Eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee (eeeeeeeeeeeeeeeeeeeeeeeeeee)

There are two kinds of fibers in our muscles, red and white. When an athlete trains for long distance running, he or she builds more red muscle fibers than white muscle fibers in his calf muscles. A sprinter has more white muscles. If you retrain a marathon runner to be a sprinter, most of the muscle fibers will convert to white muscles.