In research carried out at the University of Toledo in Toledo, Ohio, that explored the effects of aqua running on 5K performance, 11 well-trained competitive runners (10 males and 1 female) trained exclusively in deep water for a period of 4 weeks, averaging five to six workouts each week. These athletes preserved their average treadmill 5K performance time of about 19 minutes flat, O2max, and running economy, even though they completed no treadmill or regular running at all during the 4-week study.8
Maximal heart rate during deep-water running is about 8 to 10 percent lower than it would be during firm-ground running.9 Otherwise, the physiology of aqua running is similar to that of dry-ground running. A study carried out at the University of Montana tracked eight college-age male cross-country runners as they ran on the treadmill and in deep water at heart rates corresponding to 60 and 80 percent of the heart rate associated with O2max; oxygen consumption, ventilation, and energy expenditure were comparable in the two situations. A key physiological difference was that the athletes burned more carbohydrate and used less fat for energy when they exercised in the water.10 This is certainly not a negative factor since well-trained runners who compete at distances ranging from 800 meters to the marathon use carbohydrates as their primarily fuel.
Another disparity is that training at a specific fraction of O2max tends to feel about 20 percent harder during aqua running than in regular, dry-land running.10 This is one reason why some exercise scientists recommend working more intensely in the pool than would be done on firm ground. Higher intensity may be required to increase the oxygen-consumption rate; if a runner trains in the pool with his or her usual perceived effort, oxygen consumption may be considerably lower compared with the same perceived effort while running on land.
A potential bonus associated with running in the pool is that it might have a unique effect on lactate threshold. In one investigation, lactate levels in well-trained runners reached a modest 2 millimoles per liter during dry-land running but increased to 6 to 8 millimoles per liter at the same intensity in the water.10 This effect should stimulate leg muscles to improve lactate clearance, an effect that would heighten lactate-threshold velocity.
Soccer
Participation in soccer practices and competitions may be quite advantageous for runners. During a typical soccer game, athletes cover from 9,000 to 11,000 meters (5.6-6.2 mi), a total that normally includes about 4,000 meters (2.5 mi) of jogging, 2,000 meters (1.4 mi) of running at high but not maximal speed, 800 to 1,000 meters (.5-.6 mi) of maximal-speed running, 2,500 meters (1.6 mi) of walking, and 600 meters (.4 mi) of running or walking backward.11 Soccer players’ heart rates are above 150 beats per minute for most of a game, and blood lactate levels often rise as high as 6 to 10 millimoles per liter (108-180 mg/dL), comparable to the concentrations observed during 5K and 10K running competitions.
For runners, participating in a soccer competition is like conducting a prolonged, intense interval workout. The changes in direction required for soccer play may also be beneficial for leg strength, muscle balance, agility, coordination, and injury prevention. It is hardly surprising that many elite Kenyan runners began their athletic careers on the soccer pitch; Paul Tergat (five-time world cross-country champion and former world-record holder for 10,000 meters, half marathon, and marathon) is a notable example of this phenomenon.
Strength Training
Explosive and running-specific strength training are especially productive forms of cross-training for runners. As explained fully in chapters 14 and 28, both types of strength training can enhance running economy, a key predictor of performance. In addition, explosive strength training heightens maximal running speed, another great performance predictor, and has been tightly linked with improvements in performance times. Furthermore, running-specific strength training promotes resistance to fatigue and decreases the risk of injury, leading to greater training consistency. Running-specific strength training also enhances running economy and can improve lactate-threshold velocity, fatigue resistance, maximal running speed, and vO2max. As a result, running-specific training forms part of the backbone for periodized running programs, along with explosive training
Treadmill Workouts
Many runners rely on treadmill training to complete their required workouts and sometimes wonder whether treadmill running is close enough to running on firm ground to produce comparable benefits. The biomechanical differences between treadmill and land running have not been examined in a controlled scientific setting, so science provides little guidance on this issue. No one knows whether a steady regimen of treadmill running might impair running form and running economy when running on firm ground.
Runners can be reassured, however, by the fact that treadmill running can produce the same high rates of oxygen consumption and blood lactate levels observed during ground running. Thus, high-quality treadmill training can undoubtedly have positive impacts on maximal aerobic capacity, lactate-threshold velocity, and fatigue resistance.
When conducting treadmill workouts, runners should keep one factor in mind: The lack of air resistance, and perhaps subtle biomechanical alterations, associated with treadmill running make treadmill efforts less costly from an oxygen-consumption standpoint than training on firm ground. At a specific velocity of 10 miles (16 km) per hour, for example, a runner will ordinarily use less oxygen per minute and thus operate at a lower fraction of O2max on a treadmill than when running on the ground, street, or track. This means that higher speeds can generally be attained and maintained during treadmill training at a similar percentage of O2max. This is a good thing from a neuromuscular standpoint because it teaches the neuromuscular system to operate at a slightly higher level. It also means that a treadmill adjustment must be made if an athlete wants to train at the same intensity on the treadmill as would be achieved over regular ground. Specifically, tweaking the treadmill to a 1 percent incline will match intensities for a given speed between treadmill and ground. Running on a treadmill at 10 miles (16 km) per hour with a 1 percent incline produces about the same oxygen cost and percent of O2max as running at the same speed on perfectly flat ground.
