = 17% female; η2 = 13% male) explained the most variance in CPET V˙O2 (p < .001). All η2 values were lower for long-distance corridor walk V˙O2 (η2 ≤ 11%). Age contributed more to CPET V˙O2 than any PA variable in males (η2 = 32%), but not in females (η2 = 19%). Vigorous and total PA play important roles in CPET V˙O2 in mid to late life.

Understanding the Neurophysiological and Molecular Mechanisms of Exercise-Induced Neuroplasticity in Cortical and Descending Motor Pathways: Where Do We Stand?

Exercise is a promising, cost-effective intervention to augment successful aging and neurorehabilitation. Decline of gray and white matter accompanies physiological aging and contributes to motor deficits in older adults. Exercise is believed to reduce atrophy within the motor system and induce neuroplasticity which, in turn, helps preserve motor function during aging and promote re-learning of motor skills, for example after stroke. To fully exploit the benefits of exercise, it is crucial to gain a greater understanding of the neurophysiological and molecular mechanisms underlying exercise-induced brain changes that prime neuroplasticity and thus contribute to postponing, slowing, and ameliorating age- and disease-related impairments in motor function. This knowledge will allow us to develop more effective, personalized exercise protocols that meet individual needs, thereby increasing the utility of exercise strategies in clinical and non-clinical settings. Here, we review findings from studies that investigated neurophysiological and molecular changes associated with acute or long-term exercise in healthy, young adults and in healthy, postmenopausal women.

The Association of a Frailty Index and Incident Delirium in Older Hospitalized Patients: An Observational Cohort Study

Introduction/Background

Frailty identifies patients that have vulnerability to stress. Acute illness and hospitalization are stressors that may result in delirium and further accelerate the negative consequences of frailty.

Purpose

The purpose of this study was to determine whether frailty, identified at hospital admission and as measured by a frailty index, is associated with incident delirium.

Methods

A retrospective, observational, cohort study was done at a Veterans hospital between January 2013 and March 2014. English-speaking patients over 55 years were eligible. Exclusion criteria included inability to complete baseline assessments due to pre-existing cognitive impairment, emergent surgery; and/or admission from a nursing home, pre-existing delirium, and those with psychiatric disease or substance use disorder.

Main Outcomes and Measures

Frailty index (FI) variables included cognitive screening, physical function and comorbidities. The FI was calculated as a proportion of possible deficits (range 0 to 1; higher scores indicate increased frailty). Incident delirium was measured daily by an expert clinician interview.

Results

A total of 247 patients were admitted and 218 met inclusion/exclusion criteria, with a mean age of 71.54 years (SD = 9.53 years) and were predominantly white (92.7%) and male (91.7%). Participants were grouped using FI ranges as non-frail (FI <0.25, n=56 (26%)), pre-frail (FI =0.25–0.35, n=86 (39%)), and frail (FI >0.35, n=76 (35%)). Pre-frailty and frailty were associated with incident delirium (non-frail: 3.6% vs pre-frail: 20.9% vs frail: 29.3%, p=0.001) and total delirium days (mean day =non-frail 0.04 vs pre-frail 0.35 vs frail 0.57, p=0.003). After adjustment for sociodemographic factors, pre-frail (adjusted OR=5.64, 95% CI: 1.23, 25.99) and frail status (adjusted OR=6.80, 95% CI: 1.38, 33.45) were independently associated with delirium.

Conclusion

This study demonstrates that a frailty index is independently associated with incident delirium and suggests that admission assessments for frailty may identify patients at high risk of developing delirium.

Fitness, independent of physical activity is associated with cerebral blood flow in adults at risk for Alzheimer's disease

Patterns of decreased resting cerebral blood flow (CBF) within the inferior temporal gyri, angular gyri, and posterior cingulate are a feature of aging and Alzheimer's disease (AD) and have shown to be predictive of cognitive decline among older adults. Fitness and physical activity are both associated with many indices of brain health and may positively influence CBF, however, the majority of research to date has examined these measures in isolation, leaving the potential independent associations unknown. The purpose of this study was to determine the unique contributions of fitness and physical activity when predicting CBF in cognitively healthy adults at risk for AD. One hundred participants (63% female) from the Wisconsin Registry for Alzheimer's Prevention underwent a maximal exercise test, physical activity monitoring, and a 3-D arterial spin labeling magnetic resonance imaging scan. For the entire sample, fitness was significantly associated with CBF while accounting for physical activity, age, gender, APOE ε4, family history of AD, education, and handedness (p = .026). Further, fitness explained significantly more variance than the combined effect of the covariates on CBF (R2 change = .059; p = .047). These results appear to be gender dependent, our data suggest fitness level, independent of physical activity, is associated with greater CBF in regions that are known to decline with age and AD for female (p = .011), but not male participants.

Cardiorespiratory fitness is differentially associated with cortical thickness in young and older adults

Aging is associated with reductions in gray matter volume and cortical thickness. One factor that may play a role in mitigating age-associated brain decline is cardiorespiratory fitness (CRF). Although previous work has identified a positive association between CRF and gray matter volume, the relationship between CRF and cortical thickness, which serves as a more sensitive indicator of gray matter integrity, has yet to be assessed in healthy young and older adults. To address this gap in the literature, 32 young and 29 older adults completed treadmill-based progressive maximal exercise testing to assess CRF (peak VO₂), and structural magnetic resonance imaging (MRI) to determine vertex-wise surface-based cortical thickness metrics. Results indicated a significant CRF by age group interaction such that Peak VO₂ was associated with thicker cortex in older adults but with thinner cortex in young adults. Notably, the majority of regions demonstrating a positive association between peak VO₂ and cortical thickness in older adults overlapped with brain regions showing significant age-related cortical thinning. Further, when older adults were categorized as high or low fit based on normative data, we observed a stepwise pattern whereby cortex was thickest in young adults, intermediate in high fit older adults and thinnest in low fit older adults. Overall, these results support the notion that CRF-related neuroplasticity may reduce although not eliminate age-related cortical atrophy.

The Godin-Shephard leisure-time physical activity questionnaire: validity evidence supporting its use for classifying healthy adults into active and insufficiently active categories

This study provided validity evidence for the Godin-Shephard Leisure-Time Physical Activity Questionnaire (GSLTPAQ) to classify respondents into active and insufficiently active categories. Members of a fitness center [45 women and 55 men; mean (SD) age=45.5 (10.6) yr.] completed the questionnaire. Using only moderate and strenuous scores, those with a leisure score index≥24 were classified as active; those with a score≤23 were classified as insufficiently active. VO2max, percentage of body fat, and electronic records of fitness center attendance were the validation variables. In a visit to the fitness center, participants completed the GSLTPAQ and a certified exercise specialist performed a physical fitness evaluation. A multivariate analysis of covariance (MANCOVA) indicated the group of respondents classified as active had higher VO2max and lower percentage of body fat than the group of respondents classified as insufficiently active. An analysis of covariance (ANCOVA) indicated the group of respondents classified as active had higher electronic records of fitness center attendance than the group of respondents classified as insufficiently active. Therefore, these pieces of validity evidence support the use of the questionnaire's classification system among healthy adults.

