Aging of skeletal muscle: a 12-yr longitudinal study.

The present study examines age-related changes in skeletal muscle size and function after 12 yr. Twelve healthy sedentary men were studied in 1985-86 (T1) and nine (initial mean age 65.4 +/- 4.2 yr) were reevaluated in 1997-98 (T2). Isokinetic muscle strength of the knee and elbow extensors and flexors showed losses (P < 0.05) ranging from 20 to 30% at slow and fast angular velocities. Computerized tomography (n = 7) showed reductions (P < 0.05) in the cross-sectional area (CSA) of the thigh (12.5%), all thigh muscles (14.7%), quadriceps femoris muscle (16.1%), and flexor muscles (14. 9%). Analysis of covariance showed that strength at T1 and changes in CSA were independent predictors of strength at T2. Muscle biopsies taken from vastus lateralis muscles (n = 6) showed a reduction in percentage of type I fibers (T1 = 60% vs. T2 = 42%) with no change in mean area in either fiber type. The capillary-to-fiber ratio was significantly lower at T2 (1.39 vs. 1. 08; P = 0.043). Our observations suggest that a quantitative loss in muscle CSA is a major contributor to the decrease in muscle strength seen with advancing age and, together with muscle strength at T1, accounts for 90% of the variability in strength at T2.

Validity of the minimum data set for assessing nutritional status in nursing home residents.

The Minimum Data Set (MDS), a Health Care Financing Administration (HCFA)-mandated resident assessment system used in community nursing homes, is potentially useful for assessing nutritional status. We compared anthropometric measures of nutritional status available in the MDS [weight and body mass index (BMI)] with other anthropometric and bioelectrical measures of nutritional status, not available on the MDS. We also studied associations of MDS-measured clinical characteristics of nursing home residents with anthropometric and bioelectrical measures of lower and higher nutritional status, defined as measures in the 25th percentile and below, and 75th percentile and above, respectively. Data were from a sample of residents of an academic long-term care facility (n = 186, 75% female, mean age 89.9 +/- 5.6 y). Results were as follows: 1) MDS measures of weight and BMI were significantly correlated with all the anthropometric and bioelectrical measures of nutritional status in women, and most measures in men; 2) some MDS variables, including poor oral intake and advanced cognitive decline, were significantly associated with two or more anthropometric and bioelectrical measures of low nutritional status; and 3) complaints of hunger were significantly associated with two or more anthropometric and bioelectrical measures of high nutritional status. Results suggest that 1) weight and BMI, available in the MDS, are correlated with other measures of nutritional status not available, and 2) MDS clinical variables are associated with measures of low and high nutritional status, and may be useful in identifying patients at nutritional risk.

Total body potassium and body fat: relevance to aging.

Understanding the mechanisms that govern sarcopenia (depletion of muscle mass with age) may suggest ways to preserve lean tissue and functional capacity, and to maintain quality of life in the elderly. We investigated the body-composition changes in normal aging in a cross-sectional study of 188 healthy volunteers aged 20-89 y, which examines the differences in body cell mass and fat as a function of age. In aging, the assumptions of indirect body-composition-measurement techniques, such as the "constant" hydration coefficient of lean body mass or the "constant" density of fat-free mass, may not hold. Therefore, we selected body-composition-measurement techniques that are not sensitive to assumptions about the composition of lean tissue. Cellular mass, lean body mass, and fat were assessed "directly" by total body potassium (TBK) measurements and neutron inelastic scattering. Our results show that TBK content declines at a rate of 7.20 +/- 1.00 mg K.kg body wt-1.y-1 for females (r = 0.601, P < or = 0.001) and 9.16 +/- 0.96 mg K.kg body wt-1.y-1 for males (r = 0.710, P < or = 0.001). Body fat measurements by neutron inelastic scattering have shown a significant increase of percentage body fat with age for female volunteers between the ages of 20 and 50 y and a continuous increase for male volunteers throughout adult life.

A multi-center comparison of dual energy X-ray absorptiometers: in vivo and in vitro soft tissue measurement.

