Running Science

by Owen Anderson

  Comparing High-Intensity and Traditional Base Training

  It might be argued that conventional base training is nonetheless an effective way to boost running strength and thus decrease the risk of subsequent injury during more intense phases of training, but this contention ignores the fact that the strength gained in training is always velocity specific.11 Strength acquired at slow speeds does not automatically transfer to faster muscle contraction (e. g., faster running velocities). In this sense, running at easy base speeds provides poor preparation for higher-speed running. There is also no proof that traditional base training periods lower the rate of injury during follow-up training. With their emphasis on increased volume, traditional base periods may actually increase injury rates.

  Recent research carried out by Mark Tarnopolsky, Martin Gibala, and their colleagues in the department of kinesiology and the department of medicine at McMaster University in Hamilton, Ontario, Canada, suggests that base periods containing significant amounts of high-intensity training are superior to conventional base periods.12 These researchers became interested in the possibility of relying on high-quality—and even sprint—training during base periods after they examined several scientific studies showing that high-intensity sprint-interval training increases the maximal activity of mitochondrial enzymes.13-15 Mitochondrial enzymes are the key chemicals that allow muscle cells to use oxygen at higher rates, thus heightening aerobic capacity, or O2max.

  The research team also noted that high-intensity sprint training tends to produce two key adaptations that are beneficial for endurance runners: a reduced rate of glycogen usage during exercise and a smaller buildup of lactate during strenuous effort. A decrease in the rate at which glycogen is burned during running promotes stamina because more glycogen fuel remains in the tank to be used after any specific duration of effort. A diminished buildup in lactate can indicate that lactate, a key fuel for running, is being used more effectively for energy: It is being broken down quickly instead of accumulating in the muscles and blood.

  As if all that were not enough, many studies have shown that high-intensity sprint training upgrades performance during exertions that rely primarily on aerobic metabolism.16, 17 Finally, sprint intervals improve the buffering capacity of muscles (i.e., the ability to control advances in acidity),18, 19 an effect that usually promotes better tolerance of high-intensity running and thus greater endurance at intense paces.

  Such findings suggest that reasonable amounts of high-intensity work might be optimal during a base-building phase of training, promoting many adaptations that would be tremendously useful during subsequent periods of strenuous training. To put high-intensity base-building to the test, Tarnopolsky, Gibala, and colleagues recruited 16 fairly fit male McMaster University students who normally worked out two to three times a week by running, cycling, or swimming. The average age of the students was 22, mean mass was 172 pounds (78 kg), body mass index was 23 (i.e., they were not overweight or obese), and average O2max was 52.6 ml • kg-1 • min-1.

  At random, eight of the subjects were assigned to the sprint-training group, and the other eight were placed in an endurance-training group that used the old-fashioned base with moderately paced distance work. All training was carried out on a cycle ergometer. The base training period lasted 2 weeks, and the six total workouts were performed on Monday, Wednesday, and Friday of each week with 1 to 2 recovery days between sessions.

  The sprint- and endurance-training bases were incredibly different. For the sprint group, training consisted of 30-second, maximal, all-out intervals, with power outputs soaring as high as 700 Watts and 4 minutes of recovery between intervals; the recovery consisted of either rest or light cycling at an intensity of about 30 Watts. This was done progressively: The subjects completed four maximal intervals during the first and second workouts, five all-out reps during workouts three and four, and six scalding intervals for workouts five and six. Meanwhile, the endurance group started with 90 minutes of work during sessions one and two at the modest intensity of 65 percent of O2max, moved up to 105 minutes of cycling for sessions three and four, and peaked to 120 minutes of exertion during workouts five and six—all the while remaining at the workload of 65 percent of O2max, a traditional base intensity.

  Before and after the base periods, all subjects completed a 30K (18.6 mi) and a 2K (1.2 mi) time trial. After the 2 weeks of base training, the time required to finish the 30K (18.6 mi) trial dropped by 10.1 percent for the sprint group and by 7.5 percent for the endurance group; this difference was not statistically significant. After the base, average power output during the 30K (18.6 mi) trial rose by 10 percent for the sprint-training group and by 6.5 percent for the endurance-training group; again, this disparity was not statistically relevant. Finishing time in the 2K (1.2 mi) test improved by 4.1 percent for the sprint group and by 3.5 percent for the endurance group; the difference was not statistically significant. Similarly, mitochondrial enzyme activity increased in both groups by essentially the same amount after the base period, and so did muscle glycogen content.

  The high-intensity sprint group spent just 2 to 3 minutes per workout exercising at high intensity—and trained for just 18 to 27 minutes total per session with recovery time included. Meanwhile, the endurance-training group logged from 90 to 120 minutes per workout. Overall, for the whole 2-week period, those in the sprint group completed 15 minutes of quality intervals and spent only 135 minutes training, with recovery time included, in contrast to the 630 minutes of work put in by the endurance-training subjects. In effect, each minute of sprint-interval training produced the same benefits as 42 minutes of endurance training at 65 percent of O2max.

