She proved it by finishing fifth in the mountain bike world championship 24-hour race in Canberra last week.
It is just 18 months since a serious accident in Dunedin threatened to end her international career.
Greene (28) completed 19 laps (380km) in the 24 hours and finished fifth.
Dunedin pathologist Hannah Thorne (33) completed 18 laps (360km) and finished eighth.
Mark Williams, of Queenstown, completed 21 laps (420km) and finished seventh in the men's race.
Greene had qualified for the world 24-hour event in Alberta in July last year by winning the New Zealand title in March 2009.
But she cracked her pelvis in five places and fractured her hip when hit by a car while she was out cycling a month later.
It was the strong desire to get back on her mountain bike that enabled Greene to endure the pain and struggle back to full fitness.
Greene was off her bike for four months and resumed full training in April, a year after the accident.
"I wanted to get back early but I couldn't be stupid," Greene said.
"It took time to become pain-free and I had to ease into it gradually."
Creene said the hardest part of the race in Canberra was at the start.
"It took me three hours and two laps to get into a rhythm, but as soon as that happened I was away."
Greene moved her way up through the 30-strong women's field, and clocked her fastest time on the penultimate lap.
During the early part of the race, Greene boosted her energy by consuming gels and sports drinks, but during the night she stopped for two minutes each lap to consume hot milo, hot custard, mashed potatoes and pumpkin soup.
She rides her mountain bike to work every day and does gym sessions to improve her core strength, using a Swiss ball and doing sit-ups.
Greene is coached by Jon Richardson, who concentrated on getting his charge's muscles strong enough again to cope with a 24-hour race.
Thorne started mountain biking when she moved to New Zealand from England in 2003.
She has competed in several 12-hour events but this was her first 24-hour race.
"My goal was just to finish. "It gave me as sense of achievement. I need a goal to aim at."
She said she struggled with mental lows during the race.
"I had to concentrate on my goal and play focus games with my mind and make sure I had enough to eat and drink."
Thorne lives in Dunedin with her partner, Mark Sharman, who was the mechanic for the Otago riders.
She travels to Christchurch each week to work.
