Age-associated changes in skeletal muscles and their effect on mobility: an operational diagnosis of sarcopenia

Sarcopenic obesity and inflammation in the InCHIANTI study

The aging process is often paralleled by decreases in muscle and increases in fat mass. At the extreme these two processes lead to a condition known as "sarcopenic obesity" (Roubenoff R. Ann NY Acad Sci 904: 553-557, 2000). Research suggests that inflammatory cytokines produced by adipose tissue, especially visceral fat, accelerate muscle catabolism and thus contribute to the vicious cycle that initiates and sustains sarcopenic obesity. We tested the hypothesis that obesity and poor muscle strength, hallmarks of sarcopenic obesity, are associated with high circulating levels of proinflammatory cytokines in a random sample of the residents of two municipalities in the Chianti geographic area (Tuscany, Italy). The study sample consisted of 378 men and 493 women 65 yr and older with complete data on anthropometrics, handgrip strength, and inflammatory markers. Participants were cross-classified according to sex-specific tertiles of waist circumference and grip strength and according to a cut point for obesity of body mass index > or =30 kg/m(2). After adjusting for age, sex, education, smoking history, physical activity, and history of comorbid diseases, components of sarcopenic obesity were associated with elevated levels of IL-6, C-reactive protein, IL-1 receptor antagonist, and soluble IL-6 receptor (P < 0.05). Our findings suggest that global obesity and, to a greater extent, central obesity directly affect inflammation, which in turn negatively affects muscle strength, contributing to the development and progression of sarcopenic obesity. These results suggest that proinflammatory cytokines may be critical in both the development and progression of sarcopenic obesity.

Carotenoids as protection against sarcopenia in older adults

Sarcopenia, or loss of muscle mass and strength, plays a major role in the disablement process in older adults and increases the risk of impaired physical performance, falls, physical disability, frailty, and death. Oxidative stress is a major mechanism implicated in the pathogenesis of sarcopenia; aging muscle shows increased oxidative damage to DNA, protein, and lipids. Carotenoids quench free radicals, reduce damage from reactive oxygen species, and appear to modulate redox-sensitive transcription factors such as NF-kappaB that are involved in the upregulation of IL-6 and other proinflammatory cytokines. Recent epidemiological studies in community-dwelling older adults show that low serum/plasma carotenoids are independently associated with low skeletal muscle strength and the development of walking disability. These observations are consistent with a growing number of studies showing that a diet with high intake of fruits and vegetables is associated with a reduced risk of inflammation, hypertension, diabetes, cardiovascular disease, and mortality.

Endocrine therapies for sarcopenia in older men

This review looks at new therapeutic developments for the increasingly recognized problem of sarcopenia. Increased adiposity and reduced lean body mass characterize ageing men. The potential therapeutic role of the growth hormone/insulin-like growth factor axis, androgen modulators and myostatin inhibition are discussed.

Lower extremity strength and power are associated with 400-meter walk time in older adults: The InCHIANTI study

BACKGROUND

It has been suggested that lower extremity muscle power is more important for physical function in older adults compared to strength, and that there is a nonlinear relationship between power or strength and physical function that might be indicative of a threshold above which the association between muscle function and physical function is no longer evident. This study examined the association between lower extremity strength or power with the time to complete a 400-meter walk, and attempted to identify thresholds within the relationship.

METHODS

A cross-sectional analysis of a sample of 384 females and 336 males aged > or = 65 years from the InCHIANTI study ("Invecchiare in Chianti," i.e., Aging in the Chianti Area) was conducted. Measures included 400-meter walk time, lower extremity strength and power, comorbidities, and sociodemographic variables (age, gender, height, education, cognitive function, depression).

RESULTS

Linear regression models showed that both lower extremity strength and power were significant predictors of 400-meter walk time, although power explained marginally more of the variance in 400-meter walk time. Quadratic models of lower extremity strength and power fit the data slightly better than the linear models. Regardless of gender, comorbidities, or normalization scheme for strength and power, the curvilinear form of the relationship between strength or power and 400-meter walk time remained the same.

