Sarcopenia (loss of muscle), the undiagnosed epidemic
Is a loss of strength, mobility, and functionality an inevitable part of ageing?
No, it is not. It is a consequence of disuse, suboptimal hormone levels, dietary, and nutrient considerations, and other variables, all of which are compounded by ageing. One of the greatest threats to an ageing adult's ability to stay healthy and functional is the steady loss of lean body mass - muscle and bone in particular.
The medical term for the loss of muscle is sarcopenia, and it is starting to get the recognition it deserves by the medical and scientific community. For decades, that community has focused on the loss of bone mass (osteoporosis) but paid little attention to the loss of muscle mass commonly seen in ageing populations. Sarcopenia is a serious healthcare and social problem that affects millions of ageing adults. This is no exaggeration. As one researcher recently stated:
"Even before significant muscle wasting becomes apparent, ageing is associated with a slowing of movement and a gradual decline in muscle strength, factors that increase the risk of injury from sudden falls, and the reliance of the frail elderly on assistance in accomplishing even basic tasks of independent living. Sarcopenia is recognized as one of the major public health problems now facing industrialized nations, and its effects are expected to place increasing demands on public healthcare systems worldwide" (Lynch, 2004)
Sarcopenia and osteoporosis are directly related conditions, one often following the other. Muscles generate the mechanical stress required to keep our bones healthy; when muscle activity is reduced it exacerbates the osteoporosis problem, and a vicious circle is established, which accelerates the decline in health and functionality.
What defines sarcopenia from a clinical perspective? Sarcopenia is defined as the age-related loss of muscle mass, strength, and functionality. Sarcopenia generally appears after age 40 and accelerates after the age of approximately 75. Although sarcopenia is mostly seen in physically inactive individuals, it is also commonly found in individuals who remain physically active throughout their lives. Thus, it is clear that although physical activity is essential, physical inactivity is not the only contributing factor. As with osteoporosis, sarcopenia is a multifactorial process that may involve decreased hormone levels (in particular, GH, IGF-1, MGF, and testosterone), a lack of adequate protein and calories in the diet, oxidative stress, inflammatory processes, chronic, low level, diet-induced metabolic acidosis, as well as a loss of motor nerve cells.
A loss of muscle mass also has far-ranging effects beyond the obvious loss of strength and functionality. Muscle is a metabolic reservoir. In times of emergency, it produces the proteins and metabolites required for survival after a traumatic event. In practical terms, frail elderly people with decreased muscle mass often do not survive major surgeries or traumatic accidents, as they lack the metabolic reserves to supply their immune systems and other systems critical for recovery.
There is no single cause of sarcopenia, as there is no single cause for many human afflictions. To prevent and/or treat it, a multi-faceted approach must be taken, which involves hormonal factors, dietary factors, supplemental nutrients, and exercise.
The major dietary considerations that increase the risk of sarcopenia are a lack of adequate protein, inadequate calorie intake, and low level, chronic, metabolic acidosis.
Although it is generally believed the "average" American gets more protein, than they require, the diets of older adults are often deficient. Compounding is possible reductions in digestion and absorption of protein, with several studies concluding protein requirements for older adults are higher than for their younger counterparts (Young, 1990; Campbell et al., 1994; Campbell et al., 1996). These studies indicate that most older adults do not get enough high-quality protein to support and preserve their lean body mass.
There is an important caveat on increasing protein, which brings us to the topic of low level, diet-induced, metabolic acidosis. Typical Western diets are high in animal proteins and cereal grains, and low in fruits and vegetables. It has been shown that such diets cause low-grade metabolic acidosis, which contributes to the decline in muscle and bone mass found in ageing adults (Frassetto et al., 2001). One study found that by adding a buffering agent (potassium bicarbonate) to the diet of post-menopausal women the muscle wasting effects of a "normal" diet were prevented (Frassetto et al., 1997). The researchers concluded the use of the buffering agent was " potentially sufficient to both prevent continuing age-related loss of muscle mass and restore previously accrued deficits."
