Recent research shows that we can now add sarcopenia, loss of strength and muscle size with aging, to the list of medical problems associated with inflammation. Older people who suffer from sarcopenia are far more likely to have high blood levels of the markers of inflammation such as CRP, SED rate and adiponectin (Aging Clinical and Experimental Research, August 2017;29(4):745–752). Another article lists many other markers of inflammation associated with sarcopenia (Int J Mol Sci, 2010; 11(4): 1509–1526).
Between 25 and 50 percent of North Americans over the age of 65 suffer from sarcopenia that is significant enough to limit their daily activities (J. Am. Geriatr. Soc, 2004;52:80–85). We know that a regular exercise program is the best way to slow down this loss of strength and coordination, but even if you exercise regularly, you will still lose muscle as you age (Aging Male, September-December 2005).
After age 40, people lose more than 8 percent of their muscle size per decade, and by age 70, the rate of muscle loss nearly doubles to 15 percent per decade, markedly increasing risk for disability and disease (Am J Epidemiol, 1998;147(8):755–763; Nutr Rev, May 2003;61(5 Pt 1):157-67).
Sarcopenia is strongly associated with other conditions associated with inflammation, including:
- having excess body fat (J Gerontology A Biol Sci Med Sci, 2011;66:888–895; Curr Gerontol Geriatr Res, 2012;2012:216185)
- eating a pro-inflammatory diet that raises blood sugar levels (J Gerontology A Biol Sci Med Sci, Jan 2012;67A(1):74–81)
- being diabetic (Med J Aust, 2016;205(7):329-333)
- having low vitamin D levels (Molecular Aspects of Medicine, Dec 2008;29(6):407-4140)
- not exercising
- any chronic disease
What is Inflammation?
Your immunity helps to protect you from infections and also helps you heal wounds. However, your immunity is supposed to dampen down after an infection has passed or an injury is healed. If your immunity stays active, it can use the same cells and chemicals to attack you.
It can punch holes in arteries to start forming plaques that can lead to heart attacks. It can damage the genetic material in cells to increase risk for cancers, and it can accelerate the loss of nerves to cause the debilitating muscle weakness so common in older people. An overactive immunity can cause muscle cells to break down through mitochondrial dysfunction and induced cell death called apoptosis (Clin Calcium, 2017;27(1):45-52; Int J Mol Sci, 2010 Apr 12;11(4):1509-26).
Why You Lose Muscle Fibers with Aging
Muscles are made of thousands of individual muscle fibers just as a rope is made up of many individual strands. A single nerve innervates each muscle fiber. With aging, you lose nerves, and with each loss of a muscle’s nerve, you lose that muscle fiber to make the muscle smaller and weaker. For example, the vastus medialis muscle in the front of your thigh contains about 800,000 muscle fibers when you are 20, but at age 60, it has only about 250,000 fibers.
Exercise to the Rescue
If inflammation is a major cause of sarcopenia, treatment should include:
- an anti-inflammatory diet that includes lots of vegetables, fruits, nuts, beans, whole grains and other seeds, and restricts sugar-added foods, all sugared drinks, meat from mammals, processed meats and fried foods
- maintaining a healthful weight
- keeping blood levels of hydroxy vitamin D above 20 ng/ml
- avoiding smoke and alcohol
At this time, the most effective way to decrease the rate at which you lose muscle size and function is to exercise regularly. Eighty-year-old men who still competed in sports have been found to have more muscle fibers than inactive younger men (Journal of Applied Physiology, March 24, 2016).
Muscles are made up primarily of two types of fibers: fast-twitch fibers that govern strength and speed, and slow-twitch fibers that govern endurance. Inactivity and aging both cause a far greater loss of the fast-twitch muscle fibers that govern strength and speed (J Cell Mol Med, Sept 2009;13(9B):3032-50), which explains why you lose strength and speed with aging long before you lose endurance.
Inactivity causes rapid loss of muscle size and strength. If you inactivate a leg by putting it in a cast, you lose a significant amount of muscle size in just four days (Nutrition, Acta Physiol (Oxf), March 2014;210(3):628-41).
Resistance exercise increases muscle size and strength in older people (Med. Sci. Sports Exerc, 2011;43 (2):249–58), but with aging you need to work much longer to gain the amount of strength that a younger person would get with the same program (Med. Sci. Sports Exerc, 2011;43(2):249–58).
Prolonged periods of inactivity due to bed rest, injured nerves, casting or even decreasing the force of gravity cause loss of muscle tissue which leads to insulin resistance, higher blood sugar levels and increased risk for diabetes (Med Hypotheses, 2007;69(2):310-21). Gaining fat decreases your ability to respond to insulin and can shorten your life.
Benefits of Lifelong Exercise
A group of lifelong competitive athletes over 50 who train four to five times per week did not lose as many of the nerves that innervate muscles and therefore retained more muscle size and strength with aging than their non-athlete peers (The Physician and Sportsmedicine, October 2011;39(3):172-8).
Other studies have shown that lifelong competitive runners over 60 had almost the same number of muscle fibers as 25-year-olds. If you are not a lifelong exerciser, it is never too late to start. Studies in animals show that elderly rats that had been sedentary throughout their adult lives formed new muscle fibers 13 weeks after they were put on an aggressive exercise program.
Before beginning a new exercise program, though, check with your doctor to make sure you do not have a condition that will be harmed by exercise.
Gabe Mirkin, M.D., is a sports medicine doctor and fitness guru. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin has run more than 40 marathons and is now a serious tandem bike rider with his wife, Diana. His website is http://drmirkin.com/. Click to read Gabe’s full bio.