It's time to make a choice. You can either increase the average intensity, or speed, of your training or you can decrease it. Which option is more likely to help you improve as a runner?
If you chose the first option, don't feel bad. The benefits of high-intensity training are constantly being touted in the media and by fitness experts. But the correct choice is option two. If you're like most runners, the counterintuitive decision to reduce the average intensity of your training will enable you to go faster on race day.
Proof comes from a new study published in the International Journal of Sports Physiology and Performance. Unlike most studies that claim to address the question of how runners should train, this one actually has real-world relevance. Instead of using a handful of nonathlete college students as subjects, it used 30 experienced recreational runners. And instead of using a physiological metric such as VO2 max to measure the effects of different training methods, it used performance in a 10K time trial.
The study was led by Jonathan Esteve-Lanao, a running coach and exercise physiologist at the University of Madrid, who is one of the few researchers anywhere in the world who conducts experiments with this type of design. The purpose of the study was to compare the effects of two different training intensity distributions on running performance. Half of the subjects were instructed to do 50 percent of their training at low intensity, another 25 percent at moderate intensity, and the remaining 25 percent at high intensity. A second group of runners was asked to do 80 percent of their training at low intensity, no training at moderate intensity, and the remaining 20 percent at high intensity. The two groups were instructed to do the same total amount of running: between 30 and 40 miles per week.
All of the runners completed a 10K time trial before the training period began. After 10 weeks, they ran a second time trial to determine which group had improved more. On average, members of the "polarized" training group (so named because of the lack of moderate-intensity running) improved their 10K times by 41 seconds more than the members of the other groups.