With the music blasting, the lights dropped low and her feet locked into the pedals of the exercise bike, Kyra Fancey’s adrenaline started pumping.
It was her first spin class — and her last.
“[The instructor] was just giving us more instructions on making the resistance on the bike harder and to go faster and to move up and down and you’re dancing on the bike,” recalled Fancey, who took the class in December 2023.
She said her muscles started to ache midway thorough, but not in the usual way.
“I felt my like thighs really giving away,” Fancey said. It felt like the muscle in her right leg had “ripped.”
Fancey said she felt pressured to push through because she couldn’t detach her feet from the pedals and she didn’t feel like she could ask for help.
“I didn’t know anything bad could come out of it other than some sore muscles,” said Fancey, who was 24 at the time and frequently went to the gym for cardio and strength training.
But days after the workout, she said the pain in her legs became “excruciating” and her urine turned dark brown.
“I felt like I was dying,” said Fancey, who lives in St. John’s.
At the hospital, she was admitted with a life-threatening condition called exercise-induced or exertional rhabdomyolysis, rhabdo for short.
The illness can happen after an intense workout and is when muscle tissue breaks down, leaking enzymes and proteins into the bloodstream. These substances can lead to an imbalance of electrolytes, which can cause dehydration and heart issues. And in high amounts, the proteins can damage the kidneys.
In March, Newfoundland and Labrador Health Services raised concern over a surge in cases over the past few months among young women in part of the province.
More young women in St. John’s are getting muscle damage from intense exercise
“We’ve just seen quite a lot of activity regarding fairly strenuous exertional exercise causing this and people posting what they’re doing,” said Dr. Richard Barter, clinical chief of emergency medicine for Newfoundland and Labrador Health Services in St. John’s.
Between October 2025 and April, emergency rooms in the province’s eastern area, which includes St. John’s, logged 20 cases of rhabdo — mostly women between the ages of 19 and 30. It’s a “worrisome” trend, Barter said, noting that typically the area would expect to see between eight to 14 cases in a given year.
Exercise-induced rhabdo cases aren’t tracked across Canada, though Barter previously said the normal rate of rhabdo is about 4.5 to eight cases per 100,000 people each year. Research in the United States found that, between 2000 and 2019, the condition sent more than 40,000 Americans to hospital emergency rooms.
That study found the most common activities sparking rhabdo were exercising without equipment, weightlifting and football. The majority of cases were in men between the ages of 16 and 35. It also found a 10-fold increase in ER visits from the first decade to the second.
While the study didn’t look into what’s behind the increase, its researchers speculated that changing exercise trends likely contributed, with high-intensity interval training (or HIIT) classes becoming more popular in 2014 and weight training in 2015.
Rhabdo usually happens after “unaccustomed exercise,” according to Dr. Mark Tarnopolsky, division head of neuromuscular and neurometabolic disorders at McMaster University in Hamilton.
“It’s usually if you do something that you’re just not used to and you really push it too hard,” said Tarnopolsky, adding it can also happen when people return to working out after taking some time off.
Whenever you do a new exercise or start working out again after a break, it’s common for your muscles to feel tight or stiff in the days after.
“If it’s really extreme and you can barely bend your legs, your arms are stuck and you can’t straighten them out and, or you start to have dark-coloured urine … that means that you’re damaging your muscles so badly that the proteins are spilling out in the urine,” he said.
When that happens, Tarnopolsky said people should go to the emergency room, so they can get started on IV fluids to keep things from getting worse.
In rare cases, when protein levels in the bloodstream get too high, they can damage the kidneys and the person could require dialysis, Tarnopolsky said. He said that while it’s possible that it could result in long-term kidney damage, it’s unlikely.
The condition can also lead to compartment syndrome, which is when the muscles become so swollen that they need to be cut open to relieve the pressure. Again, Tarnopolsky said, this is a rare consequence.
Other possible issues include seizures, blood clotting or heart arrhythmias triggered by an imbalance of electrolytes.
Experts question whether social media is playing a role, with people challenging themselves or their friends to take part in strenuous activities, or fitness influencers encouraging people to work out in ways they maybe haven’t before.
“Avoid the influencers on the internet. That’s where you run into problems,” said Tarnopolsky.
But there hasn’t been much research into this, so it’s hard to know for sure.
Heat also plays a role, said Tarnopolsky. Higher temperatures increase muscle breakdown and can lead to dehydration, all of which impact the kidneys.
Since one of the biggest risks is overexerting oneself, Tarnopolsky said that no matter how fit you are, you can experience rhabdo. Research has found that it often affects both military personnel and athletes.
But that doesn’t mean people can do intense workouts provided they follow a certain diet and exercise rules, said Tarnopolsky, who works with a small number of people who actually have a genetic disorder that makes them more prone to getting rhabdo.
Melissa Denny, owner of Peak Performance Training & Nutrition in Brockville, Ont., said she’s on high alert for potential cases of rhabdo.
“There’s a lot more social media pressure on getting back to that … supermodel look,” she said. “So people are really training super, super hard and catching up on these really intense classes, like spin, HIIT.”
But, Denny said, people forget that proper diet, hydration and recovery are a big part of the equation.
Denny said a top priority during her classes is keeping people safe. Her trainers do that by keeping class sizes small so instructors can check in on everyone, offering water and a cool towel, and reminding them to take breaks and hydrate.
Dr. Tarnopolsky, meanwhile, said the main ways to prevent rhabdo are staying hydrated, listening to your body, and slowing building up if you start a new form of exercise. He said if you’ve already had rhabdo, you’re also unlikely to get it again.
How far is too far to push your workout?
Even though she has fully recovered, Fancey still can’t shake what happened to her at spin class more than two years ago.
“I still struggle with panic attacks, sometimes with regard to when I try to go to a gym,” she said, adding she’s created a home gym, which makes her feel more comfortable.
She also sticks to “gentle movements” that are helping her “create a healthy relationship with exercise.”
