Biomedical subjects

Jonathan F Bean

Publications and source records attributed to Jonathan F Bean.

14 recordsLinked to original sources

PubMed2006

Association of cardiorespiratory fitness and levels of C-reactive protein: data from the National Health and Nutrition Examination Survey 1999-2002.

BACKGROUND: Elevated C-reactive protein (CRP) is a risk factor for atherosclerosis. Cardiorespiratory fitness, the ability of active skeletal muscle to utilize oxygen during aerobic exercise, can be impaired by atherosclerotic changes peripherally affecting the vasculature or centrally perturbing the heart and coronary arteries. However, the association between cardiorespiratory fitness and CRP has not been adequately examined. METHODS: We examined 1438 adults aged 20-49 years with reliable measures of fitness and non-missing values in CRP from Health and Nutrition Examination Survey 1999-2002. Subjects with major cardiovascular and respiratory conditions were excluded from fitness test which measured the estimated maximal oxygen uptake (VO2max), by a submaximal exercise test. Levels of CRP were quantified by utilizing latex-enhanced nephelometry. RESULTS: In both genders, we observed inverse associations between estimated VO2max and levels of CRP after controlling for age, race, body mass index category, hypertension, diabetes, smoking status, alcohol consumption, and use of medications including aspirin, non-steroidal anti-inflammatory drugs, steroid, lipid-lowering agents, antimicrobials, or estrogen/progesterone (in women). Men in the 2nd, 3rd, and 4th quartiles of CRP concentrations had lower estimated VO2max compared to the first quartile (regression coefficients for quartile 2, -1.54 ml/kg/min, p=0.105; quartile 3, -1.46 ml/kg/min, p=0.130; quartile 4, -2.64 ml/kg/min, p=0.009; p for trend 0.013). Women in the highest quartile of CRP had a significantly lower estimated VO2max (2.40 ml/kg/min, p=0.023) compared to the lowest (p for trend 0.025). CONCLUSIONS: CRP levels, inversely related to cardiorespiratory fitness, are important indicators of exercise tolerance and may be useful in targeting individuals requiring endurance intervention to prevent loss of cardiovascular fitness and function.

Adult↗

PubMed2006

Does gynecologic surgery contribute to low back problems in later life? An analysis of the women's health and aging study.

OBJECTIVE: To examine whether women with potential injuries to the abdominal and pelvic musculature from past gynecologic surgery are at higher risk for low back pain (LBP). DESIGN: Cross-sectional population-based study. SETTING: Eastern region of the city and county of Baltimore, MD. PARTICIPANTS: Disabled women (N=1002) aged 65 and older, 448 of whom reported gynecologic surgery who were participants in the Women's Health and Aging Study. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: LBP presence in the last year, LBP severity for the last month, and adjudicated lumbar diagnoses (disk disease, stenosis) were examined in relation to reports of surgical menopause or ovarian surgery adjusted for LBP risk factors. RESULTS: Women with surgical menopause experienced more moderate LBP (adjusted odds ratio [AOR]=1.59; 95% confidence interval [CI], 1.1-2.3) than women without surgical menopause. Women with ovarian surgery also experienced more moderate LBP than women without ovarian surgery, but this association was not statistically significant (AOR=1.39; 95% CI, 0.96-2.09). Gynecologic surgery was not associated with an increased likelihood of lumbar disk disease or stenosis. CONCLUSIONS: Surgical menopause may increase the risk of moderate LBP. Further research is needed to determine how gynecologic surgery might influence low back pathology. Abdominal and pelvic muscle rehabilitation after gynecologic surgery may provide protection from LBP later in life.

Aged↗

PubMed2006

Exercise in the elderly: research and clinical practice.

Exercise programs for elderly patients have received much attention recently for their potential role in preventing illness and injury, limiting functional loss and disability, and alleviating the course and symptoms of existing cardiac, pulmonary, and metabolic disorders. The basic components of an exercise training program include strength, endurance, balance, and flexibility. This article reviews the main attributes of each, along with some of the most recent research defining their roles in health care. Where available, it discusses specific recommendations for prescribing exercise modalities. Finally, it presents suggestions for developing integrated exercise programs and enhancing patient compliance.