Lung function profiles and aerobic capacity of adult cigarette and hookah smokers after 12 weeks intermittent training

INTRODUCTION

Pulmonary function is compromised in most smokers. Yet it is unknown whether exercise training improves pulmonary function and aerobic capacity in cigarette and hookah smokers and whether these smokers respond in a similar way as do non-smokers.

AIM

To evaluate the effects of an interval exercise training program on pulmonary function and aerobic capacity in cigarette and hookah smokers.

METHODS

Twelve cigarette smokers, 10 hookah smokers, and 11 non-smokers participated in our exercise program. All subjects performed 30 min of interval exercise (2 min of work followed by 1 min of rest) three times a week for 12 weeks at an intensity estimated at 70% of the subject's maximum aerobic capacity (VO2max). Pulmonary function was measured using spirometry, and maximum aerobic capacity was assessed by maximal exercise testing on a treadmill before the beginning and at the end of the exercise training program.

RESULTS

As expected, prior to the exercise intervention, the cigarette and hookah smokers had significantly lower pulmonary function than the non-smokers. The 12-week exercise training program did not significantly affect lung function as assessed by spirometry in the non-smoker group. However, it significantly increased both forced expiratory volume in 1 second and peak expiratory flow (PEF) in the cigarette smoker group, and PEF in the hookah smoker group. Our training program had its most notable impact on the cardiopulmonary system of smokers. In the non-smoker and cigarette smoker groups, the training program significantly improved VO2max (4.4 and 4.7%, respectively), v VO2max (6.7 and 5.6%, respectively), and the recovery index (7.9 and 10.5%, respectively).

CONCLUSIONS

After 12 weeks of interval training program, the increase of VO2max and the decrease of recovery index and resting heart rate in the smoking subjects indicated better exercise tolerance. Although the intermittent training program altered pulmonary function only partially, both aerobic capacity and life quality were improved. Intermittent training should be advised in the clinical setting for subjects with adverse health behaviors.

Cardiorespiratory fitness and brain diffusion tensor imaging in adults over 80 years of age

A positive association between cardiorespiratory fitness (CRF) and white matter integrity has been consistently reported in older adults. However, it is unknown whether this association exists in adults over 80 with a range of chronic disease conditions and low physical activity participation, which can influence both CRF and brain health. This study examined whether higher CRF was associated with greater microstructural integrity of gray and white matter in areas related to memory and information processing in adults over 80 and examined moderating effects of chronic diseases and physical activity. CRF was measured as time to walk 400 m as quickly as possible with concurrent 3T diffusion tensor imaging in 164 participants (57.1% female, 40.3% black). Fractional anisotropy (FA) was computed for cingulum, uncinate and superior longitudinal fasciculi. Mean diffusivity (MD) was computed for dorsolateral prefrontal cortex, hippocampus, parahippocampus, and entorhinal cortex. Moderating effects were tested using hierarchical regression models. Higher CRF was associated with higher FA in cingulum and lower MD in hippocampus and entorhinal cortex (β, sex-adjusted p: -0.182, 0.019; 0.165, 0.035; and 0.220, 0.006, respectively). Hypertension attenuated the association with MD in entorhinal cortex. Moderating effects of chronic diseases and physical activity in walking and climbing stairs on these associations were not significant. The association of higher CRF with greater microstructural integrity in selected subcortical areas appears robust, even among very old adults with a range of chronic diseases. Intervention studies should investigate whether increasing CRF can preserve memory and information processing by improving microstructure and potential effects of hypertension management.

A double robust approach to causal effects in case-control studies

In a recent issue of the Journal, VanderWeele and Vansteelandt (Am J Epidemiol. 2011;174(10):1197-1203) discussed an inverse probability weighting method for case-control studies that could be used to estimate an additive interaction effect, referred to as the "relative excess risk due to interaction." In this article, we reinforce the well-known disadvantages of inverse probability weighting and comment on the desirability of the described parameter. Further, we review an existing double robust estimator not considered by VanderWeele and Vansteelandt, the case-control-weighted targeted maximum likelihood estimator, which has improved properties in comparison with a previously described inverse-probability-weighted estimator. This targeted maximum likelihood estimator can be used to target various parameters of interest, and its implementation has been described previously for the risk difference, relative risk, and odds ratio.

Sensitivity analysis for causal inference under unmeasured confounding and measurement error problems

In this article, we present a sensitivity analysis for drawing inferences about parameters that are not estimable from observed data without additional assumptions. We present the methodology using two different examples: a causal parameter that is not identifiable due to violations of the randomization assumption, and a parameter that is not estimable in the nonparametric model due to measurement error. Existing methods for tackling these problems assume a parametric model for the type of violation to the identifiability assumption and require the development of new estimators and inference for every new model. The method we present can be used in conjunction with any existing asymptotically linear estimator of an observed data parameter that approximates the unidentifiable full data parameter and does not require the study of additional models.

Aerobic capacity reference data in 3816 healthy men and women 20-90 years

Purpose

To provide a large reference material on aerobic fitness and exercise physiology data in a healthy population of Norwegian men and women aged 20–90 years.

Methods

Maximal and sub maximal levels of VO₂, heart rate, oxygen pulse, and rating of perceived exertion (Borg scale: 6–20) were measured in 1929 men and 1881 women during treadmill running.

Results

The highest VO_2max and maximal heart rate among men and women were observed in the youngest age group (20–29 years) and was 54.4±8.4 mL·kg⁻¹·min⁻¹ and 43.0±7.7 mL·kg⁻¹·min⁻¹ (sex differences, p<0.001) and 196±10 beats·min⁻¹ and 194±9 beats·min⁻¹ (sex differences, p<0.05), respectively, with a subsequent reduction of approximately 3.5 mL·kg⁻¹·min⁻¹ and 6 beats·min⁻¹ per decade. The highest oxygen pulses were observed in the 3 youngest age groups (20–29 years, 30–39 years, 40–49 years) among men and women; 22.3 mL·beat⁻¹±3.6 and 14.7 mL·beat⁻¹±2.7 (sex differences, p<0.001), respectively, with no significant difference between these age groups. After the age of 50 we observed an 8% reduction per decade among both sexes. Borg scores appear to give a good estimate of the relative exercise intensity, although observing a slightly different relationship than reported in previous reference material from small populations.

Conclusion

This is the largest European reference material of objectively measured parameters of aerobic fitness and exercise-physiology in healthy men and women aged 20–90 years, forming the basis for an easily accessible, valid and understandable tool for improved training prescription in healthy men and women.

