Murphy spent the last season at Bridgend Ravens in the Welsh Premiership, before making his comeback against a Wigan Warriors XIII side on Sunday.
The Scorpions won 20-16 and Murphy says he is already feeling the damage playing the sport does to the body.
He said: “It was a bit of a shock to the system. I’ve got a few niggles now that I didn’t get all season with Bridgend in the Welsh Premiership. But I definitely enjoyed myself and it was good to get the win.
“Playing for Scorpions is a similar standard to Bridgend but it’s just a lot tougher. You don’t get a break in the game playing Rugby League and the constant tackles to the ground don’t do your back any good either.”
Murphy was part of the Crusaders squad that was disbanded when the club pulled out of Super League. He was the only member of the squad to switch to rugby union.
Now he is back at the Scorpions, Murphy says he can’t wait to get back to playing competitive rugby league in Championship 1.
He said: “The last time I played at The Gnoll was for Bridgend when we had a really good win over Neath a few weeks ago. Hopefully I’ll be experiencing exactly the same against Barrow on Sunday.
“They’re in joint second place at the moment so it’s going to be tough but if we can carry on with how we played against Wigan then we’ll go alright and I’m confident that we can win if we play like we did, especially if the weather conditions are better.
“I plan on staying for the rest of the season as I think we can really do well this year. It’s not too late for us. We’ve only played five games, there are 13 more to go, and if we can play like we did against Wigan for the rest of the season then I’m 100% confident that we can challenge for that top four and get promoted.”