If Trump and Biden raced on foot from White House to Washington Monument, who would win? ?

Trump because Biden doesn't even know where the Washington Monument is.

Trump wins. He has Ivanka contact her good ol' Dem buddies in the theater to get an athlete made up to impersonate him. The Secret Service spirits him away from the finish line, saying "get him right to Walter Reed to be checked out." Trump waits in a secure area of Walter Reed to switch/claim win/get right to MI for rally.

Biden would have to be able to find it.

Biden is in a lot better shape than Trump.  Biden follows in a long tradition of Presidents, and candidates, exercising.  I mean, he's no superman, but he's relatively fit for his age.  For example, there's footage out there of Biden biking (unfortunately without a helmet).  Trump really doesn't exercise at all.  Reportedly he believes that humans are born with a finite amount of energy and that exercising depletes it uselessly.  During the 2016 campaign he told a reporter that the only exercise he got was waving his arms around at rallies.  Trump does play a lot of golf (a LOT of golf.  He's golfed, on average, ever four days of his administration IIRC, despite promising to almost never golf if he were elected).  But Trump eliminates most of the exercise value of golf by riding in a golf cart all the time.  He even rides his golf cart onto the greens, something which is a big no-no in the golf world but which he can get away with because he mostly golfs at courses he owns.  Trump is, objectively, obese.  By his own admission he eats mostly junk food.  There's also a telling incident from a G7 meeting a couple years ago.  The various world leaders had decided to walk from one venue to another.  It wasn't very far, a few hundred yards IIRC.  But Trump took a golf cart instead.  The belief is that Trump simply didn't have the stamina to walk that far and wanted to avoid embarrassment

Trump is too over weighted to race anywhere. Biden is old, maybe, but I'm betting he would at least make it out the door.

Neither.  Trump couldn't walk it and Biden couldn't find it.                  

Probably Biden. Why? Because even though he's older, Biden looks in better shape than Trump. Trump is fat. More than likely from overdoing it on Mcdonald's.

Trump would be a clear win.  Biden is slow.  Slow in the head and slow in the body.  He would also get lost part way and not know which way to continue, and he would forget why he is racing or walking.  He'd be a basket case part way, wondering where he is and why.  Trump is quick witted and his body keeps up just fine.  He would keep walking and wouldn't stop until he was at the WM.  In fact, I could see just a couple of minutes after the start - Trump stopping briefly to instruct Biden which direction he is supposed to continue walking, when Biden suddenly stops confused.  Then Trump continues ahead and ends up way ahead of the confused Biden, who probably never makes it to the WM.

Trump would go the speed of light because of all the sugar he´s drinking

Biden would forget that there was a race and would never come to it