Benefits of exercise and dietary measures to optimize shifts in body composition with age

Ageing is associated with changes in body composition, including an increase and redistribution of adipose tissue and a decrease in muscle and bone mass, beginning as early as the fourth decade of life. These changes have significant implications for the health and functioning of the individual because of their associations with chronic disease expression and severity, as well as geriatric syndromes such as mobility impairment, falls, frailty and functional decline. Therefore, understanding the preventive and therapeutic options for optimizing body composition in old age is central to the care of patients in mid-life and beyond. Pharmacological interventions are currently available for maintaining or improving bone mass, and much current interest is focused on anabolic agents that will preserve or restore muscle mass, as well as those that can potentially limit adipose tissue deposition. However, in this brief review, non-pharmacological modulation of body composition through appropriate dietary intake and physical activity patterns, will be discussed. There is sufficient evidence currently to suggest that a substantial portion of what have been considered 'age-related' changes in muscle, fat and bone are in fact related either to excess energy consumption, decreased energy expenditure in physical activity, or both factors in combination. In addition, selective underconsumption of certain macro- or micronutrients contributes to losses of muscle and bone mass. Each of the three compartments will be considered in turn, with recommendations for optimizing the size of these body tissue stores in early adulthood, and minimizing undesirable changes typically seen in middle and old age.

Battling insulin resistance in elderly obese people with type 2 diabetes: bring on the heavy weights

Exercise improves insulin resistance and has beneficial effects in preventing and treating type 2 diabetes. However, aerobic exercise is hindered in many type 2 diabetic patients because of advancing age, obesity, and other comorbid conditions. Weight lifting or progressive resistance training (PRT) offers a safe and effective exercise alternative for these people. PRT promotes favorable energy balance and reduced visceral fat deposition through enhanced basal metabolism and activity levels while counteracting age- and disease-related muscle wasting. PRT improves insulin sensitivity and glycemic control; increases muscle mass, strength, and endurance; and has positive effects on bone density, osteoarthritic symptoms, mobility impairment, self-efficacy, hypertension, and lipid profiles. PRT also alleviates symptoms of anxiety, depression, and insomnia in individuals with clinical depression and improves exercise tolerance in individuals with cardiac ischemic disease and congestive heart failure; all of these aspects are relevant to the care of diabetic elders. Moreover, PRT is safe and well accepted in many complex patient populations, including very frail elderly individuals and those with cardiovascular disease. The greater feasibility of using PRT over aerobic exercise in elderly obese type 2 diabetic individuals because of concomitant cardiovascular, arthritic, and other disease provides a solid rationale for investigating the global benefits of PRT in the management of diabetes.

Longitudinal changes in body composition in older men and women: role of body weight change and physical activity

BACKGROUND

Estimates of body-composition change in older adults are mostly derived from cross-sectional data.

OBJECTIVE

We examined the natural longitudinal patterns of change in fat-free mass (FFM) and fat mass (FM) in older adults and explored the effect of physical activity, weight change, and age on these changes.

DESIGN

The body composition measured by hydrodensitometry and the level of sports and recreational activity (SRA) of 53 men and 78 women with a mean (+/-SD) initial age of 60.7 +/- 7.8 y were examined on 2 occasions separated by a mean (+/-SD) time of 9.4 +/- 1.4 y.

RESULTS

FFM decreased in men (2.0% per decade) but not in women, whereas FM increased similarly in both sexes (7.5% per decade). Levels of SRA decreased more in men than in women over the follow-up period. Baseline age and level of SRA were inversely and independently associated with changes in FM in women only. Neither age nor level of SRA was associated with changes in FFM in men or women. Weight-stable subjects lost FFM. FFM accounted for 19% of body weight in those who gained weight, even in the presence of decreased levels of SRA. Loss of FFM (33% of body weight) was pronounced in those who lost weight, despite median SRA levels >4184 kJ/wk.

CONCLUSIONS

On average, FM increased; however, the increase in women was attenuated with advancing age. The decrease in FFM over the follow-up period was small and masked the wide interindividual variation that was dependent on the magnitude of weight change. The contribution of weight stability, modest weight gains, or lifestyle changes that include regular resistance exercise in attenuating lean-tissue loss with age should be explored.

