But what may surprise people is that inside that bundle of energy is a heart valve, the result of picking up rheumatic fever in his teenage years.
Like his former team-mate, Canterbury centre Robbie Fruean, who also had the condition, Popoali'i was laid low and eventually had to have an operation to install a heart valve in 2006.
The former Wellington flier still "gets a jab" every month to keep his blood flow normal, and may have to get a new valve in another five years.
But despite that off-field drama, Popoali'i says he does not let the valve have any influence on his rugby career.
"It hasn't affected me at all, really. I have it checked out every year and it may have to be replaced. But it hasn't held me back at all," he said.
Popoali'i (21) has been a real jack-in-the-box on the left wing for Otago, as he tries to make an impression for his new side.
He made the move south from Wellington this season in the hope of getting more game time, and making a Super 15 side.
"It was a bit crowded up there [Wellington] for outside backs so I thought I'd have a crack down here. A whole lot of us came down and are really enjoying it."
Popoali'i made an instant impression in the Otago jersey, showing out on the blue and gold colours at the national sevens tournament at Queenstown at the start of the year, good enough to win selection in the national side.
That got him under the tutelage of national coach Gordon Tietjens, and into the legendary fitness sessions.
Popoali'i said he really enjoyed the sevens circuit under Tietjens, getting to see the world, and play some footy.
"And he got me a lot fitter.You really get around the park when you play sevens. That has really helped me with my game now."
Popoali'i, who is of Samoan descent, was born in Auckland. He moved to Wellington when he was 12, but now is enjoying his new southern home.
He will start on the left wing today and is looking to get into the match against a dangerous Northland side.
"Last time, against Hawkes Bay, it was a bit of a forward-oriented match so we hope to get a bit more ball. This week the boys have talked about attitude and sticking to the game plan."
Otago will need to get the ball into the hands of Popoali'i more if it wants to get back on track after the disappointing loss to Hawkes Bay last week.
It is a critical week for the side, with three games in eight days and it must start off with a victory today.
The return of Tony Brown at first five-eighth will help the cause, while much is expected of Jayden Spence in his starting debut.
Otago does have the major advantage of not having played this week, while Northland is still licking its wounds after losing narrowly to Taranaki on Wednesday.
Captain Jared Payne is a big loss, out with a hip injury, and fellow back Aaron Bancroft was concussed against Taranaki and is unavailable.
Big lock Mark Burman is also out.
Otago v Northland
• Whangarei, today, 4.35pm
• Referee: Ben Skeen (Auckland)
• TAB odds: Otago $1.75, Northland $2.
Otago: Glenn Dickson, Joe Hill, Ben Atiga, Jayden Spence, Buxton Popoali'i, Tony Brown, Sean Romans, Gareth Evans, Eben Joubert (captain), Paul Grant, Tom Donnelly, Daniel Ramsay, Kees Meeuws, Jason Macdonald, Halani Aulika.
Reserves: Liam Coltman, James McGougan, Rob Verbakel, TJ Ioane, Johnny Legg, Hayden Parker, Sam Giddens, Scott Manson.
Northland: Lachie Munro, Simon Munro, Rene Ranger, Derek Carpenter, Bryce Heem, Ash Moeke, Wayne Ngaluafe, Cam Goodhue, Dan Pryor, Joel McKenty (captain), Marty Veale, Bryce Williams, Scott Vessey, Ross Wright, Justin Davies.
Reserves: Tevita Vaipulu, Aterea Davis, Dan Faleafa, Cam Eyre, Rhyan Caine, Jack McPhee, Warren Dunn, Jamie Corsi.
