The metabolic syndrome

The purpose of this Position Stand is to provide an overview of issues critical to understanding the importance of exercise and physical activity in older adult populations. The Position Stand is divided into three sections: Section 1 briefly reviews the structural and functional changes that characterize normal human aging, Section 2 considers the extent to which exercise and physical activity can influence the aging process, and Section 3 summarizes the benefits of both long-term exercise and physical activity and shorter-duration exercise programs on health and functional capacity. Although no amount of physical activity can stop the biological aging process, there is evidence that regular exercise can minimize the physiological effects of an otherwise sedentary lifestyle and increase active life expectancy by limiting the development and progression of chronic disease and disabling conditions. There is also emerging evidence for significant psychological and cognitive benefits accruing from regular exercise participation by older adults. Ideally, exercise prescription for older adults should include aerobic exercise, muscle strengthening exercises, and flexibility exercises. The evidence reviewed in this Position Stand is generally consistent with prior American College of Sports Medicine statements on the types and amounts of physical activity recommended for older adults as well as the recently published 2008 Physical Activity Guidelines for Americans. All older adults should engage in regular physical activity and avoid an inactive lifestyle.

Exercise and physical activity for older adults

As people get older, they may fall more often for a variety of reasons including problems with balance, poor vision, and dementia. Up to 30% may fall in a year. Although one in five falls may require medical attention, less than one in 10 results in a fracture.
This review looked at the healthcare literature to establish which fall prevention interventions are effective for older people living in the community, and included 159 randomised controlled trials with 79,193 participants.  
Group and home-based exercise programmes, usually containing some balance and strength training exercises, effectively reduced falls, as did Tai Chi. Overall, exercise programmes aimed at reducing falls appear to reduce fractures.
Multifactorial interventions assess an individual's risk of falling, and then carry out treatment or arrange referrals to reduce the identified risks. Overall, current evidence shows that this type of intervention reduces the number of falls in older people living in the community but not the number of people falling during follow-up. These are complex interventions, and their effectiveness may be dependent on factors yet to be determined.  
Interventions to improve home safety appear to be effective, especially in people at higher risk of falling and when carried out by occupational therapists. An anti-slip shoe device worn in icy conditions can also reduce falls.
Taking vitamin D supplements does not appear to reduce falls in most community-dwelling older people, but may do so in those who have lower vitamin D levels in the blood before treatment.  
Some medications increase the risk of falling. Three trials in this review failed to reduce the number of falls by reviewing and adjusting medications. A fourth trial involving family physicians and their patients in medication review was effective in reducing falls. Gradual withdrawal of a particular type of drug for improving sleep, reducing anxiety, and treating depression (psychotropic medication) has been shown to reduce falls.
Cataract surgery reduces falls in women having the operation on the first affected eye. Insertion of a pacemaker can reduce falls in people with frequent falls associated with carotid sinus hypersensitivity, a condition which causes sudden changes in heart rate and blood pressure.
In people with disabling foot pain, the addition of footwear assessment, customised insoles, and foot and ankle exercises to regular podiatry reduced the number of falls but not the number of people falling.
The evidence relating to the provision of educational materials alone for preventing falls is inconclusive.

Interventions for preventing falls in older people living in the community

Background: Pulmonary rehabilitation is recognized as a core component of the management of individuals with chronic respiratory disease. Since the 2006 American Thoracic Society (ATS)/European Respiratory Society (ERS) Statement on Pulmonary Rehabilitation, there has been considerable growth in our knowledge of its efficacy and scope.

Purpose: The purpose of this Statement is to update the 2006 document, including a new definition of pulmonary rehabilitation and highlighting key concepts and major advances in the field.

Methods: A multidisciplinary committee of experts representing the ATS Pulmonary Rehabilitation Assembly and the ERS Scientific Group 01.02, “Rehabilitation and Chronic Care,” determined the overall scope of this update through group consensus. Focused literature reviews in key topic areas were conducted by committee members with relevant clinical and scientific expertise. The final content of this Statement was agreed on by all members.

Results: An updated definition of pulmonary rehabilitation is proposed. New data are presented on the science and application of pulmonary rehabilitation, including its effectiveness in acutely ill individuals with chronic obstructive pulmonary disease, and in individuals with other chronic respiratory diseases. The important role of pulmonary rehabilitation in chronic disease management is highlighted. In addition, the role of health behavior change in optimizing and maintaining benefits is discussed.

Conclusions: The considerable growth in the science and application of pulmonary rehabilitation since 2006 adds further support for its efficacy in a wide range of individuals with chronic respiratory disease

Read More: http://www.atsjournals.org/doi/abs/10.1164/rccm.201309-1634ST

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An official American thoracic society/European respiratory society statement: Key concepts and advances in pulmonary rehabilitation

Regular exercise offers protection against all-cause mortality, primarily by protection against cardiovascular disease and Type 2 diabetes mellitus. The latter disorders have been associated with chronic low-grade systemic inflammation reflected by a two- to threefold elevated level of several cytokines. Adipose tissue contributes to the production of TNF-alpha, which is reflected by elevated levels of soluble TNF-alpha receptors, IL-6, IL-1 receptor antagonist, and C-reactive protein. We suggest that TNF-alpha rather than IL-6 is the driver behind insulin resistance and dyslipidemia and that IL-6 is a marker of the metabolic syndrome, rather than a cause. During exercise, IL-6 is produced by muscle fibers via a TNF-independent pathway. IL-6 stimulates the appearance in the circulation of other anti-inflammatory cytokines such as IL-1ra and IL-10 and inhibits the production of the proinflammatory cytokine TNF-alpha. In addition, IL-6 enhances lipid turnover, stimulating lipolysis as well as fat oxidation. We suggest that regular exercise induces suppression of TNF-alpha and thereby offers protection against TNF-alpha-induced insulin resistance. Recently, IL-6 was introduced as the first myokine, defined as a cytokine that is produced and released by contracting skeletal muscle fibers, exerting its effects in other organs of the body. Here we suggest that myokines may be involved in mediating the health-beneficial effects of exercise and that these in particular are involved in the protection against chronic diseases associated with low-grade inflammation such as diabetes and cardiovascular diseases.