Accidental Falls↗

PubMed2006

Linking C-reactive protein to late-life disability in the National Health and Nutrition Examination Survey (NHANES) 1999-2002.

BACKGROUND: Chronic inflammation, measured by interleukin-6, predicts incident disability among elderly people. However, little is known about the relation of C-reactive protein (CRP) to disability. METHOD: Participants (>60 years old, N = 1680) were from the National Health and Nutrition Examination Survey 1999-2002. Disability in activities of daily living (ADL), instrumental activities of daily living (IADL), leisure and social activities (LSA), lower extremity mobility (LEM), and general physical activities (GPA) was obtained by self-report. Peak muscle power was the product of isokinetic peak leg torque and peak force velocity. Functional limitations were evaluated via habitual walking speed, which was obtained from a 20-foot timed walk. CRP levels were quantified by using latex-enhanced nephelometry. RESULTS: Elevated CRP levels were associated with disability in IADL, LSA, LEM, and GPA, independent of basic demographics, chronic medical diseases, health behaviors, as well as nutritional markers. The corresponding odds ratios of disability for each standard-deviation increase in natural-log-transformed CRP were 1.18 (95% confidence interval [CI], 1.02-1.35), 1.18 (95% CI, 1.00-1.39), 1.17 (95% CI, 1.03-1.33), and 1.17 (95% CI, 1.05-1.31), respectively. The relationship diminished after additional adjustment of leg power and/or walking speed, meaning that impairment in leg power and limitations in gait speed likely mediate the association between CRP and disability. CRP had an inverse relationship to leg power and walking speed. Likewise, additional adjustment for leg power substantially diminished the association between CRP and walking speed, suggesting a mediating effect of power between CRP and gait speed. CONCLUSIONS: Independent of chronic diseases, elevated CRP is associated with multiple domains of disability through mediation of muscle power, habitual gait speed, or both. Future research is needed to understand CRP as a risk factor for disability in older populations.

Activities of Daily Living↗

PubMed2006

Exploring how peak leg power and usual gait speed are linked to late-life disability: data from the National Health and Nutrition Examination Survey (NHANES), 1999-2002.

OBJECTIVE: To investigate the relation of both peak leg power and usual gait speed in their association with varying domains of late-life disability. DESIGN: Participants (> or =60 yrs of age, n = 1753) were from the National Health and Nutrition Examination Survey, 1999-2002. Disability in activities of daily living, instrumental activities of daily living, leisure and social activities, lower limb mobility, and general physical activities was obtained by self-report. Peak muscle power was the product of isokinetic peak leg torque and peak force velocity. Functional limitations were evaluated via usual gait speed, which was obtained from a 20-foot timed walk. RESULTS: Low usual gait speed was associated with disability independent of basic demographics, cognitive performance, co-morbidities, health behaviors, and inflammatory markers. The odds ratios for disabilities in activities of daily living, instrumental activities of daily living, leisure and social activities, lower limb mobility, and general physical activities for each standard-deviation increase in walking speed were 0.72 (95% confidence interval [CI], 0.59-0.87), 0.63 (95% CI, 0.52-0.77), 0.57 (95% CI, 0.45-0.72), 0.56 (95% CI, 0.47-0.67), and 0.74 (95% CI, 0.64-0.85), respectively. The odds ratios for disabilities in activities of daily living, instrumental activities of daily living, leisure and social activities, lower limb mobility, and general physical activities for each standard-deviation increase in leg power were 0.70 (95% CI, 0.55-0.89), 0.67 (95% CI, 0.53-0.86), 0.62 (95% CI, 0.47-0.83), 0.58 (95% CI, 0.47-0.72), and 0.73 (95% CI, 0.61-0.87), respectively. Supplementary adjustment for walking speed mildly attenuated the relation of leg power to disability. CONCLUSION: Peak leg power and habitual gait speed were associated with varying domains of late-life disability. The association between peak leg power and disability seems to be partially mediated through usual gait speed.

Activities of Daily Living↗

PubMed2005

Upper and lower limb muscle power relationships in mobility-limited older adults.

