Sarcopenia (in Greek, sarx for flesh and penia for loss) is considered, “poverty of the flesh” (Rosenberg, 1997). The term is sometimes used interchangably with frailty and cachexia in the geriatric population ito describe the loss of skeletal muscle and progressive weakness that occurs with aging. Sarcopenia can also be used to describe the phenomenon in of the loss of lean body mass in younger individuals who have this constellation of features. The description of sarcopenia is also used to describe the associated changes in the nervous system, endocrine system, cardiovascular system, levels of inflammation, and body fat distribution. It also describes poor nutrition and reduced physical activity that is associated with aging and higher risk for chronic disease. The most prominent effects are greatly reduced mobility and loss of independence in the older population (Roubenoff, 2000).
Surprisingly, sarcopenia may develop as early as 30 years of age when body weight gain and accumulation of fat mass masks the outward signs of muscle loss (See figure below). Often between 30 and 60 years of age, the average adult gains approximately 0.45 kg (1 lb) of fat and loses about 0.23 kg (0.5 lb) of muscle yearly. Loss of muscle mass then accelerates to 2% annually beginning at 60 years of age (Waters, 2010). The rate of muscle loss is variable, with a total muscle cross-sectional area reduction of about 40% between 20 and 60 years of age (Waters, 2010). The prevalence of sarcopenia increases from 13-24% in persons under 70 years of age then skyrockets to >50% in persons over 80 years of age (Baumgartner, 1998). The wide variability in the progression of sarcopenia is affected by age-related systemic changes and lifestyle choices (Rom, 2012; Cruz-Jentoft, 2010).
The sedentary sarcopenia lifestyle
The simplest view on the development of sarcopenia is explained by loss of muscle mass known as muscle atrophy. This muscle loss is due to physical inactivity that is common in modern life. Certain people that you may know may harbor the early signs of sarcopenia even before the age of 30, although research does not include them in the current definition. The simple absence of stimuli that promotes muscle formation may fundamentally explain age-related muscle loss (Roubenoff, 1999). A sedentary lifestyle with no increased energy expenditure above resting level such as sitting, lying down, and watching television has been shown to be a major risk factor for sarcopenia (Chastin, 2012). Malnutrition can also increase the risk of inflammatory disorders such as insulin resistance and cardiovascular disease that can result in a greater need for health care (Pipek, 2020).
Many studies have shown that prolonged periods of bed rest can result in a 30% reduction of muscle volume, particularly in muscles of the lower limbs in (Narici, 2011).
Exercise can reverse sarcopenia
It is never too late to reverse age-related muscle decline. A study looking at an eight-week strength training program in the 90-year-old age group demonstrated an over 100% increase in strength from the pre-exercise baseline and a 48% increase in walking speed (Fiatarone, 1990). Another study following a 12-week strength training program of three days a week in older adults resulted in increased muscle strength, muscle tissue hypertrophy, and increased myofibrillar protein turnover (Frontera, 1988). Even a resistance training program of only one day per week in older adults improved muscle strength in a similar manner to a resistance training program of 3 days per week (Taaffe et al. 1999). This effect has also been found to decreased associated osteoporosis.
A progressive resistance training program should be tailored to an individual’s goals to prevent sarcopenia. The program should be challenging, not overwhelming, and should be continuously adjusted to stimulate muscle growth. Orange Theory and CrossFit are good examples of programs that promote muscle development in continuously changing workout programs. Before starting any exercise program, it is important to check with your physician. If you are unfamiliar with strength training, starting off with a trainer is a good idea to gain familiarity and ensure safety with the exercises.
Resistance training is a form of exercise in which muscle contract against an external load. Examples of resistance training include free weights, exercise machines, body weight exercises, and use of elastic bands. This can be very helpful to prevent sarcopenia.
The classic resistance training program to build muscle consists of 8 to 10 exercises that target the major muscle groups, done in sets of 8 t o12 repetitions. The last 2-3 repetitions should be somewhat difficult at about 60% to 80% of a one-repetition maximum. To see changes, it is important to do this program two to three times per week, although in the previous study, even once per week is more beneficial than not participating at all.
High-intensity Interval Training
Some people like to participate in high-intensity interval training (HIIT) which approximates the challenges in life like running for the bus or carrying a sudden heavy load. HIIT allows you to gain the benefits of exercise in a much shorter time frame.
