Interval running for distance running ?

Fortunately, modern science has brought training back into focus, emphasizing the importance of utilizing a wide variety of workouts, including the fast stuff. For instance, a study conducted at The University of Western Ontario, showed that just six weeks of sprint interval training elicited similar jumps in VO2 max and running performance compared to regular endurance training. Most importantly, the interval training took a fraction of the time than the more traditional training program, offering comparable results. When you get more bang for your buck, why wouldn't you ramp up the intensity occasionally?

Other recent research out of the University of Copenhagen showed similar results via a seven-week training program. After instructing a group of runners to reduce their mileage by 50 percent and add in interval training sessions three times each week, participants improved their 5K times by nearly a minute. This was all despite the fact that they were actually running less.

If that's not convincing enough, there's even a study that shows runners actually tend to enjoy intervals more than steady-state running. Perhaps too much LSD leads to mental staleness in the same way too much too much high-intensity training did. To be sure, balance is key. '