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

The effect of obesity combined with low muscle strength on decline in mobility in older persons: results from the InCHIANTI study

OBJECTIVE

Both obesity and muscle impairment are increasingly prevalent among older persons and negatively affect health and physical functioning. However, the combined effect of coexisting obesity and muscle impairment on physical function decline has been little studied. We examined whether obese persons with low muscle strength experience significantly greater declines in walking speed and mobility than persons with only obesity or low muscle strength.

DESIGN

Community-dwelling adults aged > or = 65 years (n = 930) living in the Chianti geographic area (Tuscany, Italy) were followed for 6 years in the population-based InCHIANTI study.

MEASUREMENTS

On the basis of baseline measurements (1998-2000), obesity was defined as body mass index (BMI) > or = 30 kg/m(2) and low muscle strength as lowest sex-specific tertile of knee extensor strength. Walking speed and self-reported mobility disability (ability to walk 400 m or climb one flight of stairs) were assessed at baseline and at 3- and 6-year follow-up.

RESULTS

At baseline, obese persons with low muscle strength had significantly lower walking speed compared with all other groups (P < or = 0.05). In longitudinal analyses, obese participants with low muscle strength had steeper decline in walking speed and high risk of developing new mobility disability over the 6-year follow-up compared with those without obesity or low muscle strength. After the age of 80, the differences between groups were substantially attenuated. The differences seen in walking speed across combination of low muscle strength and obesity groups were partly explained by 6-year changes in muscle strength, BMI and waist circumference.

CONCLUSIONS

Obesity combined with low muscle strength increases the risk of decline in walking speed and developing mobility disability, especially among persons < 80 years old.

Genetic and environmental effects on isometric muscle strength and leg extensor power followed up for three years among older female twins

The purpose of this study was to examine changes in the contribution of genetic and environmental effects to isometric knee extensor strength and leg extensor power among 63- to 76-year-old female twins over a 3-yr follow-up. At baseline in 2000 the sample comprised 206 monozygotic (MZ) and 228 dizygotic (DZ) twin individuals, and at follow-up in 2003 the sample comprised 149 MZ and 164 DZ twin individuals. Genetic modeling showed that genetic effects explained 58% (95% CI: 46–68%) of the variance in muscle strength at baseline and 56% (95% CI: 41–68%) at follow-up, with no occasion-specific genetic effect. Nonshared environmental effects accounted for 42% (95% CI: 32–54%) of the variation at baseline and 15% (95% CI: 7–26%) at follow-up. In addition, new nonshared environmental effects explained the remaining variance, 29% (95% CI: 22–37%) of muscle strength at follow-up. For muscle power, the same genetic effects accounted for 67% (95% CI: 57–74%) of the variation at baseline and 48% (95% CI: 34–61%) at follow-up. Nonshared environmental effects in common at both measurement points explained 33% (95% CI: 25–43%) of the total variation at baseline and 11% (95% CI: 5–21%) at follow-up. The remaining variance of muscle power at follow-up was accounted for by time-specific environmental effects. Results indicated that the contribution of genetic effects to isometric muscle strength was stable, whereas for leg extensor power the proportion of genetic effects decreased during the follow-up. We observed new specific environmental effects underlying follow-up muscle strength and power, which effects could be due to the onset of new disease processes or changes in lifestyle.

Mobility limitations in persons with psychotic disorder: findings from a population-based survey

BACKGROUND

There are few reports on mobility limitations in persons with psychotic disorder although restrictions in mobility may aggravate the general functional limitations of these patients. Our aim was to investigate mobility limitations among subjects with psychotic disorder in a general population-based sample.

METHODS

A nationally representative sample of 6,927 persons aged 30 and older self-reported mobility limitations in an interview and was examined in performance tests. Diagnostic assessment of DSM-IV psychotic disorders combined SCID interview and case note data. Lifetime-ever diagnoses of psychotic disorder were classified into schizophrenia, other nonaffective psychotic disorders and affective psychoses.

RESULTS

Self-reported mobility limitations were highly prevalent in persons with schizophrenia and other nonaffective psychosis, but not in the affective psychosis group. After adjusting for age and sex, persons with schizophrenia and other nonaffective psychoses but not affective psychoses had significantly increased odds of having both self-reported and test-based mobility limitations as well as weak muscle strength. Schizophrenia remained an independent predictor of mobility limitations even after controlling for lifestyle-related factors and chronic medical conditions. Among persons with nonaffective psychoses, higher levels of negative symptoms predicted mobility limitations.

CONCLUSION

Self-reported mobility limitations are prevalent already at a young age in persons with schizophrenia and other nonaffective psychotic disorders, and among older persons with these disorders both self-reported limitations and measured performance tests show lower capacity in mobility. Difficulties in mobility are associated with negative symptoms. Mental health care professionals should pay attention to mobility limitations in persons with psychotic disorder.

The aging population--is there a role for endocrine interventions?

The expected increase in the aging population will have a significant impact on society and the health system in the coming years and decades. Enhancing healthspan, "healthy aging", and thus extending the time that the elderly are able to function independently is a significant task and is imperative. Age-dependent changes such as weight loss, sarcopenia and anorexia, which contribute to the development of frailty in the elderly are discussed. The role of the age-dependent decrease in growth hormone secretion in this process and the potential benefits and risks of hormonal interventions to delay, prevent or reverse frailty in the elderly are reviewed.

Sarcopenia in nursing home residents

The age-associated loss of muscle mass and muscle strength described by the term sarcopenia is highly relevant for functionality among nursing home residents. Nevertheless, the scientific literature concentrating on sarcopenia in this population is scarce. For practical reasons, common definitions of this entity, which rely on dual energy x-ray absorptiometry (DEXA) and bioimpedance analysis (BIA), cannot be applied in this setting. Anthropometric measurements like arm muscle circumference and calf circumference seem to be most suitable. Handgrip may be used as an alternative. Prevalence data show a wide range but are mostly high. There is a close association of the degree of sarcopenia with dependence among residents. The pathophysiology of sarcopenia in this population is strongly influenced by comorbidity and often there is significant overlap with the cachexia syndrome. At present, physical exercise is regarded to be the most promising therapeutic option, with resistance training being superior to endurance programs. Physical exercise has been successful even among Alzheimer patients and physically restrained residents. It has to be accompanied by the provision of adequate and diverse meals based on individual energy and nutrient requirements. Special attention should be paid to the treatment of vitamin D deficiency if present. New therapeutic options include Whole Body Vibration, oral supplements with essential amino acids and leucine, ACE-inhibitors, and cytokine-modifying drugs.

