Doctors were unable to resuscitate Ged Clarke, 39, at hospital, following the Reading race on Sunday, but he was pronounced dead later in the afternoon.
Mr Clarke, who was married with two children, ran a Twitter account called @12pmclub, aimed at encouraging people to exercise at lunch time.
His widow, Estelle Clarke, said: “He will be remembered for great belief in doing things to the best of his ability, something his family will continue in believing for him.”