In 1966, five healthy men of twenty were put to bed for three weeks, and their fitness was measured before and after. Thirty years later the same five, now fifty, were measured again.
Three decades of ageing had cost them less than those three weeks in bed.
Then they trained for six months, and it gave back everything the thirty years had taken. At fifty, the capacity of their hearts, lungs and muscles stood where it had at twenty.
Ageing is inevitable, but how you age depends a good deal on what you do. Five men is a small number, and the larger counts below point the same way: much of what gets blamed on birthdays belongs to the chair. Birthdays take the blame. The chair did the work.
Here are ten things movement does. Each is marked "tested", where people were assigned to exercise, or "linked", where they were only watched.
1. It rebuilds the engine
Fitness here means one thing: how much oxygen your heart, lungs and muscles can move and use when you work flat out. It is the engine under everything else, and it is what the five men lost in bed and won back.
Linked. How long you live. 122,007 adults sent for a treadmill test were followed for about eight years. (The treadmill was introduced in 1818 as a punishment for prisoners. It has come up in the world.) The least fit died at five times the rate of the fittest. Being below average for your age, set against above average, carried the same added risk as smoking. There is no warning label on a sofa. And no level was too high: the top group did better than the one below it, past seventy as well.
Across 33 follow-ups with 102,980 healthy people, each step up in fitness, about the difference of jogging one kilometre an hour faster, went with 13% fewer deaths.
Linked. Your resting pulse. 2,798 healthy Danish men were followed for 16 years. The fitter men had slower resting pulses. Each 10 beats a minute more went with 16% more deaths, even after fitness was allowed for, and a pulse above 90 went with three times the deaths of one at 50 or below.
These people were watched. Fit people differ from unfit ones in other ways, and illness lowers fitness before it kills. What makes the link worth acting on is the five men: fitness answers to training.
Two honest notes about them. In those thirty years they had put on a quarter of their weight again and doubled their body fat. And none of them, at fifty, reached the peak he had trained up to at twenty. Training took them back to where they began. It did not make them twenty.
They were measured a third time at sixty. Forty years of living had by then cost them 27% of their capacity. Three weeks in bed at twenty had cost 26%. And the loss between fifty and sixty ran about four times as fast as it had between twenty and fifty, with age and illness both at work. So the fifties are no time to ease off.
Pick something that gets you out of breath, whether brisk walking, swimming, cycling or dancing, and keep at it until talking takes effort. Then count your pulse for a full minute while sitting quietly, write it down, and count it again in a few months.
2. It lowers blood pressure
Tested. Across 93 tests with 5,223 people, endurance training lowered blood pressure by about 3.5 points on the upper figure and 2.5 on the lower. In people whose pressure was high to begin with, the fall was 8.3 and 5.2.
The heart is where this whole subject began. In 1949 Jerry Morris noticed that the drivers of London's double-decker buses had more heart disease than the conductors, who spent their shifts climbing the stairs. Postmen who walked or cycled their rounds had fewer heart attacks than the men behind the counter.
Take the stairs like a conductor. A at home will show you whether yours is coming down.
3. It may protect the brain
This is the claim made most confidently, and it deserves the full picture.
Tested, in favour. Across 36 tests in adults over fifty, exercise improved thinking, whether it was aerobic work, weights or tai chi. And a year of brisk walking grew the brain's memory centre: Dementia Risk: What It's Linked To, and What You Can Change, linked below, has that one.
Tested, against. 1,635 sedentary adults aged 70 to 89 were assigned to two years of walking, strength and flexibility work, or to health classes. On tests of thinking and memory, there was nothing between the two groups.
Linked, and questioned. When 10,308 London civil servants were followed for 27 years, how active they were in midlife made no difference to who developed dementia. What did show was that the people who went on to develop it began moving less up to nine years before the diagnosis. The illness may slow people down long before it has a name, and that would make active people look protected. It is an awkward finding, and the awkward ones are worth keeping.
Linked. Fitness. 191 Swedish women rode an exercise bike to exhaustion in 1968. Over the next 44 years, the fittest had 88% less dementia than those of middling fitness, and when it came, it came about nine and a half years later. It is a small count.
Linked. Dancing. 469 people over 75 were followed for five years. Dancing went with less dementia, along with reading, board games and playing an instrument. Physical activity as a whole did not.