Relationship between performance-based and laboratory tests for lower-limb muscle strength and power assessment in healthy older women

The aim of the study was to assess the relationship between performance-based and laboratory tests for muscular strength and power assessment in older women. Thirty-two women aged 68.8 +/- 2.8 years were recruited. All participants were asessed for: (a) two performance-based tests--the box-stepping test (mean 296 +/- 51 J) and two-revolution maximum test (mean 7.1 +/- 2 kg) performed while pedalling on a cycle ergometer; and (b) muscular function tests--maximal instantaneous peak power jumping on a force platform (mean 1528 +/- 279 W); maximal voluntary contraction (MVC) during knee extension (mean 601 +/- 571 N) and leg press (mean 626 +/- 126 N), and leg press power (mean 483 +/- 98 W) on a dynamometer. Using univariate analysis, performance-based tests were compared with laboratory muscle strength and power measurements. Muscle power correlated most strongly with the performance-based tests for both jumping and leg press power (r-values between 0.67 and 0.75; P < 0.01). The correlation with muscle strength measures ranged between 0.48 and 0.61 (P < 0.01). The proposed tests may have particular relevance in geriatric and rehabilitation environments as they represent an easy, practical, and inexpensive alternative for the assessment of muscular strength and power.

Longitudinal analysis of early stage sarcopenia in aging rhesus monkeys

We present a longitudinal study using the rhesus monkey to determine biochemical and histological changes in vastus lateralis (VL) muscle fibers and whether these changes correlate with muscle mass loss. Dual-energy X-ray absorptiometry (DXA) was used to determine body weight, body fat and to estimate upper leg muscle mass in 12 adult male rhesus monkeys over 12 years. Muscle mass (MM) was evaluated at years 6, 9 and 12 of the study. Concurrently, VL muscle biopsy samples were collected. Muscle tissue was sectioned, stained and individual muscle fibers were analyzed for fiber type, cross-sectional area (CSA) and mitochondrial electron transport system (ETS) enzyme abnormalities. The animals' body weight did not change over time, however a significant increase in DXA-measured percent body fat was observed. Significant MM loss occurred in the upper leg over 12 years. A reduction in muscle fiber CSA significantly contributed to the MM loss observed in the VL of middle-aged rhesus monkeys. An age-dependent increase in muscle fibers developing mitochondrial enzyme abnormalities due to mitochondrial DNA deletion mutations was observed. The longitudinal approach of this study demonstrated that significant muscle changes occurred during middle age in a cohort of aging rhesus monkeys.

Low serum carotenoids are associated with a decline in walking speed in older women

BACKGROUND AND OBJECTIVES

Walking speed is an important measure of physical performance that is predictive of disability and mortality. The relationship of dietary factors to changes in physical performance has not been well characterized in older adults. The aim was to determine whether total serum carotenoid concentrations, a marker for fruit and vegetable intake, and serum selenium are related to changes in walking speed in older women.

SUBJECTS AND METHODS

The relationship between total serum carotenoids and selenium measured at baseline, 12, and 24 months follow-up and walking speed assessed at baseline and every six months for 36 months was examined in 687 moderately to severely disabled women, 65 years or older, living in the community.

RESULTS

Mean total serum carotenoids were associated with mean walking speed over three years of follow-up (P = 0.0003) and rate of change of walking speed (P = 0.007) in multivariate linear regression models adjusting for age, body mass index, and chronic diseases. Mean serum selenium was associated with mean walking speed over three years of follow-up (P = 0.0003) but not with the rate of change of walking speed (P = 0.26).

CONCLUSIONS

These findings suggest that a higher fruit and vegetable intake, as indicated by higher total serum carotenoid concentrations, may be protective against a decline in walking speed in older women.

Nutritional status and self-reported and performance-based evaluation of physical function of elderly persons in rural Bangladesh

AIM

To investigate the impact of nutritional status on self-reported as well as performance-based indicators of physical function in a rural elderly population in Bangladesh.

METHODS

A cross-sectional study conducted in Matlab, Bangladesh, included 457 randomly selected community-living elderly persons aged 60 years or more (60-92 years; 69 +/- 7 years). Mobility, activities of daily living (ADL), performance tests, handgrip strength, the Mini Nutritional Assessment (MNA) and a structured questionnaire were used to assess physical function, nutritional status, socioeconomic status and health status, respectively. Descriptive and linear hierarchical regression analyses were applied.

RESULTS

Seven per cent of the participants reported limitations in mobility, and 8% reported limitations in ADL. However, more than half of the participants had difficulties in performing one or more items in the performance tests. According to the MNA, 26% of the participants were undernourished and 62% were at risk of malnutrition. More undernourished participants than well-nourished participants reported limited mobility, impaired ADL and difficulties in the performance tests. A corresponding reduction in grip strength was observed in the undernourished group. Accordingly, higher MNA scores, indicating better nutritional status, were significantly associated with higher mobility index, higher ADL index, higher performance tests index, and higher scores in handgrip strength. These associations remained after adjusting for demographic, socioeconomic and health status differences.

CONCLUSIONS

Good nutritional status is important for the physical function of elderly people, even after controlling for possible confounders. Performance tests indicated a higher degree of functional impairment than that observed by self-reported estimation.

Development and validation of a short portable sarcopenia measure in the African American health project

BACKGROUND

Poor muscle size and function (sarcopenia) have an important role in the age-associated disability process. However, no commonly accepted index of sarcopenia exists for use in epidemiological studies.

METHODS

A cohort of 998 community-dwelling African Americans 49-65 years' old at baseline was used to construct the short portable sarcopenia measure (SPSM). SPSM was conceptualized as a measure of sarcopenia that combines estimates of muscle quantity and function into a single scale, is based on component items that can be obtained easily in the field, represents muscle status at a single time point that can be used without sex-specific adjustments, and can be used to follow change in muscle status over time with each person as his or her own control. We used exploratory factor analysis (EFA) to identify a unidimensional scale based on timed chair rises, lean mass, and grip strength divided by height. We used these three items and their EFA factor weights to construct SPSM (mean 9.0, median 9, range 0 [worst] to 18 [best] at baseline). Construct validity of the new measure, over a period of 36 months was examined.

RESULTS

SPSM required 8.5 pounds of equipment and 12.4 minutes to complete. It showed good score distribution and convergent, discriminant, and predictive validity with measures of muscle function, body composition, physical performance, psychological factors, and functional limitation cross-sectionally and with muscle function and body composition longitudinally. Extensive sensitivity analyses confirmed SPSM's robustness.

CONCLUSIONS

SPSM is a brief, portable, and valid measure of sarcopenia for use in epidemiological research. Similar studies in other populations are needed.

Effects of aging and arm swing on the metabolic cost of stability in human walking

To gain insight into the mechanical determinants of walking energetics, we investigated the effects of aging and arm swing on the metabolic cost of stabilization. We tested two hypotheses: (1) elderly adults consume more metabolic energy during walking than young adults because they consume more metabolic energy for lateral stabilization, and (2) arm swing reduces the metabolic cost of stabilization during walking in young and elderly adults. To test these hypotheses, we provided external lateral stabilization by applying bilateral forces (10% body weight) to a waist belt via elastic cords while young and elderly subjects walked at 1.3m/s on a motorized treadmill with arm swing and with no arm swing. We found that the external stabilizer reduced the net rate of metabolic energy consumption to a similar extent in elderly and young subjects. This reduction was greater (6-7%) when subjects walked with no arm swing than when they walked normally (3-4%). When young or elderly subjects eliminated arm swing while walking with no external stabilization, net metabolic power increased by 5-6%. We conclude that the greater metabolic cost of walking in elderly adults is not caused by a greater cost of lateral stabilization. Moreover, arm swing reduces the metabolic cost of walking in both young and elderly adults likely by contributing to stability.

