President Joe Biden remains "a healthy, vigorous, 80-year-old male who is fit to successfully execute duties of the presidency," his physician wrote in a memo released hours after the president underwent a routine annual physical at Walter Reed National Military Medical Center on Thursday morning.

Kevin O'Connor — who has been Biden's primary care doctor since 2009 — wrote that the most notable update from Biden's last physical in November 2021 was his COVID-19 infection over the summer, but said the president has not experienced any lingering symptoms that could be characterized as "long COVID."

As part of the physical, Biden underwent routine skin cancer surveillance. O'Connor said one "small lesion" on the president's chest was excised on Thursday and sent for traditional biopsy and that the results are pending. O'Connor noted that Biden spent a "good deal of time" in the sun when he was young and that he had several non-melanoma skin cancers removed before assuming the presidency.

Biden, who at age 80 is the first octogenarian president in American history, has faced repeated questions about his physical and mental fitness — inquiries that have intensified as he prepares for an expected reelection bid. He would be 82 at the start of a second term, and 86 at the end of eight years in the White House.

Biden has previously said that his health will be a key consideration in his ultimate decision over to run for reelection, but he has told his advisers he feels healthy and energized despite his age.

After his physical, Biden was seen jogging back toward the White House from Marine One.

O'Connor said Biden underwent an "extremely detailed neurologic exam" that did not find any signs of neurological disorders such as stroke, multiple sclerosis or Parkinson's disease.

Biden has several minor medical conditions he is treated for: non-valvular atrial fibrillation, a common type of irregular heartbeat; hyperlipidemia, or high cholesterol; gastroesophageal reflux; seasonal allergies; spinal arthritis; and mild sensory peripheral neuropathy of the feet, which causes a "subtle difference" in heat and cold sensation in the feet. O'Connor said all the conditions were stable, and that the president takes three common prescription medications and two common over-the-counter medications to treat them.

Biden's age and health is sure to become a top campaign issue regardless of who he runs against. Republicans have already begun to make Biden's age a key focal point for attacks.

Nikki Haley, the former U.S. Ambassador to the United Nations who recently announced a bid for the Republican presidential nomination, used her announcement speech to call for "mandatory mental competency test" for all politicians above the age of 75.

"America is not past our prime," she said Wednesday. "It's just that our politicians are past theirs."

Arkansas Gov. Sarah Huckabee Sanders (R) used her response to Biden's State of the Union address last week to showcase the fact that Biden is "the oldest president in American history." The nation's youngest governor at 40 years old, Sanders called Biden "unfit to serve as commander in chief."

Both Haley and Sanders explicitly called for a "new generation" of leaders to emerge and take the place of current politicians.

Former president Donald Trump, who is 76, has also sought to make Biden's age and issue — giving him the nickname "Sleepy Joe" and questioning his vitality and mental acuity. Trump, who is overweight and has acknowledged poor eating habits, has faced attacks from Biden's allies over his own physical and mental fitness.

Biden does not use any tobacco products or drink alcohol, O'Connor wrote, and continues to work out at least five days per week. The president's blood work was all normal and, at 6 feet and 178 pounds, he is at a healthy weight.

In a six-page summary of Biden's physical released by the White House in November 2021, O'Connor noted that the president's gait had become "stiffer and less fluid" over time. He pointed out a case of spinal arthritis and the lingering effects of a foot fracture Biden suffered shortly after the 2020 election. The report, which described Biden as a "healthy, vigorous 78-year-old male," noted that he has a history of atrial fibrillation, was taking blood thinners, and was on medication for cholesterol, seasonal allergies and reflux that had caused persistent coughing and throat-clearing.

In Thursday's report, O'Connor said none of those conditions appeared to have worsened. Of Biden's stiffened gait, O'Connor said the medical team he assembled concluded that "much of his stiffness is in fact a result of degenerative ("wear and tear") osteoarthritic changes (or spondylosis) of his spine."

"The President's gait remains stiff, but has not worsened since last year," O'Connor wrote. "Examination this year was unchanged, with the exception of possibly tighter hamstrings and calves."

While medical advances in recent years have significantly reduced the vulnerabilities of older people, aging experts have noted that older individuals typically are more susceptible to more severe health risks and have a harder time recovering from falls, accidents and unexpected illnesses.

Biden has said it is fair for people to ask about his age, but White House aides have dismissed concerns over the president's expected plan to seek a second term in his 80s. White House press secretary Karine Jean-Pierre was asked Thursday whether Biden felt up to the job even though he will be at 86 at the end of a second term. "Yes," she responded simply.

But polls show Biden's age is an issue among voters: A February 2022 Washington Post-ABC News poll found that 54 percent of Americans said Biden does not have the mental sharpness to serve effectively as president, up from 43 percent in May 2020. While 83 percent of Democrats said Biden was mentally sharp, that dropped to 34 percent among independents and 7 percent among Republicans.

In a 2020 paper reviewing Biden's medical and family history, Stuart Jay Olshansky, a professor of public health at the University of Illinois at Chicago, described Biden as a "super ager," a term for an elderly person whose physical and mental capabilities are more indicative of someone several years younger. Olshansky has pointed out that Biden's parents both lived past 85 and that he had fewer medical complications and took fewer medications than most people his age.

Despite the rigors of the presidency, Biden has not suffered serious injury or experienced major sicknesses since taking office. He endured a bout with COVID-19 last year, working from home and experiencing only mild symptoms, the White House said at the time. He was prescribed Paxlovid and experience a rebound infection —meaning he tested negative after a few days and then again tested positive for the virus — but otherwise recovered uneventfully from his bout with COVID. The president has been vaccinated and received two coronavirus boosters, along with the updated bivalent COVID vaccine.

In June, Biden toppled off his bike near his Delaware vacation home after his shoe got caught in the toe cage as he was coming to a stop. White House aides pointed out that Biden got up and kept biking, and noted that it is not uncommon for cyclists using toe cages to fall down.

Occasionally, the president has grown prickly over questions about his mental acuity and his fitness for office.

When asked about his age, Biden often asks people to judge him by his actions, rather than his date of birth.

"They've been saying this about my age since I began to run," he told CNN's Jake Tapper last year. "You can come work out with me in the morning."

Speaking to PBS News Hour last week, Biden described himself as "great respecter of fate," and promised to be "completely, thoroughly honest" about the status of his health.

"I think people have to just watch me," he said, adding that his impromptu response to heckling Republicans during his State of the Union address led several people to say "my God, age is not an issue anymore."