A condition sometimes known as “silent killer” can be triggered by running and other forms of high-intensity exercise.

According to Runners World, rhabdomyolysis, commonly known as “rhabdo”, occurs when muscle cell contents seep into the bloodstream.

Professor William O. Roberts explained: “Almost anyone who exercises to boost performance will release or leak some creatine kinase into the bloodstream, but it becomes concerning when the muscle cell releases its contents, including potassium or myoglobin, which leads to complications.”

Nonetheless, he pointed out: “The chances of developing rhabdomyolysis are low unless you significantly increase your training volume or intensity. This could lead to various overuse injuries.”

The NHS’ Scottish Muscle Network highlights that cases of rhabdo, though uncommon, are most often triggered by exertion, like “prolonged repetitive exercise with eccentric characteristics, resulting in muscle tension, strain, and injury,” or by other causes such as falls, prolonged muscle compression, electric shocks, and severe burns, as noted by the Liverpool Echo.

Symptoms can include muscle cramps or aches that are more intense than anticipated, dark-coloured urine, and experiencing weakness or fatigue.

The Centers for Disease Control and Prevention (CDC) confirms symptoms can arise at any time after a muscle injury. The report advises: “For some individuals, symptoms may take several days to manifest post-injury. If you experience any of these symptoms at any time, do not disregard them. Seek immediate medical attention.”

“Earlier diagnosis means an earlier start to treatment and a greater chance of recovery without permanent health effects.”