An inquest has been opened and adjourned into the death of Nottingham Forest owner Nigel Doughty.
Mr Doughty was found collapsed in the gym of his home in Skillington, Grantham, Lincolnshire, by family members last Saturday afternoon.
An inquest at Lincoln Cathedral Centre today heard that post- mortem tests carried out on the 54-year-old had so far proved inconclusive.
Mr Doughty was described as fit and well by his family when he told them he was going to work out in the gym in a separate annex at his home at around midday on Saturday.
Just over an hour later, at 1.15pm, he was found in the gym "collapsed and lifeless".
Emergency services were called and paramedics attended the property.
They attempted to resuscitate Mr Doughty, but he was confirmed dead at the scene at 1.59pm.
Police attended and confirmed there was no suspicious circumstances surrounding his death.
They believed Mr Doughty, who was born in Park Village, north west London, had died of natural causes.
A post-mortem examination was carried out by a pathologist at Queen's Medical Centre in Nottingham on Monday.
The pathologist was unable to give a definitive cause of death and further histological and toxicological tests have been carried out, the coroner was told.
His wife, Lucy, formally identified his body in Grantham on Tuesday.
Today, Coroner Colin Allerston adjourned the inquest to a date to be fixed pending the results of the further tests.
Tributes have poured in following the death of the father-of-four.
Labour leader Ed Miliband led the tributes, calling him "kind and generous".
Mr Doughty, who saved Nottingham Forest from administration when he bought the club for £11 million in 1999, led a Small Business Taskforce which made recommendations to Labour late last year that will be considered as part of the party's policy-making process.
Mr Miliband spoke of his shock after hearing the news and wrote on social networking site Twitter: "I am shocked and saddened to hear of Nigel Doughty's death. I was with him only a week ago and he was full of life, enthusiasm and vigour.
"He was a kind, generous man with a deep desire to make the world a better place. My heart goes out to his wife, Lucy, and his children.
"We mourn his death deeply and will sorely miss him."
Nottingham Forest confirmed the news of Mr Doughty's death in a statement, which read: "It is with enormous sadness that Nottingham Forest announce the death of the club's owner, Nigel Doughty.
"Mr Doughty, who was 54, was found dead earlier today in his gym at his home in Skillington, Lincolnshire.
"The club would like to appeal for the privacy of Mr Doughty's family to be observed at this sad time.
"The club will be making no further comment."
During his 10 years at the City Ground, the club won promotion back to the Championship in 2008, three years after their relegation.
Under manager Billy Davies, the Reds reached the play-offs in each of the last two seasons.
Forward Garath McCleary praised Mr Doughty for the work he did, saying: "He has done so much for Forest, which was not always best appreciated. My thoughts are with his family."