K-Fed, 33, was training with a Sydney Aussie rules football team as part of Australian hit Excess Baggage.

At first it was feared the former backing dancer was suffering a heart attack.

Paramedics gave the star oxygen before taking him to hospital, where an ECG indicated he hadn’t in fact suffered cardiac arrest.

Kevin, who was 17st at the start of the series, was kept at Sydney’s Mt Druitt hospital for further tests.

A spokesperson for Channel 9 said: “Kevin was at Doonside with the Giants, completing an AFL-related challenge.

“He did his challenge, which was running and catching the ball, then while his (in-series weight-loss partner) was taking the same challenge, he reported chest pains and a racing heart.

Health scare … Kevin Federline became ill while filming fitness showFrank Thorne

“Obviously on this show we have a lot of paramedics on standby and they treated him for the first signs of a minor cardiac arrest, called an ambulance and had him taken to hospital.”

Kevin split with Britney in 2006, after two years of marriage.

At his biggest … Keven Federline before taking part in the showXclusive Pix Ltd

They have two sons together ? Sean Preston, six, and five-year-old Jayden James.

Having piled on the weight in recent years, Kevin agreed to do the show to kick-start his fitness programme.

Ex … Kevin Federline with former wife Britney SpearsGetty

But the incident is the second time he has needed medical help since filming started nine weeks ago.

During the first show, filmed in the tropical region of The Kimberleys, Western Australia, he collapsed and was treated for heat stress.

Piling on the pounds … Kevin put on weight following his divorce from BritneyBig