  Since the resulting adaptations were the same, this means that sprint training was a far more efficient way to build a base. There is also a strong implication that if a few more intervals had been included in the spring training or if additional moderate-intensity work had been added to the challenging intervals, the sprint-focused base efforts would have far outstripped the endurance-based exertions in terms of the magnitudes of the resulting adaptations.

  High-Intensity Training Does Not Increase Injury

  No evidence exists to suggest that higher-quality training heightens the risk of injury during base periods. Since total time spent training (e.g., volume) is usually the best predictor of running injury,1 a traditional, endurance-oriented base, in which distance is steadily ramped up, might be much harder on muscles and tendons than a high-intensity base.

  Indeed, the fact that sprint training is carried out in a base period does not automatically mean that the sprint work should be undertaken unwisely or excessively. The high-quality work would be modest in volume and would only gradually progress in difficulty and extent. A focus on higher-quality training would also invite neuromuscular development on board during base periods. Thus, both the neuromuscular and cardiovascular systems would be prepared for the rigors of subsequent stages of training.

  Conclusion

  A base period is a time to get started on upgrading O2max and the seven key physiological variables that determine performance: tlimvO2max, vO2max, running economy, lactate-threshold speed, maximal running speed, resistance to fatigue, and running-specific strength. Base periods work best when they make runners fitter. When runners have higher capacities, they are able to train at higher intensities during subsequent periods of training and thus make more substantial improvements in their performance characteristics. Traditional base periods do a modest job of making runners fitter. It makes sense to replace traditional bases with foundation periods that initiate the forward progress of critical physiological variables. Base periods do not need to feature the volume included in later phases of training, but they do require an essential core of quality to optimize the training process.

  Circuit training (see chapter 13) should be a particularly effective training modality during base periods. Circuit training advances aerobic capacity, lactate threshold, running economy, and vO2max. Its
high-quality running elements enhance neuromuscular development. Circuit work also builds whole-body strength, which should promote resistance to fatigue and heightened running economy. The completion of two circuit sessions per week, along with the inclusion of some additional high-quality running on a third day, would help create an extremely productive base period that would make runners fully prepared for the demands of subsequent, challenging running-specific strength training and intense running workouts.

  Chapter 25

  Enhancing Economy

  As outlined in chapter 8, running economy—the rate of oxygen consumption associated with a specific running speed—is an important determiner of performance.1 At competitive running velocities, individuals who have lower oxygen costs associated with such speeds generally fare better in the competitions than do runners with higher costs, although other factors such as neural output, lactate-threshold speed, and resistance to fatigue may be more important than running economy in certain situations. So how do runners enhance economy? There are a number of factors to consider, including some that have a greater impact than others.

  Changes in Running Form

  Exercise scientists have been curious about whether changes in running form can enhance economy. In a study carried out at Wake Forest University in the United States, researchers asked a group of runners to incorporate a number of new form elements into their running, including greater flexion of the knee during the stance phase of gait, more upright posture, and better control of the arms and upper body.2 Somewhat surprisingly, these popular changes in form did not improve running economy to any significant degree. It is possible that the study duration was not long enough (10 weeks) for improvements in economy to occur; the time needed for economy enhancement in response to form alteration has not been well established. It is also possible that the form adjustments advocated in this research were not the correct ones.

  The Wake Forest scientists had their subjects adopt longer strides and a heel-strike landing pattern during running, for example. While heel striking is a very popular form of running, and studies suggest that at least 75 to 90 percent of endurance runners use this technique instead of midfoot or forefoot striking,3 recent research reveals that heel striking is linked with higher impact forces and a longer stance phase of gait,4 factors that could actually increase the cost of running and thus harm economy. Using relatively longer strides while running is also risky from an economy standpoint because longer steps can increase braking forces during impact with the ground and thus increase the work and oxygen cost required to run at a specific speed.

  Despite the inability of the Wake Forest study to link form changes with better running, exercise scientists have continued to speculate that certain changes in running form would have a positive impact on running economy. Specifically, scientists have been intrigued by the idea that form adjustments leading to less energy wasted on braking forces and reduced vertical oscillations of the center of mass can enhance running economy.5 Running form intended to reduce braking forces and vertical oscillations would incorporate a slight forward lean of the body from the ankles (figure 25.1a) during gait so that the body would tend to bounce forward rather than straight up with each step, midfoot striking (figure 25.1b; heel striking is linked with greater braking forces), a high cadence, and a relatively neutral shin angle at foot strike.

  Figure 25.1 A (a) slight forward lean of the body and a (b) midfoot strike are thought to reduce braking forces.