Genetics of maximal walking speed and skeletal muscle characteristics in older women

The aim of this study was to examine whether maximal walking speed, maximal isometric muscle strength, leg extensor power and lower leg muscle cross-sectional area (CSA) shared a genetic effect in common. In addition, we wanted to identify the chromosomal areas linked to maximal walking speed and these muscle characteristics and also investigate whether maximal walking speed and these three skeletal muscle characteristics are regulated by the same chromosomal areas. We studied 217 monozygotic (MZ) and dizygotic (DZ) female twin pairs aged 66 to 75 years in the Finnish Twin Study on Aging study. The DZ pairs (94) were genotyped for 397 microsatellite markers in 22 autosomes and X-chromosome. Genetic modeling showed that, muscle CSA, strength, power and walking speed shared a genetic effect in common which accounted for 7% of the variation in CSA, 51% in strength, 37% in power and 35% in walking speed. The results of an explorative multipoint linkage analysis suggested that the highest LOD score found for each phenotype was 2.41 for walking speed on chromosome 13q22.1, 2.14 for strength on chromosome 15q14, 2.84 for power on chromosome 8q24.23, and 2.93 for muscle CSA on chromosome 20q13.31. Also a suggestive LOD score, 2.68, for muscle CSA was found on chromosome 9q34.3. The chromosomal areas of a suggestive linkage for strength and power partly overlapped LOD scores higher than 1.0 being seen for these phenotypes on chromosome 15. The present study was the first genome-wide linkage analysis to be conducted for these multifactorial and clinically important phenotypes underlying functional independence in older women.

Sarcopenic obesity: definition, cause and consequences

PURPOSE OF REVIEW

Older obese persons with decreased muscle mass or strength are at special risk for adverse outcomes. We discuss potential pathways to muscle impairment in obese individuals and the consequences that joint obesity and muscle impairment may have on health and disability. Tantamount to this discussion is whether low muscle mass or, rather, muscle weakness should be used for the definition.

RECENT FINDINGS

Excess energy intake, physical inactivity, low-grade inflammation, insulin resistance and changes in hormonal milieu may lead to the development of so-called 'sarcopenic obesity'. It was originally believed that the culprit of age-related muscle weakness was a reduction in muscle mass, but it is now clear that changes in muscle composition and quality are predominant. We propose that the risk of adverse outcomes, such as functional limitation and mortality, is better estimated by considering jointly obesity and muscle strength rather than obesity and muscle mass and the term 'sarcopenic obesity' should be revisited.

SUMMARY

Recognition of obese patients who have associated muscle problems is an essential goal for clinicians. Further research is needed to identify new target for prevention and cure of this important geriatric syndrome.

Dynamic models for the study of frailty

Frailty can be viewed as resulting from the degradation of multiple interacting physiologic systems that are normally responsible for healthy adaptation to the daily demands of life. Mathematical models that can quantify alterations in the dynamics of physiologic systems and their interactions may help characterize the syndrome of frailty and enable investigators to test interventions to prevent its onset. One theoretical mathematical model reported by Varadhan et al. in this issue of the Journal represents one type of regulatory process that may become altered in frail individuals-the stimulus-response mechanism [Varadhan, R., Seplaki, C.S., Xue, Q.L., Bandeen-Roche, K., Fried, L.P. Stimulus-response paradigm for characterizing the loss of resilience in homeostatic regulation associated with frailty. Mech. Ageing Dev., this issue]. This model focuses on the timing of recovery from a single stimulus, rather than the full array of responses that might be altered in a complex dynamical system. Therefore, alternative models are needed to describe the wide variety of behaviors of physiologic systems over time and how they change with the onset of frailty. One such model, based on a simple signaling network composed of a lattice of nodes and the bi-directional connections between them, can reproduce the complex, fractal-like nature of healthy physiological processes. This model can be used to demonstrate how the degradation of signaling pathways within a physiologic system can result in the loss of complex dynamics that characterizes frailty.

Optimal protein intake in the elderly

The recommended dietary allowance (RDA) for protein, as promulgated by the Food and Nutrition Board of the United States National Academy of Science, is 0.8 g protein/kg body weight/day for adults, regardless of age. This value represents the minimum amount of protein required to avoid progressive loss of lean body mass in most individuals. There is an evidence that the RDA for elderly may be greater than 0.8 g/kg/day. Evidence indicates that protein intake greater than the RDA can improve muscle mass, strength and function in elderly. In addition, other factors, including immune status, wound healing, blood pressure and bone health may be improved by increasing protein intake above the RDA. Furthermore, the RDA does not address the recommended intake of protein in the context of a balanced diet. Concerns about potential detrimental effects of increased protein intake on bone health, renal function, neurological function and cardiovascular function are generally unfounded. In fact, many of these factors are improved in elderly ingesting elevated quantities of protein. It appears that an intake of 1.5 g protein/kg/day, or about 15-20% of total caloric intake, is a reasonable target for elderly individuals wishing to optimize protein intake in terms of health and function.

Effects of resistance training on lower-extremity impairments in older people with hip fracture

OBJECTIVE

To study the effects of resistance training on muscle strength parameters, mobility, and balance.

DESIGN

Randomized controlled trial.

SETTING

Research laboratory and senior gym.

PARTICIPANTS

Population-based sample of eligible 60- to 85-year-old community-dwelling men and women 0.5 to 7.0 years after hip fracture. Forty-six people had no contraindications and were willing to participate in the exercise trial.

INTERVENTION

Twelve-week intensive progressive strength-power training (n=24), aiming to reduce asymmetric deficit in leg muscle strength and power, or no intervention (n=22).

MAIN OUTCOME MEASURES

Isometric knee extension torque (KET) and leg extension power (LEP) measured in the weaker and stronger leg and the asymmetric deficit ([weak/sum both legs]x100%), 10-m walking speed, dynamic balance test, and self-reported outdoor mobility.

RESULTS

KET increased in both legs (P<.021), LEP tended to increase in the weaker leg (P=.071), and asymmetric LEP deficit decreased (P=.010) after training compared with the control group. LEP of the stronger leg, asymmetric KET deficit, walking speed, and balance performance were not significantly affected by training. Self-reported ability to walk outdoors improved after training. The compliance to the training was over 90%, and few adverse events (n=4; mainly musculoskeletal) were likely to be caused by the training.

CONCLUSIONS

Intensive resistance training is feasible for people with a hip fracture and improved muscle strength and power. More intensive training especially for the weaker leg may be needed to obtain more marked effects on asymmetric deficit, mobility, and balance. Also, the timing and duration of training program should be considered. (ISRCTN identifier ISRCTN34271567.)