Aerobic training, in which large groups of muscle are engaged for a prolonged period of time, is less likely promote increased muscle strength; however, it can increase the cross-sectional area of muscle fibers, mitochondrial volume, and muscle enzyme activity (Rom, 2012).
The American College of Sports Medicine and American Heart Association suggest a minimum of two non-consecutive days per week of strength training (Nelson, 2007).
Individuals with poor performance due to sarcopenia initially can achieve improvement even with less frequent training. Side effects are rare, but it is still advisable to review a new exercise program with your physician first especially if you have pre-existing diseases (Burton, 2010).
A very important study compared older and younger strength-trained subjects, the maximal isometric torques, the speed of movements, cross-sectional areas of muscle, as well as the content of muscle fibers called myosin and tropomyosin and found them to be identical. These findings suggest that strength training can be used to counteract muscle wasting related to age (Klitgaard, 1990).
Diet is more important in sarcopenia than we ever imaged
Aging is associated with decreased food intake that has been called the “anorexia of aging” or in younger old population, “skinny fat”. A decrease in food intake is thought to play a critical role in sarcopenia (Morley, 2001).
Reduced food intake may be due to living alone with little or no support, a diminished interest in cooking, less hunger and thirst, chewing and swallowing difficulty, digestion problems, and inadequate absorption of nutrients.
Food choices are usually less than ideal with a reliance on convenient processed foods which are high in carbohydrate calories and low in healthy proteins, healthy fats, vitamins, and minerals. A similar effect occurs with an excessive caloric intake which leads to obesity, hiding the loss of muscle mass behind the fat called “sarcopenic obesity”. Excessive caloric consumption or storage creates chronic low-level inflammation and metabolic dysfunction which further exacerbates muscle wasting (Plutzky, 2009).
Protein in Older Adults
If you are concerned about sarcopenia, remember that animal protein provides the proper ratio of essential amino acids that are very important for building muscle (Volpi, 2003). Black beans and kidney beans contain similar ratios of essential amino acids except for methionine. Hence rice is consumed for the addition of methionine. The nine essential amino acids that humans cannot synthesize are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. But make sure you stay away from processed proteins due to the extra fillers and preservatives. Protein powders may be a good alternative if you have difficulty consuming enough protein daily.
One of the essential amino acids has been found to be particuarly helpful in preserving muscle mass is leucine. Leucine is found in beef, lamb, pork, poultry, fish, dairy products, beans as well as nuts and seeds. It has been found to play an important role in regulating muscle metabolism and is known to prevent muscle wasting (Rom, 2012 #1). A study that increased the proportion of leucine in a mixture of essential amino acids given to older subjects was found to reverse impaired protein synthesis in muscle (Katsanos, 2006).
The best protein-rich foods to consider adding to your diet include grass-fed and finished beef, organic chicken, wild fish such as tuna and salmon, organic whey protein, black or kidney beans, fermented dairy such as yogurt, kefir, and natto.
Older adults who are concerned about developing sarcopenia should eat nutritionally dense foods as the absorption of nutrients is usually impaired.
Older adults require more protein/kilogram body weight than do younger adults because older adults have lower rates of protein breakdown and synthesis (Nowson, 2015).
The current recommended daily allowance (RDA) for protein is 0.8 grams per kilogram (g/kg) for adults and the recommended dietary allowance (RDA) for protein is 1.0 to 1.3 grams per kilogram (g/kg) for older adults (Chernoff, 2004, Nowson, 2015)
Protein after Exercise
Following exercise, your muscles are most receptive to nutrition so it is important to consume a drink or meal with some added carbohydrate and protein within 30 minutes of completing an exercise. This helps rehydrate and fuel your muscles to begin the muscle repair process.
A 2015 study in The American Journal of Clinical Nutrition found that omega-3 fatty acid supplementation from fish slowed the decline in muscle mass and function in older adults (Smith, 2015).
Hormones and sarcopenia work against each other
There is a great deal of debate around the modulation of growth hormone levels to promote the anabolic phase of muscle growth, so physicians have instead begun to assess thyroid and testosterone levels.
Older adults are at increased risk of vitamin D insufficiency due to various factors. As people age, the skin’s ability to synthesize vitamin D efficiently is reduced, and the kidney is less able to convert vitamin D to its active form; in addition, inadequate sunlight exposure which is essential for vitamin D synthesis and low consumption of dietary vitamin D are common among the elderly (Dirks-Naylor, 2011). Vitamin D plays an important role in skeletal muscle tissue by maintaining the function of the type II muscle fibers, to preserve muscle strength and prevent falls (Montero-Odasso, 2005).
