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The health and vigor of the candidates are issues in the presidential election. But what does 70 really look like for ordinary Americans who aren't running for president? And what health markers are good at other decades?

The health and vigor of Democratic nominee Hillary Clinton and GOP candidate Donald Trump continue to matter in the presidential election, in large part, because of their ages.

If he wins, Trump, at 70, would be the oldest person ever elected president. Clinton, who is 68, would be the second-oldest, after Ronald Reagan, who was 69 at his inauguration.

But despite Clinton’s recent bout with pneumonia and Trump’s sniffles at their first debate, the candidates appear to be in good health when compared to their age-group peers.

Clinton watches her steps when she descends stairs, as do many women her age, with good reason: One-fourth of people over the age of 65 fall every year.

Trump weighs 236 pounds — at 6 feet 3 inches that makes him overweight, not obese — which is not bad for a person who gets no regular aerobic exercise and eats a lot of fast food.

Both have demonstrated the ability to withstand the rigors of constant traveling, hand-shaking and 14- to 15-hour days on the campaign trail, which would be daunting for many younger people.

So what does 70 really look like for the average American who's not running for president? And what’s normal if you’re 30, 40, 50, 60 or 80?

Our health is the sum of factors specific to us, such as lifestyle and genetics, but there are markers at each decade that it helps to know.

THIRTIES

Older people may long to be 30 again, but in fact, our physical decline began at 20, at least when it comes to our brains. Gray matter, the stuff that processes memory, emotions, sight and planning, among other things, begins to decline in our 20s, while our physical bodies are still approaching their peak, which generally occurs in our late 20s or early 30s.

The 30s, however, bring a sort of plateau. Although most of our skeleton is built by the time we turn 20, we continue to build bone until around 30. Around age 35, our bone mass starts to decline. Our muscles and hearing also begin to slightly decline, but this may not be noticeable for another decade or so.

We may notice, however, that we're less flexible and the dreaded decline in metabolism begins. Without changing any eating or exercise habits, the average man burns 12 fewer calories each day once he hits 30, Joan Raymond reported for Today.

Women's fertility begins to decline, and men may begin to lose their hair. By 35, two-thirds of men will have hair loss, according to the American Hair Loss Association.

Our blood pressure becomes more important. There is evidence that elevated readings in our 30s may set the stage for heart disease later.

The ideal blood pressure reading is 120/80 or less, according to the Heart Association, and this standard remains consistent throughout adulthood. (Children and adolescents have lower levels, based on their size and age, and seniors may have higher with no ill effect.)

FORTIES

Stand up straight; this is the decade in which you may begin to shrink.

Beginning in their 40s, people can lose one-fourth to one-half inch of height per decade, as our bones thin, the vertebrae in our backs collapse and the arches in our feet flatten. The shrinkage is most pronounced in women.

Baltimore researchers studying aging found that women lose 2 inches between ages 30 and 70, and by age 80, they are 3 inches shorter than their peak height.

Meanwhile, our muscle mass began to decline, a side effect of aging called sarcopenia when it becomes pronounced. If we're sedentary, the mitochondria that power our muscle cells decline and fat moves in, "marbling your muscle until it looks more like rib eye than lean top sirloin," Ginny Graves wrote for Prevention magazine. The changes make it not only harder to pick up heavy objects, but to lose weight.

Even more distressingly, a British study showed a 3.7 percent decline in cognitive ability among 7,000 people over the course of their 40s. (The speed at which we process information peaks around 18.) By our 40s, we may notice slight declines in our capacity to remember and reason.

On the other hand, our emotional IQ — the ability to recognize emotions in other people — is climbing, and will peak in our 40s or 50s, according to researchers at the Massachusetts Institute of Technology.

FIFTIES

In our 50s, declines in brain function may become noticeable as we become more forgetful as neurons shrink and have fewer connections. Women experiencing menopause (the average onset is 51, according to the Mayo Clinic) may be particularly susceptible to problems with memory and cognition because of fluctuating hormone levels.

Our eyes become more sensitive to glare and we may begin having problems with night vision, and need reading glasses to see things that are close, according to the AARP.

Our metabolism, which began to slow in our 30s, and can decline as much as 1 percent a year, is making it more difficult to maintain our ideal weight, which — as unfair as this may seem — is the same ideal weight we tried to reach in our 20s. (It's based on build and height, not age.)

