Our ability to respond to exercise is retained as we age. Both an 80 year old and a 20 year old will experience cellular adaptations to exercise, including increased strength and muscle size. Our total capacity reduces as we age, with the 80 year old producing roughly half the muscle force as the 20 year old. But the ability to affect change is is still there. This is an innate human ability and has more to do with our DNA than it does our will power or cultural habits. Exercise stimulates cells to remodel themselves. Exercise can cause bone, nerve, neuron, heart, lung, connective tissue and of course muscle remodeling.
Ability to recover from exercise diminishes somewhat as we age, requiring longer rest periods between bouts of challenging exercise, but no matter what age we are, exercise stimulates DNA to give instructions to cells to adapt to the exercise.
While strength potential of some muscle fibres may well be half at age 80 of what can be achieved in the 20's through 40's, (study) most people over age 50-60 are so far below their strength potential that getting up to half their younger potential is still a significant improvement that would be life changing. Interestingly fast twitch fibres used primarily in sprinting and strength training still preserved a fair amount of youthful function despite age related shrinking (atrophy). Study
If you're human, and not dead yet, exercise can make you better at moving, and these gains can be very profound if you've lost mobility due to being less active as the years pile on.
The main cause of slip and fall in the elderly is reduced strength and power in the muscles responsible for early recovery from slipping or going off balance; mainly muscles around the hip and lower extremities. Strengthen those muscles and you're less likely to fall down, and less likely to fracture if you do fall.
Study Study Study
You'll also go up and down stairs and get in and out of chairs better, or.. be able to enjoy the outdoors more. I'm middle aged and can already appreciate the difference staying athletic has provided me. I'm not as fit as I was in my 20's and 30's, but I'm fairing better than many of my equally aged early generation Xrs who found a less active path.
I'm not saying seniors need to become athletes, but it is noteworthy that many seniors have decided to do so and we can see the bar can be set pretty high if the desire is there. Masters athletes in their 50's through 90+ are enjoying rejuvenated bodies with many developing greater levels of fitness than they had in their youth. Achieving a mere fraction of this potential can liberate many seniors from reduced mobility, and also prevent injury and illness. Not a cure-all for sure, but profound benefit that can substantially increase enjoyment of life, and maybe add a few years as well.
Most seniors are not very active and their strength has dropped well below baseline, leaving a lot of room for improvement, despite an age related reduction in total fitness potential.
Here's an example of a recreational marathon runner who started running marathons at age 48, and has continued to do so at age 91. From age 50 to 64 his finish times remained about the same at 4 hours. By his late 80's finish times levelled off at 10 hours.
Br J Med Med Res. 2015;8(12):1074-1079.Aging, Fitness, and Marathon Times in a 91 Year-old Man Who Competed in 627 Marathons.Addison O1, Steinbrenner G1, Goldberg AP2, Katzel LI1.
I'm not saying running is the focus here, I used that example just because there was an interesting study following a marathoner from age 48 to age 91. Find an activity you like and do it.
Overall strength training has been shown to be the most important as we age, because it's overall muscle atrophy and loss of strength that reduces our mobility and basic function.
Before that's read as leaving out aerobic, I personally intended on competing in mountain biking for as many decades as I am able. I'm 49. I also intend on keeping up visits to the gym for good old iron-pumping.
A study from the University of Michigan has shown that seniors can build about 2.5 pounds of lean muscle mass over about 19 weeks of progressive strength training; strength increased by 25-30% over the same period.
Dr. Mark Peterson, one of the study authors, identifies strength as one of the most important factors in maintaining function. Typically people become more sedentary as they age increasing the rate of loss of lean muscle mass and strength, and consequently less functional movement capacity.
Instead of loss of function though, seniors can actually gain function, and gain lean muscle simply by strength training.
The study authors are careful to explain that starting slow and easy with basic movements at home is important and that transitioning to gym with exercise equipment and adding more complex moves and heavier loads as one progresses is the key to muscle strength and size development.
Older and stronger: Progressive resistance training can build muscle, increase strength as we age | University of Michigan Health System
Resistance Exercise for the Aging Adult: Clinical Implications and Prescription Guidelines (PDF). The American Journal of Medicine (2011) 124, 194-198. Co-author: Paul M. Gordon, Ph.D., MPH., director of PAEIR.
A study in Taiwan looked at over 1000 men and woman of about age 74. The study showed that those who exercised regularly were significantly less likely to suffer symptoms of depression.
J Nurs Res. 2015 Nov 20. [Epub ahead of print]Regular Exercise and Depressive Symptoms in Community-Dwelling Elders in Northern Taiwan.Chang SH1, Chien NH, Chen MC.
Curr Aging Sci. 2015;8(3):248-55.The Effect of Aerobic Exercise on Quantity and Quality of Sleep Among Elderly People Referring to Health Centers of Lar City, Southern of Iran; A Randomized Controlled Clinical Trial.Sharif F, Seddigh M, Jahanbin I1, Keshavarzi S.
Just exercise ok?