The anti-inflammatory effect of exercise

humansduring dynamic knee-extensor exercise in Effect of temperature on skeletal muscle energy

Background Age-related loss of strength is disproportionally greater than the loss of mass, suggesting maladaptations in the neuro-myo-tendinous system. Myofibers are often misshaped in aged and diseased muscle, but systematic analyses of large sample sets are lacking. Our aim was to investigate myofiber shape in relation to age, exercise, myofiber type, species, and sex. Methods Previously collected vastus lateralis muscle biopsies (n=265) from 197 males and females, covering an age-span of 20 to 97 years, were examined. The gastrocnemius and soleus muscles of 7 C57BL/6 mice were also examined. Immunofluorescence and ATPase stainings of muscle cross-sections were used to measure myofiber cross-sectional area (CSA) and perimeter, from which a shape factor index (SFI) was calculated in a fiber type specific manner (type I and II in humans; type I, IIa, IIx and IIb in mice). Heavy resistance training (RT) was performed 3 times per week for 3-4 months by a subgroup (n=59). Correlation analyses were performed comparing SFI and CSA with age, muscle mass, maximal voluntary contraction (MVC), rate of force development (RFD), and specific force (MVC/muscle mass). Results In human muscle, SFI was positively correlated with age for both type I (R2=0.20) and type II (R2=0.38) myofibers. When subjects were separated into age cohorts, SFI was lower for type I (p<0.001) and II (p<0.001) myofibers in Young (20-36) compared to Old (60-80), and higher for type I (p<0.05) and II (p<0.001) myofibers in the Oldest Old (>80) compared to Old. The increased SFI in old muscle was observed in myofibers of all sizes. Within all three age cohorts, type II myofibers SFI was higher than for type I myofibers (p<0.001), which was also the case in mice muscles (p<0.001). Across age cohorts, there was no difference between males and females in SFI for either type I (p=0.496/0.734) or II (p=0.176/0.585) myofibers. Multiple linear regression revealed that SFI, after adjusting for age and myofiber CSA, has independent explanatory power for 8 out of 10 indices of muscle mass and function. RT reduced SFI of type II myofibers in both Young and Old (p<0.001). Conclusions Here, we identify type I and II myofiber shape in humans and mice as a hallmark of muscle ageing, that independently predicts volumetric and functional assessments of muscle health. RT reverts the shape of type II myofibers, indicating that lack of neuromuscular activation might lead to myofiber deformity.

https://www.biorxiv.org/content/biorxiv/early/2023/06/07/2023.06.05.543651.full.pdf

Marked irregular myofiber shape is a hallmark of human skeletal muscle aging and is reversed by heavy resistance training

different loading patterns and repeated exercise bouts proteasome component genes with exercise: effect of Expression patterns of atrogenic and ubiquitin

Muscle fiber denervation is a major contributor to the decline in muscle mass and function during aging. Heavy resistance exercise is an effective tool for increasing muscle mass and strength, but whether it can rescue denervated muscle fibers remains unclear. Therefore, the purpose of this study was to investigate the potential of heavy resistance exercise to modify indices of denervation in healthy elderly individuals. 38 healthy elderly men (72±5 years) underwent 16 weeks of heavy resistance exercise while 20 healthy elderly men (72±6 years) served as non-exercising sedentary controls. Muscle biopsies were obtained pre and post training, and midway at eight weeks. Biopsies were analysed by immunofluorescence for the prevalence of myofibers expressing embryonic myosin (MyHCe), neonatal myosin (MyHCn), nestin, and neural cell adhesion molecule (NCAM), and by RT-qPCR for gene expression levels of acetylcholine receptor (AChR) subunits, MyHCn, MyHCe, p16 and Ki67. In addition to increases in strength and type II fiber hypertrophy, heavy resistance exercise training led to a decrease in AChR α1 and ε subunit mRNA (at eight weeks). Changes in gene expression levels of the α1 and ε AChR subunits with eight weeks of heavy resistance exercise supports the role of this type of exercise in targeting stability of the neuromuscular junction. The number of fibers positive for NCAM, nestin, and MyHCn was not affected, suggesting that a longer timeframe is needed for adaptations to manifest at the protein level.

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Michael Kjaer

Papers

humansduring dynamic knee-extensor exercise in Effect of temperature on skeletal muscle energy

Marked irregular myofiber shape is a hallmark of human skeletal muscle aging and is reversed by heavy resistance training

different loading patterns and repeated exercise bouts proteasome component genes with exercise: effect of Expression patterns of atrogenic and ubiquitin

Human skeletal muscle acetylcholine receptor gene expression in elderly males performing heavy resistance exercise.

increased stiffness of the human patellar tendon Habitual loading results in tendon hypertrophy and