Republican Trump, 78, has repeatedly boasted about his own vigor since starting a second term, while mocking his 82-year-old Democratic predecessor Joe Biden as decrepit and mentally unfit for office.

But now it is Trump, who will also be 82 at the end of his presidency, under the stethoscope.

"I felt I was in very good shape. Good heart," Trump told reporters aboard Air Force One, adding that "I took a cognitive test. I don't know what to tell you other than I got every answer right."

The billionaire arrived at the Walter Reed military hospital in the Washington suburbs earlier in the day -- after a delay due to talks on tariffs.

"I have never felt better, but nevertheless, these things must be done!" Trump said on Truth Social earlier this week.

Trump has repeatedly been accused of a lack of openness about his health despite huge interest in the wellbeing of America's commander-in-chief.

Stating that he underwent both cardio and cognitive tests, Trump said a report would be released by his doctor on Sunday.

The White House said previously that presidential physician Sean Barbabella would give a readout of the physical and that "of course" it would provide the full report.

"I can confirm the president is in very good shape, as you see on a near daily basis," Press Secretary Karoline Leavitt told reporters earlier.

She said Trump would not be having a general anesthetic -- which is normally used for procedures such as colonoscopies -- but added there is "a lot that goes into it to make sure the president is accomplishing all of his goals."

Trump is a prolific golfer who abstains from alcohol and cigarettes.

But he is also known to indulge in fast food and famously enjoys well-done steaks, although he appears noticeably thinner than during his first term.

- 'Healthiest individual' -

Trump's personal and White House doctors have at times made outlandish claims about his health.

In 2015, during Trump's first presidential run, his doctor Harold Bornstein released a letter saying the tycoon "unequivocally, will be the healthiest individual ever elected to the presidency."

Bornstein later told CNN that Trump himself "dictated that whole letter. I didn't write that letter."

The White House doctor in his first term, Ronny Jackson, said in 2018 that with a healthier diet Trump could "live to be 200 years old."

Jackson's report then suggested Trump should aim to lose 10 to 15 pounds but said he was generally in "excellent health," adding that there were no signs of "any cognitive issues."

A year later, an exam found the 6-foot-3 (1.9 meter) Trump weighed 243 pounds (110 kilograms), up seven pounds since shortly before taking office, making him technically obese. It said he was taking medication to treat high cholesterol.

In 2020, Trump told Fox News he aced a test for cognitive impairment by repeating the phrase "person, woman, man, camera, TV."

Age became a major issue in the 2024 election when Trump and Biden faced off as the oldest major party candidates in history.

Biden was forced to drop out of the race after a stumbling performance in a TV debate against Trump in June that put concerns over his cognitive health to the top of the agenda.

Since returning to office Trump has repeatedly compared his own vigor to Biden's, while the White House has accused the previous administration of covering up what it says was the Democrat's decline.