She was determined to prove them wrong - and after many years of physical therapy to heal the damage to her neck and hip, she now regularly runs ultramarathons.
The road to recovery was slow as she gradually built her strength, but she stayed motivated by setting herself bigger and bigger challenges.
“Getting over the 10km hump was particularly difficult," she said. "I changed my running stance and began wearing minimalist shoes, and both these things have made a huge difference. They don’t suit everyone, but have enabled me to run long distances again.”
Over the past three years, Chantelle has run six ultramarathons and has many more on her wishlist, including the Mountainman in Switzerland in August and the Manaslu Mountain Trail race in the Himalayas in November.
She is a development athlete for kora and recently won a coveted place on the Gore-Tex Experience Tour Alpine Quattrathlon, a four day mountain biking, trail running, road biking and road running adventure through Germany, Austria, Switzerland and Italy.
Her love of the active life - and tolerance for cold weather - are the result of her upbringing in a small town in Northern Ontario, Canada.
“Although we had a lot of snow and winter lasted more than half the year, there weren't a lot of organized sports facilities,” she said.
“My dad taught me from an early age that there's no such thing as bad weather, only bad clothing. He started taking me on long ski trails from the time I was six months old. So my philosophy has always been to just gear up and get out there.”
Much of her childhood was spent outdoors, enjoying an exhilarating array of activities: camping, hiking, running, nordic skiing, snowshoeing, sailing, canoeing and mountain biking.
“It was all more about exploring and enjoying the beauty of wild places rather than thinking of it as sport," she said. "In fact the only organized sport I played was ice hockey - I was the only girl on the team.”
A few years ago she moved to a small town in the Swiss Alps, where she works as international director of operations for an educational travel company.
Most mornings she rises early to run the trails near her home, covering 120-150 km per week over five days. On weekends she runs for four to eight hour stretches, or heads into the mountains for 100k bike rides with friends.
She takes a break from running on Mondays and Fridays, instead heading for the gym for CrossFit sessions.
“I’ve learned to space out my training properly to avoid injury,” she explained. “I listen to my body and if I need a rest day, I’ll take it - or I might break up a longer run into two shorter runs.”
Though the hectic schedule and early starts can be tough, Chantelle believes it’s good preparation for the demands of an ultramarathon.
“I learn to run tired and in the dark, just me and my head torch on a trail,” she said.
It also helps her deal with the demands of her day job.
“My job is sometimes stressful and I spend lots of time interacting with people, so I really enjoy the solitude of a run before or after work.
"Lots of people head straight from to the office without taking a break, but I think it’s very useful to take some time out for yourself. Being able to get away from it all makes me a better human being and a better worker too.”
Last year she suffered a setback during the North Face Ultra-Trail du Mont-Blanc TDS race, the longest and toughest ultramarathon she’d tackled, at 120 km and 7250 m of elevation gain.
“I didn't feel as well prepared or as rested as I should have at the start line, but the first 10 hours seemed a breeze,” she recalled.
"I was two hours ahead of my predicted time which meant my support crew nearly missed me at the first checkpoint. The night hours were beautiful and serene, a gorgeous clear star-filled night. I still felt really strong 16 hours in, when heading down a steep descent, someone from behind slipped and knocked me down.
"My foot got trapped under a rock in the fall which saved me from flying over the edge, but did give me a broken toe. I made it to the finish, but lost a lot of time in that last limp to the end. But I would do it again in a heartbeat.”
Happily, she is now back to full strength and relishing the season ahead. “Trail running is such a wonderful way to see a new place and connect with nature,” she said.
“It’s very different from a marathon where you might be surrounded by thousands of people.
“On the trail, it’s less about competing against others and more about competing against yourself. People help each other out and every trail is an adventure.”