The Full Scope And Range Of The Problem

Growing weakness makes us feel like doing less, which makes us weaker still. During our 50s, the rate of strength loss accelerates for most and we may experience some significant health challenges. As we retire, we tend to become more sedentary still and as our strength declines further, even the common daily activities of life can become challenging.8 In 2009, 25 percent of Medicare beneficiaries that were 65 and older reported that they were having trouble performing at least one activity of daily living. Notice how people over the age of 60 act and move. It will send chills down your spine as you imagine yourself or a loved one in that same situation. The following section will share the medical conditions that drive this downward spiral. Learning about them will be useful as you understand the full scope and range of the problem. The disease that relegates us to the Frail Trail downhill pathway. We call this an epidemic, because unless preventive action is taken, every single person on earth, rich or poor, will suffer from the active process leading to sarcopenia. Neural motor units, which contract muscles, begin to die or lose their ability to function. It is important to note that muscle size is not nearly as critical as strength in evaluating the course of this disease.

Another Brick In The Wall

Strength loss is highly associated with the nervous system’s inability to voluntarily activate muscles. Accordingly, the number and magnitude of associations for low physical performance or disability are greater for low muscle strength than low muscle mass. The good news is that strength begins to return with strength training more quickly than lost muscle mass, meaning that regaining important physical abilities can occur more quickly than the time needed to significantly increase muscle mass.9 Muscle strength is also lost faster with age than muscle mass. Of course, the phenomenon of weakness and frailty with aging has been around for thousands of years. In fact, sarcopenia is one of the world’s major public health problems. So it is surprising that peerreviewed research only began looking into its causes in the last few decades. Accordingly, the mechanisms underlying sarcopenia are not yet fully understood. But, because discussion of remedies and cures always involves understanding causes, it is important to summarize the current state of knowledge and where research is heading. As Theodosius Dobzhansky, one of the leading biologists of the twentieth century, said, Nothing in biology makes sense except in the light of evolution. In this section, we will review when and how our human genome evolved and what conditions created our current genome. Fifty thousand years ago, the world was populated with a variety of Homo sapiens that looked like we do now.

Hard Feelings

If one of them turned up in a modern morgue, the local pathologist would notice nothing peculiar. Stephen Jay Gould observed, There has been no biological change in humans in 40,000 or 50,000 years. Everything we call culture and civilization we’ve built with the same body and brain. The lesson is not that evolution stopped 50,000 years ago. Evolution is, of course, ongoing. Rather, Gould’s statement reminds us that it is important to remember that the preponderance of evolutionary forces that produced our species as it exists today occurred over eons. These forces are vast in their effect in comparison to what biological change has occurred in the relative blink of an eye during which human civilization has existed. We are very much the same biological animal that our ancestors of 50,000 years ago were. What is startlingly different today is the environment we have constructed to live and work in that allows for very different diets and physical behavior in the modern era. We are just waking up to the health ramifications of this sudden epic change in our circumstances. Our genome evolved through natural selection. Natural selection functions to select for genes that create a competitive advantage in terms of an organism’s ability to survive and reproduce.

It's Too Late

By chance, variations in our genetic material constantly occur, primarily in the form of mutations. Some variations were advantageous, in the sense that they improved our ability to survive and reproduce. Such advantageous variations became more common as individuals with such variations lived longer and had more progeny and thus became incorporated in our genome. For untold generations, genes were selected that gave early hominids competitive advantages in the environment in which they lived. And it was not just our muscles that were designed for that environment. Favorable adaptations in every part of our bodies over untold ages were selected because they created some form of competitive advantage in that environment. Our next step, having learned that our bodies were designed for success in the environment existing in the millennia leading up to the late Stone Age, is to examine what is known about that world. This will inform us about our genes and our biology today and take us further down the path to understanding why sarcopenia saps our strength beginning in our thirties. Walking and running 20–30 miles a day looking for food was common. Hunting and killing immensely powerful animals, and defending ourselves and our families, was brutal and physically demanding. Our genetic inheritance traces to the period when competition faced by all humans for survival involved very high levels of physical activity. Because there was an advantage in surviving in a harsh world of intense physical activity, variations between humans that were favorable in such a world were selected and flourished in the gene pool. Strong, muscular humans were fitter, did better in this competitive climate, and had more progeny. Favorable genetic variations were passed on, giving subsequent generations a similar competitive advantage. This process of natural selection resulted in a population designed for and perfectly suited to survive and perform well under these conditions of intense physical activity. We still carry the genes that allow our bodies to perform best under such conditions. And now we can envision what genome was needed to survive in such harsh conditions. Have you ever heard of sarcopenia?