Leisure-time physical activity is a significant predictor of stroke and total mortality in Japanese patients with type 2 diabetes: analysis from the Japan Diabetes Complications Study (JDCS)

AIMS/HYPOTHESIS

Our aim was to clarify the association between leisure-time physical activity (LTPA) and cardiovascular events and total mortality in a nationwide cohort of Japanese diabetic patients.

METHODS

Eligible patients (1,702) with type 2 diabetes (mean age, 58.5 years; 47% women) from 59 institutes were followed for a median of 8.05 years. A comprehensive lifestyle survey including LTPA and occupation was performed using standardised questionnaires. Outcome was occurrence of coronary heart disease (CHD), stroke and total mortality. The adjusted HR and 95% CI were calculated by Cox regression analysis.

RESULTS

A significant reduction in HR in patients in the top (≥ 15.4 metabolic equivalents [MET] h/week) vs the bottom tertile (≤ 3.7 MET h/week) of LTPA, adjusted by age, sex and diabetes duration, was observed in stroke (HR 0.55, 95% CI 0.32, 0.94) and total mortality (HR 0.49, 95% CI 0.26, 0.91) but not in CHD (HR 0.77, 95% CI 0.48, 1.25). The HR for stroke became borderline significant or nonsignificant after adjustment for lifestyle or clinical variables including diet or serum lipids. The significantly reduced total mortality by LTPA was independent of these variables and seemed not to be, at least mainly, attributed to reduced cardiovascular disease.

CONCLUSIONS/INTERPRETATION

In Japanese persons with type 2 diabetes, LTPA of 15.4 MET h/week or more was associated with a significantly lower risk of stroke partly through ameliorating combinations of cardiovascular risk factors. It was also associated with significantly reduced total mortality but independently of cardiovascular risk factors or events. These findings, implying differences from Western diabetic populations, should be considered in the clinical management of East Asians with diabetes.

Mortality risk score prediction in an elderly population using machine learning

Standard practice for prediction often relies on parametric regression methods. Interesting new methods from the machine learning literature have been introduced in epidemiologic studies, such as random forest and neural networks. However, a priori, an investigator will not know which algorithm to select and may wish to try several. Here I apply the super learner, an ensembling machine learning approach that combines multiple algorithms into a single algorithm and returns a prediction function with the best cross-validated mean squared error. Super learning is a generalization of stacking methods. I used super learning in the Study of Physical Performance and Age-Related Changes in Sonomans (SPPARCS) to predict death among 2,066 residents of Sonoma, California, aged 54 years or more during the period 1993-1999. The super learner for predicting death (risk score) improved upon all single algorithms in the collection of algorithms, although its performance was similar to that of several algorithms. Super learner outperformed the worst algorithm (neural networks) by 44% with respect to estimated cross-validated mean squared error and had an R2 value of 0.201. The improvement of super learner over random forest with respect to R2 was approximately 2-fold. Alternatives for risk score prediction include the super learner, which can provide improved performance.

Direct effects of leisure-time physical activity on walking speed

OBJECTIVE

This study quantifies the effects of leisure-time physical activity (LTPA) on walking speed independently of body composition in an elderly cohort, and in those elderly with metabolic derangements due to age, diabetes, and cardiovascular disease (CVD).

METHODS

1655 community-dwelling women and men >55 years were measured for body composition (lean mass : fat mass ratio, LNFAT) , based on estimated bioelectric impedance by using population-specific prediction equations derived from dual-energy x-ray absorptiometry. In addition to LNFAT, LTPA, diabetes, CVD, walking speed, and other covariates were measured biannually over an 8-year period. LTPA was categorized as <22.5 Mets/week, ≥ 22.5 Mets/week, based on public-health recommended guidelines, and LNFAT was dichotomized based on its sex-specific median. Direct effects of high vs. low LTPA on walking speed were estimated for fixed levels of LNFAT, which represented an intermediary variable in the analysis. Stratified estimates of effects were obtained using subject status (e.g., age≥75 years, diabetes, CVD) at each visit.

RESULTS

Walking speed was significantly greater (0.74, 0.75 m/s in women and men, respectively) if subjects experienced LTPA ≥22.5 Mets/week and > median LNFAT, compared with <22.5 Mets/week and ≤ median LNFAT (0.68, 0.69 m/s). While direct effects of LTPA contributed to higher walking speed, none were significant in the overall, nor the stratified groups of subjects, of either sex.

CONCLUSIONS

Walking speed increases with greater LTPA and LNFAT in the elderly, but there was no evidence to indicate that walking speed increases from LTPA independently of body composition and the metabolic processes it represents.

Population intervention causal effects based on stochastic interventions

Estimating the causal effect of an intervention on a population typically involves defining parameters in a nonparametric structural equation model (Pearl, 2000, Causality: Models, Reasoning, and Inference) in which the treatment or exposure is deterministically assigned in a static or dynamic way. We define a new causal parameter that takes into account the fact that intervention policies can result in stochastically assigned exposures. The statistical parameter that identifies the causal parameter of interest is established. Inverse probability of treatment weighting (IPTW), augmented IPTW (A-IPTW), and targeted maximum likelihood estimators (TMLE) are developed. A simulation study is performed to demonstrate the properties of these estimators, which include the double robustness of the A-IPTW and the TMLE. An application example using physical activity data is presented.

Patient-reported physical activity questionnaires: a systematic review of content and format

Background

Many patients with chronic illness are limited in their physical activities. This systematic review evaluates the content and format of patient-reported outcome (PRO) questionnaires that measure physical activity in elderly and chronically ill populations.

Methods

Questionnaires were identified by a systematic literature search of electronic databases (Medline, Embase, PsychINFO & CINAHL), hand searches (reference sections and PROQOLID database) and expert input. A qualitative analysis was conducted to assess the content and format of the questionnaires and a Venn diagram was produced to illustrate this. Each stage of the review process was conducted by at least two independent reviewers.

Results

104 questionnaires fulfilled our criteria. From these, 182 physical activity domains and 1965 items were extracted. Initial qualitative analysis of the domains found 11 categories. Further synthesis of the domains found 4 broad categories: 'physical activity related to general activities and mobility', 'physical activity related to activities of daily living', 'physical activity related to work, social or leisure time activities', and '(disease-specific) symptoms related to physical activity'. The Venn diagram showed that no questionnaires covered all 4 categories and that the '(disease-specific) symptoms related to physical activity' category was often not combined with the other categories.

Conclusions

A large number of questionnaires with a broad range of physical activity content were identified. Although the content could be broadly organised, there was no consensus on the content and format of physical activity PRO questionnaires in elderly and chronically ill populations. Nevertheless, this systematic review will help investigators to select a physical activity PRO questionnaire that best serves their research question and context.