CONCLUSIONS

Lower extremity muscle strength and power are both important predictors of the 400-meter walk time. Although curvilinear relationships existed between muscle strength and power and the 400-meter walk time, the data do not indicate a clear threshold for either strength or power above which the performance in the 400-meter walk test plateaus.

Falls, sarcopenia, and growth in early life: findings from the Hertfordshire cohort study

Recent studies have shown that people whose early growth is poor have an increased risk of sarcopenia. Sarcopenia is an important risk factor for falls, but it is not known whether poor early growth is related to falls. The authors investigated this association in the Hertfordshire Cohort Study (1998-2004), where 2,148 participants from the United Kingdom provided their history of falls. Grip strength was used as a marker of sarcopenia. Birth weight, weight at 1 year, and conditional infant growth were analyzed in relation to history of falls. The prevalence of any fall in the last year was 14.3% for men and 22.5% for women. Falls in the last year were inversely related to adult grip strength, height, and walking speed in men and women as well as to lower conditional infant growth in men (odds ratio = 1.27, 95% confidence interval: 1.04, 1.56 per standard deviation decrease in conditional infant growth; p = 0.02). This association was attenuated after adjustment for grip strength. These findings support an association between poor early growth and falls in older men that appears to be mediated partly through sarcopenia. The lack of a relation with birth weight suggests that postnatal rather than prenatal influences on muscle growth and development may be important regarding the risk of falls in later life.

The Fischer 344/NNiaHSd X Brown Norway/BiNia is a better model of sarcopenia than the Fischer 344/NNiaHSd: a comparative analysis of muscle mass and contractile properties in aging male rat models

Sarcopenia, characterized by profound muscle atrophy and the loss of contractile function, contributes significantly to the development of frailty and functional impairment in older age. Although present in aging humans, rat models have failed to clearly demonstrate a similar degree of this age-associated loss of muscle mass and function. This investigation compared two models of rats raised specifically for aging studies, the Fischer 344/NNiaHSd (F344/N) and the Fischer 344/NNiaHSd X Brown Norway/BiNia (F344/NXBN), and sought to determine which model provides the most accurate representation of human sarcopenia. We found that aging had no effect on F344/N muscle mass or contractile function in the extensor digitorum longus (EDL) and soleus (SOL). Conversely, in the F344/NXBN model, aging was found to decrease EDL and SOL mass and contractile function. These changes were sufficient to satisfy the proposed criteria for the diagnosis of human sarcopenia based upon muscle mass and contractile function. Results indicate that the F344/NXBN provides a better model of the alterations seen in aging human muscle than the F344/N rat model.

Endocrine therapies for sarcopenia in older men

This review looks at new therapeutic developments for the increasingly recognized problem of sarcopenia. Increased adiposity and reduced lean body mass characterize ageing men. The potential therapeutic role of the growth hormone/insulin-like growth factor axis, androgen modulators and myostatin inhibition are discussed.

Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies

BACKGROUND

Studies of the association between obesity, and total mortality and cardiovascular events in patients with coronary artery disease (CAD) have shown contradictory results. We undertook a systematic review to determine the extent and nature of this association.

METHODS

We selected cohort studies that provided risk estimates for total mortality, with or without cardiovascular events, on the basis of bodyweight or obesity measures in patients with CAD, and with at least 6 months' follow-up. CAD was defined as history of percutaneous coronary intervention, coronary artery bypass graft, or myocardial infarction. We obtained risk estimates for five predetermined bodyweight groups: low, normal weight (reference), overweight, obese, and severely obese.

FINDINGS

We found 40 studies with 250,152 patients that had a mean follow-up of 3.8 years. Patients with a low body-mass index (BMI) (ie, <20) had an increased relative risk (RR) for total mortality (RR=1.37 [95% CI 1.32-1.43), and cardiovascular mortality (1.45 [1.16-1.81]), overweight (BMI 25-29.9) had the lowest risk for total mortality (0.87 [0.81-0.94]) and cardiovascular mortality (0.88 [0.75-1.02]) compared with those for people with a normal BMI. Obese patients (BMI 30-35) had no increased risk for total mortality (0.93 [0.85-1.03]) or cardiovascular mortality (0.97 [0.82-1.15]). Patients with severe obesity (> or =35) did not have increased total mortality (1.10 [0.87-1.41]) but they had the highest risk for cardiovascular mortality (1.88 [1.05-3.34]).

INTERPRETATION

The better outcomes for cardiovascular and total mortality seen in the overweight and mildly obese groups could not be explained by adjustment for confounding factors. These findings could be explained by the lack of discriminatory power of BMI to differentiate between body fat and lean mass.

Magnesium and muscle performance in older persons: the InCHIANTI study

BACKGROUND

The role of magnesium in maintaining muscle integrity and function in older adults is largely unknown.

OBJECTIVE

We aimed to investigate the relation between serum magnesium concentrations and muscle performance in older subjects.

DESIGN

Data are from the baseline examination conducted between September 1998 and March 2000 of the InCHIANTI (aging in the Chianti area) study, a prospective epidemiologic survey of risk factors for late-life disability. From among 1453 randomly selected community residents completing a home interview, 1138 men (46%) and women (aged 66.7 +/- 15.2 y; x +/- SD) with complete data on muscle performance and serum magnesium who were not severely cognitively compromised and had no evidence of kidney disease or hypercalcemia were included in the analysis. Muscle performance was evaluated by grip strength, lower-leg muscle power, knee extension torque, and ankle extension isometric strength and was normalized for age and body mass index (BMI) within each sex.

RESULTS

After adjustment for age, sex, BMI, laboratory variables, presence of chronic diseases, muscle area, muscle density, and physical activity level, serum magnesium concentrations were significantly associated with indexes of muscle performance, including grip strength (beta = 2.0 +/- 0.5, P = 0.0002), lower-leg muscle power (beta = 8.8 +/- 2.7, P = 0.001), knee extension torque (beta = 31.2 +/- 7.9, P < 0.0001), and ankle extension strength (beta = 3.8 +/- 0.5, P < 0.0001).

CONCLUSIONS

The serum magnesium concentration is an independent correlate of muscle performance in older persons. Whether magnesium supplementation improves muscle function remains to be shown.

Is grip strength associated with health-related quality of life? Findings from the Hertfordshire Cohort Study

OBJECTIVE

to investigate the relationship between grip strength and health-related quality of life (HRQoL).

DESIGN

cross-sectional survey within a cohort study design.

SETTING

the county of Hertfordshire in the UK.

PARTICIPANTS

a total of 2,987 community-dwelling men and women aged 59-73 years of age.

MEASUREMENTS

grip strength was used as a marker of sarcopaenia and measured using a Jamar dynamometer. HRQoL was assessed using the eight domain scores of the Short Form-36 (SF-36) questionnaire, and subjects in the lowest sex-specific fifth of the distribution were classified as having 'poor' status for each domain.

RESULTS

men and women with lower grip strength were significantly more likely to report a poor as opposed to excellent to fair overall opinion of their general health (GH) [odds ratio (OR) per kilogram decrease in grip strength = 1.13, 95% CI = 1.06-1.19, P < 0.001 in men, 1.13, 95% CI = 1.07-1.20, P < 0.001 in women]. Among men, after adjustment for age, size, physical activity and known co-morbidity, decreased grip strength was associated with increased prevalence of poor SF-36 scores for the physical functioning (PF) (OR per kilogram decrease in grip strength = 1.03, 95% CI = 1.01-1.06, P = 0.007) and GH domains (OR = 1.03, 95% CI = 1.01-1.05, P = 0.01). Similar associations were seen in women.