Mediating relationships within the Disablement Process model: a cross-sectional study of the oldest-old

The Disablement Process model proposes a pathway for how chronic diseases in late life can lead to disability, with the variables in the main pathway designated as pathology, impairment, functional limitations, and disability. The model also suggests that psychosocial and contextual variables in the periphery of the model affect disability outcomes. The current study included 149 Swedish adults aged 86, 90, or 94 living in the community or in institutions who answered questions and performed tasks of physical and cognitive ability. A series of regressions were used to test the mediating role of variables within the main pathway of the model, as well as the ability of psychosocial variables to mediate main pathway relationships. Results indicated that physical limitations accounted for between 31 and 52% of the direct effects between impairments and disability, but delayed recall did not mediate these relationships. For the tests of psychosocial variables, mastery was a consistent mediator between impairments and functional limitations, and also mediated several relationships between functional limitations and disability variables. Depression and loneliness also mediated some of the relationships within the main pathway, but explained a smaller percentage of the total effects than mastery. The study concludes that the Disablement Process model is an effective biopsychosocial approach in describing and predicting disability in the oldest-old. In addition, the course of disability seems to be buffered by certain psychosocial variables, particularly feelings of mastery.

TNF promoter polymorphisms associated with muscle phenotypes in humans

Tumor necrosis factor-alpha (TNF-alpha) is a potent catabolic factor to skeletal muscle. Single-nucleotide polymorphisms (SNPs) in the promoter region of the TNF-alpha coding gene, TNF, have been implicated in the interindividual variation in TNF-alpha production via transcriptional regulation. The present study investigated the association of muscle phenotypes with five TNF promoter SNPs, which potentially have biological significance. Female and male volunteers (n = 1,050) from the Baltimore Longitudinal Study of Aging were genotyped, and their regional and total body muscle mass, and arm and leg muscle strength were measured. Results indicated that putative high-expression alleles at positions -1031 and -863, individually or in combination in the haplotype 1031C-863A-857C-308G-238G, were associated with lower muscle mass in men. Specifically, carriers of -1031C, compared with noncarriers, exhibited lower arm muscle mass (6.4 +/- 0.1 vs. 6.8 +/- 0.1 kg, P = 0.01) and appendicular skeletal muscle mass (ASM) (24.3 +/- 0.4 vs. 25.4 +/- 0.2 kg, P = 0.02), with leg muscle mass and the ASM index (ASMI; kg/m(2)) also tending to be lower (P = 0.06 and 0.07). Similarly, -863A allele carriers (linked with -1031), compared with noncarriers, exhibited lower arm muscle mass (6.4 +/- 0.1 vs. 6.8 +/- 0.1 kg, P = 0.04). Carriers of the haplotype 1031C-863A-857C-308G-238G, compared with noncarriers, exhibited lower arm muscle mass (6.3 +/- 0.2 vs. 6.8 +/- 0.1 kg, P < 0.01), trunk muscle mass (25.7 +/- 0.5 vs. 26.9 +/- 0.3 kg, P < 0.05), and ASM (24.1 +/- 0.5 vs. 25.3 +/- 0.2 kg, P < 0.025), with tendencies for lower leg muscle mass and ASMI (P = 0.07 and 0.08). Results indicate that genetic variation in the TNF locus may contribute to the interindividual variation in muscle phenotypes in men.

Epidemiology of hip and knee pain in a community based sample of Italian persons aged 65 and older

OBJECTIVE

To describe prevalence, characteristics and correlates of hip pain (HP) and knee pain (KP) in an Italian community based cohort aged 65 and older (65+).

METHOD

Baseline survey (1998-2000), population-based study in the Chianti area (Tuscany, Italy); 1299 persons aged 65+ were selected from the city registry of Greve in Chianti and Bagno a Ripoli (multistage sampling method); 1006 participants (564 women and 442 men, age 75.2+/-7.1) provided information for this analysis. Persons reporting HP/KP in the past 4 weeks were recorded and their Western Ontario and McMaster University Osteoarthritis Index pain score (WPS-range 0-20) calculated. Potential correlates of HP/KP, including clinical, lifestyle and psycho-social features and physical measures, were tested in age- and gender-adjusted regression analyses and then entered a multivariate regression model.

RESULTS

HP was reported by 11.9% participants, while 22.4% reported KP and 7.2% both conditions. Climbing/descending stairs and walking were the activities eliciting more severe pain in either condition. Average WPSs were 5.6+/-3.5 for HP and 5.4+/-10.4 for KP. Both HP and KP were related to back pain, reduced hip abduction, reduced muscle power and increased trunk flexibility. HP was also related to KP and poor self-rated health (SRH), while KP to HP, foot pain, high body mass index, reduced knee passive flexion and knee extension torque, low education.

CONCLUSION

In a community sample of an Italian persons aged 65+, the prevalence of KP almost doubled that of HP. While both conditions were related to pain in other joints and specific joint impairment, only HP was related to poor SRH, and only KP to mechanical overload.

Higher circulating levels of uric acid are prospectively associated with better muscle function in older persons

BACKGROUND

Previous studies have shown that oxidative protein damage is independently associated with low grip strength and that dietary intake and circulating levels of antioxidant vitamins are positive predictors of muscle strength among older persons. Since uric acid (UA), has strong antioxidant properties, we tested the hypothesis that UA levels is cross-sectionaly associated with muscle strength and protective against the decline of strength over the aging process.

SUBJECTS AND METHODS

789 InCHIANTI Study participants underwent baseline serum UA, handgrip and knee extension torque measurements. Of these, 497 participants (226 men and 271 women, mean age 76.0+/-5.4 years) also had follow-up strength measures. Lifestyle, comorbidities, nutritional profile, inflammatory markers and other laboratory measures were considered as potential confounders.

RESULTS

Follow-up strength measures significantly increased across baseline UA tertiles. After adjusting for potential confounders and analogous baseline strength measures, higher baseline UA levels still remained significantly associated with higher follow-up strength measures.

CONCLUSIONS

Our findings suggest that higher levels of UA might represent a protective reaction aimed at counteracting the excessive production of free radicals that cause muscle protein damage and eventually contribute to the decline of muscle mass and strength.

Target population for clinical trials on sarcopenia

The term "sarcopenia" describes the progressive decline of muscle mass, strength and function occurring with aging. It is not considered a disease, but the direct consequence of the aging process on the skeletal muscle. Multiple demographic (e.g. gender, race), biological (e.g. inflammatory status) and clinical (e.g. diabetes, metabolic syndrome, congestive heart failure, medications) factors are able to influence (positively or negatively) the skeletal muscle quality and quantity. The extreme paucity of clinical trials on sarcopenia in literature is mainly due to difficulties in designing studies able to isolate the aging process from its multiple and interconnected consequences. In the present review, we present the major factors to consider as potential sources of biased results when evaluating potential candidates for clinical trials on sarcopenia. The development of clinical trials exploring the nature of the sarcopenia process is urgent, but several controversial issues on this hallmark of aging still need clarification.

The developmental origins of sarcopenia: using peripheral quantitative computed tomography to assess muscle size in older people

BACKGROUND

A number of studies have shown strong graded positive relationships between size at birth, grip strength, and estimates of muscle mass in older people. However no studies to date have included direct measures of muscle size.

