Understanding the minimal dose of physical activity required to achieve improvement in physical functioning and reductions in disability risk is necessary to inform public health recommendations. To ...examine the effect of physical activity dose on changes in physical functioning and the onset of major mobility disability in The Lifestyle Interventions and Independence for Elders (LIFE) Study. We conducted a multicenter single masked randomized controlled trial that enrolled participants in 2010 and 2011 and followed them for an average of 2.6 years. 1,635 sedentary men and women aged 70-89 years who had functional limitations were randomized to a structured moderate intensity walking, resistance, and flexibility physical activity program or a health education program. Physical activity dose was assessed by 7-day accelerometry and self-report at baseline and 24 months. Outcomes included the 400 m walk gait speed, the Short Physical Performance Battery (SPPB), assessed at baseline, 6, 12, and 24 months, and onset of major mobility disability (objectively defined by loss of ability to walk 400 m in 15 min). When the physical activity arm or the entire sample were stratified by change in physical activity from baseline to 24 months, there was a dose-dependent increase in the change in gait speed and SPPB from baseline at 6, 12, and 24 months. In addition, the magnitude of change in physical activity over 24 months was related to the reduction in the onset of major mobility disability (overall P < 0.001) (highest versus the lowest quartile of physical activity change HR 0.23 ((95% CI:0.10-0.52) P = 0.001) in the physical activity arm. We observed a dose-dependent effect of objectively monitored physical activity on physical functioning and onset of major mobility disability. Relatively small increases (> 48 minutes per week) in regular physical activity participation had significant and clinically meaningful effects on these outcomes.
ClinicalsTrials.gov NCT00116194.
What is dynapenia? Clark, Brian C., Ph.D; Manini, Todd M., Ph.D
Nutrition (Burbank, Los Angeles County, Calif.),
05/2012, Volume:
28, Issue:
5
Journal Article
Peer reviewed
Open access
Abstract Dynapenia (pronounced dahy-nuh-pē-nē-a , Greek translation for poverty of strength, power, or force) is the age-associated loss of muscle strength that is not caused by neurologic or ...muscular diseases. Dynapenia predisposes older adults to an increased risk for functional limitations and mortality. For the past several decades, the literature has largely focused on muscle size as the primary cause of dynapenia; however, recent findings have clearly demonstrated that muscle size plays a relatively minor role. Conversely, subclinical deficits in the structure and function of the nervous system and/or impairments in the intrinsic force-generating properties of skeletal muscle are potential antecedents to dynapenia. This review highlights in the contributors to dynapenia and the etiology and risk factors that predispose individuals to dynapenia. In addition, we address the role of nutrition in the muscular and neurologic systems for the preservation of muscle strength throughout the life span.
OBJECTIVES
To develop an evidence‐based definition of sarcopenia that can facilitate identification of older adults at risk for clinically relevant outcomes (eg, self‐reported mobility limitation, ...falls, fractures, and mortality), the Sarcopenia Definition and Outcomes Consortium (SDOC) crafted a set of position statements informed by a literature review and SDOC's analyses of eight epidemiologic studies, six randomized clinical trials, four cohort studies of special populations, and two nationally representative population‐based studies.
METHODS
Thirteen position statements related to the putative components of a sarcopenia definition, informed by the SDOC analyses and literature synthesis, were reviewed by an independent international expert panel (panel) iteratively and voted on by the panel during the Sarcopenia Position Statement Conference. Four position statements related to grip strength, three to lean mass derived from dual‐energy x‐ray absorptiometry (DXA), and four to gait speed; two were summary statements.
RESULTS
The SDOC analyses identified grip strength, either absolute or scaled to measures of body size, as an important discriminator of slowness. Both low grip strength and low usual gait speed independently predicted falls, self‐reported mobility limitation, hip fractures, and mortality in community‐dwelling older adults. Lean mass measured by DXA was not associated with incident adverse health‐related outcomes in community‐dwelling older adults with or without adjustment for body size.