OBJECTIVE: To assess intra- and inter-site soft tissue variability by dual energy X-ray absorptiometry (DXA). DESIGN: Cross-sectional trial. SETTING: Three medical research institutions. SUBJECTS: Five humans (in vivo) and four phantoms (in vitro), configured from two whole body phantoms with artificial skeletons and thickness overlays. INTERVENTIONS: Duplicate total-body DXA scans were performed on all subjects at each institution within a 15 d period. RESULTS: All intra-site coefficients of variation (CV) were < 0.5% for total tissue mass, but in vitro and in vivo Cvs were 7.2% and 2.3% for fat mass (FM) and 2.5% and 0.9% for lean mass (LM), respectively. Several total-body and regional FM and LM measurements were significantly different between sites (P < 0.05), with percent differences between sites ranging from 2.6-13.3% for FM and from 1.6-13.6% for LM. Site 2 was consistently lower for FM and Site 3 was consistently lower for LM. CONCLUSIONS: These results stress the need for both rigorous and standardized cross-calibration procedures for soft tissue measurement by DXA.

A randomized controlled trial of the effect of exercise on sleep.

We tested the hypothesis that exercise would improve subjective sleep quality and activity in depressed elders. A 10-week randomized controlled trial was utilized. Participants consisted of a volunteer sample, aged > 60 with a diagnosis of major or minor depression or dysthymia. A total of 32 subjects aged 60-84 years with a mean age of 71.3 +/- 1.2 years was used. Intervention consisted of a supervised weight-training program three times a week or an attention-control group. Main outcome measures were Pittsburgh Subjective Sleep Quality Index (PSQI), Likert Scale of Subjective Sleep Quality and Quantity. Paffenbarger Activity Index. Geriatric Depression Scale (GDS). Beck Depression Inventory (BDI), Hamilton Rating Scale of Depression (HRSD), and the Medical Outcomes Survey Short Form 36 (SF-36). Results showed that exercise significantly improved all subjective sleep-quality and depression measures. Depression measures were reduced by approximately twice that of controls. Habitual activity was not significantly increased by exercise. Quality of life subscales significantly improved. In a forward stepwise multiple regression, percent improvement in GDS and percent increase in strength remained significant predictors of the improvement in total PSQI score (r = 0.71, p = 0.0002). In conclusion, weight lifting exercise was effective in improving subjective sleep quality, depression, strength, and quality of life without significantly changing habitual activity.

A randomized controlled trial of progressive resistance training in depressed elders.

BACKGROUND: Depression in elderly people may be contributed to by the multiple losses of aging. Exercise has the potential to positively impact many of these losses simultaneously. We tested the hypothesis that progressive resistance training (PRT) would reduce depression while improving physiologic capacity, quality of life, morale, function and self-efficacy without adverse events in an older, significantly depressed population. METHODS: We conducted a 10-week randomized controlled trial of volunteers aged 60 and above with major or minor depression or dysthymia. Subjects were randomized for 10 weeks to either a supervised PRT program three times a week or an attention-control group. RESULTS: A total of 32 subjects aged 60-84, mean age 71.3 +/- 1.2 yr, were randomized and completed the study. No significant adverse events occurred. Median compliance was 95%. PRT significantly reduced all depression measures (Beck Depression Inventory in exercisers 21.3 +/- 1.8 to 9.8 +/- 2.4 versus controls 18.4 +/- 1.7 to 13.8 +/- 2, p = .002; Hamilton Rating Scale of Depression in exercisers 12.3 +/- 0.9 to 5.3 +/- 1.3 versus controls 11.4 +/- 1.0 to 8.9 +/- 1.3, p = .008). Quality of life subscales of bodily pain (p = .001), vitality (p = .002), social functioning (p = .008), and role emotional (p = .02) were all significantly improved by exercise compared to controls. Strength increased a mean of 33% +/- 4% in exercisers and decreased 2% +/- 2% in controls (p < .0001). In a multiple stepwise regression model, intensity of training was a significant independent predictor of decrease in depression scores (r2 = .617, p = .0002). CONCLUSIONS: PRT is an effective antidepressant in depressed elders, while also improving strength, morale, and quality of life.

Leg power in young women: relationship to body composition, strength, and function.