Sex-dependent associations between daily physical activity and leg exercise blood pressure responses

The authors examined interindividual and sex-specific variation in systolic (SBP) and diastolic (DBP) blood pressure responses to graded leg-extension exercise in healthy older (60-78 yr) women (n = 21) and men (n = 19). Maximal oxygen uptake (VO2max), body composition, physical activity (accelerometry), and vascular function were measured to identify predictors of exercise BP. Neither VO2max nor activity counts were associated with the rise in SBP or DBP during exercise in men. The strongest predictors of these responses in men were age (SBP: r2 = .19, p = .05) and peak exercise leg vasodilation (DBP: r2 = -.21, p < .05). In women, the modest relationship observed between VO2max and exercise BP was abolished after adjusting for central adiposity and activity counts (best predictors, cumulative r2 = .53, p < .05, for both SBP and DBP). These results suggest that determinants of variation in submaximal exercise BP responses among older adults are sex specific, with daily physical activity influencing these responses in women but not men.

Peak oxygen uptake and cardiovascular risk factors in 4631 healthy women and men

INTRODUCTION

Many studies suggest that cardiorespiratory fitness, measured as peak oxygen uptake (VO2peak), may be the single best predictor of cardiovascular morbidity and premature cardiovascular mortality. However, current reference values are either estimates of oxygen uptake or come from small studies, mainly of men. Therefore, the aims of this study were to directly measure VO2peak in healthy adult men and women and to assess the association with cardiovascular risk factor levels.

METHODS

A cross-sectional study of 4631 volunteering, free-living Norwegian men (n = 2368) and women (n = 2263) age 20-90 yr. The data collection was from June 2007 to June 2008. Participants were free from known pulmonary or cardiovascular disease. VO2peak was measured by ergospirometry during treadmill running. Associations (odds ratios, OR) with unfavorable levels of cardiovascular risk factors and a cluster of cardiovascular risk factors were assessed by logistic regression analysis.

RESULTS

Overall, mean VO2peak was 40.0 ± 9.5 mL·kg(-1)·min(-1). Women below the median VO2peak (<35.1 mL·kg(-1)·min(-1)) were five times (OR = 5.4, 95% confidence interval = 2.3-12.9) and men below the median (<44.2 mL·kg(-1)·min(-1)) were eight times (OR = 7.9, 95% confidence interval = 3.5-18.0) more likely to have a cluster of cardiovascular risk factors compared to those in the highest quartile of VO2peak (≥40.8 and ≥50.5 mL·kg(-1)·min(-1) in women and men, respectively). Each 5-mL·kg(-1)·min(-1) lower VO2peak corresponded to ∼56% higher odds of cardiovascular risk factor clustering.

CONCLUSIONS

These data represent the largest reference material of objectively measured VO2peak in healthy men and women age 20-90 yr. Even in people considered to be fit, VO2peak was clearly associated with levels of conventional cardiovascular risk factors.

Developmental origins of physical fitness: the Helsinki Birth Cohort Study

Background

Cardiorespiratory fitness (CRF) is a major factor influencing health and disease outcomes including all-cause mortality and cardiovascular disease. Importantly CRF is also modifiable and could therefore have a major public health impact. Early life exposures play a major role in chronic disease development. Our aim was to explore the potential prenatal and childhood origins of CRF in later life.

Methods/Principal Findings

This sub-study of the HBCS (Helsinki Birth Cohort Study) includes 606 men and women who underwent a thorough clinical examination and participated in the UKK 2-km walk test, which has been validated against a maximal exercise stress test as a measure of CRF in population studies. Data on body size at birth and growth during infancy and childhood were obtained from hospital, child welfare and school health records. Body size at birth was not associated with adult CRF. A 1 cm increase in height at 2 and 7 years was associated with 0.21 ml/kg/min (95% CI 0.02 to 0.40) and 0.16 ml/kg/min (95% CI 0.03 to 0.28) higher VO_2max, respectively. Adjustment for adult lean body mass strengthened these findings. Weight at 2 and 7 years and height at 11 years became positively associated with CRF after adult lean body mass adjustment. However, a 1 kg/m² higher BMI at 11 years was associated with −0.57 ml/kg/min (95% CI −0.91 to −0.24) lower adult VO_2max, and remained so after adjustment for adult lean body mass.

Conclusion/Significance

We did not observe any significant associations between body size at birth and CRF in later life. However, childhood growth was associated with CRF in adulthood. These findings suggest, importantly from a public point of view, that early growth may play a role in predicting adult CRF.

Long-term prognostic role of functional limitations among women with breast cancer

BACKGROUND

The long-term prognostic role of functional limitations among women with breast cancer is poorly understood.

METHODS

We studied a cohort of 2202 women with breast cancer at two sites in the United States, who provided complete information on body functions involving endurance, strength, muscular range of motion, and small muscle dexterity following initial adjuvant treatment. Associations of baseline functional limitations with survival were evaluated in delayed entry Cox proportional hazards models, with adjustment for baseline sociodemographic factors, body mass index, smoking, physical activity, comorbidity, tumor characteristics, and treatment. Difference in covariates between women with and without limitations was assessed with Pearson χ(2) and Student t tests. All statistical tests were two-sided.

RESULTS

During the median follow-up of 9 years, 112 deaths were attributable to competing causes (5% of the cohort) and 157 were attributable to breast cancer causes (7% of the cohort). At least one functional limitation was present in 39% of study participants. Proportionately, more breast cancer patients with functional limitations after initial adjuvant treatment were older, less educated, and obese (P < .001). In multivariable models, functional limitations were associated with a statistically significantly increased risk of death from all causes (hazard ratio [HR] = 1.40, 95% confidence interval [CI] = 1.03 to 1.92) and from competing causes (HR = 2.60, 95% CI = 1.69 to 3.98) but not from breast cancer (HR = 0.90, 95% CI = 0.64 to 1.26). The relationship between functional limitations and overall survival differed by tumor stage (among women with stage I and stage III breast cancer, HR = 2.02, 95% CI = 1.23 to 3.32 and HR = 0.74, 95% CI = 0.42 to 1.30, respectively).

CONCLUSION

In this prospective cohort study, functional limitations following initial breast cancer treatment were associated with an important reduction in all-cause and competing-cause survival, irrespective of clinical, lifestyle, and sociodemographic factors.

Lower-body function, neighborhoods, and walking in an older population

BACKGROUND

Poor lower-body capacity is associated with reduced mobility in older populations.

PURPOSE

This study sought to determine whether neighborhood environments (e.g., land-use patterns and safety) moderate that association.

METHODS

The study is based on a cross-sectional sample of 884 people aged > or =65 years identified through service organizations in Alameda County CA, Cook County IL, Allegheny County PA, and Wake and Durham counties NC. In-person interviews focused on neighborhood characteristics, physical and cognitive function, and physical activity and walking. Functional capacity was tested using measures of lower-body strength, balance, and walking speed. The main outcome was time spent walking in a typical week (<150 vs > or =150 minutes per week). Objective environmental measures were also included. Estimates of main and interaction effects were derived from regression models.

