Biomedical subjects

Stephen B Kritchevsky

Publications and source records attributed to Stephen B Kritchevsky.

At least 37 records · Page 2Linked to original sources

PubMed2005

Reciprocal influence of concurrent walking and cognitive testing on performance in older adults.

This study investigated how cognitive and walking performance are influenced when performed concurrently in older adults and what factors are associated with poorer dual-task responses. Using a dual-task study design, 217 subjects aged 74-85 years completed three information processing test conditions--(1) no test; (2) push-button simple reaction-time; and (3) visual-spatial decision reaction-time; and three walking test conditions--(1) seated; (2) walking over a 20m straight course; and (3) walking over 20m with a turn. Push-button and visual-spatial reaction-times increased approximately 21% and 6%, respectively, while walking compared to sitting (p<0.008). Reaction-time tests had a relatively weak impact on walking-time. Poorer dual-task walking-time responses correlated with slower walking velocity and weaker muscle strength (p< or =.062). Findings suggest that walking requires significant cognitive resources among older adults and slower-walking adults and weaker adults may require higher cognitive loading while walking.

Age Factors↗

PubMed2005

Preinfection systemic inflammatory markers and risk of hospitalization due to pneumonia.

RATIONALE: Elevated proinflammatory cytokines are associated with severity of pneumonia, but the role of preinfection cytokine levels in the predisposition to pneumonia in humans is less clear. OBJECTIVE: To ascertain role of preinfection inflammatory markers on susceptibility to community-acquired pneumonia (CAP). METHODS: Longitudinal analysis over 6.5 yr of a cohort that consisted of 70- to 79-yr-old well-functioning elderly individuals. MEASUREMENTS: Association between preinfection tumor necrosis factor (TNF), interleukin 6 (IL-6), and C-reactive protein (CRP) levels and CAP requiring hospitalization. RESULTS: Of the 3,075 participants, 161 (5.2%) developed at least one episode of CAP requiring hospitalization over a median duration of 3.3 yr. The highest tertiles of TNF (> 3.7 pg/ml) and IL-6 (> 2.4 pg/ml) were associated with increased risk of CAP, and the adjusted odds ratios were 1.6 (95% confidence interval [CI], 1.02-2.7) and 1.7 (95% CI, 1.1-2.8), respectively. The adjusted risk of CAP with at least one of these markers in the highest tertile was 1.6 (95% CI, 1.1-2.3). TNF and IL-6 levels in the highest tertile had a synergistic effect (p = 0.01 for interaction), and risk of CAP for both markers in the highest tertile was 2.8 (95% CI, 1.8-4.3). An FEV(1) of 50% or less of predicted was associated with the highest risk of CAP (adjusted odds ratio, 3.6; 95% CI, 2.3-5.6). Furthermore, TNF and IL-6 levels modified risk of CAP in participants with coexisting medical conditions and history of smoking. CONCLUSION: In the well-functioning elderly subjects, preinfection systemic levels of TNF and IL-6 were associated with higher risk of CAP requiring hospitalization in smokers and those with coexisting medical conditions.

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PubMed2005

Angiotensin-converting enzyme insertion/deletion genotype, exercise, and physical decline.

CONTEXT: Physical performance in response to exercise appears to be influenced by the angiotensin-converting enzyme (ACE) insertion (I)/deletion (D) genotype in young adults, but whether this relationship could help explain variation in older individuals' response to exercise has not been well studied. OBJECTIVE: To determine whether the ACE genotype interacts with significant physical activity to affect the incidence of mobility limitation in well-functioning older adults. DESIGN, SETTING, AND PARTICIPANTS: The Health Aging and Body Composition (Health ABC) Cohort Study, conducted in the metropolitan areas of Memphis, Tenn, and Pittsburgh, Pa. A total of 3075 well-functioning community-dwelling adults aged 70 through 79 years were enrolled from 1997 to 1998 and had a mean of 4.1 years of follow-up. MAIN OUTCOME MEASURE: Incident mobility limitation defined as the report of difficulty walking a quarter of a mile (0.4 km) or walking up 10 steps on 2 consecutive semiannual interviews (n = 1204). RESULTS: Physically active participants (those reporting expending > or =1000 kcal/wk in exercise, walking, and stair climbing) were less likely to develop mobility limitation regardless of genotype. However, activity level interacted significantly with the ACE genotype (P = .002). In the inactive group, the ACE genotype was not associated with limitation (P = .46). In the active group, those with the II genotype were more likely to develop mobility limitation after adjusting for potential confounders compared with those with ID/DD genotypes (adjusted rate ratio, 1.45, 95% confidence interval, 1.08-1.94). The gene association was especially strong among participants reporting weightlifting. Exploration of possible physiological correlates revealed that among active participants, those with the II genotype had higher percentage of body fat (P = .02) and more intermuscular thigh fat (P = .02) but had similar quadriceps strength as those with ID/DD. CONCLUSIONS: Among older individuals who exercised, those with the ACE DD or ID genotypes were less likely to develop mobility limitation than those with the II genotype. Regardless of genotype, individuals who exercised were less likely to develop mobility limitation than those who did not exercise.