BACKGROUND: Lower limb muscle power impairments are modifiable factors underlying mobility limitations in older adults. This study examined relationships between upper and lower limb muscle power and their role in predicting mobility performance among community-dwelling older adults. METHODS: A cross-sectional analysis was conducted. Participants included 37 mobility-limited adults (24 women, 13 men), aged 65 to 93 years. Measures included upper (elbow extension) and lower limb (double leg press) one repetition maximum (1RM), and muscle power at both 40% and 70% one repetition maximum. Physical performance measures included stair climb time, the Short Physical Performance Battery, and 4-meter walk time. Factors commonly mediating the relationship between impairments and physical performance were analyzed as covariates. RESULTS: Participants had a mean age of 76 years, had five chronic medical conditions, and manifested moderate mobility limitations. Although the associations between the upper and lower limbs were strong (p <.001), the magnitude of association was greater for power (r =.88-.89) as compared to strength (r =.69). Multivariate regression analyses revealed consistently strong relationships between limb muscle power and mobility performance measures. Substituting upper for lower limb power within these models did not materially weaken the relationships. CONCLUSION: Muscle power appears to be a more generalized attribute between the upper and lower limbs than is muscle strength, suggesting that mechanisms underlying velocity of movement, as opposed to force production, may be important factors underlying muscle power in elderly persons. Additionally, upper limb muscle power measures may serve as a useful surrogate measure of limb power having implications for clinicians and researchers.

Aged↗

PubMed2004

High-intensity resistance training improves muscle strength, self-reported function, and disability in long-term stroke survivors.

BACKGROUND AND PURPOSE: To evaluate the efficacy of supervised high-intensity progressive resistance training (PRT) on lower extremity strength, function, and disability in older, long-term stroke survivors. METHODS: Forty-two volunteers aged 50 years and above, 6 months to 6 years after a single mild to moderate stroke, were randomized into either a control group of upper extremity stretching or a PRT group that received a 12-week supervised high-intensity resistance training program consisting of bilateral leg press (LP), unilateral paretic and nonparetic knee extension (KE), ankle dorsiflexion (DF), and plantarflexion (PF) exercises. Functional performance was assessed using the 6-minute walk, stair-climb time, repeated chair-rise time, and habitual and maximal gait velocities. Self-reported changes in function and disability were evaluated using the Late Life Function and Disability Instrument (LLFDI). RESULTS: Single-repetition maximum strength significantly improved in the PRT group for LP (16.2%), paretic KE (31.4%), and nonparetic KE (38.2%) with no change in the control group. Paretic ankle DF (66.7% versus -24.0%), paretic ankle PF (35.5% versus -20.3%), and nonparetic ankle PF (14.7% versus -13.8%) significantly improved in the PRT group compared with the control. The PRT group showed significant improvement in self-reported function and disability with no change in the control. There was no significant difference between groups for any performance-based measure of function. CONCLUSIONS: High-intensity PRT improves both paretic and nonparetic lower extremity strength after stroke, and results in reductions in functional limitations and disability.

Aged↗

PubMed2004

Benefits of exercise for community-dwelling older adults.

UNLABELLED: This focused review highlights the benefits of exercise and physical activity for community-dwelling older adults. It is part of the study guide on geriatric rehabilitation in the Self-Directed Physiatric Education Program for practitioners and trainees in physical medicine and rehabilitation. This article specifically focuses on the benefits of physical activity and exercise for older adults with regard to morbidity, mortality, and disability. It discusses the appropriate preexercise screening and evaluation procedures for older adults contemplating exercise. Last, it reviews the current literature on the benefits of varying modes of exercise to modify the most prevalent chronic medical conditions of late life, including arthritis, heart disease, diabetes, stroke, pulmonary disease, and osteoporosis. OVERALL ARTICLE OBJECTIVE: To summarize the current knowledge regarding the therapeutic benefits of exercise for community-dwelling older adults.

Accidental Falls↗

PubMed2004

Increased Velocity Exercise Specific to Task (InVEST) training: a pilot study exploring effects on leg power, balance, and mobility in community-dwelling older women.

