A runner who died at the finishing line of the London Marathon had suffered breathing problems in the weeks before the race.
Robert Berry, 42, described how breathing during a training run was "a big struggle" in a post on his blog just seven days before Sunday's event.
He wrote: " I have now used my inhaler 3 times in the last week whereas I might use it 3 times in year."
He said his goal for the marathon was to run it in under three hours and 30 minutes.
Mr Berry was running to raise money for the National Osteoporosis Society and more than £30,000 has been donated via his JustGiving page since he died.
On April 1, just under a fortnight before the race, he wrote: " What a nightmare this morning was. Yesterday I did a gentle 5 miles as my breathing still not too good and knees a little achy.
"Today on the other hand my eyes were itching, nose running and breathing a big struggle."
He wrote that a woman at the charity he was running for had suggested his condition was " not hayfever but due to pollution and the dust from the Sahara".
He added: " Hope so as I don't want to be running like this during the Marathon."
Mr Berry collapsed and died on Sunday despite receiving medical help.
He wrote on his fundraising page that he was supporting the National Osteoporosis Society in tribute to his "inspirational" mother, who was diagnosed with the brittle bone condition at the age of 52.
The amount raised at 7pm last night stood at almost £3,000 b ut has now reached more than 10 times that amount through more than 2,700 donations.
In a message on his personal website, Mr Berry, from Reading, Berkshire, wrote: "This page is dedicated to my mum, who despite being diagnosed with osteoporosis at the relatively early age of 52 years, has been an inspiration through the continued positive outlook she has displayed ever since, despite some quite clear discomfort."
The National Osteoporosis Society said in a statement: "It is with great sadness that the National Osteoporosis Society has learnt of the death of Robert Berry, one of our runners in this weekend's London Marathon.
"The charity would like to express its heartfelt condolences to Mr Berry's family and friends."
Claire Severgnini, chief executive of the charity, said: "Our immediate concerns are for Mr Berry's family. Our thoughts and deepest sympathies are with them at this tragic time."
Tributes and donations began pouring in to his fundraising page after news of his death broke.
Janet Lewis wrote: " Your mum has a good son and will no doubt be so proud of you."
Eric Sheley posted: " My condolences to Rob's family and friends. Such a tragic end to a wonderful challenge."
Katie Weeks said: " So sad, hope your family take comfort from the amount you raise for this fantastic charity."
A statement from race organiser Virgin Money said: "It is with regret that we can now confirm that Mr Robert Berry, aged 42, collapsed at the finish of the London Marathon. He was immediately taken to one of our medical facilities where he was treated by four consultants, including one in emergency medicine. He was transferred to St Mary's Hospital, where he was pronounced dead.
"The organisers of the Virgin Money London Marathon would like to continue to express their sincere condolences to the family and friends of Mr Berry and our thoughts and deepest sympathies are with them all at this difficult time."
The last death in the event was in 2012 when hairdresser Claire Squires, 30, from North Kilworth, Leicestershire, collapsed a mile from the finishing line and died later from cardiac failure.
Mr Berry, who worked in IT services, ran the Reading half-marathon last month.
His website includes an interview with his mother Anne, where she describes having limited mobility as a result of osteoporosis.
"Despite the regular pain and discomfort, with the two hip operations on bones the density of someone typically the age of 100, I am able to walk short distances and with my husband's support it is manageable," says Mrs Berry.
According to his training regime, Mr Berry had been preparing for the marathon since December.