The take-home lesson from this study is that - although older adults require adequate intakes of high-quality proteins to maintain their muscle mass (as well as bone mass), it should come from a variety of sources and be accompanied by an increase in fruits and vegetables as well as a reduction of cereal grain-based foods. The use of supplemental buffering agents such as potassium bicarbonate, although effective, does not replace fruits and vegetables for obvious reasons, but maybe incorporated into a supplement regimen.
As most are aware, with ageing comes a general decline in many hormones, in particular, anabolic hormones such as Growth Hormone (GH), DHEA, and testosterone. Also, researchers are looking at Insulin-like Growth factor one (IGF-1) and Mechano Growth factor (MGF), which are essential players in the hormonal milieu responsible for maintaining muscle mass as well as bone mass. Without adequate levels of these hormones, it is virtually impossible to maintain lean body mass, regardless of diet or exercise. It has been shown, for example, that circulating GH declines dramatically with age. In old age, GH levels are only one-third of that in our teenage years. Also, ageing adults have a blunted GH response to exercise as well as a reduced output of MGF (Hameed et al., 2003), which explains why older adults have a much more difficult time building muscle compared to their younger counterparts.
However, when older adults are given GH, and then exposed to resistance exercise, their MGF response is markedly improved, as is their muscle mass (Hameed et al., 2004). Another hormone essential for maintaining lean body mass is testosterone. Testosterone, especially when given to men low in this essential hormone, has a wide range of positive effects. One review looking at the use of testosterone in older men (Gruenewald et al., 2003) concluded:
Contrary to popular belief, women also need testosterone! Although women produce less testosterone, it is as essential to the health and well-being of women as it is for men.
The above is a highly generalized summary and only the tip of the proverbial iceberg regarding various hormonal influences on sarcopenia. A full discussion on the role of hormones in sarcopenia is well beyond the scope of this article. Needless to state, yearly blood work after the age of 40 is essential to track your hormone levels, and if needed, treat deficiencies via Hormone Replacement Therapy (HRT). Private organizations like the Life Extension Foundation offer comprehensive hormone testing packages, or your doctor can order the tests. However, HRT is not for everyone and maybe contraindicated in some cases. Regular monitoring is required, so it is essential to consult with a medical professional versed in the use of HRT, such as an endocrinologist.
Several supplemental nutrients should be especially helpful for combating sarcopenia, both directly and indirectly. Supplements that have shown promise for combating sarcopenia are creatine, vitamin D, whey protein, acetyl-L-carnitine, glutamine, and buffering agents such as potassium bicarbonate.
The muscle atrophy found in older adults comes predominantly from a loss of fast-twitch (FT) type II fibres which are recruited during high-intensity, anaerobic movements (e.g. weightlifting, sprinting, etc.). Interestingly, these are exactly the fibres creatine has the most profound effects on. Various studies find creatine given to older adults increases strength and lean body mass (Chrusch et al., 2001; Gotshalk et al., 2002; Brose et al., 2003). One group concluded: "Creatine supplementation may be a useful therapeutic strategy for older adults to attenuate loss in muscle strength and performance of functional living tasks."
It is well established that vitamin D plays an essential role in bone health. However, recent studies suggest it is also essential for maintaining muscle mass in ageing populations. In muscle, vitamin D is essential for preserving type II muscle fibres, which, as mentioned above, are the very muscle fibres that atrophy most in ageing people. Adequate vitamin D intakes could help reduce the rates of both osteoporosis and sarcopenia found in ageing people (Montero-Odasso et al., 2005) leading the author of one recent review on the topic of vitamin D's effects on bone and muscle to conclude:
As previously mentioned, many older adults fail to get enough high-quality protein in their diets. Whey has an exceptionally high biological value (BV), with anti-cancer and immune-enhancing properties among its many uses. As a rule, higher biological value proteins are superior for maintaining muscle mass compared to lower quality proteins, which may be of particular importance to older individuals. Finally, data suggests "fast" digesting proteins such as whey may be superior to other proteins for preserving lean body mass in older individuals (Dangin et al., 2002).
