This tempo can be immediately put to use in training, for example by running 400-meter intervals in 83 seconds.
Improving vO2max and Running Economy
Once vO2max tempo is determined, appropriate workouts that advance vO2max can be created. As discussed in chapter 9, Billat and her colleagues at the University of Lille, the Center of Sport Medicine, and the National Center of Health in France made a head start on this process when they asked eight experienced runners to take part in 4 weeks of training that included one interval session based on vO2max per week.2 The vO2max tempo for these athletes was 72 seconds per 400 meters, and the interval workout created by Billat was simply 5 × 1,000 meters in 3 minutes each, with 3-minute, easy jog recoveries. (In vO2max sessions, recovery durations are always equal to work-interval periods.) Covering 1,000 meters in 3 minutes involves running at exactly 72 seconds per 400-meter tempo.
vO2max training cannot exist in a vacuum; it is always blended with easy sessions and other quality workouts. In Billat’s research there was one other quality workout during each week of training: a session that included two long 20-minute intervals at 85 percent of vO2max. If vO2max happened to be 20 kilometers per hour (5.55 m/sec), the speed for this long-interval sessions was 85 percent of that, or 17 kilometers per hour (4.72 m/sec, or about 5:40 per mile). There was a 5-minute, easy jog recovery between the two 20-minute intervals. All other sessions were conducted at an easy pace.
Although O2max did not budge at all over the 4-week training period, vO2max rose by 3 percent from 20.5 kilometers per hour to 21.1 kilometers per hour. This indicates that the economy factor in vO2max was the key mechanism by which vO2max improved, not the aerobic capacity factor. In other words, after the vO2max training period, the runners were able to run faster while using the same internal oxygen-delivery system as before.
Indeed, running economy improved by an astounding 6 percent in Billat’s research. This 6 percent gain in economy is particularly impressive. In scientific research carried out to explore the effects of different kinds of training on economy, the observed gains in economy have usually been far less than the one induced by Billat and her colleagues with the vO2max-based training. For example, enhancements of economy associated with hill work or strength training are usually in the 3 percent range.
To see if more would be better, Billat and co-workers put their eight athletes through 4 additional weeks of training, but this time the runners carried out three interval sessions at vO2max each week, again using the 5 × 3 minute protocol but at the new vO2max established after the initial 4 weeks. The workout at 85 percent of vO2max and easy runs were blended with these torrid sessions.
The next 4-week follow-up revealed that more vO2max training is not always better. This major increase in vO2max work served primarily to increase muscle soreness and blood levels of norepinephrine, a stress hormone, and decrease the runners’ quality of sleep. In addition, vO2max, running economy, and lactate-threshold speed all refused to improve in the face of the trio of weekly vO2max sessions. A logical conclusion is that about one vO2max session per week may be optimal for upgrading vO2max in experienced runners, while three such sessions represent overkill.
30-30 Workouts
Working under the reasonable assumption that the completion of more vO2max running per workout could be productive, rather than more vO2max workouts per week, Billat began experimenting with different work-interval lengths. In a follow-up study, Billat and her co-researchers asked the runners to complete vO2max sessions that consisted of 30-second intervals at vO2max instead of the classic 3-minute durations.3 The runners warmed up with 15 minutes of easy jogging and then alternated 30-second work intervals at vO2max with 30-second recoveries at 50 percent of vO2max, sustaining this pattern for as long as possible. A runner with a vO2max tempo of 78 seconds per 400 meters would have been covering 154 meters in each 30-second interval. (Calculate this distance by dividing 30 by 78 and then multiplying by 400.)
The runners also employed a second kind of quality workout in this follow-up investigation: a continuous run, sustained for as long as possible, at a velocity of about 91 percent of vO2max. During the 30-second interval workout, the athletes were running at an average tempo of 78 seconds per 400 meters, broken up into 30-second chunks with 30-second breaks; in the continuous session the runners moved along at a pace of 85 seconds per 400 meters, without stopping, until fatigue brought the effort to a halt. The athletes conducted both sessions on a synthetic track while breathing through portable, telemetric, metabolic analyzers that allowed Billat to determine their actual rates of oxygen consumption.
