One of the many changes that happen with age is a decline in muscle mass and muscle strength. This is referred to as sarcopenia, a common condition in older people that impacts their functionality. This makes them frailer and prone to falls. Most adults reach peak muscle strength and mass in their late 20s and early 30s and experience a gradual decline as they age. This creates problems later in life. When you lose muscle mass, it affects overall functionality, making it more difficult to lift heavy objects and do activities that require strength and balance. It also increases the risk of falls and injuries. As you might expect, loss of muscle mass is greater in people who aren’t active and those who don’t strength train.
Why Do We Lose Muscle Mass and Strength with Age?
What are the factors that influence the loss of muscle strength and mass with age? A decrease in hormone levels is one factor, hormones like testosterone, growth hormone and IGF-1, but there is also a decrease in functional motor neurons, motor units in the nervous system that tell a particular group of muscle fibers to contract. This causes the muscle fibers that the motor neuron innervates to decrease in size. Aging has its greatest impact on fast-twitch fibers, ones that are geared towards strength and power. It affects these “strength and power” fibers more than slow-twitch fibers, aerobic-type, endurance fibers that produce less force.
As motor neurons are lost, some remodeling also takes place. When a motor neuron dies, another motor neuron usually the type that innervates slow-twitch fibers re-innervates the affected muscle fibers. Fast-twitch motor fibers are transformed into slow-twitch ones. This reduces muscle size and force production, particularly for moves that require rapid velocity contractions like power moves. Muscle strength and power are impacted more than muscle endurance. With age, muscle protein synthesis also decreases, making it more difficult for muscle to grow, repair and regenerate.
Resistance Training: Your Best Defense Against Muscle Loss
Resistance training using weight that’s 80 to 85% of your one-rep max is the best way to preserve strength and muscle mass as you age. Heavier weights stimulate fast-twitch muscle fibers, the kind that you lose more of with age. These are the ones you want to target through training to minimize loss of muscle strength and power. If you’re lifting light weights and doing multiple reps, you’re targeting slow-twitch fibers. This does little to preserve muscular strength and power as you grow older.
If you’re trying to preserve fast-twitch muscle fibers, high-intensity cardio and plyometric moves are better than moderate-intensity exercise that work mostly slow-twitch muscle fibers. You lose more fast-twitch fibers than slow-twitch ones as you age and strength and power moves target these fibers. Unfortunately, many older adults work mainly slow-twitch muscle fibers when they exercise, using lighter weights and multiple reps and walking at a moderate pace rather than interval training. This does little to preserve strength, power and muscle mass. Time to up the intensity!
Research shows that even elderly adults can increase muscle strength through strength training. In fact, older adults experience roughly the same absolute strength gains as younger people but they usually begin at a lower level of strength. Regular strength training throughout life can certainly pay off. You may have been inspired by seniors like Jack LaLanne who had remarkable strength and muscle definition when he was in his 90s. When you don’t challenge your muscles through regular resistance training, they atrophy due to disuse. The good news is your neuromuscular system is highly responsive to training even at an older age.
The Importance of Protein for Maintaining Strength and Muscle Mass
Diet is important too. Most young people get enough protein in their diet but this isn’t always true of older adults. As mentioned, muscle protein synthesis decreases with age. According to one study, an older adult can preserve more muscle mass by consuming 25 to 30 grams of protein with every meal. Seniors may need more than the recommended amount of protein daily to maximize protein synthesis and prevent loss of muscle mass. Another good time to consume protein is after resistance training, within an hour after completing a workout to maximize muscle protein synthesis. Take advantage of this “window period.”
The Bottom Line?
You can’t completely prevent loss of strength and muscle mass with age but regular resistance training and high-intensity exercise can make a big difference. It’s never too late to start. Research shows that elderly people who begin a strength training program not only develop greater strength, they increase muscle mass. This is based on CT scans looking at the cross-sectional area of muscle. Regular strength training is also important for maximizing your metabolic rate, which slows with age. Strength training isn’t just for 20 and 30 years old who want bigger muscles. It’s for everyone. Are you getting the full benefits that strength training offers?
References:
J Nutr Health Aging. 2005 Nov-Dec;9(6):408-19.
The University of New Mexico. “Sarcopenia: The Mystery of Muscle Loss” Chantal Vella, M.S. and Len Kravitz, Ph.D.
Curr Opin Clin Nutr Metab Care. 2009 January; 12(1): 86–90.
J Nutr. 2006 Feb;136(2):525S-528S.
Physical Dimensions of Aging. Waneen Spirduso. Human Kinetic Publishing.
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