CONCLUSIONS

our findings suggest that lower grip strength is associated with reduced HRQoL in older men and women. This does not appear to be explained by age, size, physical activity or co-morbidity and may reflect the link between sarcopaenia and generalised frailty. Individuals with sarcopaenia may benefit from interventions to improve muscle mass and strength before the onset of chronic disorders usually associated with impaired HRQoL.

Epidemiology of back pain in a representative cohort of Italian persons 65 years of age and older: the InCHIANTI study

STUDY DESIGN

Clinico-epidemiologic study in the Chianti area (Tuscany, Italy).

OBJECTIVES

To describe prevalence and correlates of back pain in a representative sample of the population.

SUMMARY OF BACKGROUND DATA

Back pain is common in old age and is related to functional limitations, but back pain characteristics and correlates in older adults, which may be targeted by specific interventions, are still underinvestigated.

METHODS

A total of 1,299 persons aged 65 or older were selected from the city registry of Greve in Chianti and Bagno a Ripoli; 1,008 (565 women; 443 men) were included in this analysis. Back pain in the past 12 months was ascertained using a questionnaire. Potential correlates of back pain were identified in age- and sex-adjusted regression analyses, and their independent association with back pain was tested in a multivariate model.

RESULTS

The prevalence of frequent back pain was 31.5%. Back pain was reported less often by men and the very old, was primarily located in the dorsolumbar and lumbar spine, was moderate in intensity and mainly elicited by carrying, lifting, and pushing heavy objects. Among participants who reported frequent back pain, 76.3% had no back pain-related impairments; 7.4% of the overall study population had back pain-related functional limitation. Back pain participants were significantly more likely to report difficulty in heavy household chores, carrying a shopping bag, cutting toenails, and using public transportation. Limited trunk extension, depression, low levels of prior-year physical activity, and hip, knee, and foot pain were independent correlates of back pain.

CONCLUSIONS

Frequent back pain is highly prevalent in the older population and is often associated with conditions that are potentially reversible.

Muscle mass and functional recovery in women with hip fracture

OBJECTIVE

To investigate the association between muscle mass and functional recovery in women with hip fracture.

DESIGN

A total of 200 of 230 women with hip fracture admitted consecutively to a rehabilitation hospital were investigated in this survey study. Lean mass (LM) was assessed by dual-energy x-ray absorptiometry, 23.1 +/- 7.9 (mean +/- SD) days after fracture occurrence. Appendicular LM (aLM) was calculated as the sum of LM in arms and legs. Because metal implants (prostheses and nails) affect the regional assessment of body composition, aLM was corrected by substituting LM in the unfractured leg for LM in the fractured leg: corrected aLM = (LM in unfractured leg x 2) + LM in arms. We used two approaches to adjust corrected aLM for body size: corrected aLM divided by height squared (aLM/ht), and corrected aLM adjusted for height and fat mass (residuals). Functional recovery was assessed by using Barthel index scores.

RESULTS

After adjustment for body size, corrected aLM was neither significantly correlated with Barthel index scores nor with the change in Barthel index scores after rehabilitation. Also, after stratification for quintiles of aLM/ht and residuals, no significant differences in functional recovery were found among the five groups.

CONCLUSIONS

LM assessed after hip fracture is not associated with functional outcome in women.

Strength training in older adults: an empowering intervention

PURPOSE

This study evaluated the benefits of adding a psychological empowerment intervention (PEI) to traditional strength training (TST) on social cognitive variables in community-dwelling older adults.

METHODS

Thirty-eight participants were randomly assigned to either a PEI or a TST intervention for 6 wk. Before random assignment and following training, participants completed measures of self-efficacy for upper and lower body strength as well as the desire to be able to lift specific amounts of weight. Both treatments involved two sessions per week of center-based training and one session per week of home-based training. The PEI condition also included a group-mediated intervention that was designed to increase self-efficacy for physical strength and the desire for upper and lower body strength.