METHODS

We studied 313 men and 318 women born in Hertfordshire, United Kingdom between 1931 and 1939 who were still resident there and had historical records of growth in early life. Information on lifestyle was collected, and participants underwent peripheral quantitative computed tomography to directly measure forearm and calf muscle size.

RESULTS

Birth weight was positively related to forearm muscle area in the men (r = 0.24, p <.0001) and women (r = 0.17, p =.003). There were similar but weaker associations between birth weight and calf muscle area in the men (r = 0.13, p =.03) and in the women (r = 0.17, p =.004). These relationships were all attenuated by adjustment for adult size.

CONCLUSION

We present first evidence that directly measured muscle size in older men and women is associated with size at birth. This may reflect tracking of muscle size and is important because it suggests that benefit may be gained from taking a life course approach both to understanding the etiology of sarcopenia and to developing effective interventions.

Sarcopenia: its assessment, etiology, pathogenesis, consequences and future perspectives

Sarcopenia is a loss of muscle protein mass and loss of muscle function. It occurs with increasing age, being a major component in the development of frailty. Current knowledge on its assessment, etiology, pathogenesis, consequences and future perspectives are reported in the present review. On-going and future clinical trials on sarcopenia may radically change our preventive and therapeutic approaches of mobility disability in older people.

Natural history and risk factors for bone loss in postmenopausal Caucasian women: a 15-year follow-up population-based study

In this 15-year follow-up study, we found that the estimated rate of bone loss at the femoral neck (FN) for women aged 45-68 was linear at a rate of 1.67% per year, but quadratic for lumbar spine (LS) at a rate of 3.12% initially, and slowing down with age. We also confirmed the protective role of HRT, increasing weight, and lean mass in long-term bone loss.

INTRODUCTION

The objective was to describe the natural history of bone loss and explore the role of environmental factors in postmenopausal women over a 15-year period.

METHODS

Bone mineral density (BMD) at the FN and the LS were measured in postmenopausal women from the Chingford Study. Height, weight, HRT status, and calcium/vitamin D supplement were assessed at each visit. Osteoarthritis of hip and spine was assessed by X-ray at baseline and at year 8.

RESULTS

A total of 955 postmenopausal women with an average age of 54.7 at baseline were included. Both FN and LS BMD decreased significantly with age (p<0.0001). The decline was larger in the LS (-3.12% per year), which showed a quadratic relationship, than in the FN (-1.67% per year) with a linear relationship. The rate of bone loss was reduced by one third annually for the FN and LS respectively in current HRT users. Change in weight was positively associated with both DeltaFN and DeltaLS BMD (beta=0.16% and 0.09% change in DeltaFN and DeltaLS BMD per kilogramme change in weight respectively, p<0.0001 for both sites). Spine OA and progression were positively associated with DeltaLS BMD (beta=1.22% change in DeltaLS BMD per grade in spine OA and 0.45% change in DeltaLS BMD for patients who progressed, p<0.0001 for spine OA and p=0.002 for spine OA progression). Spine OA (beta=0.54% change in DeltaFN BMD per grade, p<0.0001), but not progression, and hip OA were positively associated with DeltaFN BMD. Furthermore, both age and body weight at baseline were positively associated with both DeltaFN and DeltaLS BMD (beta=0.02-0.04% change in DeltaFN and DeltaLS BMD per year increase in age at baseline and 0.004-0.007% change in DeltaFN and DeltaLS BMD per kilogramme increase in weight at baseline, all p<0.0001).

CONCLUSION

This large population-based longitudinal study demonstrated that the decline of BMD over 15 years is linear with age for the FN, but quadratic for the LS. The study confirmed the protective role of HRT, increased weight and lean mass in long-term bone loss.

Enhancing quality of life in older adults: a comparison of muscular strength and power training

Background

Although progressive resistance strength training (ST) has been found to improve various measures of physical functioning in older adults, the benefit to quality of life is unclear. Additionally, recent evidence suggests that high velocity power training (PT) may be more beneficial for physical functioning than ST, but it is not known whether this type of training impacts quality of life. The purpose of this study was to compare changes in multiple measures of quality of life resulting from ST vs. PT in older adults. A no exercise group was also included as control comparison condition.

Methods

Forty-five older adults (M age = 74.8 years; SD = 5.7) were randomly assigned to either a) PT, b) ST, or c) control group (no exercise). Measures of self-efficacy (SE), satisfaction with physical function (SPF), and the Satisfaction with Life Scale (SWL) were assessed at baseline and following training. The resistance training conditions met 3 times per week for 12 weeks at an intensity of 70% 1 repetition maximum.

Results

A series of ANCOVA's comparing between group differences in change and controlling for baseline values revealed significant group differences in all three measures: SE (F_(2,31) = 9.77; p < .001); SPF (F_(2,32) = 3.36; p = .047); SWL (F_(2,31) = 4.76; p = .016). Follow up analyses indicated that the PT group reported significantly more change in SE, SPF, and SWL than the control group whereas the ST group reported greater change than the control group only in SE.

Conclusion

These pilot data indicate that high velocity power training may influence multiple levels of quality of life over and above the benefits gained through traditional strength training.

Low plasma carotenoids and skeletal muscle strength decline over 6 years

BACKGROUND

Higher intake of fruits and vegetables appears to protect against inflammation, poor physical performance, and disability, but its relationship with muscle strength is unclear. We examined the association between total plasma carotenoids, an indicator of fruit and vegetable intake, and changes in muscle strength over a 6-year follow-up in the participants aged 65 years and older in the InCHIANTI study, a population-based study in Tuscany, Italy.

METHODS

Plasma carotenoids were measured at enrollment (1998-2000). Hip, knee, and grip strength were measured at enrollment and 6 years later (2004-2006) in 628 of the 948 participants evaluated at baseline. Poor muscle strength was defined as the lowest sex-specific quartile of hip, knee, and grip strength at enrollment. The main outcome was poor muscle strength at the 6-year follow-up visit among those participants originally in the upper three quartiles of strength at enrollment.

RESULTS

Overall, 24.9% (110/441), 25.0% (111/444), and 24.9% (118/474) participants developed poor hip, knee, and grip strength, respectively. After adjusting for potential confounders, participants in the lowest versus the highest quartile of total plasma carotenoids at enrollment were at higher risk of developing poor hip (odds ratio [OR] = 3.01, 95% CI, 1.43-6.31, p =.004), knee (OR = 2.89, 95% CI, 1.38-6.02, p =.005), and grip (OR = 1.88, 95% CI, 0.93-3.56, p =.07) muscle strength at the 6-year follow-up visit.

CONCLUSION

These findings suggest that older community-dwelling adults with lower plasma carotenoids levels, a marker of poor fruit and vegetable intake, are at a higher risk of decline in skeletal muscle strength over time.