So exercise sharpens thinking in most of the tests that have been run. That it prevents dementia has not been shown.
Move for the benefits that are proven, and count the brain as a likely extra.
4. It reaches your cells
Telomeres are the protective caps at the ends of your chromosomes, and they wear down with age. Key Factors That Speed Up Aging (And How to Slow Them Down) has what shortens them.
Linked. Among 5,823 American adults, the most active had longer telomeres than the sedentary, by an amount equal to about nine years of ageing.
Tested. 124 inactive adults were assigned to six months of running, interval training or weight training, or to no change. All three kinds of training raised fitness. Running and intervals raised the enzyme that rebuilds telomeres two- to three-fold, and the telomeres lengthened. With weights, neither moved.
That is no case against weights, which do things running cannot. And what longer caps are worth in years, this test could not say.
If you only lift, add something that leaves you breathing hard.
5. It spares the joints
If joint pain keeps you from exercise, know that inactivity leads to stiffness and more discomfort. The fear behind it is wear.
Linked. Across 114,829 people, arthritis of the hip or knee was found in 3.5% of recreational runners, 10.2% of people who did not run, and 13.3% of competitive runners. The sofa and the podium both did worse than the park. It is a link, and old injuries may explain part of it.
Where a joint is already sore, exercise has been tested and reduces the pain. The Harsh Truth About Aging: Decline or Longevity?, linked below, has that finding. Swimming, yoga and tai chi all work the body while going easy on the joints.
On a sore day, do less. Do not do nothing.
6. It lifts mood
Tested, with a caution. Across 218 tests with 14,170 people with depression, walking or jogging, yoga and strength training each brought a moderate improvement, and harder exercise did more. The caution: only one of the 218 was rated at low risk of bias, so the true size is uncertain.
Tested. Sleep. Across 66 reports, regular exercise improved the quality of sleep moderately and added a little to its length.
On a low day, walk first and judge the day afterwards.
7. It steadies blood sugar
Exercise is often said to "balance your hormones". Insulin is the one with tests behind it.
Tested. Across 47 tests with 8,538 people with type 2 diabetes, structured exercise lowered the long-term blood sugar marker by 0.67 points. More than 150 minutes a week lowered it by 0.89, and less by 0.36. How to Fix Blood Sugar Spikes Naturally has the food side, and what a ten-minute walk after meals did.
Walk after your largest meal.
8. It goes with fewer cancers
Linked. Among 1.44 million adults, the most active had lower rates of 13 cancers than the least active, among them lung by 26%, colon by 16% and breast by 10%. For ten of the thirteen, the gap held after body weight was taken into account. Smoking muddies the lung figure.
One cancer went clearly the other way. Melanoma was 27% more common in the most active, which fits more hours outdoors. Sunlight is how your skin makes vitamin D, and it is worth having. For the long hours, the first answer is shade and a hat.
Take the walk outside, and take a .
9. Intervals save time
Interval training is short bursts of intense activity, each followed by recovery. It is sold on the "afterburn", the calories you go on burning afterwards. Why Diet and Exercise Are Non-Negotiable for Fat Loss has how small that is.
Tested. Fat. Across 13 tests in overweight adults, intervals and steady training took off the same amount of fat. Intervals did it in about 40% less time.
Tested. Lifespan. 1,567 Norwegians aged 70 to 77 were assigned for five years to intervals twice a week, steady training twice a week, or ordinary advice. Deaths did not differ between the groups by more than chance could explain.
So intervals are a time-efficient way to train: a shortcut, and for once the shortcut is real. They are not required.
If you are short of time, go harder for less of it.
10. It keeps you on your feet
Tested. Independence. The 1,635 adults in the brain section were tested on something else as well: whether they could still walk 400 metres. After about two and a half years, 30.1% of the exercise group had lost that ability, against 35.5% of the health-class group. They were 70 to 89 years old and had been sedentary when they started.
The reverse has been tested too. Healthy older adults who spent ten days in bed lost muscle, leg strength, stair-climbing power, fitness and walking speed. Days in bed are never free, so after an illness, get moving again as soon as you safely can.
Stretching has less to show. It improves how far a joint can move. Whether that changes daily life is "conflicting" across 22 reports. Touching your toes is pleasant. It has yet to be shown to carry your shopping.