CONCLUSION
The panel agreed that both weakness defined by low grip strength and slowness defined by low usual gait speed should be included in the definition of sarcopenia. These position statements offer a rational basis for an evidence‐based definition of sarcopenia. The analyses that informed these position statements are summarized in this article and discussed in accompanying articles in this issue of the journal. J Am Geriatr Soc 68:1410‐1418, 2020.
See related editorial by Cesari et al in this issue
Dynapenia and Aging: An Update Manini, Todd M; Clark, Brian C
The journals of gerontology. Series A, Biological sciences and medical sciences,
01/2012, Volume:
67A, Issue:
1
Journal Article
Peer reviewed
Open access
In 2008, we published an article arguing that the age-related loss of muscle strength is only partially explained by the reduction in muscle mass and that other physiologic factors explain muscle ...weakness in older adults (Clark BC, Manini TM. Sarcopenia =/= dynapenia. J Gerontol A Biol Sci Med Sci. 2008;63:829-834). Accordingly, we proposed that these events (strength and mass loss) be defined independently, leaving the term "sarcopenia" to be used in its original context to describe the age-related loss of muscle mass. We subsequently coined the term "dynapenia" to describe the age-related loss of muscle strength and power. This article will give an update on both the biological and clinical literature on dynapenia-serving to best synthesize this translational topic. Additionally, we propose a working decision algorithm for defining dynapenia. This algorithm is specific to screening for and defining dynapenia using age, presence or absence of risk factors, a grip strength screening, and if warranted a test for knee extension strength. A definition for a single risk factor such as dynapenia will provide information in building a risk profile for the complex etiology of physical disability. As such, this approach mimics the development of risk profiles for cardiovascular disease that include such factors as hypercholesterolemia, hypertension, hyperglycemia, etc. Because of a lack of data, the working decision algorithm remains to be fully developed and evaluated. However, these efforts are expected to provide a specific understanding of the role that dynapenia plays in the loss of physical function and increased risk for disability among older adults.
Sarcopenia ≠ Dynapenia Clark, Brian C.; Manini, Todd M.
The journals of gerontology. Series A, Biological sciences and medical sciences
63, Issue:
8
Journal Article
Peer reviewed
Open access
Maximal voluntary force (strength) production declines with age and contributes to physical dependence and mortality. Consequently, a great deal of research has focused on identifying strategies to ...maintain muscle mass during the aging process and elucidating key molecular pathways of atrophy, with the rationale that the loss of strength is primarily a direct result of the age-associated declines in mass (sarcopenia). However, recent evidence questions this relationship and in this Green Banana article we argue the role of sarcopenia in mediating the age-associated loss of strength (which we will coin as dynapenia) does not deserve the attention it has attracted in both the scientific literature and popular press. Rather, we propose that alternative mechanisms underlie dynapenia (i.e., alterations in contractile properties or neurologic function), and urge that greater attention be paid to these variables in determining their role in dynapenia.
High-load resistance training (HL) may be contraindicated in older adults due to pre-existing health conditions (e.g. osteoarthritis). Low-load blood flow restricted (BFR) resistance training offers ...an alternative to HL with potentially similar strength improvement.
To compare muscle strength, cross-sectional area (CSA), physical function, and quality of life (QOL) following 12-weeks of HL or BFR training in older adults at risk of mobility limitations.
Thirty-six males and females (mean: 75.6years 95% confidence interval: 73.4–78.5, 1.67m 1.64–1.70, 74.3kg 69.8–78.8) were randomly assigned to HL (70% of one repetition maximum 1-RM) or low-load BFR (30% 1-RM coupled with a vascular restriction) exercise for the knee extensors and flexors twice per week for 12weeks. A control (CON) group performed light upper body resistance and flexibility training. Muscle strength, CSA of the quadriceps, 400-m walking speed, Short Physical Performance Battery (SPPB), and QOL were assessed before, midway and after training.
Within 6-weeks of HL training, increases in all strength measures and CSA were evident and the gains were significantly greater than the CON group (P<0.05). The BFR group had strength increases in leg extension and leg press 1-RM tests, but were significantly lower in leg extension isometric maximum voluntary contraction (MVC) and leg extension 1-RM than the HL group (P<0.01). At 12-weeks HL and BFR training did not differ in MVC (P=0.14). Walking speed increased 4% among all training groups (P<0.01) and no changes were observed for overall SPPB score and QOL (P>0.05).
