Strength Training
Along with high-speed running and explosive work, one of the best enhancers of running economy is strength training. In a study carried out with female collegiate runners who incorporated strength training into their overall programs, including adding a variety of running-relevant movements such as squatting, the participants upgraded running economy by about 3 percent over a 12-week period, while runners without the strength training failed to enhance economy at all.10 Several other investigations have linked the adoption of strength training with enhancement of running economy.11-13
One mechanism involved in this linkage is probably that strength training improves coordination while running, thus lowering the cost of movement because lower energy and oxygen expenditures are required to correct movements that are not optimal. Strength training may also improve force production while the feet are on the ground, in part by strengthening individual muscle cells in relevant muscles. As muscle cells become stronger, perhaps fewer cells and motor units are needed to run at a specific velocity, thus reducing the oxygen cost of that speed.
An important area of future strength-training and running-economy research will undoubtedly be whether running-specific strength training (i.e., strength training focusing on movements that mimic the mechanics of running) is superior to more general strength training. Research has shown that the gains in strength associated with strength training are specific to the movements involved in the training as well as to the velocity of those movements.14, 15 For example, the strength of the quadriceps muscles during squatting movements is undoubtedly enhanced more by actual squat training than by leg-extension exercises using similar resistance, even though the latter focuses intently on the quads. In a similar vein, running-specific strength training—with an emphasis on one-leg squats, partial squats, bench step-ups, runner’s poses, bicycle leg swings, eccentric reaches with toes, among others—should be better than general movements (e.g., two-leg squats and exercises on machines) from the standpoints of propulsive force production and injury protection during running.
Other Factors
Carrying out explosive work and conducting appropriate strength training can enhance economy, but so can a variety of other training techniques and strategies. Running unshod, upgrading psychological skills, tapering, drafting, carrying out hill training, using vO2max training, and losing weight have all been linked with improved economy.
Running Barefoot
As noted in chapter 8, one of the easiest steps a runner can take to improve his or her economy is simply to take off those shoes. A change from shod to barefoot running generally upgrades running economy by 1 to 3 percent.16 There is debate about whether this improvement is entirely a consequence of the mass of running shoes—moving 11-ounce running shoes or even the lightest racing flats through space costs energy and therefore oxygen—or is also a result of changes in form associated with barefoot running.16
When moving from shod to barefoot gait, runners commonly shift from heel to midfoot striking, strike the ground with greater plantar flexion at the ankle, and adopt a higher stride rate, factors that might be linked with better economy.17 Runners should not adopt barefoot running quickly and cavalierly, however, as the work performed by various regions of the legs may dramatically increase with a shift from shod to shoeless running; specifically, the calf muscles are much more active during barefoot running and susceptible to injury during the transition.
Psychological Skills
The adoption of specific psychological skills may also improve economy. Research suggests that runners who employ an associative strategy—focusing on relaxing and coordinating breathing and body-segment movements during running—tend to have superior economy compared with runners who use a disassociative technique in which mental focus is on ideas and events removed from the actual act of running.18
Overall mood also plays a significant role in determining running economy. Runners who are depressed and anxious tend to have poorer economy than runners who are optimistic and relaxed.19 In addition, runners who adopt an empowerment strategy, in which they feel more in control of their training and are less weighed down by bad workouts and unrealistic expectations, tend to have significantly better economy compared with runners who appear to be less empowered.18 Positive self-talk strategies also seem to be effective at enhancing economy.19
Tapering
Tapering is another training technique that can enhance running economy. In a study carried out with 5K runners, individuals who cut training volume by about 60 percent over a 1-week period improved economy significantly. Note that these runners also focused heavily on fast 400-meter training during the tapering week, which might have accounted for at least some of the economy upgrade.20 Other inquiries have supported the idea that reductions in training volume can promote better running economy.21
Hill Training
As described in chapter 15, hill training is another strategy that enhances economy. In classic Scandinavian research, runners who added hill running and hill bouncing to their training over a 12-week period upgraded economy by 3 percent.22 It is important to note that although such improvements in economy seem small, they are linked with important changes in performance. Each 1 percent gain in economy can lead to a 1 percent faster race time, and thus a 3 percent economy enhancement could bring a marathon runner from a time of 3:05 down to the much more desired 2:59:30.
vO2max
Running economy is a variable that is built in to vO2max. Inherently, vO2max is an expression of a runner’s ability to increase running velocity as much as possible, given the constraints of his or her oxygen-consumption system. A high vO2max automatically means solid economy because a runner could not extract high speeds from his or her oxygen-delivery system unless economy was quite good. Thus, training methods that increase vO2max also tend to enhance running economy.
One of the best ways to optimize vO2max—and thus running economy—is to carry out training that contains quality segments conducted at very close to vO2max itself.23 These quality portions of workouts are usually intervals lasting from 30 to 180 seconds, with recoveries equal to the work-interval times. Each work interval is performed at vO2max, which is commonly estimated from an all-out 6-minute test on the track. (See chapter 26 for more on vO2max.)