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PubMed2005

Skeletal muscle fatigue, strength, and quality in the elderly: the Health ABC Study.

We examined the muscle fatigue characteristics in older men and women and determined whether these were related to the size, strength, or quality of muscle. A total of 1,512 men and women aged 70-79 yr from the Health, Aging, and Body Composition Study participated in this study. Muscle cross-sectional area and attenuation were determined with computed tomography. Skeletal muscle fatigue and strength (peak torque) of the knee extensors and flexors were measured using isokinetic dynamometry. Men were more fatigue resistant than women for both knee extension (fatigue index: 70.4 +/- 15.3 vs. 66.9 +/- 14.3%; P < 0.05) and knee flexion (67.9 +/- 16.4 vs. 64.9 +/- 17.6%; P < 0.05). Peak torque and muscle quality (specific torque) were higher in men than women for knee extension (99.6 +/- 28.2 vs. 63.0 +/- 16.8 N x m and 1.62 +/- 0.43 vs. 1.51 +/- 0.39 N x m/cm2; both P < 0.05) and for knee flexion (74.0 +/- 26.4 vs. 49.6 +/- 15.9 N x m and 2.47 +/- 1.29 vs. 2.22 +/- 0.78 N x m/cm2; both P < 0.05). Total work and power output was greater in men compared with women for both the quadriceps (1,353 +/- 451 vs. 832 +/- 264 J and 87.7 +/- 33.5 vs. 53.3 +/- 19.2 W; both P < 0.05) and the hamstrings (741 +/- 244 vs. 510 +/- 141 J and 35.4 +/- 16.0 vs. 23.7 +/- 10.2 W; both P < 0.05). In both genders, the quadriceps was able to perform more work with greater power compared with the hamstrings. Those who were stronger actually had greater fatigue after adjusting for age, race, physical activity, and total body fat. In conclusion, older men were more fatigue resistant than women, although in both men and women greater fatigue was not related to muscle weakness.

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PubMed2005

Inflammatory markers and cardiovascular health in older adults.

In the past decade inflammatory markers have emerged as strong independent risk indicators for cardiovascular disease. Even though adults over the age of 65 experience a high proportion of such events, most epidemiologic data are from middle-aged populations. In this review we examine the role that inflammatory markers play in the prediction of incident cardiovascular disease specifically in older adults. In studies of adults < 65 years, IL-6, TNFalpha and IL-10 levels have been shown to predict cardiovascular outcomes. The data on C-reactive protein are inconsistent, but CRP levels appear to be less useful in old-age than in middle-age. Fibrinogen levels predict mortality but in a non-specific manner. In the elderly inflammatory markers are non-specific measures of health and predict both disability and mortality even in the absence of clinical cardiovascular disease. Thus it is possible that, in older age-groups, interventions designed to prevent cardiovascular disease through the modulation of inflammation would also be helpful in reducing disability and mortality.

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PubMed2005

Socioeconomic differences in cognitive decline and the role of biomedical factors.