Strength and balance have the most to show, and the ageing article linked below has all of it: what eight weeks of lifting did for people of ninety, how long you should be able to stand on one leg, and what loading does for thinning bones.
Whatever else you do, keep one thing in the week that works your legs.
What a lifetime of it looks like
Those are the ten. Here is what they add up to over fifty years.
125 cyclists aged 55 to 79, who had ridden for most of their adult lives, were put through measurements of heart, lungs, muscle, nerves, hormones, bone and thinking. The aim was to see what ageing looks like when inactivity is taken out of the picture.
Fitness tracked age more closely than anything else did. Even so, it varied so much from one rider to the next that no measurement could tell how old any one of them was.
Then their immune systems were compared with those of 75 inactive people of the same age and 55 young adults. The thymus, the gland that turns out new immune cells, normally shrinks with age. The cyclists' output of new cells matched the young adults'.
Not every sign of immune ageing was spared.
The far end of that road has been measured as well. Nine lifelong cross-country skiers of about 81, one of them a former Olympic champion, were tested against six healthy untrained men of the same age. The skiers' fitness was nearly double: the highest recorded in anyone past eighty, and comparable to that of untrained men forty years younger.
People who are still riding at 79 or skiing at 81 may have had a head start that the others lacked. On head starts, Your Genes Aren't Your Destiny: How Much of Your Health Is Up to You has the count in which habits weighed more than three times as much as genes for the length of a life.
They had not stopped ageing. They had stopped adding to it.
Is it too late to start?
315,059 Americans aged 50 to 71 were asked how active they had been in their teens, in their twenties, in their late thirties, and from 40 to 61.
Linked. Those who had been active all the way through had 36% fewer deaths than those who never had. Those who had been inactive for most of their adult lives and took it up between 40 and 61 had 35% fewer.
One point separated a lifetime of exercise from a late start. It rests on people's memory of their own past, and memory is no stopwatch. It does agree with the five men at fifty.
How much is enough
Less than you might fear. The usual minimum is 150 minutes a week of moderate activity, or 75 of vigorous.
Linked. Among 661,137 adults, those who did some activity but less than that minimum had 20% fewer deaths than those who did none. The first minutes buy the most. At one to two times the minimum it was 31%, and at three to five times, 39%. At ten times the minimum there was no sign of harm.
When you do it matters less than whether you do. Among 63,591 British adults over forty, packing the week's activity into one or two sessions went with about 30% fewer deaths, much the same as spreading it out.
And it need not be exercise. The word itself pushed aside an Old English one, plega, which survives as "play", and play counts. 25,241 people who did no exercise at all wore activity trackers. Those whose days held three bursts of hard effort, a minute or two each, had 38 to 40% fewer deaths over the next seven years than those whose days held none. A counts your active minutes for you.
What keeps it going is another matter. Why Motivation Fails — and What Keeps Habits Going After It Does has the 66 reports in which valuing exercise got people started and enjoying it was the better guide to who stayed. So pick the kind you like.
Start light and build slowly. Chest pain, dizziness or a pain that sharpens as you go all mean stop.
Keep moving
Go back to the five men. Three weeks in bed cost them more than thirty years of living, and as much as forty. Six months of effort paid the thirty years back. Bed turned out to be a faster ageing treatment than thirty birthdays. The body remains adaptable at any age.
Small, consistent efforts accumulate. Every step, lift and stretch counts, and the figures above say how little it takes to start counting.
Today, climb one flight of stairs fast enough to feel it. Then keep moving.
Want the strength and balance side? The Harsh Truth About Aging: Decline or Longevity? — grip, walking pace, standing on one leg, and what lifting did for people of ninety.
More worried about your memory than your legs? Dementia Risk: What It's Linked To, and What You Can Change — hearing, blood pressure, movement and sleep, and the year of walking that grew the brain's memory centre.
Do you know someone who blames it all on their age? Send them this, and take the stairs together.
Disclaimer: This article is general information. For advice about your own health, talk to a qualified health professional. If you have a health condition or have been inactive for a long time, start gently and build up.
Affiliate Disclosure: This article contains affiliate links. As an Amazon Associate, All For Life earns from qualifying purchases, at no extra cost to you. We only link to products we would recommend without the commission.
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