Rhabdomyolysis is damage to the muscles from overuse and heatstroke. Repetitive exercises such as sit-ups, push-ups, squats, and weight lifting can lead to rhabdomyolysis.
With sudden, intense exercise, the muscles can start to break down. The contents of the muscle cell are released into the blood and travel to the kidneys. The kidneys try to filter these cells and get plugged up. Serious problems can occur without treatment.