The ability to generate high forces at high velocity (power) is an important component of physiologic reserve for both athletic performance and functional capacity. A comparison was made between different laboratory methods and field tests designed to evaluate leg power. Nineteen young healthy untrained women participated in this study. Maximum power during the double leg press (KP) occurred between 56-78% of the one repetition maximum (1-RM) and averaged (404 +/- 22 W). Rank-ordered correlation showed an association between KP and another measure of leg power measured on the leg extensor power rig (LR) when expressed per kg LBM (Rho = 0.565, P < 0.016). KP was also related to the 1-RM achieved on the double leg press (R2 = 0.584, P < 0.001). The KP test also correlated with the vertical jump (R2 = 0.538, P < 0.004) and maximal power output during the Wingate anaerobic power test (R2 = 0.299, P < 0.015). However, double leg press power was not related to time to run 40 yards (R2 = 0.020, P < 0.573) or maximal gait velocity (R2 = 0.136, P < 0.121). These results suggest that maximal power during the double leg press occurs at a higher percentage of maximal strength than previously reported. Double leg press power was related to vertical jump performance, validating this field test as a measure of leg muscle power in young women.

A 20-yr longitudinal study of Olympic oarsmen.

Nine 1972 silver-medalist oarsmen were studied before the Olympic Games and 10 and 20 yr later. Peak power, metabolic responses, and heart rate were recorded during rowing ergometry; blood lactate was measured following exercise. The skinfold equation yielded percent body fat. The average change (multiple analysis of variance) among measurements from 1972 to 1992 was 37.5 +/- 3% (P < 0.01). Average changes between 1972 and 1982 and between 1982 and 1992 were similar, 17 and 18%, respectively (P < 0.01). The most significant change between 1972 and 1992 was decreased peak blood lactate (106%). Decreases in peak power, VE, and VO2 (ml.kg-1.min-1) were all similar, approximately 40%, and were significant. Body fat increased (from 12.3 to 15.6%), and absolute VO2 and relative VO2 (lean body mass) decreased 30% (P < 0.01). Only body weight, heart rate, and O2 pulse showed smaller changes, but these changes were still significant (P < 0.05). Relative peak VO2 decreased from 65.5 to 46.8 ml.kg-1.min-1 from 1972 to 1992 and at a rate of 10%.decade-1. The most significant changes between 1972 and 1982 were increases in percent body fat (from 12.3 to 16.3%) and decreases in VO2 values (P < 0.01). There was less change in body fat between 1982 and 1992, but lactate significantly decreased (P < 0.01), as did peak power and absolute and relative VO2 and VE. Although fitness levels in former elite oarsmen decreased each decade, these declines were somewhat arrested by regular aerobic training. Body fat increased and metabolic capacity decreased rapidly during the first decade, whereas anaerobic capacity decreased more significantly in the second decade. Anaerobic capacity diminished at a significantly greater rate than aerobic capacity, probably as a result of the aging process and emphasis on aerobic training in post-competitive years.

Analysis of body-composition techniques and models for detecting change in soft tissue with strength training.

The purpose of this study was to compare the ability of various body-composition assessment techniques to detect changes in soft tissue in older, weight-stable women (50-70 y of age) completing a 1-y randomized, controlled trial of progressive resistance training. The intervention group (n = 20) performed high-intensity strength-training 2 d/wk with five different exercises; the control group (n = 19) was untreated. Hydrostatic weighing, 24-h urinary creatinine, computed tomography of thigh sections, total body potassium, and tritium dilution techniques were used to measure increases in total fat-free mass (FFM) and the muscle and water components of FFM. A decrease in fat mass (by hydrostatic weighing) was seen in the strength-trained women compared with the control subjects (P - 0.01-0.0001). Anthropometry, bioelectric impedance, dual-energy X-ray absorptiometry, and total body nitrogen and carbon did not measure any significant change in soft tissue. The choice of a body-composition technique is important when designing a study expected to affect soft tissue, because not all techniques available are precise enough to detect small changes.

Effects of age on energy expenditure and substrate oxidation during experimental overfeeding in healthy men.

