Run Faster with High Intensity Interval Training
"If you want to run fast, the saying goes, you've got to run fast. To stoke speed, most runners do traditional speedwork: aiming for near race pace over distances of 400 meters or more, with recovery periods equal to the length of the repeat (or slightly less). Or you can get fast even faster with supershort, superfast efforts, sometimes referred to as high intensityinterval training (HIIT)."
This is the beginning paragragh from this Runner's World article on HIIT training and increasing speed and endurance. I like the article and it is a quick read with tips, examples, and reasons why quick speed bursts will help your training. The author does a great job giving the information. The only thing I am not sold on, is the extremely cautious attitude when trying it out. My feeling is, if you run a couple times a week and you do a 5-6 minute jog warm up, there shouldn't be a problem. I wouldn't choose to start running today, and do so by going out and sprinting a lot though. However, I do think the average couple times a week jogger would benefit greatly from this.