The first possible reason is biology. Crossfit emphasizes high intensity workouts, muscle confusion and complex movements with little rest that push the body to its limits. This can be taken too far and lead to a condition known as “rhabdomyolysis,” in which damaged skeletal muscle tissue can be released into the bloodstream and lead to kidney failure. (…)
Those who possess the trait for sickle cell (mainly blacks and Hispanics) are more vulnerable to the condition.