Correlation between manual muscle strength and interleukin-6 (IL-6) plasma levels in elderly community-dwelling women

Sarcopenia is a loss of muscle mass related to aging and leads to muscle performance decline. An increase in inflammatory mediator levels, especially of IL-6, has been associated to reduced muscle strength in the elderly. The aim of the present cross-sectional study was to correlate IL-6 plasma levels with manual muscle strength (MMS) in 63 community-dwelling elderly women. (71.2+/-7.4years). IL-6 was measured using enzyme-linked immunosorbent assay (ELISA) and MMS was measured using the JAMAR dynamometer. Pearson's test was used to explore the relationship between the outcomes at the significance level of alpha=0.05. IL-6 levels (2.56+/-3.44pg/ml) and MMS (22.86+/-4.62kgf) exhibited an inverse correlation (r=-0.2673 and p=0.0373). The increase in IL-6 plasma levels possibly contributed toward the reduction in manual muscle strength among the elderly women studied.

Effects of whole-body vibration exercise on lower-extremity muscle strength and power in an older population: a randomized clinical trial

BACKGROUND AND PURPOSE

Vibration training is a relatively new exercise intervention. This study investigated the effects of vibration exercise on strength (force-producing capacity) and power in older adults who are healthy.

PARTICIPANTS AND METHODS

Thirty participants (mean age=73.7 years, SD=4.6) were randomly assigned to a vibration exercise training (VIB) group or an exercise without vibration training (EX) group. The interventions consisted of 3 sessions per week for 8 weeks. Outcome measures included isokinetic flexor and extensor strength and power of the hip, knee, and ankle.

RESULTS

The VIB group significantly improved ankle plantar flexor strength and power compared with the EX group. However, there were no significant differences between the VIB and EX groups for knee flexor or extensor strength.

DISCUSSION AND CONCLUSION

Vibration training contributed to an increase in plantar flexor strength and power. However, the strength gains for the knee and hip flexors and extensors for the VIB group and the EX group were comparable. Future vibration protocols should explore different body positions to target muscles higher up on the leg.

A força de preensão manual é boa preditora do desempenho funcional de idosos frágeis: um estudo correlacional múltiplo

A força de preensão manual (FPM) associa-se com a funcionalidade de idosos, mas há dúvidas sobre o valor dessa relação em todas as situações. O estudo observou a correlação entre FPM de idosos residentes em instituições de cuidados permanentes (asilos) e o desempenho funcional (DF) em tarefas específicas e inespecíficas para as mãos. Participaram 12 homens (70±6 anos; 64±9 kg; 160±10 cm) e sete mulheres (77±11 anos; 49±10 kg; 147±10 cm). A FPM foi medida com dinamômetro hidráulico. As tarefas motoras propostas foram: caminhar 10 m na velocidade máxima (C10), timed up & go test (TUGT), colocar e retirar chave de fechadura (TCCF) e tirar e recolocar lâmpada em um bocal (TCLB). O teste de Wilcoxon revelou que os homens apresentaram melhores desempenhos que as mulheres em todos as medidas, exceto IMC, TCCF e TCLB (p<0,05). Os coeficientes de Spearman revelaram que três testes apresentaram correlações significativas com a FPM: TRLB (r = -0,54; p = 0,018); TUGT (r = -0,67; p = 0,002) e C10 (r = -0,69; p = 0,001). A correlação múltipla entre a FPM e o conjunto dos testes revelou-se igualmente significativa (R-múltiplo = 0,66; p<0,04). Conclui-se que a FPM pode ser uma boa preditora do desempenho em tarefas motoras em idosos frágeis, investindo-se de potencial para apreciação da funcionalidade como um todo, enquanto variável de exposição epidemiológica.

Oxidative stress and severe walking disability among older women

BACKGROUND

Oxidative stress has been implicated in sarcopenia and the loss of muscle strength with aging, but the relationship between oxidative stress and decrease in muscle strength and physical performance has not been well characterized. Serum protein carbonyls are markers of oxidative damage to proteins and are caused by oxidative stress.

METHODS

Serum protein carbonyls were measured at baseline and compared with a decrease in walking speed and development of severe walking disability (inability to walk or walking speed <0.4 m/sec) over 36 months of follow-up in 545 moderately to severely disabled women, aged > or =65 years, living in the community in Baltimore, Maryland (the Women's Health and Aging Study I).

RESULTS

After adjusting for age, body mass index, smoking, and chronic diseases, log(e) protein carbonyls (nmol/mg) were associated with a decrease in walking speed over 36 months (P=.002). During follow-up, 154 women (28.2%) developed severe walking disability. After adjusting for the same potential confounders, log(e) protein carbonyls were associated with incident severe walking disability (hazards ratio 1.42, 95% confidence interval, 1.02-1.98, P=.037).

CONCLUSION

High oxidative stress, as indicated by oxidative damage to proteins, is an independent predictor of decrease in walking speed and progression to severe walking disability among older women living in the community.

Grip strength and the metabolic syndrome: findings from the Hertfordshire Cohort Study

INTRODUCTION

Sarcopenia, the loss of muscle mass and strength with age, is significantly associated with type 2 diabetes in older people.

AIM

To determine whether there is a relationship between grip strength and features of the metabolic syndrome.

DESIGN

Cross-sectional study.

METHODS

Data were collected on grip strength, fasting glucose, triglycerides and HDL cholesterol, blood pressure, waist circumference and 2 h glucose after an oral glucose tolerance test, in a population-based sample of 2677 men and women aged 59-73 years.

RESULTS

In men and women combined, a standard deviation (SD) decrease in grip strength was significantly associated with higher: fasting triglycerides (0.05 SD unit increase, 95%CI 0.02-0.09, p = 0.006); blood pressure (OR 1.13, 95%CI 1.04-1.24, p = 0.004); waist circumference (0.08 SD unit increase, 95%CI 0.06-0.10, p < 0.001); 2 h glucose (0.07 SD unit increase, 95%CI 0.03-0.11, p = 0.001) and HOMA resistance (0.05 SD unit increase, 95%CI 0.01-0.09, p = 0.008), after adjustment for gender, weight, age, walking speed, social class, smoking habit and alcohol intake. Lower grip strength was also significantly associated with increased odds of having the metabolic syndrome according to both the ATPIII (OR 1.18, 95%CI 1.07-1.30, p < 0.001) and IDF definitions (OR 1.11, 95%CI 1.01-1.22, p = 0.03).

DISCUSSION

Our findings suggest that impaired grip strength is associated with the individual features, as well as with the overall summary definitions, of the metabolic syndrome. The potential for grip strength to be used in the clinical setting needs to be explored.

Muscle Mass and Functional Recovery in Men with Hip Fracture

OBJECTIVE

To investigate the association between muscle mass and functional recovery in men after hip fracture.

DESIGN

We investigated 27 of 33 men admitted consecutively to a rehabilitation hospital after hip fracture. For each patient, we also studied two control women, matched for age and fracture type. Lean mass (LM) was assessed by dual-energy x-ray absorptiometry (DXA) 21.9 +/- 7.5 (mean +/- SD) days after fracture occurrence in the 27 men (22.8 +/- 7.2 days in the 54 control women). Appendicular LM (aLM) was calculated as the sum of LM in arms and legs. Functional recovery was assessed using Barthel index scores. Barthel index efficiency was calculated as the change in the Barthel index score after rehabilitation divided by the length of stay in hospital.

