Now, the self-confessed stubborn Central Otago lad is representing New Zealand as a seated thrower at the Oceania Athletic Championships.
Kayla Hodge hears about his remarkable progress in the past four years and his athletics dream that started just seven months ago.
"Miracle Mac."
That is what doctors called Mac Denniston when he started walking and talking again after a traumatic brain injury from a mountainbike crash in 2020.
But it was a crash doctors initially did not think the Alexandra teenager would survive.
Naturally a sporty child, Denniston was out mountainbiking with his friends when he caught too much speed when attempting a jump and fell off his bike.
"I missed the landing of the jump, and I landed flat, and then smacked my head," Denniston said.
The now 18-year-old suffered a traumatic brain injury and was flown to Dunedin Hospital, and then Starship Hospital in Auckland, where he stayed for just over three weeks in the paediatric intensive care unit.
He then spent three weeks in Starship’s neurology word and was later moved to the Wilson Centre, a child rehabilitation centre on the North Shore, for two months.
After learning how to "do everything again", Denniston returned home after three months, minus three pieces of his skull bone which were removed during surgery on the night of his crash in Dunedin.
Three weeks after returning to Alexandra, Denniston headed to Dunedin, where he had a craniectomy to put the skull bones back in, and the doctors — who also worked on Denniston the night of his accident — were blown away by his progress.
"The doctors said I wasn’t supposed to live," Denniston said.
"It’s a good motivational thing so I can prove them wrong."
Prove them wrong he has. Denniston is among a strong Otago group selected to represent New Zealand at the Oceania Athletics Championships, in Fiji, next week.
But he has his mother, Maree, to thank for his start in athletics.
Denniston has always been involved in sport — "I gave everything a go before my accident" — but things looked a little different as he worked through his fatigue, co-ordination and balance.
In October last year, Denniston’s mother "dragged" him to an athletics event in Dunedin to give the sport another go.
"Turns out I was pretty good, so I kept at it."
Athletics New Zealand para athletes lead coach Raylene Bates took Denniston under her wing and he entered the national secondary schools competition last December.
It was there he went through proper classification testing and was classed as a F34 seated thrower, and competed seated for the first time.
That turned out to a pretty easy transition for Denniston, who won one gold and two silver medals, in discus, shot put and javelin, at the event.
"It’s been pretty good.
Bates, who lives in Dunedin and coaches fellow Dunedin para thrower Holly Robinson, helped Denniston from afar, and also visited Central Otago regularly to coach him.
Denniston’s mother also lent a hand when Bates was not there in person.
Watching other Dunedin para athletes, like Robinson, getting to their pinnacle events under Bates was exciting as he could see where he could get in the future.
Since starting throwing seven months ago, Denniston has won countless medals and is the national under-18 record holder in the F34 discus (19.99m), shot put (7.21m), and javelin (15.86m).
Now he gets the chance to test himself internationally at the Oceania event.
While Denniston is "a bit nervous" about the competition in Fiji, he is also excited and looking forward to pushing himself further — and hopefully snag another medal.
"Can’t let the country down — got to bring home the gold or a medal," Denniston said.
Para athletics had a core group of good athletes Denniston — who draws inspiration from Tom Walsh — had met around the country, and looks forward to meeting up with again.
But his biggest support had been his family; father, Chris, brother Jake, 20, and, of course, his mother.
"Yeah, it’s pretty nice having Mum there because I wouldn’t do it otherwise."
After the Oceanias, Denniston will get back to training and in the gym, where he has become a regular.
He plans to head to Canberra in January to get internationally classified, before hopefully competing at nationals in Dunedin, the Australian championships and other Otago events in the mix.
The Los Angles Paralympics in 2028 have been earmarked as his long-term goal, but Denniston is under no illusion about the work ahead of him.
"There’s a long way to go."
Otago athletes for
Oceania Championships
Senior men: Cameron Moffitt, John Gerber, Hayato Yoneto
Senior women: Becky Aitkenhead
Para men: Mac Denniston, Josh Chisholm
Masters: Liz Mitchell, Jim Blair, Alison Newall, Noni Callander, Barbara Patrick, Dalise Sanderson, Rob Homan