Additional Nutrients of interest
There are several additional nutrients worth considering when developing a comprehensive supplement regimen designed to prevent and or treat sarcopenia. In no particular order, they are fish oils (EPA/DHA), acetyl-l-carnitine, glutamine, and buffering agents such as potassium bicarbonate. There is a good scientific reason to believe they would be beneficial for combating sarcopenia, but data specific to sarcopenia is lacking. For example, EPA/DHA has been found to preserve muscle mass (e.g. is anti-catabolic) under a wide range of physiological conditions. The anti-inflammatory effects of fish oils would also lead one to believe they should be of value in the prevention or treatment of sarcopenia. In general, fish oils have so many health benefits. It makes sense to recommend them here.
Acetyl-l-carnitine also offers many health benefits to ageing people, and data suggest it should be useful in combating this condition. More research specific to sarcopenia is needed, however.
Glutamine is another nutrient that should be useful in an overall plan to combat sarcopenia. Finally, data does suggest that bicarbonate and citrate buffering agents containing minerals such as potassium, magnesium, and calcium can reverse the metabolic acidosis caused by unbalanced western diets. However, I hesitate to recommend this particular strategy as it does not address the root cause, which is the diet itself. Much greater health benefits will result from improving the diet over adding in this supplement. Also, there are potential problems that could result from excessive intakes of buffer salts, such as hyperkalemia and the formation of kidney stones.
Exercise is the lynchpin to the previous sections. Without it, none of the above will be an effective method of preventing/treating sarcopenia. Exercise is the essential stimulus for the systemwide release of various hormones such as GH, as well as local growth factors in tissue, such as MGF. Exercise is the stimulus that increases protein and bone synthesis and exerts other effects that combat the loss of essential muscle and bone as we age. Exercise optimizes the effects of HRT, diet, and supplements, so if you think you can sit on the couch and follow the above recommendations - think again.
Although any exercise is generally better than no exercise, all forms of exercise are not created equal. You will note, for example, many of the studies listed at the end of this article have titles like: "GH and resistance exercise" or "creatine effects combined with resistance exercise" and so on. Aerobic exercise is great for the cardiovascular system and helps keep body fat low, but when scientists or athletes want to increase lean mass, resistance training is always the method.
Aerobics does not build muscle and is only mildly effective at preserving the lean body mass you already have. Thus, some form of resistance training (via weights, machines, bands, etc.) is essential for maintaining or increasing muscle mass.
The CDC report on resistance exercise for older adults summarizes it as:
"In addition to building muscles, strength training can promote mobility, improve health-related fitness, and strengthen bones."
Combined with HRT (if indicated), dietary modifications, and the supplements listed above, dramatic improvements in lean body mass can be achieved at virtually any age, with improvements in strength, functionality into advanced age, and improvements in overall health and general well-being.
Hopefully, the reader will appreciate that I have attempted to cover a huge amount of territory with this topic. Each sub-section (nutrition, hormones, etc.) could easily be its article if not its book. This means each section is a general overview vs anything close to an exhaustive discussion.
To summarize, to prevent or treat sarcopenia:
I am going to conclude this article the way most people would start it, with the good news and the bad news. The bad news is, millions of people will suffer from a mostly avoidable loss of functionality and will become weak and frail as they age from a severe loss of muscle mass. The good news is that you do not have to be one of those people.
One thing is very clear: it is far easier, cheaper, and more effective to prevent sarcopenia, or at least greatly slow its progression than it is to treat it later in life. Studies have found, however, that it is never too late to start, so do not be discouraged if you are starting your sarcopenia fighting program later in life.
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About the Author
Will Brink has over 15 years' experience as a respected author, columnist and consultant, to the supplement, fitness, bodybuilding, and weight loss industry and has been extensively published. Will graduated from Harvard University with a concentration in the natural sciences and is a consultant to major supplement, dairy, and pharmaceutical companies.