Few people look forward to getting older! Fortunately, there’s much we can do from a lifestyle standpoint to slow the aging process down and stay fit and healthy at all ages and stages of life. Cells, organs, and tissues age at varying rates based on genetics and lifestyle and it’s something that we can’t completely stop but we can slow it down, sometimes dramatically through lifestyle.
Muscles age just as the rest of your body does. In fact, muscle loss begins after the age of 30 and accelerates during late middle age. With the loss of muscle mass comes a reduction in strength and the ability of muscles to generate power. In fact, research shows that loss of strength occurs at a faster rate than the loss of muscle tissue itself. However, a decline in the ability to generate power occurs the most rapidly. That’s important because you need power to push yourself out of a chair.
In addition, muscle loss is a contributor to poor metabolic health. When you have lots of healthy muscle tissue, the muscle tissue takes up glucose and you have better blood sugar control. In contrast, excess fat produces inflammatory chemicals called cytokines that lower insulin sensitivity and increase the risk of type two diabetes. So, at every stage in life, you need a healthy ratio of muscle to fat on your frame. Unfortunately, the elderly often fight a battle with sarcopenia, the age-related loss of muscle tissue accompanied by an increase in body fat.
But the amount of muscle we lose with age is only one issue. Muscles change in quality as well. In fact, the loss of muscle quality may begin before you start to lose muscle mass itself. As we age and your muscles shrink in size, loss in muscle strength is often greater than what would be expected based on the loss of muscle tissue alone. In fact, a study found that loss of muscle strength was 2 to 5 times greater than the actual loss of muscle over three years in a group of healthy individuals over the age of 70. Therefore, the muscle that remains is less effective at generating force.
How Does Muscle Quality Change?
Muscle strength depends on input from the nervous system and as well as the quantity and quality of the muscle itself. We’ll focus primarily on changes in muscle quality as opposed to nervous system input in this article.
One way in which muscle quality changes pertains to muscle fiber structure. Muscle fibers come in two main forms: fast-twitch muscle fibers and slow-twitch fibers. Fast-twitch fibers are optimized for strength and power while slow-twitch fibers are recruited during exercise that requires muscle endurance, such as long-distance running. Most people have roughly 50% fast-twitch fibers and 50% slow-twitch. However, talented strength athletes may have more fast-twitch relative to slow-twitch and endurance athletes may have more slow-twitch fibers. But scientists now know that with age, a portion of fast-twitch fibers convert to slow-twitch ones. This conversion of fiber type partially explains why we lose strength. We have fewer fast-twitch fibers capable of generating the force needed to lift a heavy object.
Research also shows that the contractile proteins inside muscle fibers, the ones that generate force, change in structure too. They degrade in such a way that cross-bridges can’t form as easily within the muscle fiber. Muscles need to form these cross bridges to generate a muscle contraction. Muscle cells also lose some of their ability to repair or remove damaged proteins within the cell itself. So, damaged proteins build up and interfere with muscle function.
In addition, as muscles lose muscle fibers, they also accumulate more fat within the muscle cell itself. Just as people put on extra body fat with age, muscles do too. But there’s good news on this front. Some research suggests that this age-related accumulation of muscle fat is the result of inactivity rather than aging. Studies looking at spinal cord injuries show this accumulation can be reduced or prevented by staying physically active. Weight loss also seems to help reduce intramuscular fat, although dieting without physical activity can also lead to further muscle loss.
Reducing Loss of Muscle Quality
Before getting discouraged about how your muscles will change with age, here’s some good news. Studies show that people who consistently exercise throughout life can maintain the muscle quality of someone up to four decades younger. Who wouldn’t want that? Exercise really is the key to successful aging.
To maximize the preservation of muscle quantity and quality means that you have to include some form of strength training and use progressive overload to continue to challenge the muscles over time. Since the loss of muscle power happens at a faster rate than the loss of strength, include power training in your routine too. This should consist of repetitions you perform at a faster or even explosive tempo. Plyometric movements like squat jumps and box jumps as well as kettlebell swings are other exercises that enhance the ability to generate power.
Unfortunately, the main exercise people do as they get older is walking and many don’t even do that on a regular basis. However, walking isn’t enough to preserve muscle quantity and quality as you age. You need focused strength training and progressive overload to challenge your muscles. Plus, walking only works the muscles in the lower body. Your upper body needs to be challenged too!
The Bottom Line
You lose muscle with every decade and the amount you lose depends on your diet and whether you strength train. But we should also be concerned about the loss of muscle quality as it happens at a faster rate and leads to strength deficits. So, make sure you’re strength training and using progressive overload when you work out. Your future health depends on it!
· Longevity & Healthspanvolume 3, Article number: 9 (2014) |
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· International Journal of Endocrinology. Volume 2014, Article ID 309570, 11 pages.
· J Cachexia Sarcopenia Muscle. 2010 Dec;1(2):129-133. Epub 2010 Dec 17.