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Biomedical subjects

Miriam E Nelson

Publications and source records attributed to Miriam E Nelson.

9 recordsLinked to original sources
PubMed2006

Strength training improves muscle quality and insulin sensitivity in Hispanic older adults with type 2 diabetes.

Hispanics are at increased risk of morbidity and mortality due to their high prevalence of diabetes and poor glycemic control. Strength training is the most effective lifestyle intervention to increase muscle mass but limited data is available in older adults with diabetes. We determined the influence of strength training on muscle quality (strength per unit of muscle mass), skeletal muscle fiber hypertrophy, and metabolic control including insulin resistance (Homeostasis Model Assessment -HOMA-IR), C-Reactive Protein (CRP), adiponectin and Free Fatty Acid (FFA) levels in Hispanic older adults. Sixty-two community-dwelling Hispanics (>55 y) with type 2 diabetes were randomized to 16 weeks of strength training plus standard care (ST group) or standard care alone (CON group). Skeletal muscle biopsies and biochemical measures were taken at baseline and 16 weeks. The ST group show improved muscle quality (mean+/-SE: 28+/-3) vs CON (-4+/-2, p<0.001) and increased type I (860+/-252 microm(2)) and type II fiber cross-sectional area (720+/-285 microm(2)) compared to CON (type I: -164+/-290 microm(2), p=0.04; and type II: -130+/-336 microm(2), p=0.04). This was accompanied by reduced insulin resistance [ST: median (interquartile range) -0.7(3.6) vs CON: 0.8(3.8), p=0.05]; FFA (ST: -84+/-30 micromol/L vs CON: 149+/-48 micromol/L, p=0.02); and CRP [ST: -1.3(2.9) mg/L vs CON: 0.4(2.3) mg/L, p=0.05]. Serum adiponectin increased with ST [1.0(1.8) microg/mL] compared to CON [-1.2(2.2) microg/mL, p<0.001]. Strength training improved muscle quality and whole-body insulin sensitivity. Decreased inflammation and increased adiponectin levels were related with improved metabolic control. Further studies are needed to understand the mechanisms associated with these findings. However, these data show that strength training is an exercise modality to consider as an adjunct of standard of care in high risk populations with type 2 diabetes.

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PubMed2004

Three-compartment model: critical evaluation based on neutron activation analysis.

There is renewed interest in Siri's classic three-compartment (3C) body composition model, requiring body volume (BV) and total body water (TBW) estimates, because dual-energy X-ray absorptiometry (DEXA) and in vivo neutron activation (IVNA) systems cannot accommodate subjects with severe obesity. However, the 3C model assumption of a constant ratio (alpha) of mineral (M) to total body protein (TBPro) and related residual mass density (D(RES)) based on cadaver analyses might not be valid across groups differing in sex, race, age, and weight. The aim of this study was to derive new 3C model coefficients in vivo and to compare these estimates to those derived by Siri. Healthy adults (n = 323) were evaluated with IVNA and DEXA and the measured components used to derive alpha and D(RES). For all subjects combined, values of alpha and D(RES) (means +/- SD, 0.351 +/- 0.043; 1.565 +/- 0.023 kg/l) were similar to Siri's proposed values of 0.35 and 1.565 kg/l, respectively. However, alpha and D(RES) varied significantly as a function of sex, race, weight, and age. Expected errors in percent body fat arising by application of Siri's model were illustrated in a second group of 264 adults, including some whose size exceeded DEXA limits but whose BV and TBW had been measured by hydrodensitometry and (2)H(2)O dilution, respectively. Extrapolation of predictions by newly developed models to very high weights allows percent fat error estimation when Siri's model is applied in morbidly obese subjects. The present study results provide a critical evaluation of potential errors in the classic 3C model and present new formulas for use in selected populations.

Absorptiometry, Photon↗
PubMed2004

The effects of multidimensional home-based exercise on functional performance in elderly people.

BACKGROUND: This study tested the hypothesis that a home-based exercise program would improve functional performance in elderly people. METHODS: We conducted a 6-month, single-blinded, randomized controlled trial. 72 community dwelling men and women (aged >/=70 years) with self-reported and laboratory-based functional impairment were recruited for the study. Participants were randomly assigned to either a home-based progressive strength, balance, and general physical activity intervention or an attention-control group that received home-based nutrition education. Functional performance was measured in the laboratory using the Physical Performance Test (PPT) and the Established Populations for Epidemiologic Studies of the Elderly (EPESE) short physical performance battery. Physiologic capacity was measured by strength (one repetition maximum), dynamic balance (tandem walk), gait speed (2-meter walk), and cardiovascular endurance (6-minute walk). RESULTS: 70 participants (97%) completed the 6-month trial. Compliance with study interventions within each group ranged from 75% in controls to 82% in exercisers. PPT increased by 6.1 +/- 13.4% in exercisers and decreased by 2.8 +/- 13.6% in controls (p =.02). EPESE improved by 26.2 +/- 37.5% in exercisers and decreased by 1.2 +/- 22.1% in controls (p =.001). Dynamic balance improved by 33.8 +/- 14.4% in exercisers versus 11.5 +/- 23.7% in controls (p =.0002). There were no differences between groups in the change in strength, gait speed, or cardiovascular endurance. CONCLUSIONS: Minimally supervised exercise is safe and can improve functional performance in elderly individuals. The improvements in functional performance occurred along with improvements in balance but without a significant change in muscle strength or endurance.