Although short intervals are sometimes criticized by coaches as nonspecific, that is, too far removed from competitive situations, the 30-30 workout appeared to offer some unique advantages. The average number of work intervals completed prior to the onset of exhaustion was 19, which meant that 9.5 minutes of quality running were completed. Out of this 9.5-minute total, 7 minutes and 51 seconds (83 percent of the total quality time) were actually spent at O2max. If this seems confusing, remember there is a lag time in oxygen-consumption rate. Even if one begins running at vO2max (a velocity), it takes a while for the oxygen-consumption mechanisms to kick into gear and begin operating at the highest-possible level; as a result, the attainment of the maximal rate of oxygen consumption is delayed.
In contrast, the continuous run at 91 percent of vO2max lasted for an average of only 8 minutes and 20 seconds and featured a total time of less than 3 minutes at the maximal rate of oxygen consumption. Overall, 309 more seconds were spent at O2max during the 30-30 effort compared with the sustained running.
Readers should not worry too much about why a continuous run at only 91 percent of vO2max was nonetheless able to produce the maximal rate of oxygen consumption, which one might expect to be reached only at speeds of 100 percent of vO2max and above. This attainment of O2max at velocities less than vO2max is due to the slow component of oxygen usage during sustained running and should not be concerning here.
A remarkable feature of the follow-up investigation was that three of the eight runners were able to continue with the 30-30 intervals for a long period of time, completing as many as 27 of the 30-second work intervals at vO2max. The completion of 27 work intervals was linked with spending 18.5 minutes at the maximal rate of oxygen consumption, or O2max. This may appear to be a paradox, since only 13.5 minutes (27 × 30 seconds) were spent at vO2max, but it is important to note that the runners often sustained maximal aerobic capacity during the 30-second recovery intervals, too, even though they were running at an intensity of only 50 percent of vO2max! The reason for this is that there is another physiological lag occurring: the runners’ bodies take longer than 30 seconds to downshift oxygen usage after their running paces slowed. This is important because many exercise physiologists believe that the total time spent at the maximal rate of oxygen consumption is an important indicator of workout value.
The 30-30 workout can thus be a powerhouse, and—anecdotally—it is tolerated very well by runners, even by rather inexperienced runners who tend to struggle with the classic 5 × 3 minutes session. In another piece of research carried out with modestly fit physical education students, Billat revealed that using 30-30 workouts twice a week can boost O2max by 10 percent in just 8 to 10 weeks.4 Billat recommended using the 30-30 session early in the season as an excellent, easily tolerated way to kick-start improvements in O2max, vO2max, running speed, and lactate-threshold speed.4
After about 4 weeks of 30-30 training, a runner could progress to 60-60 workouts, with 60 seconds at vO2max and 60 seconds of easy jog recovery. After another 4 weeks or so of 60-60, the runner could make the jump to 5 × 3 minutes, which is often considered the ultimate vO2max session. The average amount of time spent at maximal aerobic capacity during the 5 × 3 is around 10 minutes, about 25 percent more high-octane time compared with the average 30-30 session.4 Thus, moving from 30-30 up to 5 × 3 appears to be an excellent training progression.
; Note that some runners may run uniquely well with the 30-30, however. As mentioned, some of those in Billat’s research were able to complete 27 intervals during a 30-30 session, resulting in 18.5 minutes at a maximal rate of oxygen consumption. Even if such a runner spent all 5 × 3 work intervals at a maximal rate of oxygen consumption, it is unlikely that the runner would be able to amass as much time at O2max.
