No doubt about it, our bodies change as we age. But, how we age takes its toll on us at different rates based on genetics and lifestyle. In fact, there’s growing evidence that many of the changes we associate with aging are actually due to a sedentary lifestyle rather than the aging process itself. That’s encouraging news for those of us who plan on staying active as long as possible. It’s nice to know we have some control over aging!
One of the biggest concerns is the age-related loss of muscle tissue. In fact, people who don’t exercise lose as much as 3 to 5% of their muscle mass each decade after the age of 30. In addition, muscle strength declines by 20 to 40% between the ages of 20 and 70. This explains why so many older adults are sarcopenic and frail. But, what about other structures that help hold our skeleton together and keep it function, like tendons and ligaments? How do they change with age?
Healthy Tendons and Ligaments
For movement to occur, skeletal muscle must contract but they need the help of tendons and ligaments. Tendons are tough, connective tissue that connects a skeletal muscle to a bone. In contrast, a ligament consists of bands of thick connective tissue that join bone to bone. Tendons are strong because they are made up of closely-packed bundles of collagen that are cross-linked together to give them more tensile strength. When you contract a muscle, the tendon pulls on the bone and causes it to move.
One of the biggest and toughest tendons in your body is the Achilles tendon. Yet, even this tough tendon is easily injured. It’s not uncommon for people to strain or even tear their Achilles tendon, especially runners. For professional runners, this can be a career-ending injury. While you see a lot of Achilles tendon injuries in young, athletic people in their 20’s, the second peak in incidence is around the age of 70. Unfortunately, when an Achilles tendon ruptures in an older person, they often experience reduced function in the involved limb that can become chronic. If they have surgery for the rupture, they’re more likely to experience complications. So, it’s important to keep tendons as healthy as possible.
More commonly than a tear or rupture of a tendon is tendonitis or tendonosis due to irritation of a tendon or tendons. This most commonly occurs when people do the same repetitive motions over and over. This type of chronic stress irritates the tendon to the point that it becomes painful. In an older person, tendonitis has a higher risk of becoming chronic.
How is an Older Tendon Different from a Younger One?
What happens to tendons and ligaments as you age? The biggest change that your tendons undergo with age is increased stiffness. Tendons become stiffer because they lose water and the underlying fabric, collagen, and elastin, becomes more disorganized. This is partially due to a reduction in blood flow to the tendons so that the tendon gets less oxygen and nutrients. The tendon cells themselves start to divide more sluggishly, a phenomenon known as cellular senescence. Plus, the tendons become less capable of repairing themselves as they age as the cellular mechanisms they use for repair become less efficient. Some of these same processes impact the aging of ligaments as well.
One way an older tendon differs from a younger one is the older one is weaker and more prone toward injury. How does a tendon weaken? As mentioned the collagen in a younger tendon is tightly cross-linked giving it greater tensile strength, up to a point. But, a tendon can become so tightly cross-linked that it becomes rigid. This rigidity actually makes the tendon weaker and more prone toward tearing. The collagen content of an older tendon is often greater than a younger one, but elastin, the component that gives the tendon elasticity goes down. This increased rigidity and loss of elasticity reduces the strength of the tendon and makes it more injury prone.
Ligament and Tendon Aging: What Can You Do about It?
Research shows genetics and lifestyle both have an impact on the aging of the tendons and ligaments. Hormonal changes that go along with aging also speed up how rapidly these ligaments and tendons age. For example, people who suffer from an underactive thyroid have low levels of the thyroid hormone, thyroxine. Thyroxine is important for keeping tendons youthful and resistant to injury. So, people with hypothyroidism are more prone to tendon injuries.
Sex hormones play a role too. Estrogen and testosterone help prevent the excessive breakdown of collagen. As such, they help to keep ligaments and tendons youthful. Once women go through menopause, they have lower levels of estrogen and testosterone and this may contribute to the aging of these structures. In addition, for unknown reasons, people with diabetes are more prone to chronic tendonitis or tendonosis.
What about exercise? Studies show that consistent exercise over long periods of time enhances the collagen content of tendons, increases the thickness of tendons, and improves their strength. In contrast, being sedentary decreases blood flow to tendons and ligaments. This, in turn, reduces the delivery of oxygen and nutrients to these structures.
The Bottom Line
Tendons and ligaments become stiffer and more prone towards injury with age, but as the United States Public Health Service points out, exercise is one of the top five priorities for reducing the risk of early disability or death. Make sure you’re training smartly by using good form, varying the exercises you do, and by not overtraining. It’s also important to do a warm-up before ramping up the intensity of a workout. You never want to start an exercise session with cold muscles or tendons. The five or ten minutes you invest in a warm-up is time well spent. Take advantage of it!
References:
Sports Health. 2014 Jan;6(1):41-8. doi: 10.1177/1941738113485691.
J Anat. 2006 Apr; 208(4): 433–443.
WebMD.com. “Sarcopenia With Aging”
Podiatry Today. “Aging and Athletes: How Exercise Can Make a Difference”
FutureLearn.com. “How do our tendons age?”
Science Daily. “Why Tendons Break Down with Age”
J Appl. Physiol. 68:1022–1040.
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