Exercise to prevent and treat functional disability

There are myriad ways in which optimal levels of physical activity over the course of the life span could potentially contribute to the prevention of functional disability in old age. These include direct effects of exercise to maximize physiologic capacity and prevent or delay the onset of disability-related conditions and more indirect effects, such as the modulation of psychosocial factors important in the expression of disability. Epidemiologic studies strongly suggest that functional disability is inversely related to physical activity level or physical fitness in various domains. Experimental studies confirm the benefits of exercise on correlates of disability, such as impairments of muscle strength or performance-based tests of functional limitations. However, the evidence that exercise can actually prevent disability in the long-term is not yet established by data from randomized clinical trials in the general population. Secondary prevention of disability in frail elders has been shown in a few trials. The available evidence, however, suggests that a rational exercise prescription for the prevention and treatment of disability at this time should include promotion of a physically active lifestyle and specific exercises targeting aerobic capacity, strength, and balance. Differential emphasis on specific elements of this prescription may be necessary and appropriate, depending on the etiology of the disability in specific cohorts, severity of physical impairments and functional limitations, and other individual characteristics relevant to exercise feasibility, safety, and efficacy.

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.

High-velocity resistance training increases skeletal muscle peak power in older women

OBJECTIVES

Peak power declines more precipitously than strength with advancing age and is a reliable measure of impairment and a strong predictor of functional performance. We tested the hypothesis that a high-velocity resistance-training program (HI) would increase muscle power more than a traditional low-velocity resistance-training program (LO).

DESIGN

Randomized controlled trial.

SETTING

University-based human physiology laboratory.

PARTICIPANTS

Thirty women with self-reported dis-ability (aged 73 + 1, body mass index 30.1 + 1.1 kg/mn).

INTERVENTION

We conducted a randomized trial comparing changes in skeletal muscle power and strength after 16 weeks of HI or LO. Training was performed three times per week, and subjects completed three sets (8-10 repetitions) of leg press (LP) and knee extension (KE) exercises at 70% of the one-repetition maximum (IRM).

MEASUREMENTS

One-repetition maximum (1 RM) and peak power for KE and LP.

RESULTS

LP and KE relative training force and total work were similar between groups (P > .05). However, HI generated significantly higher power during training sessions than LO for LP (3.7-fold greater, P < .001) and KE (2.1-fold greater, P < .001). Although LP and KE 1RM muscle strength increased similarly in both groups asa result of the training (P < .001), LP peak power increased significantly more in HI than in LO (267 W vs 139 W, P < .001). Furthermore, HI resulted in a significantly greater improvement in LP power at 40%, 50%, 60%,70%, 80%, and 90% of the 1 RM than did LO (P <.05).

CONCLUSIONS

HI improved 1RM strength similarly and was more effective in improving peak power than was traditional LO in older women. Improvements in lower extremity peak power may exert a greater influence on age-associated reductions in physical functioning than other exercise interventions.

Recruitment of older participants in frailty/injury prevention studies

Despite the lifelong health benefits of physical activity, frailer older adults have typically been excluded from studies promoting more active lifestyles. This study documents the recruitment process and costs from a multisite study to identify effective strategies for recruiting older adults in frailty/injury prevention research. Randomized controlled clinical trials were conducted at 7 sites; an 8th site was a compliance study. Interventions reflected center- and home-based health promotion programs. Site objectives, eligibility criteria, and contact and screening methods were obtained from manuals of operation. Recruitment results (number screened, eligibility rates, randomized to screened ratios) were ascertained from recruitment data. Sites furnished estimated recruitment costs (nonlabor expenses, investigator and staff time, fringe benefits) up to signing the consent form. The sites targeted diverse populations and sample sizes. The majority revised recruitment methods to meet their recruitment goals. Most sites estimated costs of recruitment at over $300 per participant randomized. Recruitment costs were affected by staff time spent alleviating concerns about participants' health, essential interactions with family members, and arranging for transportation. Neither frailty nor intervention intensity was found to be a major predictor of recruitment outcomes. Recruitment expense was associated with selection criteria and frailty status of the target population. Older people can be successfully recruited into beneficial health promotion programs, but it is often challenging. In planning health promotion studies, investigators need to be aware of the numbers of older people they may need to screen and different strategies for increasing recruitment success.