Both training programs resulted in muscle CSA improvements and HL training had more pronounced strength gains than BFR training after 6-weeks and were more similar to BFR after 12-weeks of training. These changes in both groups did not transfer to improvements in QOL, SPPB, and walking speed. Since both programs result in strength and CSA gains, albeit at different rates, future research should consider using a combination of HL and BFR training in older adults with profound muscle weakness and mobility limitations.
•High-load and low-load blood flow restricted resistance training was compared.•Both training programs resulted in similar cross-sectional area of the quadriceps.•Most strength adaptations were apparent within 6-weeks.•Strength was highest after high-load training but not different than blood flow restricted training.•Training did not impact physical function and quality of life in older adults.
The frailty syndrome is as a well-established condition of risk for disability. Aim of the study is to explore whether a physical activity (PA) intervention can reduce prevalence and severity of ...frailty in a community-dwelling elders at risk of disability.
Exploratory analyses from the Lifestyle Interventions and Independence for Elders pilot, a randomized controlled trial enrolling 424 community-dwelling persons (mean age=76.8 years) with sedentary lifestyle and at risk of mobility disability. Participants were randomized to a 12-month PA intervention versus a successful aging education group. The frailty phenotype (ie, ≥3 of the following defining criteria: involuntary weight loss, exhaustion, sedentary behavior, slow gait speed, poor handgrip strength) was measured at baseline, 6 months, and 12 months. Repeated measures generalized linear models were conducted.
A significant (p = .01) difference in frailty prevalence was observed at 12 months in the PA intervention group (10.0%; 95% confidence interval = 6.5%, 15.1%), relative to the successful aging group (19.1%; 95% confidence interval = 13.9%,15.6%). Over follow-up, in comparison to successful aging participants, the mean number of frailty criteria in the PA group was notably reduced for younger subjects, blacks, participants with frailty, and those with multimorbidity. Among the frailty criteria, the sedentary behavior was the one most affected by the intervention.
Regular PA may reduce frailty, especially in individuals at higher risk of disability. Future studies should be aimed at testing the possible benefits produced by multidomain interventions on frailty.
BACKGROUND: Sarcopenia is thought to be accompanied by increased muscle fat infiltration. However, no longitudinal studies have examined concomitant changes in muscle mass, strength, or fat ...infiltration in older adults. OBJECTIVE: We present longitudinal data on age-related changes in leg composition, strength, and muscle quality (MQ) in ambulatory, well-functioning men and women. We hypothesized that muscle cross-sectional area (CSA) and strength would decrease and muscular fat infiltration would increase over 5 y. DESIGN: Midthigh muscle, subcutaneous fat (SF), and intermuscular fat (IMF) CSAs and isokinetic leg muscle torque (MT) and MQ (MT/quadriceps CSA) were examined over 5 y in the Health, Aging, and Body Composition study cohort (n = 1678). RESULTS: Men experienced a 16.1% loss of MT, whereas women experienced a 13.4% loss. Adjusted annualized decreases in MT were 2-5 times greater than the loss of muscle CSA in those who lost weight and in those who remained weight-stable. Weight gain did not prevent the loss of MT, despite a small increase in muscle CSA. Only those who gained weight had an increase in SF (P < 0.001), whereas those who lost weight also lost SF (P < 0.001). There was an age-related increase in IMF in men and women (P < 0.001), and IMF increased in those who lost weight, gained weight, or remained weight-stable (all P < 0.001). CONCLUSIONS: Loss of leg MT in older adults is greater than muscle CSA loss, which suggests a decrease in MQ. Additionally, aging is associated with an increase in IMF regardless of changes in weight or SF.
For nearly half a century, high mechanical loading and mechanotransduction pathways have guided exercise recommendations for inducing muscle hypertrophy. However, emerging research on low-intensity ...exercise with blood flow restriction challenges this paradigm. This article will describe the BFR exercise model and discuss its efficacy, potential mechanisms, and clinical viability.
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