Running Science

by Owen Anderson

  This does not mean that world-class sprinters could automatically become elite distance runners. Compared with an endurance runner, the world-class sprinter is different, with a fast-twitch muscle-fiber composition that makes it very difficult to run at quality speeds for prolonged periods. The announcement that maximal speed is a critically important component of endurance success is aimed at distance runners, not elite sprint athletes.

  Breaking Down Maximal Speed at the Subatomic Level

  To gain a better understanding of maximal speed and its importance for distance running, it is possible to break it down to the subatomic level, taking the components of maximal speed apart one by one. The formula for running velocity is a simple one:

  speed = stride rate × stride length

  Maximal running velocity involves the optimization of these two variables, stride rate and stride length. It’s as basic as that! If a runner wants to get faster—and thereby improve race times—he or she must increase either stride rate or stride length without dampening the other variable. For example, if a runner increases stride rate, he or she must make certain that stride length does not shorten. If a runner increases stride rate and stride length at the same time, the upswing in speed will be even greater compared with improving one variable at a time.

  To understand the options for increasing maximal speed, the subatomic equation should be examined closely. The example of an 18-minute 5K runner will work for this purpose, but the arguments work for racers at other distances and times as well. An 18-minute 5K runner typically takes about 92 strides (184 steps) per minute. A stride is two steps, one with the right and one with the left; 92 strides per minute is a normal stride rate for an experienced runner. Since this runner’s 5Ks last for 18 minutes, by definition, the runner is taking 1,656 strides (18 minutes × 92 strides = 1,656 strides), or 3,312 steps, during each race. So, the runner’s stride length is 3.02 meters per stride (5,000 meters / 1,656 strides = 3.02 meters per stride).

  The runner’s 5K speed could then be expressed as follows:

  stride rate × stride length = 5k speed

  92 strides per minute × 3.02 meters per stride = 277.8 meters per minute for 5K speed

  The rate of 277.8 meters per minute doesn’t exactly roll facilely off the tongue and is a bit cumbersome to use during training, so it should be converted to meters per second and to a tempo per 400 meters. First, 277.8 meters per minute is the same as 277.8 meters per 60 seconds, resulting in the following calculations:

  277.8 / 60 = 4.63 meters per second

  400 / 4.63 = 86.4 seconds per 400 meters

  In checking the numbers, the calculated pace is 4.63 meters per second, and there are 1,080 seconds (18 minutes) in the race. Thus, 1,080 seconds × 4.63 meters per second = 5,000 meters. The math is correct, and based on that, it is possible to begin to understand how changes in stride rate and length will determine 5K performance.

  Let’s assume the 18-minute 5K runner embarks on a program that includes high-speed sprints and explosive drills and thus improves stride rate by 1 percent. Of course, the easiest way for the runner to do this would be to simply decrease stride length a little—that way the feet would hit the ground more often and stride rate would go up. But, as mentioned previously, decreasing stride length could decrease speed, so that is not optimal. Instead, the runner should increase stride rate by decreasing foot-strike time. In other words, the stance phase of the gait cycle will be shorter: The runner will produce the same amount of propulsive force he or she always did, thereby keeping stride length the same, but over a briefer amount of time. Since less time will be spent in stance as a result of this change, the runner’s feet will hit the ground more often each minute, and stride rate will go up!

  When this runner improves stride frequency by 1 percent, the new rate will be 92.92 strides per minute. The runner’s 5K racing will also change as shown:

  92.92 strides per minute × 3.02 meters per stride = 280.6 meters per minute

  The old pace was 277.8 meters per minute, so the runner has advanced 5K speed by 2.8 meters per minute, or 1 percent. The new 5K time would be 17.82 minutes (5,000 / 280.6 = 17.82), or about 17:49. This simple, easy way to produce a 1 percent uptick in stride rate led to a 1 percent (11 / 1,080 = .01) improvement in overall 5K time.

  Of course, the same kind of thing happens if a runner upgrades stride length rather than rate. For that same hypothetical 5K runner, if stride length goes up by 1 percent, from 3.02 to 3.05 meters per stride, without a change in stride rate, the new equation is this:

  92 strides per minute × 3.05 meters per stride = 280.6 meters per minute

  This is the same velocity obtained when stride rate is increased by 1 percent. If stride rate and stride length are each increased by 1 percent, the resulting equation is this:

  92.92 × 3.05 = 283.4 meters per minute

  This is a 2 percent jump in 5K velocity, which would bring 5 K time down to about 17:38 or so. That would not be a hard thing to swallow for most 5 K competitors. In general, each 1 percent improvement in stride rate or stride length leads to a 1 percent improvement in race performance. A 5 percent uptick in stride rate and a corresponding increase in stride length would do nice things for 5K clocking—and even more for marathon times. The total 10 percent improvement would knock 1:48 off an 18-minute 5K time and would reduce a 3:19 marathon down to approximately 2:59!