Activities of Daily Living↗
PubMed2003

The benefits of strength training for older adults.

Aging is associated with a number of physiologic and functional declines that can contribute to increased disability, frailty, and falls. Contributing factors are the loss of muscle mass and strength as age increases, a phenomenon called sarcopenia. Sarcopenia can result or be exacerbated by certain chronic conditions, and can also increase the burden of chronic disease. Current research has demonstrated that strength-training exercises have the ability to combat weakness and frailty and their debilitating consequences. Done regularly (e.g., 2 to 3 days per week), these exercises build muscle strength and muscle mass and preserve bone density, independence, and vitality with age. In addition, strength training also has the ability to reduce the risk of osteoporosis and the signs and symptoms of numerous chronic diseases such as heart disease, arthritis, and type 2 diabetes, while also improving sleep and reducing depression. This paper reviews the current research on strength training and older adults, evaluating exercise protocols in a variety of populations. It is clear that a variety of strength-training prescriptions from highly controlled laboratory-based to minimally supervised home-based programs have the ability to elicit meaningful health benefits in older adults. The key challenges as this field of exercise science moves forward are to best identify the most appropriate strength-training recommendations for older adults and to greatly increase the access to safe and effective programs in a variety of settings.

Accidental Falls↗
PubMed2003

Total body protein: a new cellular level mass and distribution prediction model.

BACKGROUND: Protein is an important body component, and the presently accepted criterion method for estimating total body protein (TBPro) mass--in vivo neutron activation (IVNA) analysis--is unavailable to most investigators and is associated with moderate radiation exposure. OBJECTIVE: The objective was to derive a theoretical cellular level TBPro mass and distribution model formulated on measured total body potassium, total body water, and bone mineral and to evaluate the new model with the IVNA method as the criterion. DESIGN: The new model was developed on the basis of a combination of theoretical equations and empirically derived coefficients. TBPro mass estimates with the new model were evaluated in healthy women (n = 183) and men (n = 24) and in men with AIDS (n = 84). Total body nitrogen was measured by IVNA, total body potassium by whole-body (40)K counting, total body water by tritium dilution, and bone mineral by dual-energy X-ray absorptiometry. RESULTS: The group mean (+/- SD) TBPro mass estimates in healthy women and men and men with AIDS (8.2 +/- 0.9, 11.0 +/- 1.8, and 10.5 +/- 1.1 kg, respectively) with the new model were similar to IVNA criterion estimates (8.9 +/- 0.9, 11.1 +/- 1.6, and 10.9 +/- 1.2 kg, respectively). TBPro mass estimates with the new model correlated highly with the IVNA estimates in all subjects combined (r = 0.92, P < 0.001). The new model suggests that the composite TBPro mass within each group consists mainly of cellular protein (75-79%) and, to a lesser extent, protein in extracellular solids (19-23%) and extracellular fluid (approximately 2%). CONCLUSION: The new model provides a non-IVNA approach for estimating protein mass and distribution in vivo.

Absorptiometry, Photon↗
PubMed2002

Higher dietary variety is associated with better nutritional status in frail elderly people.

OBJECTIVE: A narrow range of food choices may lead to dietary inadequacies, a particular concern in elderly people. We hypothesized that consumption of a more diverse diet would predict better nutritional status in frail elderly persons. SUBJECTS: Subjects included 98 frail nursing home residents (36 men, 62 women), mean age 87.1+/-5.5 (72 to 98) years. METHODS: 3-day dietary variety scores ranging from 23 to 48 and fruit and vegetable variety scores ranging from 5 to 20 were calculated from weighed 3-day food records as the number of different food or fruit and vegetable choices consumed. A higher score indicates a more varied diet. Nutritional status was assessed by weight, height, body mass index (BMI), skinfold thickness, circumference measures, calculated mean arm muscle area, total body water, computerized tomography of the thigh, and total body potassium, as well as nutritional analysis, biochemical measures, and subject medical history. STATISTICAL METHODS: Univariate regression analyses were performed to investigate the relationship between clinical and nutrition variables. Multiple linear regressions were used to develop models relating dietary variety scores to possible etiologic factors as well as indicators of nutritional status. Models were controlled for age, BMI, and energy intake when appropriate. RESULTS: Mean dietary variety score was 35.2+/-4.5, and mean fruit and vegetable variety score was 11.3+/-3.0. Higher dietary variety score was associated with higher energy intake (beta = 20.5, P < .001) and both high dietary variety score and fruit and vegetable variety score were positively associated with intake for many nutrients (P < or = .05). High dietary variety score was related to high fruit and vegetable variety score and total intake of fruits and vegetables. In men, higher dietary variety score and fruit and vegetable variety score were associated with higher high-density lipoprotein (beta = 1.02), lower very-low-density lipoprotein (beta = -3.58) and triglycerol (beta = -3.51), and higher blood folate (beta = 4.72) concentrations in women (P < or = .05). In women, high dietary variety score was associated with higher BMI (beta = 0.34, P < .001) and higher total body potassium (beta = 1.30, P = .02); high fruit and vegetable variety score was associated with higher BMI (beta = 0.41), mid-arm circumference (beta = 0.34), and mid-arm muscle area (beta = 2.94) (P < or = .03). Dietary variety score was higher (mean 37.6+/-5.38 vs 34.6+/-4.14) in those who received assistance with feeding (beta = 2 .67, P = .01). History of cancer (beta = -2.04) and gastrointenstinal cancer (beta = -3.54) were associated with low dietary variety score (P < or = .05). CONCLUSIONS: The results of this study suggest that a highly varied diet in elderly nursing home residents is associated with better nutritional status as assessed by nutrient intake, biochemical measures, and body composition measures. Dietary variety score is a straightforward tool for screening and identifying people at nutritional risk, as well as a mechanism for monitoring response to nutritional, medical, and environmental interventions. Preventive measures to improve dietary variety, as measured by the dietary variety score, should be evaluated and introduced before nutrition and health complications arise.

