Speed training methods can be understood by comparing what each method asks the body to do, and why that specific demand builds a particular aspect of speed.
Definition: Speed is the capacity to move the body, or a part of it, and cover a given distance in the least possible time, it combines how quickly a person reacts, how fast the limbs cycle, and how quickly the body accelerates.
Acceleration Runs, built around short, maximal effort:
The athlete starts completely still and explodes into a 20-30 metre sprint at full (100%) intensity.
Because the effort is so intense, a long recovery of 2-5 minutes is built in before the next repetition so the nervous system, which fatigues faster than the muscles during maximal sprints, can fully reset.
This trains the body's ability to generate maximum acceleration quickly from a dead stop, the "start-up" component of speed.
Pace Races, built around sustained, sub-maximal effort:
Instead of an all-out short burst, the athlete covers a distance roughly 10-20% longer than their actual race distance, at a controlled 80-90% intensity.
An 800m runner practising over 1000m, for example, is deliberately extending their comfort zone so that the true 800m pace feels more sustainable on race day.
This trains the ability to hold a high speed for longer, i.e. speed endurance, rather than just the initial burst.
So, while both methods raise running speed, Acceleration Runs sharpen the explosive start and Pace Races extend how long that speed can be held, together they cover both halves of what "speed" means in competition.