  Improving Maximal Speed

  The way to improve maximal speed, then, is to know how to increase stride rate and stride length in ways which optimize the velocity equation. Some runners believe that sprint training is the answer, but sprint training by itself simply will not do the job. Speed work on the track may also appear to be the right medicine, but speed work is only a small part of the story. When most runners carry out speed training, they are usually working at velocities with which they are already all too familiar, making the effects of the training on maximal running speed quite small because the neuromuscular system is not being adequately challenged.

  Fortunately, the things an endurance runner needs to do to improve stride rate and stride length are quite straightforward. In fact, there are just three simple steps a runner should take to increase stride rate, and three additional steps to expand stride length.

  Before examining these factors in depth, it is important to know whether alterations in stride rate and stride length are really feasible. Are these components of gait locked in to each runner’s basic running form and mechanics, or are they quite plastic and responsive to training? This question has not yet been extensively studied because of the traditional thirst for information about O2max; as a result, the subatomic side of running has been relatively ignored. However, the work of scientists such as Paavolainen and Rusko reveals that foot-contact time and thus stride rate are quite responsive to training. The research by Paavolainen and Rusko described earlier showed that 5K runners were able to narrow their average foot-strike time from 210 to 195 milliseconds (a 7 percent improvement) without shortening stride length after just 9 weeks of training.4 As you might expect from the subatomic equation, the research team found that contact time was highly correlated with 5K success: the shorter the contact time, the faster the 5K performance.

  Some runners might think that a 15-millisecond improvement in contact time is quite small. But improvements measured in milliseconds can lead to large improvements, even in races timed in minutes and seconds. A runner completing a 10K in about 36 minutes takes about 6,624 steps, or 36 minutes × (92 strides × 2 steps), during the race. If each contact is shortened by 15 milliseconds without hurting stride length, the improvement in performance would be about 99 seconds (6,624 steps × .015 second = 99.36). Along similar lines, a marathon runner completing the race in 3:08 would take approximately 34,592 steps (188 minutes × 184 steps) in the race; a 15-millisecond improvement in contact time could lead to a 519-second improvement (34,592 steps × .015 second), enough to slip below the 3-hour mark.

  It is clear from the
available research that contact time and thus stride rate are quite plastic, varying significantly from one runner to another and responding aggressively to training. Studies carried out with elite runners cruising along at tempos between 4:45 and 5:00 minutes per mile reveal that average contact time is around 179 milliseconds—with wide variations ranging from around 160 to 190 milliseconds.

  Highest possible speeds are pbtained by minimizing contact time and heightening stride rate.

  Z Sports Images/zuma/Icon SMI

  Instead of increasing stride length, shrinking ground-contact time is the method that most runners use to attain top speeds. In general, runners pick up the pace by lengthening their strides when they are running at modest speeds. When they are already going very fast, however, stride lengthening doesn’t cut it, and further upswings in velocity are accomplished by shortening contact time and thus upgrading stride rate.5

  As mentioned, contact time and stride rate are very responsive to training. It seems likely that stride length is also trainable, but the way in which it responds to various kinds of training has not been carefully examined. It is clear that contact time can change significantly in as little as 6 to 8 weeks in response to explosive training. The possible magnitude of improvements in ground-contact time is not well known, but it’s clear that 10- to 15-millisecond increases are feasible and lead to major gains in performance. It would not be surprising to learn that some runners could improve contact time by 20 milliseconds or more, which would carve huge chunks of time from their performances.

  Methods for Increasing Stride Rate

  But what must a runner actually do in training to shorten contact time and increase stride rate without hurting stride length and thereby advance maximal speed? Fortunately, the methods are straightforward (see chapter 28 for in-depth, practical details concerning this kind of training). Following are the basic steps a runner must take to increase stride rate.

  Emphasize high-speed running. This does not mean going to the track and knocking off intervals at current or even goal 5K speed since these are paces with which a runner is already familiar and which the runner’s neuromuscular system can already handle effectively. Rather, allot time in training for running at maximal speed for 300, 150, 100, and 50 meters. These efforts force the nervous system to learn how to minimize contact time.

  Carry out explosive drills. These drills should supplement the diet of high-quality running. They require the feet to get on and off the ground as quickly as possible; at the same time, the legs are producing as much propulsive force as they can in the shortest possible time. While these drills do not usually involve actual running, they should be as specific to the gait cycle of running as possible, replicating key aspects of running biomechanics.

  Emphasize agility and coordination training. This training reduces the requirement to stabilize the leg and body when the foot makes contact with the ground. Since fewer milliseconds are required for stabilization during each interaction with the ground, contact time is abbreviated and stride rate is heightened.

  Methods for Increasing Stride Length

  To increase stride length, a runner must increase the ability to apply propulsive force to the ground. More propulsive force means longer stride lengths. There are three key ways to create more propulsion:

  Carry out running-specific strengthening movements. These movements should mimic the mechanics of running but be performed with increased resistance. Heavy weights can be used because the idea is not to get the foot on and off the ground quickly; rather, the goal is to maximize propulsive strength. Full resistance should be supported by one leg at a time, not by both legs simultaneously, since running does not involve jumping forward on two feet.

