We lose muscle strength and power as we age. How much and why does it matter?
One consequence of aging is the loss of strength and power in leg and arm muscles. When does this start to occur and at what rate of degeneration do our bodies experience this? When does it become apparent to us that even simple daily tasks such as rising from a chair or climbing stairs require more effort and time to execute?
The decline in strength of limb muscles that occurs with aging typically starts from about 40-50 years of age and regresses more rapidly after about 75 years in healthy older adults. Generally, the decline in strength occurs at a rate of about ~10% per decade or 1% per year from about 40-50 years of age, so the average healthy 80 years old can have half the strength of a 20- to 30-year-old person. In men and women who do not regularly exercise, the decline in strength and power typically starts earlier at about 40 years of age, while exercise and strength training can delay the start of that decline to the 50s for some people.
Why do we lose strength and muscle power as we age? We lose strength because we lose muscle mass and muscle volume as we age. The entire muscle gets smaller because the individual muscle fibers shrink in size, and some fibers die. The nerves that attach to the muscle fibers to allow them to contract when activated, also die.
Muscle power also declines with aging. Power is the product of both the strength and speed of a muscle. The loss of power of limb muscles is often greater than the loss of maximal strength alone because leg muscles also become slower with aging, in addition to the decreases in strength.
Why is the age-related loss of power important? Our ability to conduct daily tasks such as rising from a chair or climbing stairs is closely associated with limb power. For instance, the more powerful your legs, the more likely you will be able to rise from that low couch without needing to bolster your effort with the arm rest.
In fact, the more powerful your limb muscles the larger the buffer between your maximal limb power and the actual power needed to get out of the chair.
Is it all doom and gloom? No because regular strengthening/power exercises can significantly help offset age-related decline in strength and power.
We can move better for life by incorporating regular exercise into our daily lives. I hope you found this blog useful,
Sandra.
References
Hunter, S. K., et al. (2016). “The aging neuromuscular system and motor performance.” Journal of Applied Physiology 121(4): 982-995.