The soreness develops about six to 10 hours after exercise and peaks between 24 to 48 hours after. When the damage is more extensive, the protein myoglobin is released from the damaged fibers into the blood. Often accompanying rhabdomyolysis is an elevation of potassium in the blood. Potassium is released into the blood from damaged muscle cells. If there is a problem with kidney function, the kidney cannot excrete it causing blood potassium to reach dangerous levels.
Excessive potassium interferes with heart function and leads to heart block and cardiac arrest.
Incidences of rhabdomyolysis Cases of rhabdomyolysis are not new. One of the first associations between acute renal failure and darkly colored urine was noted in London during World War II bombings that left patients suffering from crush injuries to muscles. In the late 1960s and 1970s, several cases appeared during military training. For example, eight young men who were in a training program for Naval aviation officer candidates developed grossly discolored urine and severe muscle pain. They participated in novel strenuous exercise within 38 hours of when the dark urine was noted.