SARCOPENIA AND RESISTENCE EXERCISE
Sarcopenia is defined from the National Institute on health (NIA) as the loss
of skeletal muscle mass, quality and strength. The NIA further states that
sarcopenia refers to the Greek word “sarco” refers to flesh and “penia” indicates a deficiency. “Sarcopenia” is a generic term for the loss of skeletal muscle mass,
quality, and strength that can lead to frailty in the elderly. Sarcopenia is believed tobe due predominantly to disuse atrophy of skeletal muscle fibers….with respect tofunctional impairments, it is generally recognized that muscle weakness in the upperand lower extremities can contribute to gait problems, falls and ultimately to the loss of physical functional independence.
From the Center for Disease Control and Prevention, Atlanta, they state that
the lack of physical activity is also associated with several musculoskeletal problems that can negatively affect functional mobility. Aging which is associated with lower levels of physical activity, is also associated with loss of muscle mass (sarcopenia) and strength; physical inactivity is associated with bone loss and osteoporosis.
Osteoporosis, sarcopenia, and muscle weakness (directly and indirectly) are risk
factors for falls and, therefore, fractures, in order adults. As an overall prevention
strategy, older adults are encouraged to remain active throughout aging to help
preserve functional ability and prevent frailty.
Markers of sarcopenia
Sarcopenia is characterized first by a decrease in the size of the muscle, which causes weakness and frailty. However, this loss of muscle mass may be caused by different cellular mechanisms than those which cause muscle atrophy. For example, during sarcopenia, there is a replacement of muscle fibers with fat and an increase in fibrosis.
Benefit of exercise
Exercise and increases in activity have been shown to be beneficial in settings of sarcopenia; exercise even in the very old can increase strength and muscle function.
Lack of exercise is currently thought to be a significant risk factor, increasing the likelihood of sarcopenia.[1]
Not only muscle but the entire musculoskeletal system of muscle, neuromuscular responsiveness, endocrine function, vasocapillary access, tendon, joint, ligament, and bone, depends on regular and lifelong exercise to maintain integrity. The slow attenuation, atrophy, or loss of muscle tissue that medical professionals sometimes describe as sarcopenia (literally, "flesh loss') is currently thought to be the result of cumulative loss of musculoskeletal strength and mass associated with chronic absence of exercise of sufficient intensity or volume. However, even highly trained athletes experience the effects of sarcopenia. It is interesting to note that athletic speed and strength records are invariably set by individuals no older than 30 years of age, indicating that subtle effects of sarcopenia are already apparent.
Fiber-type changes in sarcopenia
Simple circumference measures do not provide enough data to determine whether or not an individual is suffering from severe sarcopenia. Sarcopenia is also marked by a decrease in the circumference of distinct types of muscle fibers. Skeletal muscle has different fiber-types, which are characterized by expression of distinct myosin variants. During sarcopenia, there is a decrease in "type 2" fiber circumference (Type II), but no change in type 1 fiber circumference ( type I).
Loss of satellite cell function
Satellite cells are small mononuclear cells which abut the muscle fiber. Satellite cells are normally activated upon injury or exercise. These cells then differentiate and fuse into the muscle fiber, helping to maintain its function. During sarcopenia, it is thought that there is a failure in satellite cell activation.
Therefore, the ability to repair damaged muscles or respond to nutritional signals is impaired.
Loss of anabolic signals
Extreme muscle loss is often a result of both diminishing anabolic signals, such as growth hormone and testosterone, and promotion of catabolic signals, such as pro-inflammatory cytokines.
Sarcopenia as a public-health problem
Due to the lessened physical activity and increased longevity of industrialized populations, sarcopenia is emerging as a major health concern. Sarcopenia may progress to the extent that an older person may lose his or her ability to live independently. Furthermore, sarcopenia is an important independent predictor of disability in population-based studies, linked to poor balance, gait speed, falls, and fractures. Sarcopenia can be thought of as a muscular analog of osteoporosis, which is loss of bone, also caused by inactivity and counteracted by exercise. The combination of osteoporosis and sarcopenia results in the significant frailty often seen in the elderly population.