Relatively little is known about the influence of age on energy regulation during energy imbalance. We compared the effects of overfeeding on changes in energy expenditure, substrate oxidation, and energy deposition between young men (age 23.7 +/- 1.1 [SEM] years) and older men (age 70.0 +/- 7.0) of normal body weight who were leading unrestricted lives. Changes in total energy expenditure, resting energy expenditure (REE), the thermic effect of feeding (TEF), respiratory quotient (RQ), and body energy content were determined in response to overeating by 4.09 +/- 0.07 Megajoule (MJ)/day for 21 days in 16 healthy subjects consuming a typical diet. After excluding data from one young subject with unusual results and adjusting for individual differences in excess energy intake, there was a tendency towards a smaller increase in REE in older men compared to the young men (p = .07) which was accounted for by their lower fat-free mass (p = .016). There was also a significantly smaller increase in resting energy expenditure averaged over fasting and fed states (i.e, REE + TEF) with overfeeding in older men than in young men (p < .01). Combined, these smaller increases in energy expenditure with overfeeding in the older subjects averaged an estimated 365 kilojoule (kJ)/day (8.9% of the excess energy intake) (p < .02). There were also significant effects of age on fasting RQ (p < .001) and the change in RQ with overfeeding (p < .001), but no significant increase in energy expenditure for physical activity and thermoregulation with overfeeding in either age-group. These results are consistent with the suggestion that older individuals experience both a reduction in the ability to increase energy expenditure, and an alteration in the pattern of substrate utilization, in response to overfeeding. These changes may promote cumulative increases in body energy during normal cycles of positive energy balance unless compensated for by adaptive variations in energy intake.

A multicenter comparison of dual-energy X-ray absorptiometers: in vivo and in vitro measurements of bone mineral content and density.

As part of a multicenter research project, we compared dual-energy X-ray absorptiometry (DXA) instruments at three research centers (sites 1, 2 and 3) to determine both intra- and intersite variability of bone mineral content (BMC), bone mineral density (BMD), and bone area (BA). Scans of the total body and lumbar spine were performed in duplicate on five humans (in vivo), and scans of the total body were performed on two whole body phantoms with artificial skeletons and thickness overlays (in vitro) at all sites over 15 days. The average intrasite variability in two consecutive total body BMD measurements, expressed as a percent difference, was significantly higher in vitro, 1.74 +/- 1.97%, than in vivo, 0.71 +/- 0.38% (p < 0.05). Average intrasite variability of the in vivo lumbar spine BMD was 1.08 +/- 1.12%. The intersite coefficients of variation for all BMD, BMC, and BA measurements were < 2.0%. The total body BMD from site 2 was systematically lower than at sites 1 and 3 both in vivo and in vitro (p < 0.05) with no differences in BMC and BA. Although significant, the total body BMD differences between sites were small (< 1.2%) in vivo compared with in vitro (< 2.6%) and are encouraging for the comparison and pooling of human data from multicenter trials, provided that appropriate standardized cross-calibration and analysis procedures are applied.

Long-term effects of a high-carbohydrate diet and exercise on insulin action in older subjects with impaired glucose tolerance.

Carbohydrate metabolism was assessed in 20 glucose-intolerant subjects before and after 12 wk on a high-carbohydrate diet (HC) or the diet combined with exercise training (HC-EX). The diet provided 60% of energy as carbohydrate and 20% as fat. Neither treatment altered fasting glucose or insulin concentrations or their response to a meal. During a glucose clamp (216 pmol insulin/L) glucose disposal increased from 13.2 +/- 0.83 to 14.6 +/- 0.83 mumol.kg fat-free mass-1.min-1 (P < 0.05) in both groups. During more pronounced hyperinsulinemia (654 pmol/L) glucose disposal did not change significantly (49.9 +/- 3.8 to 50.7 +/- 3.8 mumol.kg fat-free mass-1.min-1). Muscle glycogen increased in the HC-EX group (78.5 +/- 8.1 to 161.1 +/- 15.7 mmol glucose/kg muscle), with no changes in the HC group. These results do not support the recommendation to increase the dietary carbohydrate content for improving postprandial glucose metabolism or insulin action in glucose-intolerant adults unless combined with exercise training, which promotes muscle glycogen storage.

Military body fat standards and equations applied to middle-aged women.