  A relatively fast cadence (i.e., greater than or equal to 180 steps per minute) should upgrade economy because it favors midfoot striking over heel striking; heel striking increases the amount of time on the ground per step, and therefore it is more difficult to use a heel-strike pattern in conjunction with a rapid step rate. Runners can work on cadence, and thus economy, by using a metronome (no, not the kind that sits atop pianos—the small electronic models are preferable) and following its 180- to 190-beeps per minute frequency as they run. Just this simple adjustment will change form in a positive way for the majority of runners who—when metronome guided—will suddenly begin to get their feet under their centers of mass at impact with the ground and start landing with a midfoot pattern.

  Shin angle (see figure 25.2), defined as the angle between the shin and an imaginary line perpendicular to the ground and running through the knee at the exact moment the foot first touches the ground during impact, should be linked with economy, too. A highly positive shin angle of more than a few degrees means that the shin and foot are well forward of the body’s center of mass and thus will accentuate the braking forces. A negative shin angle of any degree generally means that a runner is about to fall forward on his or her face. A neutral shin angle, with the shin more or less perpendicular with the ground, indicates an absence of braking force and perhaps optimal economy.

  Figure 25.2 (a) Positive, (b) negative, and (c) nearly neutral shin angles.

  Overly positive shin angles can be transformed to slightly positive or neutral shin angles over time by increasing cadence and using the metronome at first, wearing minimal shoes with zero heel drop, or by running unshod. The resulting suite of changes—slight forward lean of the body from the ankles, a fast cadence, slightly positive to neutral shin angle at impact with the ground, and midfoot striking— should be associated with the best possible running economy. Coaches and runners can track changes in shin angle, body lean, and foot-strike pattern over time with inexpensive video cameras or with apps such as Coaches Eyes.

  Differences Between Economy and Efficiency

  Classic exercise research carried out about 30 years ago noted that marathon runners tend to have superior running economy compared with competitors at shorter distances (e.g., 5K and 10K) and middle-distance runners. At the time, this result was viewed as being logical and predictable since it was thought that marathon runners would have to be highly economical and efficient to compete well over a long distance like 42K (26.1 mi).

  Economy and efficiency have entirely different meanings, however. While economy is the oxygen cost of running at a fixed speed, efficiency is the ratio of work performed to energy expended. No study has ever documented an improvement in efficiency in response to training in endurance runners, and there is little evidence that efficiency varies widely among runners. Economy, on the other hand, is responsive to training and varies widely.

  While studies have not been able to pinpoint practices that enhance efficiency, marathon runners can improve their economy by including training typically used by middle distance runners, such as high running speeds and explosive drills.

  Jacob De Golish/Icon SMI

  When scientists took a closer look at the hypothesis that marathoners are more economical, they discovered that the runners being studied were usually having economy measured at relatively slow running velocities. When speeds quicker than marathon pace were used in economy research, middle-distance runners (i.e., competitors at 800 and 1,500 meters) were actually the most economical—more so than 5- and 10K runners and marathoners.6 This suggests that either middle-distance runners are inherently more economical than longer-distance competitors, or the use of high running speeds and explosive drills during training is an economy enhancer.

  Explosive Drills and High-Speed Training

  One of the best promoters of enhanced economy is the use of explosive drills, exercises in which there is a great emphasis on getting the feet on and off the ground quickly. In a study carried out in Australia by Rob Spurrs and his colleagues, well-trained endurance runners who incorporated explosive drills (e.g., jumps, hops, leaps, hurdle clearing) into their overall training program over a 9-week period benefited from a 3 percent improvement in economy; athletes who avoided the explosive exercises failed to enhance economy at all.7

  In another study supporting the idea that explosive training spurs economy enhancements, researcher Heikki Rusko and his colleague Neena Paavolainen asked a group of well-trained 5K runners to add explosive work (e.g., spri
nts, jumps, hops, squats) to their training program while a second group of similar runners added volume (i.e., distance) without the explosive exercises.8 Rusko and Paavolainen set up the study so that the added distance and additional explosive routines took similar amounts of time so that neither group could benefit from an increase in training time.

  After 9 weeks, the group that added explosive work enhanced economy by 3 percent and also ran a simulated 5K race 3 percent faster than previously; the group that had added distance to their training failed to upgrade economy or race performance. The mechanism for this difference appears to be that explosive training converts runners’ legs into slightly stiffer springs that provide more propulsive force with each step; in contrast, less-stiff springs tend to collapse too much during stance and lack adequate recoil power.

  Veronique Billat’s classic work also supports the idea that higher-speed training is highly beneficial to running economy. In one of Billat’s studies, experienced endurance runners added weekly training sessions conducted at vO2max (i.e., about 2K [1.2 mi] race speed) to their training programs and moved running economy in the right direction by about 4 percent over a 9-week period.9