Stress drives the sarcopenic process
All forms of stress raises cortisol levels which promotes weight gain and sarcopenia, so it is important to maintain a healthy body weight and manage stress throughout life (Ferrucci, 2002). Stress is also increased with inadequate levels of sleep
Muscles wither away from alcohol
Alcohol impairs muscle protein synthesis. Lab studies have shown that ethanol decreased muscle protein synthesis by up to 75% (Tiernan, 1986). A disease called alcoholic myopathy occurs with pronounced or long-term alcohol intake in individuals with poor dietary intake and usually results in low muscle mass and strength such as grip strength, muscle cramps, gait dysfunction, and falls. If severe, it can result in acute alcoholic myopathy which is characterized by severe muscle pain and kidney failure. Chronic alcoholic myopathy is a common complication of alcoholism affecting approximately 50% of alcohol. Compared with sarcopenia, chronic alcoholic myopathy is associated with nutritional deficiencies or liver disease and is reversible within 6–12 months if ethanol intake is discontinued (Preedy, 2001).
Smoking guarantees muscle wasting
Smokers have been found to have lower skeletal muscle mass than subjects who never smoked (Szulc, 2004) and accelerated degradation of muscle protein in elderly smokers (Rom, 2012).
The summary of sarcopenia
In summary, you do not need to fear a condition named sarcopenia, but you do need to fear the first time it is challenging to get out of a chair, the first hard fall and the eventual loss of independence. This loss of physical performance can have a great impact on quality of life. Research has shown that it is never too late to strengthen your muscles even if you make simple changes like taking the stairs more often or exercising once a week.
Baumgartner RN, Koehler KM, Gallagher D, Romero L, Heymsfield SB, Ross RR, Garry PJ, Lindeman RD. Epidemiology of sarcopenia among the elderly in New Mexico. Am J Epidemiol. 1998 Apr 15;147(8):755-63. Erratum in: Am J Epidemiol 1999 Jun 15;149(12):1161. PubMed PMID: 9554417.
Chastin SF, Ferriolli E, Stephens NA, Fearon KC, Greig C. Relationship between sedentary behaviour, physical activity, muscle quality and body composition in healthy older adults. Age Ageing. 2012 Jan;41(1):111-4. Doi: 10.1093/ageing/afr075. Epub 2011 Jul 12. PubMed PMID: 21749993.
Cruz-Jentoft AJ, Baeyens JP, Bauer JM, Boirie Y, Cederholm T, Landi F, Martin FC, Michel JP, Rolland Y, Schneider SM, Topinková E, Vandewoude M, Zamboni M; European Working Group on Sarcopenia in Older People. Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in Older People. Age Ageing. 2010 Jul;39(4):412-23. doi: 10.1093/ageing/afq034. Epub 2010 Apr 13. PMID: 20392703; PMCID: PMC2886201.
Dirks-Naylor AJ, Lennon-Edwards S. The effects of vitamin D on skeletal muscle function and cellular signaling. J Steroid Biochem Mol Biol. 2011 Jul;125(3-5):159-68. doi: 10.1016/j.jsbmb.2011.03.003. Epub 2011 Mar 21. Review. PubMed PMID: 21397021.
Ferrucci L, Penninx BW, Volpato S, Harris TB, Bandeen-Roche K, Balfour J, Leveille SG, Fried LP, Md JM. Change in muscle strength explains accelerated decline of physical function in older women with high interleukin-6 serum levels. J Am Geriatr Soc. 2002 Dec;50(12):1947-54. PubMed PMID: 12473005.
Fiatarone MA, Marks EC, Ryan ND, Meredith CN, Lipsitz LA, Evans WJ. High-intensity strength training in nonagenarians. Effects on skeletal muscle. JAMA. 1990 Jun 13;263(22):3029-34. PubMed PMID: 2342214.
Frontera WR, Meredith CN, O’Reilly KP, Knuttgen HG, Evans WJ. Strength conditioning in older men: skeletal muscle hypertrophy and improved function. J Appl Physiol (1985). 1988 Mar;64(3):1038-44. PubMed PMID: 3366726.