RESULTS

General linear models on difference scores revealed that the two groups experienced differential gains in the desire for upper body strength (P = 0.023, effect size (ES) = 0.79) and were marginally different in gains for upper body strength self-efficacy (P = 0.065, ES = 0.63). On a four-point scale, the adjusted mean (+/-SE) differences for the PEI group on the desire for upper body strength was 0.71 (+/-0.12) as compared to 0.27 (+/-0.13) for the TST group, whereas the PEI group's improvement in self-efficacy for upper body strength was 25.70 (+/-3.02) as compared to 17.18 (+/-3.19) for the TST group.

CONCLUSIONS

Empowerment-based exercise programs may be particularly motivating for older adults by creating a more meaningful physical activity experience for them.

Long-term recreational gymnastics provides a clear benefit in age-related functional decline and bone loss. A prospective 6-year study

INTRODUCTION

Bone fragility and decreased functional performance are risk factors for osteoporotic fractures. The influence of long-term recreational gymnastics on the maintenance of bone rigidity and physical performance was evaluated.

METHODS

One hundred and seven gymnasts and 110 referents (93% of the original sample) participated in this 6-year prospective study. Analysis of covariance (ANCOVA) was used to estimate the between-group differences and changes by time, and regression analyses to find predictors for changes.

RESULTS

In both groups agility and leg extensor power decreased by over 3% and 10%, respectively, but the original between-group differences, favoring the gymnasts, persisted. Proximal femur bone mineral content (BMC) decreased approximately 0.5% per year in both groups, and femoral neck section modulus decreased. Trabecular density of the distal tibia declined only marginally, and cortical area of the tibial midshaft remained unchanged, while cortical density decreased about 2% in both groups. After adjustment by age, height, weight, change in weight, and follow-up time, antiresorptive medication and high calcium intake accounted most for the maintenance of bone rigidity.

CONCLUSIONS

In spite of similar rates of decline in bone characteristics and physical performance, the recreational gymnasts' overall physical condition was comparable to the level that their less active referents had shown approximately 5 years earlier.

Aging-sensitive cellular and molecular mechanisms associated with skeletal muscle hypertrophy

Sarcopenia is an age-related loss of muscle mass and strength. The aged can increase various measures of muscle size and strength in response to resistance exercise (RE), but this may not normalize specific tension. In rats, aging reduces the hypertrophy response and impairs regeneration. In this study, we measured cellular and molecular markers, indicative of muscle hypertrophy, that also respond to acute increases in loading. Comparing 6- and 30-mo-old rats, the aims were to 1) determine whether these markers are altered with age and 2) identify age-sensitive responses to acute RE. The muscles of old rats exhibited sarcopenia involving a deficit in contractile proteins and decreased force generation. The RNA-to-protein ratio was higher in the old muscles, suggesting a decrease in translational efficiency. There was evidence of reduced signaling via components downstream from the insulin/insulin-like growth factor (IGF)-I receptors in old muscles. The mRNA levels of myostatin and suppressor of cytokine signaling 2, negative regulators of muscle mass, were lower in old muscles but did not decrease following RE. RE induced increases in the mRNAs for IGF-I, mechano-growth factor, cyclin D1, and suppressor of cytokine signaling 3 were similar in old and young muscles. RE induced phosphorylation of the IGF-I receptor, and Akt increased in young but not old muscles, whereas that of S6K1 was similar for both. The results of this study indicate that a number of components of intracellular signaling pathways are sensitive to age. As a result, key anticatabolic responses appear to be refractory to the stimuli provided by RE.