OBJECTIVES: To evaluate a dynamic form of weighted vest exercise suitable for home use and designed to enhance muscle power, balance, and mobility. DESIGN: A single-blind, randomized, controlled trial. SETTING: Outpatient exercise research facility situated within an academic long-term care center. PARTICIPANTS: Twenty-one community-dwelling women aged 70 and older with a Short Physical Performance Battery (SPPB) score between 4 and 10 (out of 12). INTERVENTIONS: Subjects were randomized into a progressive resistance-training program using weighted vests for resistance with exercises designed to be specific to mobility tasks and have a component performed at the fastest possible velocity (Increased Velocity Exercise Specific to Task (InVEST), n=11) or a control exercise group (control, n=10), which performed slow-velocity, low-resistance exercise. Both groups exercised three times a week for 12 weeks. MEASUREMENTS: Changes in muscle power, balance, and physical performance were compared. RESULTS: In comparison to control group, InVEST group manifested significant improvements (P<.05) in leg power across measurements obtained at 75% to 90% of the one-repetition maximum. Both groups demonstrated significant improvements in chair stand and SPPB score from baseline, and the InVEST group showed significant improvements in gait speed and chair stand from baseline (P<.05). InVEST produced significantly greater changes in chair stand time than control (P<.05). CONCLUSION: InVEST training appears be an effective means of enhancing leg power and chair rise in this population and is worthy of further investigation as a means of enhancing balance and mobility.

Age Factors↗

PubMed2003

Aging, muscle activity, and balance control: physiologic changes associated with balance impairment.

Older adults demonstrate increased amounts of postural sway, which may ultimately lead to falls. The mechanisms contributing to age-related increases in postural sway and falls in the elderly remain unclear. In an effort to understand age-related changes in posture control, we assessed foot center-of-pressure (COP) displacements and electromyographic data from the tibialis anterior, soleus, vastus lateralis, and biceps femoris collected simultaneously during quiet-standing trials from elderly fallers, elderly non-fallers, and healthy young subjects. Both traditional measures of COP displacements and stabilogram-diffusion analysis were used to characterize the postural sway of each group. Regression analyses were used to assess the relationship between the COP measures and muscle activity. Elderly fallers demonstrated significantly greater amounts of sway in the anteroposterior (AP) direction and greater muscle activity during quiet standing compared with the young subjects, while elderly non-fallers demonstrated significantly greater muscle activation and co-activation compared with the young subjects. No significant differences were found between elderly fallers and elderly non-fallers in measures of postural sway or muscle activity. However, greater postural sway in both the AP and mediolateral (ML) directions and trends of greater muscle activity were found in those older adults who demonstrated lower scores on clinical measures of balance. In addition, short-term postural sway was found to be significantly correlated with muscle activity in each of these groups. This work suggests that high levels of muscle activity are a characteristic of age-related declines in postural stability and that such activity is correlated with short-term postural sway. It is unclear whether increases in muscle activity preclude greater postural instability or if increased muscle activity is a compensatory response to increases in postural sway.

Accidental Falls↗

PubMed2003

A comparison of leg power and leg strength within the InCHIANTI study: which influences mobility more?

BACKGROUND: In a clinical study evaluating the functioning of mobility-limited elders, muscle power accounted for more of the variation in function than strength did. There was also evidence that the power-function relationship may be described as curvilinear. However, these findings have never been confirmed in a representative population. METHODS: An analysis was conducted using data from the InCHIANTI study, a population-based cohort of 1032 adults living in Italy. To assess the relationships between impairments in power and strength and mobility performance, we created separate multivariate linear and log-transformed regression models as well as separate logistic regression models. RESULTS: Subjects were age > or = 65 years, predominantly female (54%), with a mean age of 74.2 years, and most had mild-moderate mobility limitations (Short Physical Performance Battery score 10.5 +/- 2.1). Though leg extension power and isometric hip extension strength were closely associated, in several separate multivariate linear regression models, leg power consistently explained more of the variance than strength did in several measures of physical performance. Differences were even larger when observed in curvilinear models of power and strength. Using separate multivariate logistic regression models to examine the odds ratios for mobility limitations in persons with low muscle power versus high muscle power, and in persons with low muscle strength versus high muscle strength, we found that both factors influenced risk for mobility limitations, but low power was associated with a 2-3-fold greater likelihood than low strength. CONCLUSION: These findings identified muscle power to be a more influential proximal determinant of physical performance than impairments in strength and emphasized muscle power as an important determinant of mobility skills in older adults.

Aged↗

PubMed2003

Influence of poststroke urinary incontinence on disability: the nursing home setting.