Katsanos CS, Kobayashi H, Sheffield-Moore M, Aarsland A, Wolfe RR. A high proportion of leucine is required for optimal stimulation of the rate of muscle protein synthesis by essential amino acids in the elderly. Am J Physiol Endocrinol Metab. 2006 Aug;291(2):E381-7. Epub 2006 Feb 28. PubMed PMID: 16507602.
Klitgaard H, Mantoni M, Schiaffino S, Ausoni S, Gorza L, Laurent-Winter C, Schnohr P, Saltin B. Function, morphology and protein expression of ageing skeletal muscle: a cross-sectional study of elderly men with different training backgrounds. Acta Physiol Scand. 1990 Sep;140(1):41-54. PubMed PMID: 2275404.
Narici MV, de Boer MD. Disuse of the musculoskeletal system in space and on earth. Eur J Appl Physiol. 2011 Mar;111(3):403-20. Doi: 10.1007/s00421-010-1556-x. Epub 2010 Jul 9. Review. PubMed PMID: 20617334.
Nelson ME, Rejeski WJ, Blair SN, Duncan PW, Judge JO, King AC, Macera CA, Castaneda-Sceppa C; American College of Sports Medicine; American Heart Association. Physical activity and public health in older adults: recommendation from the American College of Sports Medicine and the American Heart Association. Circulation. 2007 Aug 28;116(9):1094-105. Epub 2007 Aug 1. PubMed PMID: 17671236.
Pipek LZ, Baptista CG, Nascimento RFV, Taba JV, Suzuki MO, do Nascimento FS, et al. (2020) The impact of properly diagnosed sarcopenia on postoperative outcomes after gastrointestinal surgery: A systematic review and meta-analysis. PLoS ONE 15(8): e0237740. https://doi.org/10.1371/journal.pone.0237740.
Preedy VR, Adachi J, Ueno Y, Ahmed S, Mantle D, Mullatti N, Rajendram R, Peters TJ. Alcoholic skeletal muscle myopathy: definitions, features, contribution of neuropathy, impact and diagnosis. Eur J Neurol. 2001 Nov;8(6):677-87. Review. PubMed PMID: 11784353.
Rom O, Kaisari S, Aizenbud D, Reznick AZ. Identification of possible cigarette smoke constituents responsible for muscle catabolism. J Muscle Res Cell Motil. 2012 Aug;33(3-4):199-208. doi: 10.1007/s10974-012-9299-4. Epub 2012 May 22. Review. PubMed PMID: 22614737.
Smith GI, Julliand S, Reeds DN, Sinacore DR, Klein S, Mittendorfer B. Fish oil-derived n-3 PUFA therapy increases muscle mass and function in healthy older adults. Am J Clin Nutr. 2015 Jul;102(1):115-22. doi: 10.3945/ajcn.114.105833. Epub 2015 May 20. PubMed PMID: 25994567; PubMed Central PMCID: PMC4480667.
Szulc P, Duboeuf F, Marchand F, Delmas PD. Hormonal and lifestyle determinants of appendicular skeletal muscle mass in men: the MINOS study. Am J Clin Nutr. 2004 Aug;80(2):496-503. PubMed PMID: 15277176.
Taaffe DR, Duret C, Wheeler S, Marcus R. Once-weekly resistance exercise improves muscle strength and neuromuscular performance in older adults. J Am Geriatr Soc. 1999 Oct;47(10):1208-14. PubMed PMID: 10522954.
Volpi E, Kobayashi H, Sheffield-Moore M, Mittendorfer B, Wolfe RR. Essential amino acids are primarily responsible for the amino acid stimulation of muscle protein anabolism in healthy elderly adults. Am J Clin Nutr. 2003 Aug;78(2):250-8. PubMed PMID: 12885705; PubMed Central PMCID: PMC3192452.
Waters DL, Baumgartner RN, Garry PJ, Vellas B. Advantages of dietary, exercise-related, and therapeutic interventions to prevent and treat sarcopenia in adult patients: an update. Clin Interv Aging. 2010;7:259–70. http://dx.doi.org/10.2147/CIA.S6920.
Wroblewski AP, Amati F, Smiley MA, Goodpaster B, Wright V. Chronic exercise preserves lean muscle mass in masters athletes. Phys Sportsmed. 2011 Sep;39(3):172-8. doi: 10.3810/psm.2011.09.1933. PubMed PMID: 22030953.