While you may not have been familiar with the term, “sarcopenia” until now, if you are over 30 you may already be experiencing its effects. Sarcopenia, one of the most pervasive health issues related to aging in the modern world, is the scientific term for muscle loss.
As you are probably well aware, we lose muscle mass as we age, so this is one condition that everyone “gets.” But does it have to be this way? Scientists are hoping that one day they will be able to say, “No, not everyone has to experience significant muscle loss in their lifetime.” Right now, however, this is the case. In fact, after age 30, you can expect to lose as much as 3 to 5 percent of skeletal muscle every 10 years. The condition, which is said to specifically speed up after age 50, is normal as far as the aging process goes. The normalcy factor, however, does not make it sound any less discouraging to those who are beginning to experience its consequences; which can range from a loss of mobility to a shortened life span.
Until recently, muscle loss was a little studied health topic. Fortunately, the science of combating muscle loss is something the researchers at Stanford University’s Blau Lab became very interested in studying. Muscles are just too important; they are the largest tissue in the body, and they not only serve as padding for bones; especially when they become more brittle, they play a vital role in our metabolic health.
To address and treat muscle loss, scientists must first learn how we make muscle and then learn why it eventually breaks down from a cellular and molecular level perspective. This is not only particularly critical as it relates to the aging population, but also to those who risk muscle loss for other health reasons, such as individuals with critical illnesses and post-surgical patients with extended recovery processes.
Anatomy of the Research
We are born with all the muscles we need to get going in life after having them formed during our embryonic development. This skeletal muscle (any muscle attached to the skeleton) is made of component fibers called Type 1, or “fast twitch” fibers and Type 2, “slow twitch” fibers.
These two types of fibers are best described using two types of athletes: a long-distance runner and a sprinter. The muscles of a long-distance runner are dominated by slow-twitch fibers which glean endurance characteristics from an abundance of capillaries and mitochondria. The sprinter’s muscles are dominated with fast-twitch fibers which provide fewer capillaries and mitochondria but faster muscle contraction and quickness.
Muscle fibers act together in groups branching off the central nervous to form motor units. The motor units work synchronously to move you throughout your daily activities.
Researchers are most excited about what they are learning by studying muscle stem cells, or MuSCs. MuSCs are also known as satellite stems which are located on the outside of muscle fibers. When these cells are activated by exercise or damage, they reproduce, differentiate, and merge to repair muscle fibers. If you have ever heard a fitness instructor talk about muscle break down or failure in order to rebuild “a better you”—this is the process they are referring to, as your MuSCs are being called to action, creating new cells that merge effectually producing new muscle fibers. To date, exercise is the only known way to combat muscle loss.
Gain & Loss
During the course of an average life, the activation of muscle stems cells is the primary way we build new muscle. In the case of the two types of athletes we mentioned earlier, their specific type of exercise tells their muscle stem cells what they need to keep doing what they do.
Those who wish to enhance this natural process by increasing muscle size often turn to the consumption of excess proteins and increased exercise in the form of weight training and lifting.
However, eventually as we age, these motion-creating processes change. After age 30, something called the myostatin pathway becomes turned on. Myostatin is a natural inhibitor of muscle growth that essentially begins to consume our body’s skeletal muscle. Unfortunately, according to scientists, this is just one of several complicated factors associated with muscle loss.
Another issue is “inflammaging,” or the chronic inflammation affecting the muscle’s microenvironment. This condition decreases the communication between muscle fibers and nerve cells, and the pathways necessary for proteins to synthesize new muscle fibers.
Other factors include an overall decline in the quality of the muscle, and what scientists call “an epidemic of inactivity.” Simply stated, our modern sedentary lifestyles exacerbate muscle loss. So, scientists have their work cut out for them; mitigating muscle loss will require having to address many circumstances.
Master Athletes & the Science
Currently they are working with what they call a class of “master athletes,” or individuals who remained highly active well into their later years. In this scenario, they will be able to determine what’s happening in the muscle as it ages naturally, unaffected by the attributes of an unhealthy lifestyle.
What they have confirmed as a certainty through this research is that remaining physically active is a highly effective solution to muscle loss. In a study of biopsies taken from 125 physically active male and female cyclists aged 55 to 79, little difference was noted between these subjects and their younger counterparts in terms of muscle condition.
While this result may sound predictable, researchers caution it is not an ultimate solution, especially for those, who due to critical illness, cannot continue with high-intensity activity and are subject to rapid muscle wasting while ill. For these specific cases they are hoping to identify potential solutions.
Scientists caution that while research is also being done in the pharmaceutical arena to develop a pill that increases muscle mass, having one quick fix of this nature would probably not be suitable for all, but may one-day be beneficial as part of a dual-therapy process that pairs exercise with some sort of intervention.
The Most Exciting Discovery
Further studies involve ordinary lab mice and mice injected with human stem cells. They found that two-thirds of the muscle stem cells in aged mice are intrinsically defective compared to those in young mice. By examining these aged muscle stem cells, they hope to learn what is dysregulating them in order to be able to rejuvenate them.
What they recently found by injecting molecules of the inflammatory mediator prostaglandin E2 directly into the muscle of both ordinary lab mice and the mice injected with human stem cells is exciting—they were able to stimulate the muscle regeneration process in all the mice.
The accumulated research thus far has scientists looking down the road to a day where, with the help of dual muscle-enhancing therapies, we will feel stronger at 80 than any generation at 80 has felt before.
In the meantime, keep an eye out for our follow-up to this story
in your next issue of What’s Up? We’ll help you start the year off
stronger with the most effective exercises to treat sarcopenia.