RESULTS

Living in a residential area, compared to a mixed-use or commercial area, was associated with less time spent walking (<150 minutes per week; OR=1.57, 95% CI=1.04, 2.38). Living in a less-compact area (greater median block length) is also significantly associated with less walking for seniors, but only among those with excellent lower-body strength.

CONCLUSIONS

Neighborhood type is associated with walking among older people, as it is among the general adult population. In individuals with poor lower-body function, no association was found between residence in a less-compact area and walking. For those people, the relationship between neighborhood characteristics and walking requires further study.

Leisure-time physical activity and all-cause mortality in an elderly cohort

BACKGROUND

Physical activity is one of the mainstays of secondary prevention in people with heart disease. It is not well understood, however, how the presence of heart disease or a history of habitual exercise prior to the study modify any mortality-sparing effects of leisure-time physical activity.

METHODS

We analyzed data from a well-described cohort of subjects aged 54 years and older at intake (median age, 70 years) from Sonoma, CA, studied between 1993 and 2001 with mortality follow-up until 2003. A history-adjusted marginal structural model was used to obtain counterfactual excess risk estimates that were pooled across the different time points. Additive interaction was examined by comparing these excess risk estimates across strata of age, heart disease, and precohort physical activity.

RESULTS

Estimates of the excess risk for 2-year all-cause mortality comparing Centers for Disease Control and Prevention-recommended levels of current physical activity to lower levels of activity ranged from -0.7% to -4.9% among subjects younger than 75 years of age and from -7.8% to -14.8% among older subjects. Heart disease or precohort physical activity were not found to modify the effect of leisure-time physical activity.

CONCLUSIONS

Our data are consistent with the view that the mortality-sparing effect of recent physical activity is independent of the presence or absence of underlying cardiac disease and the pattern of past physical activity.

Determinants of cardiorespiratory fitness in men aged 42 to 60 years with and without cardiovascular disease

Good cardiorespiratory fitness has been found to protect against cardiovascular diseases and type 2 diabetes. The purpose of this study was to investigate determinants of directly measured cardiorespiratory fitness (maximal oxygen uptake [VO2max]), including age, body composition, prevalent diseases, cardiovascular and pulmonary functions, biochemical factors, physical activity, nutrition, smoking, and alcohol consumption, in a population-based study of 936 men 42 to 60 years of age. Variables that had the strongest direct associations with VO2max (milliliters per minute) in a linear multivariate step-up regression model were body weight, heart rate at maximal exercise, mean intensity and frequency of conditioning physical activity, intake of carbohydrates, blood hemoglobin, and forced expiratory volume in 1 second. The strongest inverse associations with VO2max were heart rate at rest, age, fasting serum insulin, waist-to-hip ratio, coronary heart disease, and asthma. This model accounted for 67% of the variation of VO2max. In conclusion, mean intensity, frequency, and duration of conditioning physical activity were associated directly with VO2max. However, measurements of the function of pulmonary and cardiovascular systems, carbohydrate intake, and body composition were powerful determinants of cardiorespiratory fitness, especially in older middle-aged men.

Serum creatinine and functional limitation in elderly persons

BACKGROUND

Creatinine is a commonly used measure of kidney function, but serum levels are also influenced by muscle mass. We hypothesized that higher serum creatinine would be associated with self-reported functional limitation in community-dwelling elderly.

METHODS

Subjects (n = 1,553) were participants in the Study of Physical Performance and Age-Related Changes in Sonomans, a cohort to study aging and physical function. We explored three strategies to account for the effects of muscle mass on serum creatinine.

RESULTS

We observed a J-shaped association of creatinine with functional limitation. Above the study-specific mean creatinine (0.97 mg/dL in women and 1.15 mg/dL in men), the unadjusted odds ratio of functional limitation per standard deviation (0.20 mg/dL in women and 0.23 mg/dL in men) higher creatinine was 2.27 (95% confidence interval [CI] 1.75-2.94, p < .001) in women and 1.42 (95% CI 1.12-1.80, p = .003) in men. This association was inverted in persons with creatinine levels below the mean. Adjustment for muscle mass did not have an important effect on the association between creatinine and functional limitation. These associations remained after multivariable adjustment for demographics and health conditions but were statistically significant only in women.

CONCLUSIONS

In elderly adults, higher creatinine levels are associated with functional limitation, consistent with prior literature that has demonstrated reduced physical performance in persons with kidney disease. However, the association of low creatinine levels with functional limitation suggests that creatinine levels are influenced by factors other than kidney function and muscle mass in the elderly.

Depressive symptoms predict heart rate recovery after exercise treadmill testing in patients with coronary artery disease: results from the Psychophysiological Investigation of Myocardial Ischemia study

BACKGROUND

Depression is associated with increased risk of death among patients with coronary disease. Cardiovascular autonomic dysregulation may be one of the mechanisms by which depression exerts its effects on cardiovascular function. The purpose of this study was to determine whether depressive symptoms are associated with low heart rate variability (HRV) and prolonged HR recovery after exercise testing in patients with coronary artery disease (CAD).

METHODS

The Psychophysiological Investigation of Myocardial Ischemia (PIMI) was a large, multicenter study designed to assess psychological and physiological correlates of stress in patients with CAD. One hundred and eighty-eight patients with CAD as evidenced by at least 50% blockage of one major artery and a previous positive exercise stress test were included in this study. Patients included in this report were not taking beta blockers. Cardiovascular functioning was assessed by a modified Bruce protocol treadmill stress test. Measures of psychological functioning, including the Beck Depression Inventory (BDI), were also obtained.

RESULTS

BDI scores were negatively correlated with HR recovery (r = -0.15, p = .04). Depression scores accounted for 3.5% of the variance in HR recovery when controlling for participant age (p < .01). Depressive symptoms were related to two HRV indices (ultra-low frequency, high frequency).

CONCLUSIONS

Depressive symptoms are associated with cardiovascular autonomic nervous system dysfunction as assessed by HR recovery. This relationship is not merely due to an association of depression severity with beta blocker usage or a failure of depressed patients to achieve an adequate chronotropic response.

Correlates of Life Space in a Volunteer Cohort of Older Adults

The authors measured the spatial extent of movement of older persons (i.e., life space) and examined factors that are related to life space. A larger life space was positively correlated with self-report measures of disability. In generalized logit models adjusted for demographics and time of year, a larger life space was associated with less visual impairment, higher levels of lower extremity motor performance, global cognition, and social involvement, and with personality and purpose in life. The results suggest that the range of environmental movement in older adults is a useful indicator of health in old age and may complement measures of disability.

