A relatively unknown condition that can cause a person’s muscles to break down and leak toxins into the blood is on the rise.

The condition, highlighted earlier this year in the American Journal of Medicine, is called Rhabdomyolysis, more commonly known as rhabdo, and can cause kidney failure.

“It’s a medical phenomenon that occurs when you push your body beyond its breaking point, the muscles then break down and their cellular contents then leak inside the blood stream,” exercise physiologist Jon Cannon told CTV Your Morning.

It develops after muscle trauma, including if a person works out too hard.

Doctors have noticed an increase in reports of the condition due to the rising popularity of extreme workouts.

However, the report published in April said rhabdo is rare and not a reason to avoid high-intensity workouts.

While a little damage to muscles is beneficial for them to grow and adapt to stress, when the muscle fibres are destroyed they release a protein called myoglobin which can be harmful to the kidneys.

Cannon tells people to look out for common symptoms such as muscle pains and weakness when not moving, swelling, and dark-coloured urine.

Vomiting, irregular heartbeat and confusion are also symptoms of the condition.

Cannon told CTV’s Your Morning that these symptoms usually occur after doing a new strenuous activity, most commonly spin class.

According to a case study published in The American Journal of Medicine in April, there have been more than 40 cases of people developing rhabdo after spin class, with the majority after taking their first class.

Cannon explains this is likely due to the extreme nature of the class, combined with repetitive movements and pressure to keep up with the instructor and not to quit.

People who develop rhabdo often need to be admitted to the hospital to receive treatment.

The condition is treated with IV fluids to prevent kidney failure and it can take one to two weeks in hospital for someone to recover, says Cannon.

Some tips for avoiding rhabdo, according to Cannon, are:

  • When lifting weights increase repetitions, sets, then weight
  • For cardio activity, increase the time slowly
  • Don’t push yourself beyond your limit every workout
  • When trying a new activity work up to your maximum weight over time

“Rhabdo doesn’t take any prisoners. It takes body builders, tri-athletes,” said Cannon. “Just don’t push beyond your mental breaking point, especially if you’re a beginner.”