Theresa May continues to be embattled, facings calls to resign as Prime Minister and losing her authority in the Commons.
Corbyn and the Labour leadership are said to be anticipating an early General Election – and the MP for Islington North is preparing to be PM.
Pro-Corbyn website Skwawkbox said the Labour leader was "preparing for the demands of office with regular 15km runs" and quoted a party insider as saying "a lot of his staff get worn out just thinking about it".
Labour sources confirmed the party leader goes on "multiple" runs of 5km to 7km each week, as well as cycling, going to the gym and working on his allotment.
JEZ WE CAN: Jeremy Corbyn has been hitting the gyms and going on runs (Pic: PA)
“He cycles, he runs, he goes to the gym.”
They added the 69-year-old had always made a point of keeping fit and had taken steps to ensure his exercise regime has been maintained since becoming Labour leader in 2015.
May and Corbyn went head-to-head during PMQs in the Commons earlier today, the Labour leader urging the PM to “listen and change course, or go".
Corbyn labelled the Government "chaotic and incompetent" and pushed Mrs May to reveal her "plan B" ahead of the indicative votes process on different Brexit options.
It comes as May is due to meet the 1922 Commitee tonight amid rumours she will be asked to name her exit date.
PREPARING FOR POWER: Jeremy Corbyn is reportedly expecting an early General Election (Pic: PA)
Corbyn said: "This country is on hold while the Government is in complete paralysis.
"The vital issues facing our country – from the devastation of public services, to homelessness, to knife crime – have been neglected.
"The Prime Minister is failing to deliver Brexit because she can't build a consensus, is unable to compromise and unable to reunite the country.
"Instead she is stoking further divisions, she's unable to resolve the central issues facing Britain today and she is frankly unable to govern.
"The Prime Minister faces a very clear choice, the one endorsed by the country and many of her own pRead More – Source