Lyster, 36, had previously appeared as a contestant on Channel 9's A Farmer Wants A Wife in 2009.
Living in the small town of Mundijong, the father fell from his horse during a polocrosse tournament in Capel, WA, on Saturday morning and was flown to Perth in critical condition.
Chris Corbett from the Serpentine Foothills Polocrosse Club said Mr Lyster is an experienced horseman and the accident was shocking.
'Ralph hit the deck very hard and his horse came over him so it was a head impact straight into the ground,' he said.
'It was quite scary at the time because he was completely unresponsive and took a little bit of time to start breathing.'
He said Lyster's helmet was badly damaged, showing how hard the impact was.
Lyster was placed in an induced coma but has since been brought out and is now in a stable condition in hospital.