TlimvO2max Approach
Although the Billat vO2max formula—30-, 60-, and 180-second intervals at vO2max, with recoveries equal in duration to the intervals—is often considered to be the gold standard for vO2max-boosting training, there are cases when runners may profitably diverge from this path. Work carried out by Tim Smith and colleagues at the School of Human Life Sciences at the University of Tasmania in Australia suggests that modest expansion of vO2max work-interval length may produce striking gains in fitness.5
To enhance understanding of this Australian research, it is important to focus on the variable tlimvO2max, which is the amount of time a runner can sustain vO2max. The average tlimvO2max for all of the human runners on planet earth is 6 minutes; that’s why Billat recommends the use of the 6-minute vO2max test. For the majority of runners, the pace established in the 6-minute test will be very close to vO2max and thus is quite usable for vO2max training. However, individual runners may have readings of tlimvO2max that stray considerably from the 6-minute average. In fact, there is good reason to believe that the shortest tlimvO2max in the world is around 4 minutes and the longest is about 10 minutes. As you might expect, tlimvO2max is not a bad predictor of performance in its own right: Runners with longer values of tlimvO2max tend to fare better in competition than runners with similar vO2max values but shorter tlimvO2max values. Thus, tlimvO2max is an indicator of one’s ability to sustain a scalding running pace like vO2max.
Note, however, that the tlimvO2max situation has the potential to create troubles for some runners who can’t measure their vO2max values precisely in the laboratory—in other words, almost everyone. The trouble can come this way: Let’s say that your tlimvO2max is actually 4 minutes, but you take the 6-minute test. Since by definition you can only handle vO2max for 4 minutes, the pace established in your 6-minute test will be slower than your true vO2max; your subsequent training, revolving around the results of the 6-minute test, will actually focus on a sub-vO2max intensity instead of on the real result. The good news is that your training will still be high in quality, and eventually your tlimvO2max should climb toward at least the 6-minute mark, especially if you use longer work intervals of about 180 seconds rather than 30 seconds, for example. The reasoning here is that these longer intervals can compensate a bit for the lower intensity by allowing oxygen-consumption rate to climb. Thus, on subsequent vO2max re-tests, the pace you establish for 6 minutes should be closer to your real vO2max.
Alternately, if your tlimvO2max is really 10 minutes and you take a 6-minute test, you will probably run faster than your vO2max during the 6-minute effort, and your subsequent training will be above your real vO2max. The good news here is that these sessions might be better at augmenting your maximal running speed, which is also a good predictor of performance compared with vO2max exertions, and the sessions will also augment vO2max, lactate-threshold speed, and running economy.
In the Australian research, nine runners were asked to complete their weekly vO2max interval workouts with a work-interval duration of 60 percent of tlimvO2max instead of the usual 50 percent (the Billat formula centers on a 6-minute test ultimately followed by 3-minute work intervals with 3 minutes being 50 percent of the 6-minute tlimvO2max). Nine other runners were required to be even more courageous with work-interval lengths of 70 percent of tlimvO2max. The nine control competitors completed no work at vO2max and focused on moderate-intensity, long-duration running. All the runners were monitored over a 4-week period, and those running at 60 percent and 70 percent tlimvO2max completed two interval sessions at vO2max each week. The hitch was that the 60-percent athletes performed six work intervals at vO2max per session while the 70-percent runners conducted only five intervals per workout; the idea was that the 70-percenters were compensating for their reduced number of intervals by running longer per interval. In a departure from the classic Billat method, recovery intervals were twice as long in duration as the work intervals.
After 4 weeks and eight total interval workouts with the intensity set at vO2max and work-interval length at either 60 percent or 70 percent of tlimvO2max, only the 60-percent group had improved 3K (1.9 mi) race times significantly, enjoying a nice 18-second upgrade compared with just 6 seconds of improvement in the 70-percent group (not statistically significant) and a half-second improvement for the controls. In addition, tlimvO2max was significantly higher than before in the 60-percent group after 4 weeks of training—23 percent (50 seconds) higher—but had not improved for the other two groups of runners.
Why did the group running at 60 percent of tlimvO2max fare better than the 70-percent group? A key problem for the runners at 70 percent of tlimvO2max was that they were more likely to be unable to fully complete their work intervals compared with the group at 60 percent of tlimvO2max. In fact, the 70-percent group completed just 86 percent of its required interval time compared with the 96 percent completed by the 60 percent group; this meant that the 60-percent group spent about 768 seconds running at vO2max per vO2max workout, compared with just 655 seconds per workout for the 70-percent group. To put it simply, it is very difficult to rack up five complete intervals at vO2max within an interval workout when the work-interval duration is set at the rather-expansive 70 percent of tlimvO2max.
