Rhabdo is relatively uncommon, with about 26,000 people in the US developing it every year. Endurance athletes like marathon runners are at higher risk, as are those who do similarly intense activities, including spin classes or CrossFit. Authors of a 2021 study on exertional rhabdo noted that the condition predominantly strikes young, healthy women — and wanting to keep up with others in a fitness class could increase their risk.
“While participants in a class are allowed to tailor the level of intensity, cadence and resistance to their fitness level, it is easy to succumb to peer pressure and overexert during the activity,” they wrote. Those undergoing military training or who work in hot environments while also doing a lot of physical work (firefighters, foundry workers) are also at risk of developing rhabdo.
Dehydration doesn’t cause rhabdo, but it can make it much worse and increases the risk of deadly complications. The key is that occasional endurance activities don’t cause rhabdomyolysis. Your risk increases if you push yourself too hard without resting, according to the Cleveland Clinic. The authors of the 2021 study recommend that if you do spin class, make sure to properly hydrate, avoid any medications or supplements that can increase your risk and gradually build up exercise volume and intensity.
While it’s associated with extreme exercise, most cases are seen in people who’ve had major injuries. Rhabdo can also happen if you don’t move for a long time, cutting off normal blood flow and causing cell death. People over 65 are at increased risk of this.