Relation of plasma leptin to C-reactive protein in older adults (from the Invecchiare nel Chianti study)

Obese subjects have higher circulating levels of C-reactive protein (CRP) than normal subjects, and it has been shown that CRP per se may contribute to atherogenesis. The mechanism linking increased fat mass with high CRP levels has not been exhaustively explained. It has been suggested that adipose tissue-produced cytokines, including interleukin-6, tumor necrosis factor-alpha, and interleukin-1beta, represent the causal link between increased body fat and high CRP levels. It has been hypothesized that the hormone leptin, released by fat cells, may stimulate CRP production independent of cytokines. This study measured circulating leptin, CRP, interleukin-6, tumor necrosis factor-alpha, interleukin-1beta, and interleukin-8 in 946 community-dwelling older subjects (398 men, 548 women; age range 65 to 102 years) enrolled in a large population-based study. Confounders included demographics, functional, cognitive and affective status, diet and lifestyle, body composition, drugs, and chronic diseases. A direct association was found between leptin and CRP (p = 0.004), independent of cytokines and other possible confounders. The association was stronger in younger than in older subjects but was not influenced by gender or body mass index. In conclusion, these findings suggest that leptin may directly stimulate the production of CRP independent of fat-cell produced cytokines in older adults.

Evaluation of movement speed and reaction time as predictors of all-cause mortality in men

Muscle power is associated with mortality independent of strength, suggesting that movement speed and coordination convey health-related information. We hypothesized that movement speed is a marker of longevity. Our participants included 1196 men who performed a tapping and/or auditory simple (respond to a sound) and disjunctive (respond to a higher pitched sound) reaction-time tasks while participating in the Baltimore Longitudinal Study of Aging. Mortality was assessed over 40 years. Tapping time was associated with mortality (relative risk [RR] = 1.34 per minute, 95% confidence interval [CI], 1.05-1.70) adjusted for age, and persisted with adjustments for arm strength and power. Simple (RR = 1.17 per 100 ms, 95% CI, 1.03-1.32) and disjunctive (RR = 1.14 per 100 ms, 95% CI, 1.03-1.27) reaction times but not their difference (RR = 1.04 per 100 ms, 95% CI, 0.92-1.19) were associated with mortality after adjustments for age, neurological/psychiatric and neck/arm pain histories. Age-associated impairments in motor control systems but not the decision to move affects longevity.

Leg Extension Power Asymmetry and Mobility Limitation in Healthy Older Women

OBJECTIVE

To investigate the association of asymmetry in leg extension power (LEP) with walking and standing balance.

DESIGN

Cross-sectional analysis.

SETTING

Research laboratory.

PARTICIPANTS

Healthy female twins (N=419), ages 63 to 75 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The LEP difference between the stronger and the weaker leg, measured with the Nottingham power rig, was calculated. Ten-meter maximal walking velocity was assessed in a laboratory corridor on a wide (170 cm) and narrow (35 cm) track, and the ability to maintain tandem stance for 20 seconds was recorded.

RESULTS

The mean LEP difference +/- standard deviation between the legs was 15%+/-9% (P<.001). Those with large LEP difference had lower walking velocity and poorer standing balance than those with small LEP difference, in particular when the LEP of the stronger leg was below the median.

CONCLUSIONS

Even in healthy older women, substantial LEP asymmetry between the lower limbs was present, encumbering walking and standing balance. Lower-limb muscle power asymmetry warrants further study in order to develop well-targeted strategies for preventing mobility limitation in older people.

Axonal degeneration affects muscle density in older men and women

Using data from InCHIANTI, a prospective population-based survey of older persons, we examined the relationship of peroneal nerve conduction velocity (NCV, a measure of nerve myelination) and compound muscle action potential (CMAP, a measure of axonal degeneration) with calf muscle mass and density, two complementary measures of sarcopenia. NCV and CMAP were assessed by surface electroneurography of the right peroneal nerve conducted in 1162 participants, 515 men and 647 women, age 21-96 years, free of major neurological diseases. Cross-sectional muscle area and calf muscle density were measured using peripheral quantitative computerized tomography (pQCT). Both nerve and muscle parameters declined with age although in most cases the decline was not linear. In both sexes, CMAP, but not NCV, was independently and significantly associated with calf muscle density. These findings suggest that intrinsic changes in the muscle tissue are partially caused by a reduction in the number of motor axons.

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.