Our ideal heart rates also should remain consistent throughout adulthood: 60 to 100 beats per minute, although runners and other endurance athletes typically have rates between 40 and 60. (Clinton's is 70, according to her doctor; Trump's has not been released.)

But despite their enviable heart rates, athletes slow down, too. Research has shown that runners slow about 7 percent per decade in their 40s, 50s and 60s.

And it's time to invoke the 50-50-50 rule: By age 50, 50 percent of people will have 50 percent gray hair, Dr. Anthony Oro, professor of dermatology at Stanford University, said in Good Housekeeping magazine.

SIXTIES

In our 60s, we may worry about memory loss but we're still not at heightened risk for Alzheimer's disease; fewer than 5 percent of people with Alzheimer's are younger than 65.

And there's some evidence that neurogenesis — the creation of new brain cells — can continue into our 60s, AARP magazine has reported. Intense exercise may help maintain brainpower, some studies have shown. (But Clinton and Trump may not benefit from this: His exercise is limited to golf, and hers is yoga and walking.)

If Clinton sometimes sounds hoarse, it may not just be from the demands of campaigning. By the mid-60s, tissues in the larynx begin to weaken, which can cause a woman's voice to sound lower and hoarse, and a man's to become higher and thin, according to the American Academy of Otolaryngology – Head and Neck Surgery.

Meanwhile, in our 60s, one-third of us have hearing loss, and the pupils in our eyes have shrunk to half the size they were in our 20s, according to the National Institutes of Health.

And more than a quarter of American women have developed a thyroid condition, like hyperthyroidism or hypothyroidism. Both skew our metabolism: hyperthyroidism, by speeding it up; hypothyroidism by slowing it down.

Clinton has hypothyroidism, which she treats with pills made from dried pig glands, according to her doctor, while most women with hypothyroidism take Synthroid, a synthetic that's the No. 1 prescription drug in the U.S.

But both Clinton and Trump, who takes Crestor to control his cholesterol, are in step with their age-group peers in this regard. By our mid-60s, three-quarters of us have a chronic health condition and take some sort of prescription drug regularly. People between the ages of 65 and 69 years old fill about 14 prescriptions per year, according to the American Association of Consultant Pharmacists.

We also are more likely to need vitamins and supplements, in part, because our sense of taste and our appetites are beginning to decline and so some of us don't eat enough. (Clinton takes a B12 supplement; 10 to 15 percent of people over the age of 60 are deficient in it, the National Institutes of Health says.)

At our physical peak, we have 9,000 to 10,000 taste buds, but these shrink and die over time, and it comes harder to differentiate between different kinds of tastes, such as sweet, bitter or salty.

SEVENTIES

Our vision and hearing erode in our 70s. Sixty-eight percent of people in this decade have suffered hearing loss, and 70 percent will have cataracts after age 75. (But more than three-quarters of us are still driving.)

Our sense of smell is vanishing, too, making eating less pleasurable since enjoyment of food is linked to our ability to smell it. "By the time most of us are 80, it’s as if we don’t even have a sense of smell, at least when it comes to standard smell and taste tests," Michael Y. Park wrote for Bon Appetit.

On the bright side, our vocabulary peaks in our early 70s, if not a few years before, and after 75, we'll no longer have to have routine colonoscopies.

And if we make it another 10 years (two-thirds of men and three-quarters of women will), our risk of cancer declines.

About half of us ache from arthritis, but many of us are able to keep skiing. The 70 Plus Ski Club reports more than 3,000 members, including at least one centenarian still on the slopes.

EIGHTIES

By our 80s, more than 85 percent of us have a chronic condition that is managed by prescription drugs, which is why we fill about 18 prescriptions per year in this decade.

Although we may struggle with memory, our language skills remain intact and we can continue to improve our vocabulary. But one-third of Americans over age 85 will develop Alzheimer's disease, according to the Alzheimer's Association.

Nearly a third of us will experience incontinence. Thirty-three percent of us find it difficult to walk, and a quarter of us struggle to get out of a chair, according to Consumer Reports.

That doesn't mean we get to stop exercising, however. Even people in their 90s can benefit from strength and endurance training, according to research published in the UK's Daily Mail. Nike's newest star, Sister Madonna Buder, is a record-setting triathlete at age 86.

The best part about aging, however, may be that even as our physical challenges increase, paradoxically, our happiness does, too. Research has shown that happiness follows a U-shaped curve: We are happiest when we're youngest and oldest — even if we never make it to the White House.

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