Ruled out for the the year with a torn hamstring in late July, Jennings' breakthrough season on the left wing appeared over as he sat second on the NRL leading try-scorers' list.

Desperate to find a way back, the 22-year-old sought out use of oxygen chambers and cryotherapy after seeing Sydney Roosters winger Daniel Tupou attend a clinic on Instagram.

Approved by Souths medical staff, he visited the clinic every few days in his spare time for the oxygen and targeted ice treatment.

And it worked, halving his recovery time and returning for the Rabbitohs in round 25.

"I've never done it before, I just picked it up on Instagram so I thought I'd go down and have a look," Jennings told AAP.

"I had about 10 (sessions). Every couple of days, I did heaps of sessions because I just wanted to get back. And it helped. The oxygen chamber especially.

"The cryotherapy was like icing but it's like a gun they have, and they point it towards where the injury is.

"I was doing everything possible and it helped, I feel like I healed pretty quick and got back earlier than expected."

Each combined session of oxygen and cryotherapy costs more than $100.

But Jennings said he couldn't put a price on the opportunity to play in his first finals series.

"I felt like I wanted to do it myself because I thought it would benefit me," he said.

"I obviously told them (Souths) about it and they encouraged me to do it, they said why not, it's in your spare time."

Jennings will be rewarded on Saturday night when he runs out in the biggest game of his career against St George Illawarra.

Off-contract at the end of this season, Jennings hopes to stay at Souths after having scored 19 tries in 19 games this year.

"We've got one of the best attacking shapes and everyone is in good form and feeding off each other," Jennings said.

"I'm lucky enough to be on the end of it and getting the reward."

Australian Associated Press