Determinants of changes in bone mass and femoral neck structure, and physical performance after menopause: a 9-year follow-up of initially peri-menopausal women

This prospective study set out to determine factors that underlie changes in bone characteristics and physical performance during postmenopausal years. Of 101 peri-menopausal women that originally participated in a randomized, controlled exercise intervention trial, 80 attended the follow-up measurements 9 years later. At follow-up, bone mineral content (BMC) of the lumbar spine, femoral neck and distal radius, as well as the maximal isometric muscle strength of leg extensors and arm flexors, and maximal oxygen uptake, were measured with the same protocols and devices as at the baseline. In addition, the hip structure analysis (HSA) was used to assess changes in the structure and strength at the narrowest section of the femoral neck. Changes in physical fitness or bone characteristics were independent of the original exercise intervention. In general, physical fitness declined with age from 5% to 30% and bone characteristics from 3% to 10%, except for the lumbar spine BMC and the periosteal diameter of the femoral neck, where no changes were observed. The use of hormone therapy (HRT) was the major factor accounting for the maintenance of BMC. Use of HRT alone explained 44% of the variability in the change at the femoral neck BMC, but it was not associated with changes in physical fitness. Change in the body weight was the only factor associated with the change in physical fitness: better maintenance in body weight predicted better maintenance of physical fitness. In conclusion, our results indicate that HRT helps to maintain bone mass and structure, which are important factors in prevention of fragility fractures in later life. However, HRT had no effect on physical fitness, which is highly associated with the risk of falling, the most important cause of fractures.

Sarcopenia of aging and its metabolic impact

Sarcopenia contributes significantly to the morbidity, decrease in quality of life, and health care costs in the elderly. It is characterized by a decrease in muscle mass and strength, starting as early as the fourth decade of life in humans. Distinct muscle changes include a decrease in type 2 muscle fibers and a decrease in myosin heavy chains IIa and IIx mRNA levels. In addition, a decrease in whole body protein turnover, mixed muscle protein synthesis, myosin heavy chain synthesis, and mitochondrial protein synthesis have been reported. Different tissues and organs display different responses to aging, with more oxidative tissue generally having more age-related changes. Exercise has been shown to increase strength, aerobic capacity, and muscle protein synthesis, as well as to increase muscle mitochondrial enzyme activity in both young and older people; however, exercise does not reverse all age-related changes. The metabolic effects of sarcopenia include a decrease in resting metabolic rate secondary to decreased fat-free mass and decreased physical activity, leading to a higher prevalence of insulin resistance, type 2 diabetes mellitus, dyslipidemia, and hypertension. The way in which age-related changes in hormone levels affect muscle remains to be fully understood. The effect of replacing those hormones on sarcopenia has led to some conflicting results, but further investigations are ongoing.

Hemodynamic effects of leg crossing and skeletal muscle tensing during free standing in patients with vasovagal syncope

Physical maneuvers can be applied to abort or delay an impending vasovagal faint. These countermaneuvers would be more beneficial if applied as a preventive measure. We hypothesized that, in patients with recurrent vasovagal syncope, leg crossing produces a rise in cardiac output (CO) and thereby in blood pressure (BP) with an additional rise in BP by muscle tensing. We analyzed the age and gender effect on the BP response. To confirm that, during the maneuvers, Modelflow CO changes in proportion to actual CO, 10 healthy subjects performed the study protocol with CO evaluated simultaneously by Modelflow and by inert gas rebreathing. Changes in Modelflow CO were similar in direction and magnitude to inert gas rebreathing-determined CO changes. Eighty-eight patients diagnosed with vasovagal syncope applied leg crossing after a 5-min free-standing period. Fifty-four of these patients also applied tensing of leg and abdominal muscles. Leg crossing produced a significant rise in CO (+9.5%; P < 0.01) and thereby in mean arterial pressure (+3.3%; P < 0.01). Muscle tensing produced an additional increase in CO (+8.3%; P < 0.01) and mean arterial pressure (+7.8%; P < 0.01). The rise in BP during leg crossing was larger in the elderly.