Older people are more inclined to take it easy, but the harms of inactivity are even greater as the years pass by. In fact, a new study published in The Journal of Physiology finds that people in their 60’s and beyond suffer more harmful effects from inactivity than younger folks.
How do we know this? In the study, University of Udine researchers along with researchers from the University of Padova examined the muscles of younger and older people who were hospitalized and forced to stay in bed for at least two weeks. As you know, muscles atrophy or become smaller when you don’t use them regularly. It’s a prime example of “move it or lose it” and when you’re hospitalized, you can’t always get up and walk around.
What the researchers found was confinement to bed impacted the muscles of the elderly more than it did younger subjects. The older subjects experienced a more severe loss of muscle mass and recovery was slower. This suggests that lack of exercise and muscle movement in older people may be more harmful than in younger people and it may take more time to recover healthy muscle function. Even being a habitual couch potato is enough to lead to muscle atrophy in people of all ages, it might be particularly detrimental to the elderly. But, it’s not good to be a couch potato at any age!
The Problem of Sarcopenia and Lack of Exercise
The age-related loss of muscle mass, or sarcopenia, is common among older people and affects almost 33% of people in nursing homes. We don’t completely understand what causes sarcopenia, but it’s related to lack of exercise and age-related inflammation. No surprise here! Inflammation and lack of exercise explain a lot of the health problems people experience throughout life.
At the cellular level, sarcopenia seems to involve damaged and dysfunctional mitochondria, the energy-producing powerhouses inside all cells. This dysfunction is likely related to long-term oxidative damage. When the mitochondria are damaged and aren’t functioning optimally, the energy supply to cells suffers as well. Remember, mitochondria produce ATP, the energy currency that all muscles use to contract. Without ATP there is no movement or life.
But, mitochondria aren’t the only problem. Older people also have more anabolic resistance, meaning their muscles don’t respond as readily to anabolic stimuli that cause them to grow. Anabolic resistance seems to be related partially to an age-related increase in inflammation. See how everything is connected? In addition, elderly muscle has fewer satellite cells, cells that donate their nuclei to help muscle cells repair and become larger and stronger.
For these reasons, older people have a harder time building strength and lean body mass, but research shows that even the elderly can build muscle strength and size through supervised strength training. Muscles retain the capacity to grow even at an advanced age, although it takes more stimulation. Other factors that can worsen age-related sarcopenia is a low protein intake and a sub-optimal vitamin D level. Yes, nutrition becomes even MORE important as we age, and older people often don’t eat as much as they did when they were younger, and this can lead to nutritional deficiencies.
Maintaining Healthy Muscles as You Age
As you can see, physical activity is vital to maintaining muscle health and staying functional. If you don’t continuously challenge your muscles, they will atrophy and become smaller and less functional due to the natural aging process. So, even if you never end up in the hospital on bedrest for 2+ weeks, your muscles will gradually become smaller and weaker if you don’t challenge them. If you should ever end up on forced bed rest, strength training gives you extra “reserve” muscle to help you stay functional if you can’t move around for a few weeks.
But, maximizing muscle strength, size, and functionality later in life is more challenging due to anabolic resistance, the natural increase in inflammation & mitochondrial dysfunction that happens with aging, along with fewer satellite cells to help muscles grown and repair. So, you have to optimize nutrition as well. Due to anabolic resistance, older people need more protein to maintain healthy muscles. According to research from Purdue University, older women need 29% more protein each day relative younger women to reduce age-related muscle decline. It’s also a good idea to consume that protein throughout the day – with every meal and snack.
Since vitamin D may be a factor for some people with age-related sarcopenia, older people should work on optimizing their vitamin D status and that should start by checking a vitamin D level to see if it’s sub-optimal. Vitamin D deficiency is more common in the elderly.
Fish is a Good Source of Protein
Not only is fish a good source of protein, but fatty fish is also rich in long-chain omega-3 fatty acids. Some research suggests that omega-3’s, by reducing inflammation, helps to counter anabolic resistance. So, make sure you’re consuming fatty fish twice a week and enjoy plant-based sources of omega-3’s as well. Chia seeds, hemp seeds, walnuts, sesame seeds, and flaxseed are good sources. The omega-3’s in plant-based sources are short-chain omega-3’s and have slightly different activity. However, you do convert a portion of the short-chain omega-3’s you get through diet to long-chain, although the percentage is small, under 15%. That’s why it’s a good idea to make fish part of your diet
Beyond protein, you need resistance training, and heavy resistance training challenges your muscles more. Muscles grow in response to the stress you play on them and that stress must be progressive. So, nutrition and strength training both play a role in keeping muscles healthy and functional for a lifetime. Make sure you’re optimizing both and avoid the health problems caused by lack of exercise and sitting too much!
References:
Aging Dis. 2018 Feb; 9(1): 151–164.
Biol Sci Med Sci, 70:202-9.
The Physiological Society. “Mechanisms of sarcopenia: motor unit remodeling and muscle fiber type shifts with aging” July 10, 2018.
News-Medical.com. “Inactivity has a more severe impact on muscles of elders than young people”
Purdue University. “Elderly women may benefit from higher amounts of protein”
Biochim Biophys Acta. 2015 Nov; 1847(11): 1347–1353.
BioMed Research International. Volume 2014, Article ID 238463, 7 pages.