Updated

Hillary Clinton and Donald Trump are as different as night and day, but there is one thing they have in common, and there’s no point mincing words or being politically correct about it:

They’re both old.

Trump will be 70 years and 220 days old on January 20, Inauguration Day. If he’s the one on the Capitol steps who’s solemnly swearing to faithfully execute the office of the president of the United States, he will be the oldest person ever to do so. The moment he says “So help me God,” he’ll push Ronald Reagan, who was 16 days shy of 70 when he became president, into second place on the golden oldies list.

And Clinton? She’ll be a mere 69 years and 86 days old on Jan. 20. If she’s the one who takes the oath, she’ll move into a close second place behind Reagan, leapfrogging Dwight D. Eisenhower, who was seven years her junior.

The voters should feel comfortable that the next president is doing everything he or she can to be fit for the job going in — and that he or she will still be fit for it four or eight years from now, going out. They have the right to demand that the candidates reveal every detail of their health records and their current fitness regimens.

The candidates’ age is not a trifling matter. Human beings, unlike fine wine, do not get better as they get older. Stress is a major factor in many illnesses, and there are very few jobs, if there are any at all, that are as stressful and demanding as being the leader of the Free World. If the adage is true that the typical president ages two years for every one in office, then 70 is far from the ideal age to begin a presidency.

Having spent the last 20 years in health care and in understanding health care data, I can say with some authority that a 69- or 70-year-old president has no reasonable expectation of avoiding a health crisis over the next four or eight years. Just consider:

• The chance of having a stroke approximately doubles for each decade of life after 55.

• The average age of a first heart attack is 64.7 years old for men and 72.2 years old for women.

• 63.9 percent of men and 70.8 percent of women between 65 and 74 have high blood pressure.

• More than one in four Americans over 65 has diabetes.

• One in nine Americans 65 and older have Alzheimer’s disease. Among people 71 and older, 16 percent of women have Alzheimer’s, compared with 11 percent of men.

So we have every reason to wonder what the future holds for Clinton and Trump. Certainly, they can afford the very best health care. But just as certainly, neither has been as forthcoming as they should be about their health, their physical condition and their fitness regimen.

Trump’s personal physician, Dr. Harold N. Bornstein, has told us that he recently examined him and that he “has had no significant medical problems,” that his blood pressure is 110/65 and that his lab tests were “astonishingly excellent.” He concluded by writing, “If elected, Mr. Trump, I can state unequivocally, will be the healthiest individual ever elected to the presidency.”

Clinton’s physician, Dr. Lisa Bardack, went into considerably more detail in a health care statement she wrote in July, 2015. “Mrs. Clinton is a healthy 67-year-old female whose current medical conditions include hypothyroidism and seasonal pollen allergies,” she wrote. “Her past medical history is notable for a deep vein thrombosis in 1998 and in 2009, an elbow fracture in 2009 and a concussion in 2012…. As a result of the concussion, Mrs. Clinton also experienced double vision for a period of time and benefited from wearing glasses with a Fresnel Prism. Her concussion symptoms, including the double vision, resolved within two months and she discontinued the use of the prism.”

She concluded by writing, “She is in excellent physical condition and fit to serve as President of the United States.”

But there’s so much more that we don’t know. Our last two presidents, George W. Bush and Barack Obama, publicly maintained very healthy lifestyles. Bush was an avid mountain biker, Obama played basketball and both were visibly in excellent shape.

That’s not the case for Trump and Clinton. Despite his doctor’s glowing evaluation, Trump has a known penchant for junk food and appears overweight, which can be accompanied by hypertension, diabetes and high cholesterol, which can be precursors of heart attack or stroke. As for Clinton, it’s not unreasonable to question whether she has fully recovered from her health crisis. Until we have more detail, we can’t know whether there was an underlying condition that precipitated her fall and concussion.

If either candidate does, in fact, have a health issue, it will be much harder to control amid the stress of the presidency, so it’s hardly unreasonable to demand information about their lifestyles, their eating and drinking habits and whether they are controlling any risk factors. We know that neither of them smokes, that Trump doesn’t drink and that Clinton drinks casually, but we know absolutely nothing about their exercise routines — or even if they have one.

Whoever wins in November will be in his or her mid-70s when the next election comes around and will be pushing 80 at the end of a conceivable second term. The last thing we need is a president who feels comfortable preaching about how to fix the U.S. health care system but can’t take care of his or her own health. Clinton and Trump should demonstrate that this matters to them.

The voters should feel comfortable that the next president is doing everything he or she can to be fit for the job going in — and that he or she will still be fit for it four or eight years from now, going out. They have the right to demand that the candidates reveal every detail of their health records and their current fitness regimens.

With that in mind, I submit a put-up-or-shut-up cardiovascular challenge to Donald Trump and Hillary Clinton:

Are you getting in your 10,000 steps a day? Or, at the very least, are you getting 150 minutes of exercise each week? If your answer is yes, are you willing to prove it?

I challenge both of you to wear a Fitbit or some other fitness tracking device for the next eight weeks and let the American people monitor your physical activity.

You want to be president? Prove to us that you’re physically able to handle the job.