  Conduct ample amounts of hill training. This is the most specific form of strength training for running. More work is done per step and propulsive force that is greater than usual is required to move a runner’s body uphill compared with flat-ground running; thus, propulsive strength is advanced dramatically, leading to longer strides.

  Develop agility and coordination. As is the case with contact-time subatomic training, agility and coordination should be developed so that an optimal amount of the leg-muscle force, which is developed during ground contact, can be used for propulsion rather than mere stabilization and correction of nonproductive, uncoordinated movements.

  Incorporating the Methods for Faster Running

  The subatomic approach is the key to upgrading maximal velocity and running faster, but it is also just one component of the overall training picture. Subatomic workouts must be blended with high-quality running training to ensure that vO2max, lactate-threshold speed, running economy, and resistance to fatigue are all optimized. This will make certain that outstanding speed and stamina at quality speeds exist side by side, happy in their personal record–producing marriage. The union of high-quality running training and subatomic work is a blissful one. However, joining high-volume and subatomic work together does not work as well because high-volume effort does not optimize vO2max, lactate-threshold speed, and running economy. Although a runner might think that high-volume exertion would optimize resistance to fatigue, it is important to remember that endurance capacity and fatigue resistance are always speed specific. Running tons of miles at moderate paces enhances endurance at modest speeds—but not at more sizzling levels of effort.

  Subatomic training by itself not only makes a runner faster; it also makes it easier for a runner to sustain the higher speeds that previously were unthinkable. The reason is that subatomic training invariably leads to improvements in running economy and reduces the oxygen cost of running at a specific speed (see chapter 8).

  In Paavolainen and Rusko’s research, the subatomic drills produced an enormous running economy enhancement of 8.1 percent. One mechanism underlying this dramatic gain is probably that subatomic training improves the springiness and energy-return properties of the legs. This development saves energy because more propulsive force is created as a result of cost-free elastic recoil of muscles and tendons; thus, less force has to be created from energy-expensive muscle contractions. Subatomic training also upgrades coordination during gait, an effect that would decrease the amount of energy required for stabilizing the body, thus enhancing running economy. As a result of running economy enhancements, high-end speeds can be run at a lower fraction of O2max, and thus it is considerably easier to sustain such higher velocities. Runners can move to higher speeds in races without incurring a higher cost—and without greater perceived effort—once subatomic training has been undertaken.

  Another important consideration is that competitive races are ordinarily run at fixed percentages of maximal speed. For example, a runner whose personal record for the mile is about 5 minutes is typically running the mile at about 80 percent of maximal speed and 5Ks at around 74 percent. When maximal velocity increases, mile and 5K speeds also must increase since they are tightly linked with maximal velocity; 10K, half-marathon, and marathon velocities would also advance.

  Conclusion

  An apparent paradox of running is that extremely high-speed training with short-duration sprints and drills leads to dramatic improvements in prolonged endurance running. However, this marriage of fast with slow, of speed with endurance, is not really paradoxical: The benefits gained from explosive training—shorter ground-contact times, higher stride rates, and longer strides—are great for both short sprints and longer distances, including the marathon. The distance runner who can move very quickly over 42 meters can use the same skills of short contacts, quicker stride rate, and longer stride length to run powerfully for 42K, too. The endurance runner who has optimized maximal running velocity has a huge edge over competitors who have not developed this key performance variable.

  Chapter 12

  Resistance to Fatigue

  Resistance to fatigue is the ability to sustain a high-quality velocity, a specific fraction of O2max, or a specified percentage of maximal running speed for an extended time
without a falloff in pace or intensity. It is an important predictor of performance. However, science has not yet determined exactly what factors determine a runner’s resistance to fatigue. The top theories have focused on glycogen concentrations, the ability to dissipate heat while running, stretch-shortening cycle function, and the operations of the neural governor.

  Differences in Factors Determining Resistance to Fatigue and O2max

  Exercise scientists first became interested in resistance to fatigue when it was noticed that black South African runners could maintain a specific percent of O2max for a longer time period compared with their Caucasian peers. In a study carried out at the University of Cape Town, researchers compared the performances of the nine best Caucasian runners with the 11 best black competitors in the country.1 In this investigation, the runners had similar performance times at distances ranging up to about 3,000 meters. Beyond 3K, however, the performances of the black runners were considerably better, even though the O2max values of the two groups were identical.

  As the South African investigators searched for the mechanism(s) underlying the performance differences between the two groups, they discovered that the black runners could sustain an intensity of 89 percent of O2max for a half marathon, while the Caucasian runners could handle just 82 percent of O2max over the same distance. In fact, the Caucasian runners could maintain the intensity of 89 percent of O2max for only about 5 miles. The researchers noted that the black runners could also sustain 92 percent of O2max for a full 10K race, while their competitors were forced to drop down to 86 percent of O2max for this distance. The black runners had superior resistance to fatigue: They could run much longer than the Caucasians at any fraction of O2max.