As it turned out, the runners who did about half of their training at low intensity lowered their 10K time from an average of 39:24 to 38:00. That’s an improvement of 1:24, or 3.5 percent. Those who did roughly 73 percent of their training at low intensity lowered their 10K time from an average of 39:18 to 37:19. That’s an improvement of 1:59, or 5.0 percent.