A practical illustration of the importance of realistic individualized treatment rules in causal inference

The effect of vigorous physical activity on mortality in the elderly is difficult to estimate using conventional approaches to causal inference that define this effect by comparing the mortality risks corresponding to hypothetical scenarios in which all subjects in the target population engage in a given level of vigorous physical activity. A causal effect defined on the basis of such a static treatment intervention can only be identified from observed data if all subjects in the target population have a positive probability of selecting each of the candidate treatment options, an assumption that is highly unrealistic in this case since subjects with serious health problems will not be able to engage in higher levels of vigorous physical activity. This problem can be addressed by focusing instead on causal effects that are defined on the basis of realistic individualized treatment rules and intention-to-treat rules that explicitly take into account the set of treatment options that are available to each subject. We present a data analysis to illustrate that estimators of static causal effects in fact tend to overestimate the beneficial impact of high levels of vigorous physical activity while corresponding estimators based on realistic individualized treatment rules and intention-to-treat rules can yield unbiased estimates. We emphasize that the problems encountered in estimating static causal effects are not restricted to the IPTW estimator, but are also observed with the G-computation estimator, the DR-IPTW estimator, and the targeted MLE. Our analyses based on realistic individualized treatment rules and intention-to-treat rules suggest that high levels of vigorous physical activity may confer reductions in mortality risk on the order of 15-30%, although in most cases the evidence for such an effect does not quite reach the 0.05 level of significance.

Gender differences in the decline in aerobic capacity and its physiological determinants during the later decades of life

We investigated the hemodynamic determinants of the age-associated decline in maximal oxygen uptake (V(O2 max)) and the influence of gender on the decline in V(O2 max) and its determinants in old and very old men and women. Sedentary, 60- to 92-yr-old women (n = 71) and men (n = 29), with no evidence of cardiovascular disease, underwent maximal treadmill exercise tests during which V(O2 max) and maximal cardiac output (Q(max)) were determined. V(O2 max) and age were inversely related in both women (-23 +/- 2 ml.min(-1).yr(-1); P < 0.0001) and men (-57 +/- 5 ml.min(-1).yr(-1); P < 0.0001). The absolute slope of the V(O2 max) vs. age relationship was twofold steeper in men than in women (P < 0.0001). Q(max) was also inversely related to age in a gender-specific manner (women = -87 +/- 25 ml.min(-1).yr(-1), P = 0.0009; men = -215 +/- 50 ml.min(-1).yr(-1), P = 0.0002; P = 0.01 women vs. men). Age-related changes in maximal exercise arteriovenous oxygen content difference (a-vD(O2)) were marginally different (P = 0.08) between women (-0.12 +/- 0.03 ml.dl(-1).yr(-1), P = 0.0003) and men (-0.22 +/- 0.04 ml.dl(-1).yr(-1), P < 0.0001). Age-associated decreases in Q(max) and a-vD(O2) contributed equally to the declines in V(O2 max) in both men and women. In the later stages of life, V(O2 max), Q(max), and a-vD(O2) decrease with age more rapidly in older men than they do in older women. As a result, the gender differences dissipate in the later decades of life. Declines in Q(max) and a-vD(O2) contribute equally to the age-related decrease in V(O2 max) in men and women.

Effects of body composition and leisure-time physical activity on transitions in physical functioning in the elderly

Physical activity and body composition were examined with respect to variation in functional limitation over a 6-year period (four surveys conducted between 1994 and 2000) based on a cohort of 1,655 community-dwelling older women and men living in Sonoma, California. Measures of functional limitation and physical activity were based on standard self-report questions. Measures of body composition (lean mass, fat mass) were estimated from bioelectric impedance by using population-specific prediction equations derived from dual-energy x-ray absorptiometry. For women, a one-unit gain in lean mass:fat mass ratio reduced the report of limitation at all surveys 65.5% (95% confidence interval: 21.8, 87.4). A similar reduction was not observed for men; however, there was a 3% increase in the report of no limitation at any survey. The effect of high levels of physical activity reduced new functional limitation that occurred at the last survey by 36.8% (95% confidence interval: 0.0, 92.2) for men and 52.7% (95% confidence interval: 13.5, 91.9) for women. In summary, higher levels of physical activity appeared to reduce the risk of future functional limitation conditional on the level of functioning established early in the disablement process by lean mass:fat mass ratio.

Driving cessation and increased depressive symptoms

BACKGROUND

To understand the consequences of driving cessation in older adults, the authors evaluated depression in former drivers compared with active drivers.

METHODS

Depression (as assessed using the Center for Epidemiological Studies Depression Scale), driving status, sociodemographic factors, health status, and cognitive function were evaluated for a cohort of 1953 residents of Sonoma County, California, aged 55 years and older, as part of a community-based study of aging and physical performance. The authors re-interviewed 1772 participants who were active drivers at baseline 3 years later.

RESULTS

At baseline, former drivers reported higher levels of depression than did active drivers even after the authors controlled for age, sex, education, health, and marital status. In a longitudinal analysis, drivers who stopped driving during the 3-year interval (i.e., former drivers) reported higher levels of depressive symptoms than did those who remained active drivers, after the authors controlled for changes in health status and cognitive function. Increased depression for former drivers was substantially higher in men than in women.

CONCLUSIONS

With increasing age, many older adults reduce and then stop driving. Increased depression may be among the consequences associated with driving reduction or cessation.

Effects of physical activity and body composition on functional limitation in the elderly: application of the marginal structural model

BACKGROUND

Study of the influence of physical activity and body composition in the context of the disablement process requires analytic techniques that can address time-dependent confounding related to exposures for the occurrence of functional limitation and disability.

METHODS

We applied logistic marginal structural models to explore causal relationships between leisure time physical activity and a measure of relative muscle mass (the lean:fat mass ratio) and self-reported functional limitation. Subjects (n = 1655) were members of a population-based cohort recruited in Sonoma, California, in 1993-1994 (median age 70 years); they were surveyed 3 times over 6.5 years.

RESULTS

Based on the marginal structural model, the causal odds ratio for functional limitation with a 0.5-unit increment in relative muscle mass was 0.56 in women (95% CI = 0.46-0.67). This reduction in odds was not altered by adjustment for baseline covariates. The corresponding causal odds ratio in men was 0.77 (0.65-0.92). This also was not influenced by baseline covariates or levels of physical activity. There was evidence for an independent causal effect of increased levels of physical activity on reduction of odds of functional limitation for men but not for women. Obese women experienced no protective effect of increased lean-to-fat mass. Normal-weight women experienced a benefit with increasing levels of physical activity.

CONCLUSIONS

Marginal structural models provide a means to address time-dependent confounding, which can occur in longitudinal studies. These analyses indicate that leisure time physical activity exerts its beneficial effects through reductions in fat mass relative to lean body mass.