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PubMed2002

A home-based nutrition intervention to increase consumption of fruits, vegetables, and calcium-rich foods in community dwelling elders.

OBJECTIVE: To increase fruit, vegetable, and calcium-rich food consumption in community-dwelling, functionally impaired elderly. DESIGN: Six-month, home-based nutrition intervention study. SUBJECTS: Seventy men and women older than age 69 years were randomized to either a nutrition education intervention (n = 38) or a control group that received an exercise intervention (n = 32). INTERVENTION: Nutrition education was designed to increase fruit, vegetable, and calcium-rich food consumption. MAIN OUTCOME MEASURES: Food intake was assessed by a food frequency questionnaire. Fasting blood measures of nutrients and carotenoids were performed. Statistical Analysis Two-group randomized controlled trial with pre-test and post-test design and intention-to-treat analysis. Analysis of covariance to was used to assess differences between the two groups. Baseline and change partial correlation coefficients were performed between intake and blood nutrient levels. Paired t tests were conducted to test within-group changes. RESULTS: Compared with the exercise group, subjects in nutrition group increased their self-reported intake of fruits by 1.1 +/- 0.2 (mean +/- SEM) servings per day (2.8 to 3.9, P = .01), vegetables 1.1 +/- 0.2 servings per day (2.3 to 3.4, P = .001), and milk/dairy 0.9 +/- 0.2 servings per day (3.0 to 3.9, P = .001). There was an increase in the dietary intake of alpha-carotene and beta-carotene in the nutrition group and this correlated with the increase in blood concentrations of alpha-carotene and beta-carotene (P < or = .02; r = 0.33 and r = 0.33, respectively). CONCLUSION: The results of this study suggest that it is possible to improve the dietary intake of community dwelling elders to include more fruits, vegetables, and calcium-rich foods. Recommendations for increasing consumption of fruits, vegetables, and calcium-rich foods should be specific and individualized to meet the dietary pattern and lifestyle of the individual. Compliance should be encouraged with record keeping as well as through continuous monitoring and positive reinforcement.

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PubMed2002

A randomized controlled trial of resistance exercise training to improve glycemic control in older adults with type 2 diabetes.

OBJECTIVE: To determine the efficacy of high-intensity progressive resistance training (PRT) on glycemic control in older adults with type 2 diabetes. RESEARCH DESIGN AND METHODS: We performed a 16-week randomized controlled trial in 62 Latino older adults (40 women and 22 men; mean +/- SE age 66 +/- 8 years) with type 2 diabetes randomly assigned to supervised PRT or a control group. Glycemic control, metabolic syndrome abnormalities, body composition, and muscle glycogen stores were determined before and after the intervention. RESULTS: Sixteen weeks of PRT (three times per week) resulted in reduced plasma glycosylated hemoglobin levels (from 8.7 +/- 0.3 to 7.6 +/- 0.2%), increased muscle glycogen stores (from 60.3 +/- 3.9 to 79.1 +/- 5.0 mmol glucose/kg muscle), and reduced the dose of prescribed diabetes medication in 72% of exercisers compared with the control group, P = 0.004-0.05. Control subjects showed no change in glycosylated hemoglobin, a reduction in muscle glycogen (from 61.4 +/- 7.7 to 47.2 +/- 6.7 mmol glucose/kg muscle), and a 42% increase in diabetes medications. PRT subjects versus control subjects also increased lean mass (+1.2 +/- 0.2 vs. -0.1 +/- 0.1 kg), reduced systolic blood pressure (-9.7 +/- 1.6 vs. +7.7 +/- 1.9 mmHg), and decreased trunk fat mass (-0.7 +/- 0.1 vs. +0.8 +/- 0.1 kg; P = 0.01-0.05). CONCLUSIONS: PRT as an adjunct to standard of care is feasible and effective in improving glycemic control and some of the abnormalities associated with the metabolic syndrome among high-risk older adults with type 2 diabetes.

Aged↗