PURPOSE: This study examines the association between socioeconomic status and cognitive decline in a community-based cohort of well-functioning older adults and seeks to determine whether this link could be explained by biomedical factors. METHODS: Data are from 2574 men and women aged 70 to 79 years from Pittsburgh, PA, and Memphis, TN, participating in the Health, Aging and Body Composition study (Health ABC). Three indicators of socioeconomic status were used: education, income, and ownership of financial assets. Cognitive decline over 4 years was defined as a decrease of five points or more in the Modified Mini-Mental State Examination (3MS) score. Biomedical factors measured at baseline, included heart disease, cerebrovascular disease, diabetes, hypertension, poor pulmonary function, and high serum levels of inflammatory markers. RESULTS: Adjusted odds ratios were significantly higher in those with low education, low income, and few assets. Odds ratios ranged from 1.51 to 2.16 in the lowest socioeconomic groups. Additional adjustment for biomedical factors reduced the odds ratios of cognitive decline by an average of 2% for education, 5% for income, and 8% for the number of assets. CONCLUSIONS: Low socioeconomic status predicts a decline in cognitive function in older adults and this relationship is not mediated by biomedical factors.

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PubMed2005

The lifestyle interventions and independence for elders (LIFE) pilot study: design and methods.

The LIFE study is a multicenter pilot for a proposed full scale, two-arm randomized controlled trial that will contrast the effect of a physical activity intervention with a successful aging education program on the occurrence of incident major mobility disability (the inability to complete a 400 m walk) or death in at-risk sedentary older adults. Four hundred older adults from 4 clinical sites will be recruited for this purpose. All participants will be followed for at least 1-year; however, we will continue to follow all participants until the final randomized individual has reached the 1-year mark. This will enable us to acquire additional information about maintenance. Additional outcomes will include lower extremity physical performance as well as gait speed over 4 m and 400 m. These latter measures will provide data on the efficacy of the intervention on intermediate endpoints linked to the primary outcome of interest. The goals of the pilot study are to (a) estimate the sample size needed for a full scale trial, (b) examine the consistency of the effects of the physical activity intervention on several continuous measures of physical function, (c) assess the feasibility of recruitment, (d) evaluate study adherence and retention, (d) evaluate the efficacy of a stepped care approach for managing intercurrent illness in this at-risk population, and (e) develop a comprehensive system for monitoring and ensuring participant safety. Other goals of this pilot phase include assessments of health-related quality of life and cost-effectiveness.

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PubMed2005

Sarcopenia, obesity, and inflammation--results from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors study.

BACKGROUND: Age-related body-composition changes are associated with health-related outcomes in elders. This relation may be explained by inflammation and hemostatic abnormalities. OBJECTIVES: Our objectives were to evaluate the relation between body-composition measures [body mass index (BMI), total fat mass, and appendicular lean mass (aLM)] and C-reactive protein (CRP), interleukin 6 (IL-6), and plasminogen activator inhibitor 1 (PAI-1) and to explore the effect of obesity and sarcopenia on CRP, IL-6, and PAI-1 concentrations. DESIGN: The data are from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors (TRAIN) study baseline visit (n = 286; mean age = 66.0 y). Total fat mass and aLM were assessed with a dual-energy X-ray absorptiometry scan. Linear regressions were performed between body-composition measures and CRP, IL-6, or PAI-1 concentrations. The effect of sarcopenia and obesity (defined as the percentage of fat mass) on CRP, IL-6, and PAI-1 concentrations was evaluated with the use of analyses of covariance. RESULTS: CRP and IL-6 were positively associated with both BMI [beta = 0.027 (P = 0.03) and beta = 0.048 (P < 0.001), respectively] and total fat mass [beta = 0.049 (P < 0.001) and beta = 0.055 (P < 0.001), respectively] and were inversely associated with fat-adjusted aLM [beta = -0.629 (P = 0.002) and beta = -0.467 (P = 0.02), respectively]. PAI-1 was positively associated with both BMI (beta = 0.038, P = 0.005) and total fat mass (beta = 0.032, P = 0.007). No significant interaction was found between either obesity or sarcopenia and CRP, IL-6, and PAI-1 concentrations. Obesity remained significantly associated with high CRP and IL-6 concentrations after adjustments for sarcopenia. CONCLUSIONS: CRP and IL-6 are positively associated with total fat mass and negatively associated with aLM. Obesity-associated inflammation may play an important role in the age-related process that leads to sarcopenia. The relation of inflammation with sarcopenia was not independent of any of the considered obesity indexes.

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PubMed2005

Lower serum albumin concentration and change in muscle mass: the Health, Aging and Body Composition Study.