The Yale Physical Activity Survey for older adults: Predictions in the energy expenditure due to physical activity

OBJECTIVE

To evaluate the accuracy of the Yale Physical Activity Survey (YPAS) for older adults.

DESIGN

Fourteen-week strictly controlled diet study.

SUBJECTS/SETTING

Eleven men and 17 women, age range 55 to 78 years, spent 10 weeks in an outpatient setting and 4 weeks in an inpatient setting at the General Clinical Research Center, Noll Physiological Research Center, The Pennsylvania State University, University Park.

INTERVENTION

Subjects were provided dietary energy to maintain body weight within +/-0.5 kg of baseline weight. The daily menus contained 0.8 g protein per kilogram body weight and nonprotein energy as 60% carbohydrate and 40% fat.

MAIN OUTCOME MEASURES

Metabolizable energy intake (MEI) was measured at week 14 from the gross energy contents of food, urine, and feces, with corrections for any body composition changes during the last 6 weeks of weight maintenance. Resting energy expenditure (REE) was determined using indirect calorimetry. The thermic effect of feeding (TEF) was estimated to be 10% of the MEI. The energy expenditure due to physical activity (EEPA) was derived by the formula: EEPA=MEI-REE-TEF. This value was compared with the EEPA estimated from the YPAS. Statistical analyses performed Two-factor analysis of variance with repeated measures and paired t tests.

RESULTS

At week 14, after a minimum of 6 weeks of sustained weight stability, the derived EEPA was not different from that estimated using the YPAS for the men and the men and women combined, while the YPAS estimate was more than the measured mean value for the women (P<.05). There was wide variability in the accuracy of the EEPA prediction for individual subjects (range=-637 to 794 kcal).

APPLICATIONS/CONCLUSIONS

The YPAS may be used, with caution, to estimate the EEPA for groups of older individuals, and may provide inaccurate estimates of the EEPA in older individuals.

Brisk Walking Speed in Older Adults Who Walk for Exercise

OBJECTIVES

To determine the self-selected exercise intensity of older adults who report that they walk briskly for exercise. An additional aim of the study was to assess the contribution of self-reported physical activity to self-selected exercise intensity.

DESIGN

Observational.

SETTING

walking path.

PARTICIPANTS

Subjects consisted of 212 participants in the Study of Physical Performance and Age-Related Changes in Sonomans who stated in a detailed home interview that they walked briskly for exercise.

MEASUREMENTS

Observed brisk walking speed was measured as the time it took participants to walk half a mile at "normal brisk walking speed." Self-reported physical activity was categorized as metabolic equivalent of the task (MET) in minutes of exercise reported in the previous 7 days. Physiological measures and body composition were obtained through laboratory evaluation.

RESULTS

Men walked at an average speed+/-standard deviation of 5.72+/-0.69 km/h and women walked at an average speed of 5.54+/-0.64 km/h. Self-reported physical activity was not associated with brisk walking speed when adjusted for age and ratio of lean to fat mass.

CONCLUSION

This study found that older adults who report that they walk briskly for exercise do so at a pace considered moderate or greater in absolute intensity as indicated by their walking speed (4.83 km/h). Ninety-eight percent of men (93/95) and 97% of women (113/117) had an observed walking speed equivalent to 3 or more METs based on their calculated walking speed.

Effects of physical activity on exercise tests and respiratory function

BACKGROUND

Exercise is an important component of pulmonary rehabilitation for patients with chronic lung disease.

OBJECTIVE

To explore the role of physical activity in maintaining cardiac and respiratory function in healthy people.

METHODS

Cardiorespiratory fitness was measured by a maximal treadmill test (MTT), and respiratory function was tested by spirometry. The cross sectional study included data from 24 536 healthy persons who were examined at the Cooper Clinic between 1971 and 1995; the longitudinal study included data from 5707 healthy persons who had an initial visit between 1971 and 1995 and a subsequent visit during the next five years. All participants were aged 25-55 years and completed a cardiorespiratory test and a medical questionnaire.

RESULTS

In the cross sectional study, after controlling for covariates, being active and not being a recent smoker were associated with better cardiorespiratory fitness and respiratory function in both men and women. In the follow up study, persons who remained or became active had better MTT than persons who remained or became sedentary. Men who remained active had higher forced expiratory volume in one second (FEV(1)) and forced vital capacity (FVC) than the other groups. Smoking was related to lower cardiorespiratory fitness and respiratory function.

CONCLUSIONS

Physical activity and non-smoking or smoking cessation is associated with maintenance of cardiorespiratory fitness. Change in physical activity habits is associated with change in cardiorespiratory fitness, but respiratory function contributed little to this association during a five year follow up.

Depression decreases cardiorespiratory fitness in older women

BACKGROUND

Depression is associated with decreased physical functioning and increased morbidity and mortality from cardiovascular disease and cancer. Whereas physical fitness delays all-cause mortality, little is known of the exercise capacity of depressed women.

METHOD

SPPARCS is a community-based longitudinal study of physical activity and fitness in people > or =55 years. Of 1,246 women, 663 were free of known cardiac and cerebrovascular disease, and performed treadmill exercise. Most (71%) were interviewed and retested 2 years and 4 years later (55%). Two indicators of depression were used: (a) Center for Epidemiologic Studies-Depression Scale (CES-D) > or =16; (b) use of antidepressant medication.

RESULTS

By CES-D score, 8.4% had depressive symptoms (first round). Depressed women showed lower levels of all markers of treadmill exercise [exercise duration, peak VO2, Oxygen Uptake Efficiency Slope (OUES)].

CONCLUSIONS

Depression is associated with impaired physical fitness and treadmill exercise performance in older women.

Effects of daily activity recorded by pedometer on peak oxygen consumption (VO2peak), ventilatory threshold and leg extension power in 30- to 69-year-old Japanese without exercise habit

The relationships among walk steps, exercise habits and peak oxygen consumption (VO2peak), ventilatory threshold (VT) and leg extension power (LEP) were examined in 709 apparently healthy Japanese subjects (male 372, female 337) aged 30-69 years. Walk steps were evaluated using a pedometer. VO2peak and VT were assessed by a cycle ergometer test, while LEP was measured with an isokinetic leg extension system (Combi, Anaero Press 3500, Japan). Subjects who participated in exercise three times or more a week demonstrated significantly greater VO2peak and VT when compared with subjects without exercise habits. When a separate analysis was conducted on subjects who exercised fewer than three times per week, we found that the subgroup with the highest number of walk steps showed significantly greater VT in all male subjects and female subjects aged 30-49 years, but a significantly greater VO2peak only in females aged 30-49 years, when compared to the subgroup with the fewest walk steps. These results suggest that although some people exercise less than three times a week, if they are quite active in daily life, such activities might also confer benefits upon their fitness.

