If you were asked to describe an elderly person, what sort of words would you come up with? For many, the answer probably includes something along the lines of frail or weak. And it turns out there’s a reason for this: sarcopenia, or “age-related decrease in lean muscle mass” (Siparsky et al. 2014), is a process that begins as early as age 30.
There are an enormous number of factors that contribute to sarcopenia. One major reason is that as we age, our body is not able to synthesize muscle protein to the same extent. This is combined with an increased resistance to insulin (the hormone that lowers blood sugar) and a decreased basal metabolic rate (the energy we expend at rest), all of which result in less lean muscle mass. Some other factors include “decreased physical activity, lower hormone excretion, nutritional deficits, and possibly chronic inflammation” (Siparsky et al. 2014).
If you’re a health and fitness aficionado like myself, then this information may seem quite depressing. Luckily, sarcopenia is not inevitable. Here’s what you can do to help counteract this age-related process:
- Strength Training: Despite the reduction in protein synthesis described above, older people can still respond to both aerobic training and resistance training (so don’t think your exercise is in vain!). Further, some research shows that regular exercise 4-5 times per week can actually prevent the usual decline in muscle mass and strength with age. In a study on runners in particular, lifelong exercise prevented the loss of motor units (functional units that control muscle contraction) in participants aged 65!
- Diet: According to Paddon-Jones & Rasmussen 2009, an adequate amount of protein (~25-30 grams) with each meal is essential for protein synthesis as we age. Another dietary factor we must also take into account is the building block of protein known as an amino acid. Some amino acids are essential, meaning the body can’t synthesize them, so they must be consumed in the diet. Aging reduces the ability of skeletal muscle “to respond to low doses of essential amino acids” (Paddon-Jones & Rasmussen 2009). However, supplementation with leucine (an essential amino acid) has been shown to significantly increase protein synthesis in the elderly.
- Hormones: As men and women age, there is a decrease in the sex hormones. For men, testosterone begins to decline at age 35, and for women, estrogen declines after menopause. Decreased testosterone and decreased estrogen can both lead to reductions in lean muscle mass. Unfortunately, while the solution here seems simple, there are a number of adverse side effects with hormone therapy, including cancer. Currently, there is work on selective androgen receptor modulators (SARMs), which “bind to specific areas of androgen receptors on many cell surfaces to activate or inhibit selective functions of the steroid receptors. This selective activation/inhibition could encourage muscle growth while at the same time prevent some of the unwanted aspects of hormone therapy” (Siparsky et al. 2014). So far, the clinical trials have been promising, but there is still much research to be done on these pharmacologic options.
Hopefully this post has given you some insight into sarcopenia and strategies to incorporate to try and delay the inevitable. Sure we may not be hitting a new marathon PR in our 70s, but most of us are not doomed to become frail and weak in our old age- as long as we are willing to start putting in the work now with our diet and exercise.
By: Angleina Noriega. BS Cornell University 5/2015
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