OBJECTIVE: To characterize the association of poststroke urinary incontinence with disability progression in nursing home residents. DESIGN: In this prospective cohort study, the Minimum Data Set from the State of New York between 1994 and 1997 was utilized. From a pool of over 240,000 potential subjects, 500 met inclusion/exclusion criteria. Previously continent, first-time stroke survivors were classified as being continent or incontinent immediately after their stroke and were followed for changes in activities of daily living status (disability) at quarterly intervals for a 1 yr. In addition, a post hoc analysis was performed examining changes in activities of daily living status from the prestroke condition and exploring the relationship between poststroke impairments in continence and limitations in mobility. RESULTS: An almost 2-fold difference in level of disability was noted poststroke among those who were incontinent those who were continent (P < 0.001). This difference in disability level remained unchanged for 1 yr. Through the post hoc analysis, it was determined that, although the onset of stroke produced significant elevations in disability for both continent and incontinent stroke survivors (P < 0.001), the presence of an impairment in urinary continence was associated with a significantly greater increase (94% 13%) in disability (P < 0.001). In addition, incontinence occurred more frequently among those who had a loss in mobility function. CONCLUSION: Incontinence is a clinical factor after stroke that is associated with greater disability among nursing home residents. These findings have clinical implications for physiatrists and nursing home clinicians and provide a context in which future disability research can be conducted.

Activities of Daily Living↗

PubMed2002

The relationship between leg power and physical performance in mobility-limited older people.

OBJECTIVES: The purpose of this study was to assess the influence of leg power and leg strength on the physical performance of community-dwelling mobility-limited older people. DESIGN: Cross-sectional analysis of baseline data from a 12-week randomized controlled exercise-intervention study. SETTING: Exercise laboratory within the Department of Health Science of an urban university. PARTICIPANTS: Forty-five community-dwelling mobility-limited people (34 women, 11 men), aged 65 to 83. MEASUREMENTS: Health status, depression, cognition, physical activity, and falls efficacy; physiological measures of lower extremity strength and power; and measures of physical performance. RESULTS: Through bivariate analyses, leg power was significantly associated with physical performance as measured by stair-climb time, chair-stand time, tandem gait, habitual gait, maximal gait, and the short physical performance battery describing between 12% and 45% of the variance (R2). Although leg power and leg strength were greatly correlated (r = .89) in a comparison of bivariate analyses of strength or power with physical performance, leg power modeled up to 8% more of the variance for five of six physical performance measures. Despite limitations in sample size, it appeared that, through quadratic modeling,the influence of leg power on physical performance was curvilinear. Using separate multivariate analyses, partial R2 values for leg power and leg strength were compared, demonstrating that leg power accounted for 2% to 8% more of the variance with all measures of physical performance. CONCLUSION: Leg power is an important factor influencing the physical performance of mobility-limited older people. Although related to strength, it is a separate attribute that may exert a greater influence on physical performance. These findings have important implications for clinicians practicing geriatric rehabilitation.

Age Factors↗

PubMed2002

The 6-minute walk test in mobility-limited elders: what is being measured?

BACKGROUND: The 6-minute walk (6mw) is a well-established measure of aerobic capacity in elders with cardiorespiratory and peripheral vascular disease and may be an accurate measure of functional performance in healthy elders. In mobility-limited elders, a population at risk for disability, impairments in strength and power are predictive of performance-based measures of function. Though commonly utilized as an outcome measure among otherwise healthy mobility-limited elders, it is not clear whether the 6mw best represents a measure of functional limitation, aerobic capacity, or both. METHODS: We hypothesized that the 6mw would be strongly representative of performance-based measures of function being determined by impairments in muscle strength and power. We performed a cross-sectional analysis of 45 community-dwelling elders with mild to moderate mobility limitations. RESULTS: The 6mw was strongly associated with established functional measures (r =.61-.83; p <.001), but was poorly associated with indirect measures of aerobic capacity (r <.25; p >.05). Multivariate linear regression models demonstrated that impairments in leg strength and power, especially those at the knee and ankle, were predictive of 6mw performance. CONCLUSIONS: These findings emphasize the 6mw as a measure of functional limitation among mobility-limited elders without cardiorespiratory or peripheral vascular disease.

Activities of Daily Living↗