BACKGROUND: Low albumin concentrations in older persons increase the risk of poor health outcomes, including functional decline. OBJECTIVE: The aim of the study was to investigate the association between serum albumin concentration and skeletal muscle loss (sarcopenia) in old age. DESIGN: Serum albumin concentration was measured in 1882 black and white men and women aged 70-79 y participating in the Health, Aging and Body Composition Study. Five-year changes in appendicular skeletal muscle mass (ASMM), total-body fat-free mass (FFM), and trunk lean mass (TLM) were measured by using dual-energy X-ray absorptiometry. Confounders included health and lifestyle factors, which are markers of inflammation and protein intake. RESULTS: A low albumin concentration (< 38 g/L) was observed in 21.2% of the study participants. After adjustment for confounders, the mean (+/-SE) change in ASMM was -82 +/- 26 g per 3-g/L lower albumin concentration (P = 0.002). This association remained after persons with a low albumin concentration (< 38 g/L) were excluded. The decline in ASMM in subjects with low albumin concentrations was almost 30% higher (-930 +/- 56 g) than that in those with albumin concentrations > or = 42 g/L (-718 +/- 38 g; P < 0.01). The association between albumin and change in ASMM remained after additional adjustment for weight change. A weak association was observed for FFM, whereas no association was observed for TLM, which suggests a specific role of albumin in skeletal muscle change. CONCLUSIONS: Lower albumin concentrations, even above the clinical cutoff of 38 g/L, are associated with future loss of ASMM in older persons. Low albumin concentration may be a risk factor for sarcopenia.

Absorptiometry, Photon↗

PubMed2005

Dietary glycemic index and load, measures of glucose metabolism, and body fat distribution in older adults.

BACKGROUND: Recent evidence suggests that the rate of carbohydrate digestion and absorption may influence the development of type 2 diabetes. OBJECTIVE: The aim of this study was to examine associations of dietary glycemic index and glycemic load with predictors of type 2 diabetes in older adults. DESIGN: This study evaluated cross-sectional relations of dietary glycemic index and glycemic load with measures of glucose metabolism and body fat distribution in participants of the Health, Aging and Body Composition Study, a prospective cohort study of adults aged 70-80 y (n = 2248). RESULTS: In men, dietary glycemic index was positively associated with 2-h glucose (P for trend = 0.04) and fasting insulin (P for trend = 0.004), inversely associated with thigh intramuscular fat (P for trend = 0.02), and not significantly associated with fasting glucose, glycated hemoglobin, or visceral abdominal fat. Dietary glycemic load was inversely associated in men with visceral abdominal fat (P for trend = 0.02) and not significantly associated with fasting glucose, 2-h glucose, glycated hemoglobin, fasting insulin, or thigh intramuscular fat. In women, although dietary glycemic index and load were not significantly related to any measures of glucose metabolism or body fat distribution, the association between dietary glycemic index and 2-h glucose was nearly significant (P for trend = 0.06). CONCLUSION: The findings of this cross-sectional study indicate an association between dietary glycemic index and selected predictors of type 2 diabetes in older adults, particularly in men.

Adipose Tissue↗

PubMed2005

Short-term weight changes in community-dwelling older adults: the Health, Aging, and Body Composition Weight Change Substudy.

BACKGROUND: The frequency and short-term natural history of weight loss in community-dwelling older adults have not been described. Unintentional weight loss may be more likely to continue than intentional weight loss. OBJECTIVES: The present substudy described the frequency of a > or = 5% loss or gain in body weight in community-dwelling older adults at an annual examination of the Health, Aging, and Body Composition (Health ABC) Study and 6 mo later. The weight-management practices used by the participants were also described. DESIGN: A total of 522 older adults with either a > or = 5% weight gain (n = 116) or a > or = 5% weight loss (n = 171) in the previous year were compared with a random sample of weight-stable older adults (< 5% weight loss or gain, n = 235) at the fourth annual visit of the ongoing Health ABC Study. The participants' weight-loss intention and weight-management practices were assessed by an interview. The participants' weight was reassessed 6 mo later. RESULTS: Compared with the weight-stable participants, the participants who had lost or gained weight at the substudy baseline were more likely to have subsequent weight changes. The direction of the subsequent weight change, however, was more likely toward either maintenance of or recovery from the previous weight change. Only 4% of the participants who gained weight and 11% of those who lost weight continued to gain or lose weight, respectively. Continued weight loss was more common in the participants with unintentional weight loss than in those with intentional weight loss, but the difference was not significant. CONCLUSIONS: Weight changes were common, but most participants, including those who unintentionally lost weight, maintained their weight change or resolved their weight change in 6 mo. Unintentional weight loss appears less likely to resolve than other weight changes.