Natural history
Strength losses with ageing for men and women are relatively similar. They are greater for lower than upper extremity muscles. Maximum attainable strength peaks in mid-twenties and declines thereafter. The decline is precipitous after 65 years of age, though few longitudinal studies exist on this topic. A direct assessment of the effects of sarcopenia, even in extremely physically fit individuals, can be seen in the age-related decline in Masters athletics (track and field) world records of muscle-intensive sports, such as weight lifting. No substance-free, proven Olympic weight-lifting record has been set by any athlete of either sex or any weight class above the age of 31. However, in the non-Olympic sport of powerlifting, many world records in several weight divisions have been accomplished by athletes well into their forties, purportedly, "verified" by the International Powerlifting Federation to have been accomplished drug-free. However, that this certification carries any weight is doubtful considering that even in highly supervised events such as the Olympics, drug cheating invariably occurs (some of which is detected right away, much of it is not). Furthermore, casting doubt on any records set outside the traditional Olympic athletic system, drug cheating is rampant in professional sports that do not perform random drug testing (eg, baseball).
Diagnosis
Making the clinical diagnosis of sarcopenia is difficult for the following reasons. There is no absolute level of lean mass, body cell mass, or muscle mass for comparison. There is no generally accepted clinical test to diagnose sarcopenia. Finally, there is no accepted threshold of functional decline at which sarcopenia is implied. However, the use of whole-body dual-energy X-ray absorptiometry (DEXA) or CT scans of the abdomen to assess muscle mass is being assessed in research settings. Baumgartner et al. published a working definition of sarcopenia based on 2 standard deviations below the mean for healthy young adults which has been used in research settings.[2]
Management
Primary management of sarcopenia is through the application of a graded exercise program, across both cardiovascular and strength domains, dosed in such a way as to provoke beneficial adaptation without overloading the weakened body.[3] Possible therapeutic strategies include resistance training and aerobic activity programs, as evidenced by recent studies. Nutritional evaluation may also be indicated if malnutrition is suspected, or current nutritional intake is insufficient to maintain adequate total body mass, although increased exercise also increases appetite. Physical activity incorporating resistance training is probably the most effective measure to prevent and treat sarcopenia.
References
- Abate M, Di Iorio A, Di Renzo D, Paganelli R, Saggini R, Abate G (September 2007). "Frailty in the elderly: the physical dimension". Eura Medicophys43 (3): 407–15. PMID17117147.
- Baumgartner RN, Koehler KM, Gallagher D, et al. (April 1998). "Epidemiology of sarcopenia among the elderly in New Mexico". Am. J. Epidemiol.147 (8): 755–63. PMID9554417.
- Taaffe DR (March 2006). "Sarcopenia--exercise as a treatment strategy". Aust Fam Physician35 (3): 130–4. PMID16525526.
- Bidon C, Lachuer J, Molgó J, Wierinckx A, de la Porte S, et al. (2009). "The Extract of Ginkgo biloba EGb 761 Reactivates a Juvenile Profile in the Skeletal Muscle of Sarcopenic Rats by Transcriptional Reprogramming.". PLoS ONE 4(11):. doi:doi:10.1371/journal.pone.0007998.
- Roubenoff R (December 2007). "Physical activity, inflammation, and muscle loss". Nutr. Rev.65 (12 Pt 2): S208–12. doi:10.1111/j.1753-4887.2007.tb00364.x. PMID18240550.
- Lynch GS (May 2004). "Tackling Australia's future health problems: developing strategies to combat sarcopenia—age-related muscle wasting and weakness". Intern Med J34 (5): 294–6. doi:10.1111/j.1444-0903.2004.00568.x. PMID15151679.
- Edström E, Ulfhake B (April 2005). "Sarcopenia is not due to lack of regenerative drive in senescent skeletal muscle". Aging Cell4 (2): 65–77. doi:10.1111/j.1474-9728.2005.00145.x. PMID15771610.
- Fujita S, Volpi E (January 2006). "Amino acids and muscle loss with aging". J. Nutr.136 (1 Suppl): 277S–80S. PMID16365098.
- Visser, Marjolein; Deeg D, Lips P (2003). "Low vitamin D and high parathyroid hormone levels as determinants of loss of muscle strength and muscle mass (sarcopenia)". J. Clin. Endocrinol. Metab.88 (12): 5766–5772. doi:10.1210/jc.2003-030604. PMID14671166. Retrieved 2007-11-06
If more information is required on this topic, please access “Sacopenia” and Mary
Tinetti, MD. under Google.