The health of U.S. presidential candidates has become a central campaign issue.

Eight weeks before the presidential election, the "H" word has been pushed to the forefront, "H" as in "health." Better late than never. At last, the epitome of the power grab isn't just for those with youthful vitality. There are now two sprightly seniors who want to move into the White House in January. Hillary Clinton would be 69 years old on her first day in office – just as advanced in years as Ronald Reagan at the start of his term. At 70, Donald Trump would be the oldest person in U.S. history to take on the title of commander in chief. The question at hand: Are both in suitable condition to cope with the grueling strain of office for at least four years?

Clinton is currently at risk of losing it all. Her collapse at the 9/11 memorial event was a breaking point. Instead of an early and open acknowledgement that she had pneumonia and needed to cut back for a few days, her campaign concealed her illness. The same procedure followed in her e-mail scandal. Even if one accepts that she didn't want to show weakness at a historic moment, the secrecy only demonstrated two things: a lack of poise and a penchant for the gratuitous. Simple honesty would have made her seem (more) human.

The question now is how quickly can Clinton get back on her feet. This will determine whether or not Trump can profit from his rival's malaise. But Trump, who wished Clinton a "Get Well" on Monday that was as mendacious as it was clever, is having his "fit as a fiddle" assertions put to the test as well. His personal physician's certification of health has been challenged by reputable medical professionals as quackery. Even if it has impressed people on TV shows in the past, Trump will have to learn to throw more than fastballs to play everyday political hardball.