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PubMed2005

Weight change and the conservation of lean mass in old age: the Health, Aging and Body Composition Study.

BACKGROUND: Weight loss may contribute to the loss of lean mass with age. OBJECTIVE: The objective was to evaluate the relation between weight loss or weight gain and changes in lean mass and fat mass in older adults. DESIGN: We observed changes in weight and body composition during a 4-y period in 2163 men (47%) and women (53%) aged 70-79 y in the Health, Aging and Body Composition Study cohort. Whole-body and appendicular bone-free lean mass and fat mass were measured by using dual-energy X-ray absorptiometry. RESULTS: Weight loss and weight gain were common. In both weight losers and weight gainers, changes in lean mass as a percentage of initial lean mass were substantially smaller than changes in fat mass as a percentage of initial fat mass. However, the difference between the change in lean mass and that in fat mass was more pronounced with weight gain than with weight loss, especially in men. Small amounts of lean loss and fat gain were noted with weight stability. In multivariate models, weight loss was strongly associated with lean mass loss in both men and women, especially in men whose weight loss was concurrent with a hospitalization. CONCLUSIONS: With weight change, a greater proportion of lean mass than of fat mass was conserved, but, especially in older men, significantly more lean mass was lost with weight loss than was gained with weight gain. These findings suggest that weight loss, even with regain, could accelerate sarcopenia in older adults.

Absorptiometry, Photon↗

PubMed2005

Angiotensin-converting enzyme inhibition intervention in elderly persons: effects on body composition and physical performance.

The disablement process is often accompanied by sarcopenia or muscle loss, which is associated with virtually all identified disability risk factors. Clinically, the association between body composition and physical performance has been documented by several studies. However, loss of strength is greater than loss of muscle mass with age implying that the quality of remaining muscle may be reduced. Although there are limited data explaining potential physiological mechanisms that contribute to muscle quality, sarcopenia is frequently associated with fat accumulation, and the percentage of body fat increases with age even if weight does not. However, the relationship between fat and muscle function may not be linear, suggesting that there may be an optimal ratio of lean to fat mass for physical function. There are no definitive pharmacological interventions proven to prevent decline in physical function either by modulating body composition or by other means. One exception may be angiotensin-converting enzyme inhibitors (ACEIs). ACE is an important component of the renin-angiotensin system, the central hormonal regulator of blood pressure. Recent evidence suggests that ACEIs may improve physical function by means of direct effects on body composition in older persons, rather than through its blood-pressure-lowering effects. Clinical and genetic studies in humans and experimental evidence in animals suggest that modulation of the renin-angiotensin system is associated with metabolic and biochemical changes in skeletal muscle and fat, changes that are associated with declining physical function. ACEIs may modulate this process through a variety of molecular mechanisms including their influence on oxidative stress and on metabolic and inflammation pathways. This review describes potential biological mechanisms of ACE inhibition and its contribution to declining physical performance and changing body composition. Promising pharmacoepidemiological studies and experimental evidence in animals suggest that there are appropriate models in which to study this effect.

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PubMed2005

Muscle mass, muscle strength, and muscle fat infiltration as predictors of incident mobility limitations in well-functioning older persons.

