Any lingering questions surrounding the health of UFC light heavyweight champ Jon Jones were answered today when “Bones” went on Twitter to reveal he’d officially started full-time training for his September 21 tilt with top contender Alexander Gustafsson. Jones suffered a gruesome dislocated toe in an April outing against Chael Sonnen and had been hobbled ever since, at least until now.

“Day 1 baby!!! Kickboxing with coach Mike Winkeljohn went great, grappling with coach Greg Jackson later,” wrote the ecstatic Jones.

Jones also posted a picture of himself in “skinny-fat” mode, showing off his doughier-than-normal physique before beginning the grind towards UFC 165.

The 18-1 Jones, who celebrates a birthday later this week, is seeking a record-breaking sixth straight successful defense of his belt. Fifteen of his wins have featured some form of finish including those over Mauricio Rua, Quinton Jackson, Vitor Belfort, and Lyoto Machida.

Gustafsson is seen as a significant threat to Jones despite the title-holder’s past success. “The Mauler” holds an overall record of 15-1 with nine knockouts and can come close to matching Jones in terms of physical tools like height/reach.