Other Cardio Workouts
Although scientific research is scant, it is likely that sustained, intense exercise using various forms of cardio equipment can be beneficial for runners. Specifically, training on an elliptical machine, swimming, rowing, and sculling can provide challenges for a runner’s general strength and fatigue resistance and also heighten oxygen-consumption rates and blood lactate levels. These physiological challenges should produce adaptations and thus higher levels of fitness for runners without the higher risk of injury associated with carrying out similar-intensity sessions while running. While the effects might be small, even a 1 percent improvement in resistance to fatigue or lactate-threshold velocity could be important for a competitive runner.
A similar argument can be made for cardio sports such as cross-country skiing and even sports played with flying disks. In fact, any activity that involves rapid movement, sudden changes of direction, abrupt stopping, and high levels of coordination should produce higher oxygen-consumption rates and blood lactate levels and demand a great degree of general strength and neuromuscular control, all factors that are beneficial for runners.
Conclusion
Running-specific strength training, including explosive strength training, and cycling are the two most productive forms of cross-training for runners. Cycling training transfers gains in fitness directly to running and can be used to boost fatigue resistance, lactate-threshold velocity, and O2max. Running-specific strength training and cycling are also tools runners can use to increase their average weekly training intensity with small risk of overuse injury. Furthermore, stair climbing, aqua running, treadmill workouts, soccer participation, and other cardio workouts can preserve fitness during periods when running volume is reduced.
Chapter 18
Altitude Training
Altitude training consists of conducting workouts at
an elevation of approximately 1,527 meters (5,000 ft) or greater. Many coaches and runners believe that altitude training is highly beneficial, and elite athletes often structure their overall training programs to include periods of high-altitude work. Many coaches believe that altitude training provides a natural blood-doping effect, heightening red blood cell concentrations and thus upgrading aerobic capacity. Another popular belief is that altitude training increases lactate-threshold velocity and improves muscle buffering capacity, or the ability to compensate for increases in acidity, thus heightening resistance to fatigue; one theory of fatigue is that it is caused by acidic conditions in muscles. Many elite runners believe that altitude training expands respiratory system capacity so that more oxygenated air can be brought into the lungs during intense running.
The fact that the majority of elite Kenyan and Ethiopian runners carry out their training at altitude when they are in their home countries provides anecdotal support for the practice. Reflecting the popularity of altitude training, high-altitude training centers have appeared in such places as Kaptagat and Iten, Kenya; Flagstaff, Arizona; Colorado Springs, Colorado; and Mammoth Lakes, California.
Perceived Benefits of Altitude Training
For the past 40 years, exercise scientists have been curious about the effects of living or training at high altitude on endurance performance. Their research has explored the ways in which altitude shapes cardiovascular function, red blood cell production, lactate dynamics, and respiratory function in the endurance athlete.
Altitude training boosts hemoglobin concentrations and thus O2max. The problem with altitude training is that it reduces training speeds and thus has a negative impact on neuromuscular development and the attainment of an improved maximal velocity.
Waldhaeusl.com/Bildagentur Waldhaeusl/age fotostock
Connection Between EPO, Red Blood Cells, and O2max
It is certainly true that altitude training can have an impact on the aerobic system. Unless an endurance runner owns a personal helicopter, training at altitude also generally means that he or she is living at altitude, and altitude residency naturally boosts a runner’s blood concentration of erythropoietin (EPO), a powerful hormone synthesized in the kidneys that stimulates bone marrow to increase red blood cell production (see chapter 2). As red blood cell density increases, the blood is naturally able to carry more oxygen per unit volume. This means that the heart sends out more oxygen per beat, and that additional oxygen is delivered to the muscles in any unit of time, changes that tend to augment the aerobic system and thus O2max. A runner who manages to increase his/her O2max is often able to achieve higher levels of performance. This relationship between EPO, red blood cells, and O2max is often used as a justification for altitude training.
Although this model of altitude training and its benefits is widely accepted, it has very shaky scientific support. For one thing, O2max is not a good predictor of performance among similarly trained endurance runners. Altitude training thus appears to involve the pursuit of a variable that does not have a large impact on competitive ability. In addition, if the altitude model is valid, one would expect elite, altitude-trained Kenyan runners to have heightened hemoglobin levels compared with elite athletes who trained at sea level (hemoglobin is the oxygen-carrying molecule found inside red blood cells). Scientific research carried out at the University of Bayreuth in Germany reveals that hemoglobin mass in elite, altitude-trained Kenyans is actually no different from the hemoglobin of elite German runners trained at sea level.1 In the Bayreuth study, relative O2max was also the same in the two groups. Importantly, the Kenyans ran the 10K in about 28:29 compared with 30:39 for the Germans. Clearly, something other than altitude-enhanced red blood cells (i.e., oxygen-transport capacity of the blood) and O2max was behind the difference in performance!