RESULTS

After adjustment for age, height, fat mass, Barthel index scores at admission, and time between fracture occurrence and DXA assessment, aLM was significantly associated with Barthel index scores after rehabilitation (r = 0.480; P = 0.013) and Barthel index efficiency (r = 0.633; P = 0.001) in the 27 men. Conversely, in the 54 control women, no significant associations were found between aLM and the functional scores.

CONCLUSIONS

LM assessed after hip fracture is significantly associated with the functional outcome in men.

Central activation, muscle performance, and physical function in men infected with human immunodeficiency virus

Loss of muscle mass and limitations in activity have been reported in persons infected with human immunodeficiency virus (HIV), even those who are otherwise asymptomatic. The extent to which factors other than muscle atrophy impair muscle performance has not been addressed in depth. The purpose of this study was to determine the extent of neuromuscular activation of the knee extensors and ankle dorsiflexors of 27 men infected with HIV receiving antiretroviral therapy and its relationship to muscle performance. The central activation ratio (CAR) was determined using superimposed electrical stimulation during maximum voluntary contractions. In addition to force and power measurements, muscle cross-sectional area and composition was evaluated using computed tomography. Aerobic capacity was determined from treadmill exercise testing. Eleven of the subjects had an impaired ability to activate the knee extensors (CAR = 0.72 +/- 0.12) that was associated with weakness and decreased specific force. The reduced central activation was not associated with muscle area, body composition, aerobic capacity, CD4 count, or medication regimen. Those individuals with low central activation had higher HIV-1 viral loads and were more likely to have a history of AIDS-defining illness. These results suggest the possibility of a different mechanism contributing to muscle impairment in the current treatment era that is associated with impairment of central motor function rather than atrophy. Further investigation is warranted in a larger, more diverse population before more definitive claims are made.

Association of low plasma selenium concentrations with poor muscle strength in older community-dwelling adults: the InCHIANTI Study

BACKGROUND

Although selenium plays an important role in muscle function, the relation between circulating selenium and muscle strength in elderly adults has not been characterized.

OBJECTIVE

The objective was to examine the hypothesis that low plasma selenium is associated with poor muscle strength in older adults.

DESIGN

We measured plasma selenium and hip, grip, and knee strength in a cross-sectional study of 891 men and women aged >or=65 y from the Invecchiare in Chianti (InCHIANTI) Study, a population-based cohort study in Tuscany (Italy). Poor muscle strength was defined as the lowest quartile of hip flexion, grip, and knee extension strength.

RESULTS

Overall, mean (+/-SD) plasma selenium was 0.95 +/- 0.15 mumol/L. After adjustment for age, sex, education, total energy intake, body mass index, and chronic disease, participants in the lowest versus the highest quartile of plasma selenium were at higher risk of poor hip strength [odds ratio (OR): 1.69; 95% CI: 1.02, 2.83; P = 0.04, P for linear trend = 0.04], knee strength (OR: 1.94; 95% CI: 1.18, 3.19; P = 0.009, P for linear trend = 0.01), and grip strength (OR: 1.94; 95% CI: 1.19, 3.16; P = 0.008, P for linear trend = 0.08).

CONCLUSIONS

Low plasma selenium is independently associated with poor skeletal muscle strength in community-dwelling older adults in Tuscany.

Loss of skeletal muscle mass in aging: Examining the relationship of starvation, sarcopenia and cachexia

A loss of body weight or skeletal muscle mass is common in older persons and is a harbinger of poor outcome. Involuntary weight loss can be categorized into three primary etiologies of starvation, sarcopenia, and cachexia. Starvation results in a loss of body fat and non-fat mass due to inadequate intake of protein and energy. Sarcopenia is associated with a reduction in muscle mass and strength occurring with normal aging, associated with a reduction in motor unit number and atrophy of muscle fibers, especially the type IIa fibers. The loss of muscle mass with aging is clinically important because it leads to diminished strength and exercise capacity. Cachexia is widely recognized as severe wasting accompanying disease states such as cancer or immunodeficiency disease, but does not have a universally accepted definition. The key clinical question is whether these changes in body composition are distinct entities or represent an interdependent continuum. The importance of defining the distinction lies in developing a targeted therapeutic approach to skeletal muscle loss and muscle strength in older persons. Failure to distinguish among these causes of skeletal muscle loss often results in frustration over the clinical response to therapeutic interventions.

Admission albumin levels and functional outcome of elderly hip fracture patients: is it that important?

BACKGROUND AND AIMS

Low serum albumin level is considered a marker of poor health outcome in various medical conditions. A relationship between low albumin levels and poor functional outcome has been found in the elderly, lower albumin predicting a greater functional decline. The objective of this study was to evaluate to what extent admission albumin levels may affect the functional outcome of elderly hip fracture patients.

METHODS

This retrospective chart review study was conducted in an orthogeriatric unit of a university-affiliated referral hospital. The participants were 449 elderly patients with hip fractures, admitted for a standard rehabilitation course. Functional outcome of patients with normo-albuminemia and hypo-albuminemia was assessed by Functional Independence Measurement (FIM) at admission and discharge. Data were analyzed by t-test, Pearson's correlation, Chi-square test and Linear Regression.

RESULTS

38.8% of patients were hypoalbuminemic upon admission. These patients were older (p<0.001) and had lower Mini-Mental State Examination (MMSE) scores (p=0.003), compared with normo- albuminemic patients. Discharge FIM scores were higher in normo-albuminemic compared with hypo-albuminemic patients (total FIM 86.1+/-23.9 and 77.0+/-26.4, respectively; p<0.001; motor-FIM 60.0+/-16.3 and 53.4+/-18.0, respectively; p<0.001). Linear regression analysis showed that total FIM at discharge was inversely associated with pre-fracture function (beta -0.13; p<0.001). A high MMSE score (beta 0.16; p<0.001), female gender (beta 0.05; p=0.02) and higher admission total FIM scores (beta 0.69; p<0.001) emerged as predictors of higher total FIM scores upon discharge. Albumin levels did not independently predict better total FIM scores upon discharge (beta -0.02; p=0.36).

CONCLUSIONS

Normo-albuminemic patients present with better admission FIM scores and have higher discharge FIM scores. After controlling for possible confounders, albumin remains a non-significant predictor of higher discharge FIM scores. We suggest that low albumin levels should not be considered as adversely affecting the rehabilitation of elderly hip fracture patients.