Habitual walking and its correlation to better physical function: implications for prevention of physical disability in older persons

BACKGROUND

Our objective was to determine the association between participation in habitual physical activity (including walking, shopping, and indoor and outdoor activities) and leisure-time or sports activities on physical performance and fitness in older persons.

METHODS

In an observational study, 123 predominantly ethnic Chinese participants aged 50 years and older were recruited from a health promotion program. Main outcome measures were bioelectric impedance for body fat composition, peak oxygen consumption (VO(2)max), gait speed, handgrip strength, and chair rise time.

RESULTS

The mean age of participants was years. Those with a higher self-reported walking level had a better VO(2)max; every 1 minute per day increase in habitual walking increases VO(2)max by 0.096 (ml/kg)/min (95% confidence interval [CI] 0.027-0.165, p=.007) and is possibly associated with a faster gait speed; (95% CI 0.000-0.005, p=.078). There is an age-related rise in body fat composition, decline in VO(2)max, and slower chair rise time. Men had a lower body fat composition, better VO(2)max, and stronger handgrip.

CONCLUSIONS

Habitual walking may impart important health benefits in terms of improvement in physical performance, fitness, and its implications for the prevention of physical disability in older adults. This also reinforces the theory that low- to moderate-intensity activities may improve cardiorespiratory fitness. There is an inevitable physiological age-related decline in physical fitness.

Living arrangements and participation in leisure-time physical activities in an older population

OBJECTIVES

This is a cross-sectional investigation of living arrangements, social contacts, and level of leisure-time physical activity (LTPA) among residents of Sonoma, California, aged 55 and older.

METHODS

The odds of different levels of LTPA were assessed by living arrangements and social contacts following adjustment for measures of health, functioning, physical performance, selected health behaviors, and socioeconomic status for men and women separately (n = 2,073). Level of LTPA also was examined among married couples only (subset of sample, n = 511 spouse pairs).

RESULTS

The relationship between living arrangements, social contacts, and LTPA varied by gender and level of LTPA. Among married couples, the LTPA of the partner was the most significant predictor of the LTPA of the participant, with the exception of those who engaged in less than brisk activity.

DISCUSSION

Living arrangements and social contacts are important determinants of LTPA and should serve as the basis for future interventions.

Cardiovascular health and physical activity in older adults: an integrative review of research methodology and results

PURPOSE OF THE PAPER: The purpose of this article is to review the literature on physical activity and its relationship to cardiovascular risk factors and mortality in older adults, in an effort to clarify the specific benefits and optimal level of physical activity for cardiovascular health in the older adult population.

BACKGROUND/RATIONALE

Despite physical activity being recognized as an important factor in the quality of life of older adults, there is a lack of clarity about the optimal level of physical activity that results in positive cardiovascular health benefits.

DESIGN/METHODS

An integrative review of the literature using the MEDLINE and CINAHL databases from 1990 through August 2000 was conducted identifying articles related to physical activity and cardiac risk factors, cardiovascular health, or mortality in the older adult.

RESULTS/FINDINGS

Forty-four research articles were reviewed. The intervention studies generally provided support for positive cardiovascular changes with exercise, but the results were inconsistent, sample sizes were small, and the outcomes, interventions, and measures of physical activity differed between studies. There was wide variation in the method of measurement of physical activity in the studies. Studies showed an increase in mortality in those who had a sedentary lifestyle compared to those who were more physically active. Results were mixed related to plasma lipids levels. Three studies showed a positive effect of physical activity on blood pressure (BP), while three studies showed no relationship. Each of the studies that evaluated the relationship between physical activity and pulse rate showed a decreased rate with increased physical activity.

CONCLUSIONS

The quantity and type of physical activity that should be recommended to bring about positive effects on cardiovascular health and mortality is unclear. There is support, however, that an active lifestyle decreases mortality. There is conflicting evidence to support positive effects of physical activity on cardiac risk factors. Further research is needed with larger sample sizes, better control of extraneous variables, and using measurements of physical activity that have undergone adequate psychometric testing.

Effects of moderate-intensity exercise on physiological, behavioral, and emotional responses to family caregiving: a randomized controlled trial

BACKGROUND

The study objective was to determine the health and quality-of-life effects of moderate-intensity exercise among older women family caregivers.

METHODS

This 12-month randomized controlled trial involved a volunteer sample of 100 women aged 49 to 82 years who were sedentary, free of cardiovascular disease, and caring for a relative with dementia. Participants were randomized to 12 months of home-based, telephone-supervised, moderate-intensity exercise training or to an attention-control (nutrition education) program. Exercise consisted of four 30- to 40-minute endurance exercise sessions (brisk walking) prescribed per week at 60% to 75% of heart rate reserve based on peak treadmill exercise heart rate. Main outcomes were stress-induced cardiovascular reactivity levels, rated sleep quality, and reported psychological distress.

RESULTS

Compared with nutrition participants (NU), exercise participants (EX) showed significant improvements in the following: total energy expenditure (baseline and post-test means [SD] for EX = 1.4 [1.9] and 2.2 [2.2] kcal/kg/day; for NU = 1.2 [1.7] and 1.2 [1.6] kcal/kg/day; p <.02); stress-induced blood pressure reactivity (baseline and post-test systolic blood pressure reactivity values for EX = 21.6 [12.3] and 12.4 [11.2] mm Hg; for NU = 17.9 [10.2] and 17.7 [13.8] mm Hg; p <.024); and sleep quality (p <.05). NU showed significant improvements in percentages of total calories from fats and saturated fats relative to EX (p values <.01). Both groups reported improvements in psychological distress. Conclusions. Family caregivers can benefit from initiating a regular moderate-intensity exercise program in terms of reductions in stress-induced cardiovascular reactivity and improvements in rated sleep quality.

A comparison of physical activity levels in two contrasting elderly populations in Thailand

There is little information available on physical activity patterns in the elderly in developing countries. This is particularly important at a time when developing countries are in transition and show signs of moving toward Western style patterns of physical activity and social structure. This study is unique in that it compares the physical activity levels in two contrasting communities: a residential home and a rural community of elderly subjects in Thailand. Ninety elderly people living in a residential home and 78 elderly people living with their families in a rural community were recruited. The men in the rural community were slightly lighter and leaner than the men in the residential community, but the differences were not significant. However, the women were significantly (P < 0.001) heavier and fatter in the residential home than in the rural community. This is consistent with the higher levels of physical activity in the rural community. There was considerable variation in physical activity in this population. The physical activity level (PAL) values ranged from 1.21 to 1.73 in the residential home and from 1.21 to 3.08 in the rural community. This is apparently the first study of physical activity patterns in elderly subjects in a developing country. It highlights the variation in activity within the rural community and between both communities. The opportunities for the elderly living in the residential home to have active lifestyles are limited. It is likely that this will result in increased morbidity in the final years of life.