BACKGROUND: Lower muscle mass has been correlated with poor physical function; however, no studies have examined this relationship prospectively. This study aims to investigate whether low muscle mass, low muscle strength, and greater fat infiltration into the muscle predict incident mobility limitation. METHODS: Our study cohort included 3075 well-functioning black and white men and women aged 70-79 years participating in the Health, Aging, and Body Composition study. Participants were followed for 2.5 years. Muscle cross-sectional area and muscle tissue attenuation (a measure of fat infiltration) were measured by computed tomography at the mid-thigh, and knee extensor strength by using a KinCom dynamometer. Incident mobility limitation was defined as two consecutive self-reports of any difficulty walking one-quarter mile or climbing 10 steps. RESULTS: Mobility limitations were developed by 22.3% of the men and by 31.8% of the women. Cox's proportional hazards models, adjusting for demographic, lifestyle, and health factors, showed a hazard ratio of 1.90 [95% confidence interval (CI), 1.27-2.84] in men and 1.68 (95% CI, 1.23-2.31) in women for the lowest compared to the highest quartile of muscle area (p <.01 for trend). Results for muscle strength were 2.02 (95% CI, 1.39-2.94) and 1.91 (95% CI, 1.41-2.58), p <.001 trend, and for muscle attenuation were 1.91 (95% CI, 1.31-2.83) and 1.68 (95% CI, 1.20-2.35), p <.01 for trend. When included in one model, only muscle attenuation and muscle strength independently predicted mobility limitation (p < .05). Among men and women, associations were similar for blacks and whites. CONCLUSION: Lower muscle mass (smaller cross-sectional thigh muscle area), greater fat infiltration into the muscle, and lower knee extensor muscle strength are associated with increased risk of mobility loss in older men and women. The association between low muscle mass and functional decline seems to be a function of underlying muscle strength.

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PubMed2005

Weight change, weight change intention, and the incidence of mobility limitation in well-functioning community-dwelling older adults.

BACKGROUND: Obesity increases the risk for functional decline in later years, but the functional consequences of weight change in older adults are currently unclear. The aim of this study was to determine whether weight, weight change, and weight change intention are associated with risk for mobility limitation in elderly persons. METHODS: This study included 2,932 well-functioning black and white men and women aged 70 to 79 years, participating in the Health, Aging and Body Composition (Health ABC) Study, who were followed for 30 months. At baseline, reported weight change of 5 or more pounds during the previous year and weight change intention were assessed. Mobility limitation was defined as reported difficulty or inability to walk one-quarter mile or to climb 10 steps during two consecutive semiannual assessments during a period of 30 months. RESULTS: Approximately 30% of participants developed mobility limitation. Higher body mass index (BMI) was associated with increased risk for mobility limitation. Unintentional weight loss in the previous year was associated with increased risk for mobility limitation in the extremely obese, which was defined as BMI >or= 35 (hazard ratios [HR], =3.79; 95% confidence interval [CI], 1.84--7.79), and the normal BMI, which was defined as BMI<25 (HR, 2.55; 95% CI, 1.80--3.60). In persons with BMI 25 to 29.9, intentional weight loss (HR, 1.59; 95% CI, 1.12--2.25) and weight fluctuation with any intention (HR, 1.59; 95% CI, 1.10--2.28) increased the risk for mobility limitation. Unintentional weight gain or fluctuation did not confer additional risk for mobility limitation compared with weight stability, regardless of the level of body weight. CONCLUSION: In this cohort of well-functioning elderly persons, functional consequences of past weight change depended on the type of weight change, intentionality, and current measured body weight.

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PubMed2005

Is there a biomedical explanation for socioeconomic differences in incident mobility limitation?

BACKGROUND: The association between low socioeconomic status and poor physical functioning has been well described; biomedical factors may play an important role in explaining these differences. This study examines the association between socioeconomic status and incident mobility limitation in well-functioning older adults, and seeks to determine whether this link could be explained by biomedical factors. METHODS: Data were obtained from 3066 men and women, aged 70--79 years from Pittsburgh, Pennsylvania and Memphis, Tennessee participating in the Health, Aging and Body Composition (Health ABC) study. Three indicators of socioeconomic status were used: education, income, and ownership of financial assets. Mobility limitation was defined as reporting difficulty walking 1/4 mile or climbing 10 steps during two consecutive semiannual assessments over 4.5 years. Biomedical factors included a wide range of diseases (e.g., heart and cerebrovascular disease) and biological risk factors (e.g. hypertension, poor pulmonary function, and high serum levels of inflammatory markers). RESULTS: Adjusted hazard ratios of incident mobility limitation were significantly higher in those persons with low education, low income, and few assets. Hazard ratios ranged from 1.66 to 2.80 in the lowest socioeconomic groups. Additional adjustment for biomedical factors reduced the hazard ratios by an average of 41% for education, 17% for income, and 29% for assets. CONCLUSION: Biomedical factors can account for some of the association between socioeconomic status and incident mobility limitation. However, to reduce physical disabilities and, in particular, the socioeconomic differences therein, it may not be sufficient to solely intervene upon biological risk factors and risks of diseases.