Genetic effects in common on maximal walking speed and muscle performance in older women

The purpose was to examine whether maximal walking speed, maximal isometric knee extensor strength, and leg extensor power share genetic or environmental effects in common. The data was collected from 103 monozygotic and 114 dizygotic female twin pairs aged 63-76 years. Maximal walking speed over 10 m was measured in the laboratory corridor using photocells for timing. Isometric knee extensor strength and leg extensor power were measured using an adjustable dynamometer. The genetic models showed that strength, power, and walking speed had a genetic effect in common which accounted for 52% of the variance in strength, 36% in power, and 34% in walking speed. Strength and power had a non-shared environmental effect in common explaining 13% of variation in strength and 14% in power. The remaining variance was accounted for by trait-specific effects. Some people may be more prone to functional limitation in old age due to their genetic disposition, but this does not rule out that changes in the lifestyle of predisposed subjects may also have a major effect. Approximately half of the variation in each trait was explained by environmental effects, which suggests the importance of the physical activity to improve performance and prevent functional limitation.

Muscle quality, aerobic fitness and fat mass predict lower-extremity physical function in community-dwelling older adults

BACKGROUND

Muscle mass, strength and fitness play a role in lower-extremity physical function (LEPF) in older adults; however, the relationships remain inadequately characterized.

OBJECTIVE

This study aimed to examine the relationships between leg mineral free lean mass (MFLM(LEG)), leg muscle quality (leg strength normalized for MFLM(LEG)), adiposity, aerobic fitness and LEPF in community-dwelling healthy elderly subjects.

METHODS

Fifty-five older adults (69.3 +/- 5.5 years, 36 females, 19 males) were assessed for leg strength using an isokinetic dynamometer, body composition by dual energy X-ray absorptiometry and aerobic fitness via a treadmill maximal oxygen consumption test. LEPF was assessed using computerized dynamic posturography and stair ascent/descent, a timed up-and-go task and a 7-meter walk with and without an obstacle.

RESULTS

Muscle strength, muscle quality and aerobic fitness were similarly correlated with static LEPF tests (r range 0.27-0.40, p < 0.05); however, the strength of the independent predictors was not robust with explained variance ranging from 9 to 16%. Muscle quality was the strongest correlate of all dynamic LEPF tests (r range 0.54-0.65, p < 0.001). Using stepwise linear regression analysis, muscle quality was the strongest independent predictor of dynamic physical function explaining 29-42% of the variance (p < 0.001), whereas aerobic fitness or body fat mass explained 5-6% of the variance (p < 0.05) depending on performance measure.

CONCLUSIONS

Muscle quality is the most important predictor, and aerobic fitness and fat mass are secondary predictors of LEPF in community-dwelling older adults. These findings support the importance of exercise, especially strength training, for optimal body composition, and maintenance of strength and physical function in older adults.

Health-related implications and management of sarcopenia

The loss of muscle mass experienced in sarcopenia is a slow, progressive process. The condition is analogous to osteoporosis as a normal, albeit deleterious and equally costly, consequence of aging. There is an almost universal lack of awareness of sarcopenia, its consequences, and its prevention or management, however--which is not the case for osteoporosis. Sarcopenia has a multifactorial etiology, and interventions targeting the various mechanisms contributing to its pathogenesis have been investigated. Exercise is the only intervention that reliably increases muscle mass, strength, and power. The benefits of exercise, particularly ST, include a reduction in disease, better balance with fewer falls, and fewer fractures. Equally compelling, exercise is associated with increased independence and quality of life. Obtaining adequate nutrition via a healthy diet is a fundamental adjunct to physical activity in managing sarcopenia. Even though diet and exercise guidelines are an established part of public health recommendations, most people are not meeting target levels for physical activity or nutritional goals. Greater efforts are needed to achieve behavioral and lifestyle change on a national level. Until those changes occur, health care providers must champion the cause and make wellness strategies a priority in their practices.

Physiological functions should be considered as true end points of nutritional intervention studies

With the beginning of this millennium it has become fashionable to only follow ‘evidence-based’ practices. This generally-accepted approach cruelly negates experience or intelligent interpretation of pathophysiology. Another problem is that the great ‘meta-analysts’ of the present era only accept end points that they consider ‘hard’. In the metabolic and nutritional field these end points are infection-related morbidity and mortality, and all other end points are considered ‘surrogate’. The aim of this presentation is to prove that this claim greatly negates the contribution of more-fundamentally-oriented research, the fact that mortality has multifactorial causes, and that infection is a crude measure of immune function. The following problems should be considered: many populations undergoing intervention have low mortality, requiring studies with thousands of patients to demonstrate effects of intervention on mortality; nutrition is only in rare cases primary treatment, and in many populations is a prerequisite for survival rather than a therapeutic modality; once the effect of nutritional support is achieved, the extra benefit of modulation of the nutritional support regimen can only be modest; cost–benefit is not a valid end point, because the better it is done the more it will cost; morbidity and mortality are crude end points for the effect of nutritional intervention, and are influenced by many factors. In fact, it is a yes or no factor. In the literature the most important contributions include new insights into the pathogenesis of disease, the diminution of disease-related adverse events and/or functional improvement after therapy. In nutrition research the negligence of these end points has precluded the development and validation of functional end points, such as muscle, immune and cognitive functions. Disability, quality of life, morbidity and mortality are directly related to these functional variables. It is, therefore, of paramount importance to validate functional end points and to consider them as primary rather than surrogate end points.

Handgrip performance in relation to self-perceived fatigue, physical functioning and circulating IL-6 in elderly persons without inflammation

Background

Low grip strength is recognized as one of the characteristics of frailty, as are systemic inflammation and the sensation of fatigue. Contrary to maximal grip strength, the physical resistance of the muscles to fatigue is not often included in the clinical evaluation of elderly patients. The aim of this study was to investigate if the grip strength and the resistance of the handgrip muscles to fatigue are related to self-perceived fatigue, physical functioning and circulating IL-6 in independently living elderly persons.

Methods

Forty elderly subjects (15 female and 25 male, mean age 75 ± 5 years) were assessed for maximal grip strength, as well as for fatigue resistance and grip work (respectively time and work delivered until grip strength drops to 50% of its maximum during sustained contraction), self perceived fatigue (VAS-Fatigue, Mob-Tiredness scale and the energy & fatigue items of the WHOQOL-100), self rated physical functioning (domain of physical functioning on the MOS short-form) and circulating IL-6. Relationships between handgrip performance and the other outcome measures were assessed.

Results

In the male participants, fatigue resistance was negatively related to actual sensation of fatigue (VAS-F, p < .05) and positively to circulating IL-6 (p < .05). When corrected for body weight, the relations of fatigue resistance with self-perceived fatigue became stronger and also apparent in the female. Grip strength and grip work were significantly related with several items of self-perceived fatigue and with physical functioning. These relations became more visible by means of higher correlation coefficients when grip strength and grip work were corrected for body weight.

Conclusion

Well functioning elderly subjects presenting less handmuscle fatigue resistance and weaker grip strength are more fatigued, experience more tiredness during daily activities and are more bothered by fatigue sensations. Body weight seems to play an important role in the relation of muscle performance to fatigue perception. Elderly patients complaining from fatigue should be physically assessed, both evaluating maximal grip strength and fatigue resistance, allowing the calculation of grip work, which integrates both parameters. Grip work might best reflect the functional capacity resulting from the development of a certain strength level in relation to the time it can be maintained.