Injured former NASCAR champion Tony Stewart used social media Friday to give fans an update on his health about 30 minutes before his team was scheduled to announce Brian Vickers as his replacement for the Daytona 500.

Stewart used the live-streaming app Periscope to answer fan questions as he walked on a treadmill. He broke a vertebra last week when he crashed an all-terrain vehicle in the sand dunes of Southern California and wound up in a hospital. This is his final year in NASCAR and he is expected to race later this season once he's healed.

Stewart said he supports Vickers driving the No. 14 Chevrolet at Daytona. He also said he decided to show himself up and walking because he didn't want people to think he's being lazy.