Military circumference equations are used to assess compliance of military personnel with body fat (BF) standards. The purpose of the present study was to determine the ability of military equations to correctly classify 62 women aged 40-60 yr (50.9 +/- 6.2, mean +/- SD) as overfat or underfat using underwater weighing (UWW) as the reference method and military BF standards as diagnostic cutoffs. Values for the mean +/- SD percent BF from UWW, Army, Marine Corps, and Navy equations were 29.5 +/- 7.1, 27.3 +/- 4.7, 25.7 +/- 5.8, and 30.3 +/- 5.1, respectively. The Army and Marine Corps equations underpredicted percent BF compared to UWW, P < 0.05. Bland-Altman plots showed a lack of agreement in predicting percent BF in women 40-60 yr between equation and UWW-derived percent BF. This finding was supported by the low agreement in correctly classifying an individual as meeting or exceeding the BF standards, range 25%-57%, Cohen's kappa. The low sensitivities (range 20%-74%) and higher specificities (range 80%-98%) of the equations indicated they identified individuals who met the BF standards better than those who exceeded them. Caution must be exercised when using military prediction equations to assess compliance with military BF standards in healthy middle-aged women.

Strength improvements with 1 yr of progressive resistance training in older women.

Thirty-nine healthy women (59.5 +/- 0.9 yr) were randomized to either a control group (CON) or a progressive resistance training group (PRT) that trained twice weekly for 12 months. PRT trained at 80% or more (average of 84%) of their most recent one repetition maximum (1RM) on the lateral pull-down (LPD), knee extensor (KE), and double leg press (DLP) apparatus. One RM was measured for each exercise once monthly in PRT and at baseline, midstudy, and end of study in CON. One RM significantly increased in PRT for all muscle groups trained compared to CON (P < 0.0001). Increases of 73.7 +/- 12%, 35.1 +/- 3%, and 77.0 +/- 5%, respectively, for KE, DLP, and LPD in PRT and 12.7% +/- 8%, 3.7% +/- 3%, and 18.4% +/- 4%, respectively, in CON were observed. Approximately 50% of the gains in KE and LPD and 40% in the DLP were seen in the first 3 months of the study. In all three exercises, strength gains in PRT continued over the entire 12-month period. These data indicate that high-intensity strength training results in substantial, continual increases in strength in postmenopausal women for at least 12 months, with the greatest gains seen in the first 3 months of training.

Factors associated with low body mass index and weight loss in nursing home residents.

BACKGROUND: Undernutrition in nursing home residents is a significant and possibly modifiable public health problem. We evaluated the hypothesis that some potentially modifiable factors are associated with resident undernutrition. METHODS: This study is a cross-sectional, secondary data analysis of 6,832 community nursing home residents sampled from 202 nursing homes in 7 states. Data were from the Minimum Data Set (MDS), and HCFA-mandated resident assessment instrument used in U.S. community nursing homes. Two dependent variables represented undernutrition: (a) low body mass index (BMI), defined as the lowest quartile BMI of the sample (19.42 kg/m2 and below); and (b) weight loss, an MDS measure defined as 5% decrease in weight in 30 days, or a 10% decrease in 180 days (9.9% of the sample). Independent variables included resident demographics, eating-related variables, variables measuring functional, cognitive, and affective statuses, and medical conditions. Separate logistic regression models were estimated for low BMI and weight loss to test multivariate associations. RESULTS: Poor oral intake, eating dependency, decubiti, and chewing problems increase the likelihood of both low BMI and weight loss. Female gender, age 85 or older, bedfast, and hip fracture increase the odds of low BMI only; depressed behaviors and two or more chronic diseases increase the odds of weight loss only. CONCLUSION: Undernutrition in nursing home residents is a multifactorial syndrome. Improved oral feeding methods and treatment of depression are potentially important ways to counteract undernutrition in nursing home residents by targeting reversible features.

Relationship between physical performance and self-perceived physical function.