Lactate-Threshold Blood Concentrations
Undeterred, proponents of altitude training point out that there is another physiological bonus associated with altitude training: When running at altitude at any velocity, blood lactate levels are higher compared with running at the same velocity at sea level. Since heightened blood lactate concentrations during workouts have been linked with greater increases in lactate-threshold velocity, a decent predictor of performance, it has been assumed that training at altitude would enhance lactate-threshold velocity. Scientific support for this hypothesis is scant, however. In fact, it is much more difficult to sustain speeds greater than sea-level lactate-threshold velocity at altitude, and thus total time spent above lactate-threshold velocity during training can actually decrease at altitude.
Running Economy
Some research has suggested that training or living at altitude might enhance running economy, another predictor of endurance performance. In research carried out at the Australian Institute of Sport that looked at the impact of altitude residency on economy, nine elite athletes spent about 400 hours at a simulated altitude of 2,860 meters (9,367 ft) but carried out all their training at sea level. A control group of runners did not spend any time at simulated altitude; they trained and lived at sea level. After about 7 weeks, including sleeping at simulated altitude for 46 nights, the athletes at simulated altitude had upgraded running economy by about 3 percent; the control subjects had failed to improve at all.2
In a related study conducted at the University of Tokyo, runners who slept at a simulated altitude of 3,000 meters (9,843 ft) for 29 nights enhanced economy by approximately 5 percent, while runners who trained at the same simulated altitude but slept at sea level did not upgrade running economy at all.3 It appears that altitude or simulated-altitude residency but not training improves running economy in runners who have previously lived at sea level. The mechanism underlying this effect is unknown.
Nonhematological Effects
It is likely that altitude residency or training has other nonhematological effects that could have an impact on endurance performance. For example, it is believed that altitude residency can increase capillary growth around muscle cells (angiogenesis), improve intramuscular pH regulation, and upgrade respiratory system capacity. All of these outcomes might improve endurance-running performance, but research in these areas needs to be more fully developed.
Intermittent Hypoxic Training
The belief in the benefits of altitude training has led some exercise scientists to hypothesize that intermittent hypoxic training (IHT)—carrying out intense training at simulated altitude while living at sea level—is desirable. In IHT workouts, runners usually conduct high-speed intervals while wearing masks attached to devices that supply reduced-oxygen air. Research has failed to find a consistently positive effect of IHT on sea-level running performance, although IHT is probably beneficial for altitude exercise capacity.3, 4 In other words, IHT might prepare an athlete living at sea level for the rigors of altitude training but has little impact on running ability at sea level.
Intermittent Hypoxic Exposure
Altitude’s attractiveness has also led to the hypothesis that intermittent hypoxic exposure (IHE) while at rest—breathing in hypoxic air for 5 to 6 minutes at a time alternated with breathing normal room air for 4- to 5-minute intervals during sessions lasting a total of 60 to 90 minutes—can produce gains in athletic performance. In other words, an endurance runner might be able to sit around at home and magically breathe in fitness. Although hypoxic equipment suppliers widely tout IHE as a potent performance enhancer, there is no scientific evidence that it actually produces significant physiological changes or upswings in performances at sea level.5
Slower Training Paces at Altitude
It is often forgotten that living or training at altitude, despite its potentially positive impacts on O2max and nonhematological performance factors, almost inevitably leads to slower training compared with training at sea level. Take the case of an 18:36 5K runner, for example, who normally conducts his or her 800-meter interval training sessions at sea level in 3:00 each, right at 5K tempo. 5K speed ordinarily corresponds with an in
tensity of about 95 percent of O2max.
Now, put this runner in Kaptagat, Kenya, at an altitude of 2,438 meters (8,000 ft) to attempt the same workout. At this altitude, O2max will be reduced by about 8 percent or so compared with running at sea level. The runner’s 5K speed will remain linked with 95 percent of O2max, but now O2max has decreased by 8 percent, so 5K speed will drop by a similar amount. Although the runner will certainly try his or her best, the 800-meter intervals at Kaptagat will automatically slow from 3:00 per 800 meters to approximately 3:15 or so.
So what? Remember that a key development in endurance running is the discovery that an endurance runner is more than just a heart and a set of leg muscles: The runner has a nervous system, too. That is very important. If a runner’s neuromuscular system learns to handle and coordinate 3:15 per 800-meter tempo but fails to develop the capacity to function well at 3:00 per 800, that runner cannot optimize his or her ability to run an 18:36 5K. It will be easier to progress from 18:36 to even faster 5Ks if one is training at 3:00 per 800-meter tempo at sea level rather than a 3:15 pacing at altitude.
Running Science Page 26