Drafting and Losing Weight
Nontraining strategies can also enhance economy. Drafting behind another athlete, for example, reduces the oxygen cost of moving at a specific speed during cycling and swimming and is probably also slightly effective at lowering oxygen consumption during running.24 Losing weight also tends to upgrade economy since there is a lower oxygen expense associated with moving a smaller mass through space. The lost weight should be nonproductive weight, however. Losses in leg-muscle mass might curb propulsive force and could actually disturb coordination during running and increase foot-strike time, thus hurting economy. Losses of abdominal fat, on the other hand, usually push economy toward a lower oxygen requirement.
Anatomical Factors
Anatomical factors certainly have an effect on running economy. Runners with large, heavy feet, for example, are unlikely to have superior economy since those large feet must be swung through space with each step, a process that consumes considerable oxygen compared with swinging small feet. There is a countertheory, however, suggesting that larger feet are better for economy because they provide more stability during stance. The optimal strategy would be to have large feet during stance and tiny feet during the swing phase of gait, but unfortunately this is impossible. Informal surveys carried out with elite Kenyan runners suggest that these runners have medium-sized feet for their body size (e.g., many elite Kenyan men fall into the range of shoe sizes from 8B to 9C in U.S. sizing).25 Having medium-sized feet may produce a compromise between stability during stance and lightness during swing.
One hypothesis concerning the superiority of elite Kenyan runners is that their upgraded economy, compared with runners from the rest o
f the world, is a result of their very slim calves, which allow calf muscles to exert force on the Achilles tendon more vertically and directly, perhaps saving oxygen and making toe-off more explosive. This is a difficult hypothesis to test, however: It would be hard to make the calves of Kenyan runners fatter experimentally or to trim muscle fibers from the lateral edges of U.S. runners’ calves. It is also important to note that some research has found the running economy of elite Kenyans is not significantly different from that of elite Americans and top-level Europeans. 26, 27
Drafting during a race may reduce oxygen consumption, which could enhance running economy.
Tyler Kaufman/Icon SMI
Intriguing recent research has revealed that runners with relatively long Achilles tendons tend to have poorer running economy compared to athletes with short Achilles tendons.28 There is also evidence that the possession of a relatively longer heel bone (i.e., calcaneus) hurts economy and that having short calcaneal tubers, the posterior projections of the heel bones, was advantageous for early members of the species Homo sapiens in running down prey.28 Surprisingly, about 80 percent of the variation in economy among nonelite individuals can be explained by the length of the calcaneal tuber.28
Impact of Increasing Mileage
One of the most popular strategies for enhancing running economy is actually quite a weak stimulus for upgrading economy especially when economy is measured at competitive speeds. Many runners believe that the strategy of increasing the weekly distance run, or volume, is a powerful way to become more economical, but scientific research fails to support this contention. In classic work conducted by Finnish exercise scientists, one group of runners increased weekly running volume from 45 to 70 miles (72-113 km) while a second group remained at 45 miles (72 km) per week and added explosive training to their program. The group that added volume failed to enhance economy at all, while the explosive group improved economy significantly by approximately 3 percent.8
This Finnish research is quite revealing, giving researchers and runners a clear picture of a key mechanism by which running economy can be improved. In the study, the runners who added explosive training shortened foot-strike time as a result of the high-speed training; the change in foot-strike time was tightly correlated with the gain in economy. In effect, after explosive training, the runners’ feet needed to be on the ground for less time per step to maintain a specific velocity.
This reduction in contact time apparently reduces the oxygen cost per step and thus enhances economy. It is difficult to see why increasing the overall distance run would produce a similar effect. When distance is increased significantly, a large portion of the additional volume is conducted at submaximal intensities, the kinds of speeds that do not require a shortening of foot-strike time. Thus, the nervous system does not learn to regulate a quicker foot-strike; on the contrary, a pattern of slower running and more lethargic reaction of the feet with the ground may be locked in to the neuromuscular system, hurting economy at competitive velocities.
Training That Hampers Economy
Certain forms of training actually harm economy. For example, the use of a weight vest during running over a several-week period can hurt economy by 3 to 6 percent.29 It is not clear why this is true, although it is possible that using the vest changes coordination patterns of the motor units in the legs, in effect teaching the muscles to run while supporting greater weight, and thus negatively affects economy without the vest. The new pattern involving running with weight is not as economical as the vest-free mode of running—and this effect is maintained for awhile even after a runner abandons the vest.