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PubMed2005

Type and intensity of activity and risk of mobility limitation: the mediating role of muscle parameters.

OBJECTIVES: To investigate the association between different types of physical activity behavior and incident mobility limitation in older men and women and to examine whether muscle parameters mediate these associations. DESIGN: Cohort study with 4.5-year follow-up. SETTING: Metropolitan areas surrounding Pittsburgh, Pennsylvania, and Memphis, Tennessee. A random sample of white Medicare beneficiaries and all age-eligible blacks. PARTICIPANTS: Three thousand seventy-five black and white men and women aged 70 to 79 with no self-reported difficulty walking one-quarter of a mile or climbing 10 steps, enrolled in the Health, Aging and Body Composition (Health ABC) Study. MEASUREMENTS: Participants were classified as exercisers (reporting > or = 1,000 kcal/wk of exercise activity), lifestyle active (reporting < 1,000 kcal/wk of exercise activity and > or = 2,719 kcal/wk of total physical activity), or inactive (reporting < 1,000 kcal/wk of exercise activity and < 2,719 kcal/wk of total physical activity). The study outcome, incident mobility limitation, was defined as two consecutive, semiannual self-reports of any difficulty walking one quarter of a mile or climbing 10 steps. Thigh muscle area, thigh muscle attenuation (a marker of fat infiltration in muscle), appendicular lean soft tissue mass, and isokinetic knee extensor strength were examined as potential mediators. RESULTS: Over 4.5 years, 34.3% of men and 47.4% of women developed mobility limitation. Inactive persons had twice the risk of incident mobility limitation as exercisers (hazard ratio (HR)=2.08, 95% confidence interval (CI)=1.60-2.70, for men, HR=1.98, 95% CI=1.51-2.60, for women). Lifestyle-active men and women had an intermediate risk (HR=1.47 and 1.44, respectively). For the lifestyle active and inactive, absence of walking activity conferred an additional risk of mobility limitation. Muscle parameters did not mediate the relationship between physical activity and mobility limitation, except for knee extensor strength in men. CONCLUSION: Exercise and an active lifestyle that includes walking protect against mobility loss in older men and women. Activity effects on muscle parameters do not explain this association.

Activities of Daily Living↗

PubMed2005

Predictors of combined cognitive and physical decline.

OBJECTIVES: To determine the incidence and correlates of combined declines in cognitive and physical performance. DESIGN: Cohort study of community-dwelling older women with moderate to severe disability. SETTING: The community surrounding Baltimore, Maryland. PARTICIPANTS: Participants in the Women's Health and Aging Study I with Mini-Mental State Examination (MMSE) score or 24 or greater and walking speed greater than 0.4 m/s at baseline. MEASUREMENTS: Cognitive decline was defined as an MMSE score less than 24 and physical decline as a walking speed of 0.4 m/s or less in at least one of the three annual follow-up visits. Participants were stratified into groups based on cognitive or physical decline or both. Group characteristics were compared, and results were adjusted for age, race, education, and significant covariates. RESULTS: Of 558 women that met the baseline MMSE and walking speed inclusion criteria, 21% developed physical decline, 12% developed cognitive decline, and 11% experienced combined cognitive and physical decline. After adjustment, physical decline was associated with age, nonwhite race, former smoking, baseline walking speed, and instrumental activities of daily living (IADL) impairment. Cognitive decline was associated with age and baseline MMSE score. Combined decline was associated with age, baseline walking speed, MMSE score, IADL impairment, as well as current smoking (odds ratio (OR)=5.66, 95% confidence interval (CI)=1.49-21.54) and hemoglobin level (OR=0.68, 95% CI=0.47-0.98). CONCLUSION: Potential predictors of cognitive and physical performance decline were identified. The association between smoking and lower hemoglobin levels and combined cognitive and physical decline may represent potentially modifiable risk factors and should be confirmed in future studies.

Activities of Daily Living↗