Energy Requirements for a 100M Sprint

Talent, hard work and focused determination -- all are needed to succeed in the sprints.

Talent, hard work and focused determination -- all are needed to succeed in the sprints.

The 100-meter dash is widely considered track and field's most glamorous event, made all the more so by the world-record-setting exploits of Jamaica's charismatic Usain Bolt at the 2008 Summer Olympics. Clearly, success in this event requires a great deal of innate foot speed as well as disciplined, savvy training. But at the physiological level, what, exactly, is needed to propel a human body down the track at the fastest possible speed for about 10 to 15 seconds?

Anaerobic vs. Aerobic Energy Systems

In running, energy comes from two distinct metabolic pathways: anerobic, meaning "without oxygen," and aerobic, meaning, in effect, "oxygen alone." As a rule, the longer you maintain a given physical effort, the higher a proportion of your energy needs are derived via the aerobic pathway. Therefore, while a 26.2-mile marathon is virtually entirely aerobic, the 100-meter is almost exclusively anaerobic; this means dash specialists focus almost exclusively on workouts that exploit the anaerobic-energy pathways. To accomplish this, hit the weight room several times a week, practice the first 40 to 60 meters of the race to work on "exploding" out of the blocks -- getting a quick start is critical in an event that's over almost as soon as it begins -- and run repeat overdistance intervals or 200 to 400 meters, three to six per session, at about 85 percent to 90 percent effort, with five minutes of rest in between.

Metabolism in the Sprints

Your body relies on a variety of fuel sources for energy when you run, with the proportion of each source determined by the duration of your event as well as the intensity. Since by definition a 100-meter competitive race is an all-out affair, intensity for purposes of this article is defined as 100 percent. Your muscles can rely almost solely on a substance called creatine phosphate in events lasting 10 to 15 seconds, with the women's world record as of 2012 being 10.49 seconds and a solid preteen time in the range of 15 to 17 seconds. After the 15-second point is reached, you can then burn glycogen -- the body's storage form of sugar -- for another 30 to 40 seconds, at which point anaerobic metabolism is exhausted.

The Phosphagen System

Without going all grad-level biochemistry on you, it's worth knowing a little about the so-called phosphagen system, since for the vast majority system this supplies nearly 100 percent of energy needs in the 100-meter dash. In a nutshell, regardless of whether the fuel your muscles use starts as fat, glycogen or simple sugars, in the end, after a number of cellular chemical reactions, your muscle cells contract as a result of a molecule called ATP. This molecule can be produced only slowly in aerobic metabolism and more quickly in anaerobic glycogen metabolism, but a substance called creatine phosphate allows for the very rapid production of ATP through a process that amounts to borrowing with no intention of repaying the loan. The drawback is the stated 10- to 15-second limit of this system, but since we're talking about 100-meters, this for all intents and purposes doesn't matter.

Fueling for Top Performance

You have likely heard of "carbo-loading," a nutritional tactic used by distance runners to maximize the amount of glycogen their bodies can store in advance of their races, in theory allowing them to avoid "hitting the wall." But is there an analog to this for athletes who take just seconds to get from start to finish? That is, can you overload the phosphagen system? Unfortunately, scientific research suggests that this is not that case. For example, a study performed by an Australian team in 1998 demonstrated that even though ingesting creatine leads to increased levels of creatine phosphate in muscle, this doesn't mean better performance. By way of analogy, increasing the capacity of your car's gas tank won't make your car go any faster. So, relying on good old-fashioned nutrition and hard training is the way to go. Always stay properly hydrated, take in sufficient protein to replace the muscle you break down through repetitive sprinting and lifting weights -- about 1.8 to 2 grams per kilogram of body weight per day is a good guideline -- and fuel yourself with fresh, wholesome foods rather than soda and other sweets.

 

About the Author

L.T. Davidson has been a professional writer and editor since 1994. He has been published in "Triathlete," "Men's Fitness" and "Competitor." A former elite cyclist with a Master of Science in exercise physiology from the University of Miami, Davidson is now in the broadcast news business.

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