Overtraining, or conducting training that exceeds the body’s capacity to recover and adapt, can also disturb running economy. There are two likely mechanisms for this. One possibility is that muscles are physically damaged in the overtrained state and thus less able to use oxygen economically. When damaged, muscle cells produce less propulsive force and thus require the assistance of other muscle cells, an extra recruitment of muscle fibers that increases oxygen cost. Another likely scenario is that the nervous system becomes less responsive than usual in the overtrained state and thus does a poorer job of regulating gait. This would be a protective mechanism, of course, the nervous system’s way of telling an overtrained runner to back off for awhile.
Conclusion
It is clear from scientific research that runners have many tools in their training programs for enhancing running economy. It is extremely important for runners to use all of their economy-enhancing strategies since running economy is such a strong predictor of performance. Although runners may be daunted by the array of training techniques that have an impact on economy, they should be reassured by the knowledge that training that incorporates high-quality running, explosive drills, hill training, and strength training will be extremely economy enhancing. The pursuit of better economy should be a year-long process, not an undertaking confined to a few weeks at a time.
Chapter 26
Gaining vO2max
Optimizing vO2max produces major gains in endurance performance. As outlined in Chapter 9, vO2max is simply the minimal running velocity that elicits maximal aerobic capacity, or O2max. While O2max is a relatively poor predictor of performance among runners of fairly similar ability, vO2max has excellent predictive power. The mechanism underlying this apparent paradox is simply that a runner might have an extremely high O2max but still perform relatively poorly if somewhat-mediocre running speeds caused that runner to use nearly all of that prodigious oxygen-processing capability. In other words, a voluminous O2max is of modest benefit if running economy is subpar.
In contrast, a runner with a high vO2max is always in great shape, literally and figuratively. Such a runner can run very quickly at O2max and thus must have good running economy. Since vO2max includes an economy factor, it contains more physiological information than O2max alone and can explain differences in performance for which O2max cannot be held accountable. For example, runner A has a higher O2max than runner B, but runner B has a higher vO2max than runner A because of better running economy, which creates a lower cost of oxygen for a given velocity. Runner B will be better than runner A at O2max, vO2max, and all percentages of these variables because runner B will operate at a higher speed than runner A.
Research carried out by French exercise physiologist Veronique Billat has revealed that one of the best ways to boost vO2max is actually to run at vO2max during training.1 By working at vO2max, a runner improves neuromuscular control and thus economy while running at a rapid velocity. By attaining O2max during the session—an inevitable outcome of the training since by definition vO2max is fast enough to elicit O2max—a runner provides the optimal stimulus for expanding O2max to the greatest extent possible. The consequent changes in economy and O2max drive vO2max upward to a significant degree because vO2max depends on both economy and O2max.
Determining vO2max
To determine vO2max, a runner could visit an exercise physiology laboratory and pay a substantial amount of money to carry out an incremental treadmill test. Although the expensive laboratory equipment involved in such a test might seem to make it authoritative, a weakness is that such an exam is carried out on the treadmill, where running economy is likely to vary, compared with running on terra firma. Thus, lab vO2max is unlikely to be the same as that derived from running on a track or ground. Unless a runner plans to do all training on a treadmill, the latter variable would appear to be more useful.
The alternative to the laboratory test is for a runner to go to the track, warm up, and then—when he or she is feeling loose, energized, and ready—run as far as possible on the track for 6 minutes. The distance covered in 6 minutes can then be divided by 360 seconds to yield a very good estimate of vO2max.1 If a runner covers 1,600 meters (1 mi) in 6 minutes, the estimated vO2max would be 1,600/360 = 4.44 meters per second.
Of course, the distance covered might not be a nice round number like 1,600. Odd distances on the track can
be measured with the use of a measuring wheel purchased at a home-supply store or online from a track and field website. Naturally, a GPS device can be used as well, freeing a runner to carry out the 6-minute test on any adequate stretch of flat terrain. Coaches and runners who lack a wheel or GPS setup will have to eyeball and estimate the distance covered on the track.
To create practical and productive vO2max workouts, it is convenient to convert the vO2max from the 6-minute test into a pace per 400 meters (see table 26.1). This calculation can be made in two ways. One way is to determine the number of 400-meter segments in the distance covered and divide 360 seconds by that number. For example, running 2,000 meters in 6 minutes would correspond with a vO2max tempo of 72 seconds, which is calculated by dividing 360 seconds by 5 (the number of 400-meter segments in 2,000 meters). Covering 1,800 meters in 6 minutes would produce a vO2max tempo of 80 seconds per 400 meters, which is calculated by dividing 360 seconds by 4.5 (there being 4.5 400-meter segments in 1,800 meters).
The second method, which works well for odd track distances, uses the vO2max estimate in the calculation. For example, if a runner completes 1,728 meters during the 6-minute test, the first step is to compute vO2max. In this case, 1,728 meters divided by 360 seconds equals 4.8 meters per second. This is the estimate of vO2max. The second step is to calculate the 400-meter tempo:
400 meters / 4.8 meters per second = 83 seconds per 400 meters
Running Science Page 37