All runners benefit from a certain amount of speedwork. Speedwork can substantially improve overall health and fitness, and that applies equally to those of us who do trail running and ultramarathons. In fact, it is sometimes claimed that ultrarunners develop slow legs because we spend too large a fraction of our mileage doing long, slow distances.

But what kind of speedwork? The terminology can be confusing and often doesn't describe either how the workout is done or what the workout is supposed to accomplish. So here's a breakdown of the main types of speed work for ALL runners: