Gabe Mirkin, M.D.
An article in Sports Medicine shows that competitive athletes do not improve by increasing their volume of low intensity exercise.
One of the best young distance runners ever recently graduated from high school. The excited coach who learned that this great athlete was going to attend his university told reporters that he would increase the runner's weekly mileage from around 30 miles a week up to a hundred. The runner now has a serious long-term injury.
The high school coach had his protege running such fast intervals in practice that he had to spend several days recovering from these hard workouts and therefore couldn't run many miles. The runner went to college and tried to continue running very fast on his hard days, but he ran too many slower miles on his recovery days, which prevented him from recovering and caused his injury.