Miami Dolphins offensive tackle Jonathan Martin has said that Michael Sam showed "guts" to publicly announce that he is gay.

Sam is expected to become the first openly gay player in NFL history when he enters this year's Draft, prompting discussions over how he will be treated in the locker room environment.

Martin, who was forced out of the Dolphins' camp last season after claiming that he was being bullied and harassed by teammate Richie Incognito, believes that Sam deserves credit for deciding to come out.

"Hats off to you Michael Sam, that takes some guts #respect," Martin wrote on Twitter.

A number of other NFL players have also backed Sam following his revelation, and even US president Barack Obama has had his say on the matter.