A man is in a critical condition after competing in the Mud Sweat and Tears challenge in Canterbury today.
A St Johns ambulance spokesman said emergency services were called to Motukarara at 11.51am today where a man in his 60s suffered a serious medical incident.
He was flown via a Westpac rescue helicopter to Christchurch Hospital.
Fire service also attended the scene.
The event is based at the Motukarara race course where participants are required to complete obstacles including mud slides, forest runs, hay bale pyramid, a crawl under a sea of barbed wire, horse jumps, water jumps and mud runs, the website stated.