Speed Work vs. Speed Development
It may seem like semantics, but there is a difference between speed development and speed work, which is what runners traditionally think of when envisioning speed. While some coaches and publications use the terms interchangeably, understanding the difference between the two is important in order to appreciate how speed development workouts will benefit you, especially because they are rather unconventional workouts for a distance runner.
Speed development is training your top-end speed, i.e. the absolute fastest pace you can run, which for most runners tops out at less than 100 meters. For example, most Olympic-caliber 100-meter sprinters reach their top speed between 50-60 meters, with the exception of Usain Bolt, who reached his top speed between 60 and 80 meters during his world-record run of 9.58 seconds.
During speed development workouts, you’re not concerned with improving your metabolic energy systems (VO2 max, lactate threshold, aerobic capacity); rather, the focus is increasing the maximum amount of fast-twitch muscle fibers recruited for each stride and improving the speed at which your brain sends signals to your muscles to fire. Instead of improving your specific fitness, you’re focusing exclusively on the neuromuscular system.
On the other hand, traditional speed work, i.e., 400-meter or mile repeats, is about improving VO2max or anaerobic threshold. While you certainly recruit a greater percentage of fast-twitch muscle fibers during a set of 400m repeats compared to a long run, it’s not the purpose of the workout. Traditional speed work is, and should be, focused on improving metabolic systems.
Understanding this difference is important, especially when you’re performing speed development workouts. Traditional speed workouts are quite challenging because you’re running fast with minimal rest. Your lungs are often burning and you’re fighting hard to finish each interval. Again, this is because the goal is to improve your VO2max.
On the contrary, speed development workouts are alactic, which means you do not need oxygen for energy and don’t produce lactic acid when running them. Consequently, speed development workouts won’t have you panting or clutching your knees after each interval because they’re only 50 to 150 meters long. Moreover, you will also have a complete and full recovery between each repeat. In order to recruit maximum fast twitch muscle fibers, you must be fully recovered before each interval.