A fit and healthy young man died following a "catastrophic and unsurvivable" collapse as he ran the Brighton Marathon, an inquest has heard today.

Sam Harper Brighouse, 23, fell ill around 16 miles into the race as he competed on April 14 this year.

A post-mortem has ruled out his asthma as a cause, and has instead found he had a bowel condition which led to his collapse. 

A pathologist told his inquest today that nearly one in two long distance runners develop problems with their gut.

The biology graduate had embarked on the 26-mile running challenge to raise money for the Arms Around The Child charity which supports Aids orphans.

Although he had asthma, he was considered fit and his respiratory problems had not contributed to his sudden collapse, an inquest at Brighton County Court heard.

Instead, Mr Harper Brighouse, of Forrest Hill, south-east London, died after suffering from ischemic bowel disease, which can cause up to 75% of blood flow to be removed from the bowel.

Dr Mark Taylor, consultant pathologist at Brighton's Royal Sussex County Hospital, said the condition is initially reversible but can progress, leading to fatal circumstances.

Dr Taylor told the hearing: "We know that up to half of people who run marathons develop symptoms relating to their gastro-intestines.

"They can be minor stomach cramps, diahorrea, but on the other end of the scale, ischemic bowel can be exhibited in endurance exercise."

He added: "When it gets to that critical stage, depending on how much of the bowel has died, depends on whether the person can survive.

"Unfortunately in Sam, it was catastrophic and unsurvivable."

It was initially thought that Mr Harper Brighouse had suffered a heart attack, and attempts were made at CPR as he laid in the road.

But Mr Harper Brighouse went into cardiac arrest and his death from ischemic bowel, described by Brighton and Hove coroner Veronica Hamilton-Deeley as "extraordinarily rare and unusual", was confirmed at 2.30pm.

Dr Taylor said: "I think when someone collapses in a marathon, the most common thing to think is that they have had a heart attack.

"The initial reaction would have been to do CPR and that was started rapidly. If he had been taken to hospital immediately, might it have made a difference? I don't think so.

"I believe all his bowel was dead at that stage and even if (medical staff) thought of ischemic bowel, it wouldn't have been any help at all at that stage."

Mr Harper Brighouse probably did not notice he had ischemic bowel as its "non-specific" symptoms, such as pain and discomfort, may have led him to believe they were linked to his running.

Gastro-intestinal problems suffered by people associated with endurance sport were being increasingly examined in studies, Dr Taylor added.

Attempting to reach Mr Harper Brighouse amid the crowds of marathon runners and spectators was difficult, a senior South East Coast Ambulance Service (Secamb) staff member said.

The marathon had its own medical team but Andrew Parker, Secamb's medicines management lead and paramedic practitioner, said clearer identification would have helped to distinguish who was who on site.

He also told the inquest of a "communication confusion", with marshals unable to tell him where Mr Harper Brighouse was as he ran for about 500 yards through the large crowds carrying equipment.

"When I asked a couple of the marshals 'Where's the incident?', they said 'I don't know'."

As Mr Parker went on to the race track, he could see people waving at him, alerting him to Mr Harper Brighouse's position.

Mr Parker said: "In reality, it only took me minutes, as I did run as fast as I could, but obviously minutes in any cardiac incident is crucial."

He said the problems could have been helped by having more markers along the race route, rather than ones that marked every mile.

Ms Hamilton-Deeley suggested a possible solution: equipping runners with a gas canister-activated buoy which would rise above the crowds in an emergency. She said: "This could mean that you are looking up rather through a sea of people."

Despite the difficulties, Mr Parker praised the level of care Mr Harper Brighouse received from the medical team, saying it was to a "high standard".

And he did not think the access problems he encountered ultimately affected the patient. Speaking about Mr Harper Brighouse, he said: "He had no heartbeat, no pulse and no breathing.

"From the small amount of history at the event, it was a sudden collapse. I don't think he would have known anything about it."

The inquest is due to last until Friday.