How strong are you? The answer may tell you something about how healthy you are and your risk of dying prematurely. In a study published in the European Journal of Internal Medicine, researchers reviewed 23 research studies looking at muscle strength and the role it plays in health. They found that muscle strength was inversely related to all-cause mortality and death from heart disease independent of the number of physical activity participants engaged in and irrespective of cardiovascular fitness.
Other studies have found a similar link between muscle strength and mortality. In one study, researchers used grip strength as a measure of muscle strength since it’s a quick and easy test to perform using an instrument called a dynamometer. The force with which you can squeeze an object is an indirect measure of how much muscle you have and how functional that muscle tissue is.
One study found that elderly men and women who suffered the greatest loss of grip strength over a four- year period had a higher mortality rate over the subsequent decade. Higher hand grip strength has even been linked with stronger cognitive function and brain health. Could the loss of muscle tissue a marker for brain atrophy too?
How Muscle Loss Differs Between Men and Women
Men and women both lose muscle mass and strength over time, but men tend to lose muscle strength at a relatively steady rate between the ages of 20 and 80, whereas women experience a sharp decline in strength after menopause. Some but not all studies show women on hormone replacement therapy experience less loss of muscle strength after menopause. The reason?
You may remember that actin and myosin are myofibrillar proteins that slide past one another during a muscle contraction and are what causes the muscle to move. Some research suggests that loss of estrogen changes the way myosin functions when a muscle contracts and reduces the quality of the contraction or makes the process less efficient. The good news is resistance training helps preserve muscle mass and strength after menopause and it doesn’t have the side effects that hormone replacement therapy does.
What Role Does Nutrition Play in Preserving Muscle Strength?
Interestingly, one study found that men and women who consumed more fatty fish, rich in omega-3s, had stronger grip strength. Other research shows a correlation between vitamin D levels and grip strength. So, nutrition counts too!
It’s not surprising that muscle strength is closely correlated with health and mortality risk. Loss of muscle strength is closely tied to sarcopenia, the age-related loss of muscle tissue, a condition that commonly leads to falls and disability. Sarcopenia is mainly due to loss of fast-twitch muscle fibers, the ones that have high force capabilities, but fatigue quickly. That’s why it’s important to focus on exercise that targets fast-twitch muscle fibers.
Steady-state aerobics won’t enhance fast-twitch muscle fibers because this form of exercise predominantly uses slow-twitch fibers. Moderate-intensity aerobics may improve your endurance, but it won’t preserve the fast-twitch fibers you lose more of as you age. Exercise that DOES target fast-twitch muscle fibers is high-intensity resistance training, plyometrics and sprinting. Most older people, if they work out at all, walk or do some other form of low to moderate-intensity exercise that only activates slow-twitch fibers. Therefore, it’s not surprising that older adults lack strength and power and suffer from sarcopenia in disproportionate numbers.
Age-related sarcopenia not only makes it harder to get around and increases the risk of falls, but it also has metabolic consequences too. As you lose metabolically active muscle tissue, it lowers your resting metabolic rate and worsens the problem of age-related weight gain. With a loss of muscle tissue and an increase in body fat, insulin sensitivity declines, increasing the risk for type 2 diabetes. No wonder type 2 diabetes is so common in older people!
The Role Protein Plays in Maintaining Strength and Lean Body Mass
As mentioned, omega-3s and vitamin D are two nutrients that help preserve strength. It’s just as important, if not more so, to get enough protein. The evidence is growing that protein requirements increase with age and suggest that you may need more than the recommended amount of 0.8 grams per kilogram of protein daily to preserve muscle tissue once you reach late middle age.
A study published in the American Journal of Physiology, Endocrinology and Metabolism showed almost doubling daily protein participants from 0.8 grams per kilogram to 1.5 grams per kilogram daily boosted muscle protein synthesis. Why might older adults need more protein? Anabolic resistance, the diminished ability to respond to anabolic stimuli like amino acids from protein, becomes more of a problem with age. Eating a diet higher in protein in combination with resistance training may help compensate for anabolic resistance so the loss of muscle tissue is slowed. One study found that eating a high-protein snack before resistance training boosted muscle protein synthesis in older adults. That’s certainly an argument against training in a fasted state.
The Bottom Line
How strong you are, with grip strength being one measure of that, is one marker of how healthy you are. Greater strength implies better muscle quality. It’s true that you lose muscle mass with age, but you can limit the amount you lose through regular resistance training. Research even shows that sarcopenia is partially reversible through resistance training. Don’t forget that you not only lose muscle tissue with age, but bone loss accelerates too. Some sources even call sarcopenia the muscle equivalent of osteoporosis. High-intensity resistance training provides enough of a stimulus, by pulling on bones with force, to stimulate bone growth.
You need strong muscles to stay healthy and functional and avoid the metabolic consequences of sarcopenia. Keep resistance training and make sure you’re getting enough protein. It matters.
References:
Eur J Intern Med. 2015 Jun;26(5):303-310. doi: 10.1016/j.ejim.2015.04.013. Epub 2015 Apr 25.
Exerc Sport Sci Rev. 2010;38(2):61-67.
The Cell: A Molecular Approach. 2nd edition. Sinauer Associates; 2000.
Life Extension Magazine. “Preventing Sarcopenia”
Mercola.com. “Grip Strength May Help Predict Heart Attack and Stroke”
Curr Top Dev Biol. 2005;68:123-48.
Medscape Family Medicine. “Aging and Malnutrition: Treatment Guidelines”
Am J Physiol Endocrinol Metab. 2005 May;288(5):E883-91. Epub 2004 Dec 21.
Exerc Sport Sci Rev. 2013;41(3):169-173.
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