Characteristic #4: Raw Speed

The Cutting-Edge Runner: How to Use the Latest Science and Technology to Run Longer, Stronger, and Faster
by Matt Fitzgerald

(Page 3 of 5)

The importance of raw speed to distance running performance is often underestimated. In fact, studies have shown that maximum sprint speed is a strong predictor of performance in distance running events. In other words, the fastest runners over long distances are typically also faster than other distance runners in short sprints. Clearly then, certain physiological characteristics that underlie raw speed are not incompatible with the fatigue resistance characteristics that are also critically important to distance runners.

Science Says Studies have shown that the fastest runners over long distances (5-K and up) also tend to be the fastest in very short sprints (20-300m)

But the very best sprinters tend to have rather poor fatigue resistance, so it's also clear that some other speed characteristics are incompatible with endurance.

Research has demonstrated that sprint speed comes not so much from the ability to move one's legs quickly but from the ability to push off the ground with tremendous force: that is, to produce great power. This ability, in turn, derives mainly from certain properties of muscle fibers.

The most celebrated physiological difference between sprinters and distance runners is in muscle fiber types. The muscles of top sprinters are known to contain a very high number of type II, or fast-twitch, muscle fibers. These have greater contraction speed (or "contractility"), elasticity, and anaerobic energy capacity than type I, or slow-twitch, muscle fibers, which have greater aerobic energy capacity and fatigue resistance.

Recent findings have given us a more nuanced understanding of muscle fibers and their relation to sprint and distance running performance. We now know that the characteristics of the two basic muscle fiber types can vary by degrees. For example, there are type I muscle fibers that are able to contract as quickly as some type II muscle fibers; it is likely that talented distance runners have a lot of these "fast slow-twitch fibers." Also, at least five subtypes of type II fibers are now recognized. For example, type IIa fibers are the "classic" fast-twitch fibers: very powerful but not very fatigue-resistant. Type IIb fibers are another borderline fiber type that possesses both fast-twitch and slow-twitch characteristics, and top distance runners tend to have a lot of these as well. Type IIc fibers can adapt to training to serve as either fast-twitch or slow-twitch fibers, and better distance runners tend to have plenty of these too. So it appears that fast distance runners have a nice blend of muscle fiber types that support raw sprint speed and fatigue resistance.

There is also evidence that muscle fibers of the same type can have different degrees of contractility. Faster distance runners tend to be extremely powerful for their size. Since the muscles of these runners are small and contain many slow-twitch fibers, we can infer that what muscle they do have is highly contractile for its type.

Besides a very high number of fast-twitch muscle fibers, another characteristic that supports sprint speed but not sustained speed is muscle size. Large muscles can produce more force, hence greater speed, than smaller ones, but they consume a lot of energy, so they quickly change from an advantage to a hindrance with increasing race distance. This becomes very clear when you look at the musculature of runners competing in the various race distances from 100 meters to 10,000 meters in a track meet.

		Heart Stroke Volume
		Muscle Glycogen Storage
		Running Economy
		VO2max
Some physiological characteristics important to running are more "trainable" than others. This graph compares the effects of training on four such characteristics: heart stroke volume, muscle glycogen storage, running ecomomy, and VO2max.

Should distance runners train to increase their maximum sprint speed? The answer is no. While it is highly beneficial for a distance runner to have loads of natural sprint speed, training should focus on increasing the fraction of maximum speed that can be maintained over race distances. The types of training that most effectively produce this result also tend to slightly decrease maximum sprint speed (mainly by enhancing the slow-twitch properties and diminishing the fast-twitch properties of adaptable muscle fibers). A small amount of sprint and power (plyometrics) training is appropriate to develop the raw speed aspect of sustained speed capacity. Runners who lack natural speed and power may benefit from doing a bit more speed and power training than other runners. Natural sprinters training for distance running should avoid this type of training.

© 2005 by Matt Fitzgerald

About the Author

Matt Fitzgerald, runner, triathlete, and coach, is a former editor and current contributor for Triathlete magazine. He writes articles for such national publications as Men's Health, Men's Fitness, Outside, Fitness Runner, and the Runner's World Web site, and serves as managing editor of the sports nutrition Web site, Pioneering Muscles.