It's well known in endurance sports circles that high-intensity interval training is a great way to increase your speed over long distances as opposed to runnin

It's well known in endurance sports circles that high-intensity interval training is a great way to increase your speed over long distances as opposed to running very long distances for your training. There's some disagreement about whether or not long-distance training is actually better though because that's what runners from Kenya and Ethiopia do and it seems to be working well for them.