OBJECTIVE: The objective of this study was to compare two methods of measuring physical function in subjects with a broad range of abilities and to evaluate the effects of cognitive, social, educational, and age factors on the relationship between the two methods. DESIGN: Multiple regression analysis was used to compare self-perceived (dependent variables) with performance measures (independent variables). Covariates included age, gender, Mini-Mental State Exam score, education, living status, and depression score. SETTING: Five community-dwelling and two nursing home sites. PARTICIPANTS: 417 community-dwelling subjects and 200 nursing home residents aged 62-98 years. MEASUREMENTS: Self-perceived physical function was assessed with the physical dimension summary score of the Sickness Impact Profile, which comprises three subscales: ambulation, mobility, and body care and movement. Physical performance was evaluated by self-selected gait speed, chair-stand time, maximal grip strength, and a balance score. RESULTS: Nursing home residents and community-dwellers were significantly different (P < .0001) in all variables except age and gender. Self-perceived and performance-based measures were moderately correlated, with a range from r = -.194 to r = -.625 (P < .05). Gait speed was the strongest independent predictor of self-perceived physical function in both groups. Symptoms of depression were also an independent predictor of self-perceived function in nursing home residents; subjects who had such symptoms report more self-perceived dysfunction than would be predicted based on performance tests. CONCLUSIONS: Self-selected gait speed is a global indicator of self-perceived physical function over a broad range of abilities. External determinants (depressive symptoms, cognitive function, marital status, etc.) affect self-perceived function in both groups, but gait speed is the greatest single predictor of self-perceived function. In nursing home residents depressive symptomatology is related to self-perceived.

Aging and dietary modulation of elastase and interleukin-1 beta secretion.

Aging is associated with diminished immune function that may stem from alterations in arachidonic acid metabolism and lipid peroxidation. This study sought to determine if dietary modification of fatty acids influenced neutrophil and monocyte secretion after an in vivo inflammatory stress in older human subjects. Volunteers participated in protocols that forced their quadriceps muscles to lengthen during tension development (eccentric stress). These protocols can cause inflammatory foci in the muscle as well as alterations in circulating leukocyte function. In this study, in vivo neutrophil degranulation was assessed by plasma elastase concentrations, and mononuclear cell function was assessed by interleukin-1 beta (IL-1 beta) secretion in vitro. In response to eccentric stress, older subjects (> 60 yr old) taking a placebo had no apparent elastase response, whereas those taking fish oil supplements responded with a 142% increase in plasma elastase (P = 0.011), similar to responses of younger reference subjects (< 33 yr old) taking no supplement. Overall, elastase responses correlated with individual plasma arachidonic acid-to-eicosapentaenoic acid ratios (r = -0.881, P = 0.004). Thus apparent age-related differences in elastase release were reconciled by individual differences in fatty acid nutriture. No significant temporal changes in urinary lipid peroxide excretion or IL-1 beta secretion were observed; however, age-associated differences were found.

Effects of high-intensity strength training on multiple risk factors for osteoporotic fractures. A randomized controlled trial.

OBJECTIVE: To determine how multiple risk factors for osteoporotic fractures could be modified by high-intensity strength training exercises in postmenopausal women. DESIGN: Randomized controlled trial of 1-year duration. SETTING: Exercise laboratory at Tufts University, Boston, Mass. POPULATION: Forty postmenopausal white women, 50 to 70 years of age, participated in the study; 39 women completed the study. The subjects were sedentary and estrogen-deplete. INTERVENTIONS: High-intensity strength training exercises 2 days per week using five different exercises (n = 20) vs untreated controls (n = 19). MAIN OUTCOME MEASURES: Dual energy x-ray absorptiometry for bone status, one repetition maximum for muscle strength, 24-hour urinary creatinine for muscle mass, and backward tandem walk for dynamic balance. RESULTS: Femoral neck bone mineral density and lumbar spine bone mineral density increased by 0.005 +/- 0.039 g/cm2 (0.9% +/- 4.5%) (mean +/- SD) and 0.009 +/- 0.033 g/cm2 (1.0% +/- 3.6%), respectively, in the strength-trained women and decreased by -0.022 +/- 0.035 g/cm2 (-2.5% +/- 3.8%) and -0.019 +/- 0.035 g/cm2 (-1.8% +/- 3.5%), respectively, in the controls (P = .02 and .04). Total body bone mineral content was preserved in the strength-trained women (+2.0 +/- 68 g; 0.0% +/- 3.0%) and tended to decrease in the controls (-33+77 g; -1.2% +/- 3.4%, P = .12). Muscle mass, muscle strength, and dynamic balance increased in the strength-trained women and decreased in the controls (P = .03 to < .001). CONCLUSIONS: High-intensity strength training exercises are an effective and feasible means to preserve bone density while improving muscle mass, strength, and balance in postmenopausal women.