This Australian research reveals that 4 weeks of twice-a-week vO2max training can raise tlimvO2max and improve 3K (1.9 mi) performances to a substantial degree in already well-trained runners and does not elevate the risk of overtraining. The runners were monitored closely for fatigue, sleep quality, stress, and muscle soreness to determine whether the high-intensity vO2max training was pushing them toward the overtrained state. Secondly, 60 percent of tlimvO2max is a viable work-interval length for vO2max training. With 60 percent of tlimvO2max, the runners were able to complete 96 percent of their prescribed work-interval running. If tlimvO2max is assumed to be 6 minutes, this would mean pushing vO2max work-interval length to 3:36 instead of Billat’s standard of 3 minutes.
Conclusion
The bottom line? Runners should be progressive with their vO2max workouts, gradually working their way from 30-30 sessions up to Billat’s standard of 5 × 3 minutes and then to the Australian goal of 6 × 3:36. As long as runners are progressing with their vO2max sessions (i.e., from shorter to longer work intervals, from fewer to more work intervals per session, from an occasional vO2max session to one or two such efforts per week), the gains in fitness that accrue from vO2max training will be sizable. And vO2max training can be conducted year-round: It is so potent, and works so effectively for runners of all ability levels, that it would be absurd to confine it to short 4- to 6-week blocks, or mesocycles, of training.
Chapter 27
Upgrading Lactate Threshold
As outlined in chapter 10, running velocity at lactate threshold is an important predictor of performance at distances ranging from 800 meters to 100K (62.14 mi). This variable is simply the running speed above which lactate begins to accumulate in the blood. Running velocity at lactate threshold predicts performance so well because lactate—far from being a runner’s nemesis—is actually a key fuel that provides the energy needed to run far and fast. When running velocity at lactate threshold is high (i.e., at a good speed), the runner has an outstanding ability to break down lactate for energy inside muscle cells and also a powerful capacity to remove lactate from the blood and use it to create propulsive force.
Approaches for Optimizing Running Velocity at Lactate Threshold
As described in chapter 10, scientific research indicates that there are two somewhat different ways to approach optimizing running velocity at lactate threshold.
First, it is reasonable to train in ways that enhance muscle cells’ oxidative energy systems, including their ability to take oxygen from the blood and use it to break down lactate at high rates. Of course, if lactate is broken down extremely rapidly, lots of energy will be produced, relatively modest amounts of lactate will be spilled into the blood, and the runner with such characteristics will be a highly fit, fast competitor with a high running velocity at lactate threshold. Enhancing the oxidative energy systems involves boosting the concentrations of aerobic enzymes inside muscle fibers and augmenting the number of mitochondria within muscle cells.
The second approach to optimizing running velocity at lactate threshold, however, is quite different: It focuses on expanding the abilities of the heart and muscles to clear lactate from the blood. Lactate levels in the blood, and thus the running velocity at lactate threshold, are the result not only of the appearance of blood lactate (i.e., the rate at which lactate spills out of muscles into the bloodstream) but also the disappearance of lactate from the blood (i.e., the rate at which the muscles and the heart pull lactate out of the blood plasma). For many years, exercise scientists were not certain that it would actually be possible to improve the ability of muscles to seize large quantities of lactate from the blood and then break down the lactate for energy. However, in 1993 a study carried out by lactate expert Arend Bonen and his research group at the University of Waterloo in Ontario, Canada, showed that muscle fibers could indeed develop the capacity to clear lactate from the blood at advanced rates if the training stimulus was appropriate.1 At that time, however, no one knew how the muscles were actually transporting the lactate inward.
In 1996 Bonen and his research team discovered a unique muscle protein called MCT1 (for monocarboxylate transporter 1). Bonen and colleagues were able to show that MCT1 is indeed a lactate transporter, moving lactate directly into muscle cells where it can be metabolized for energy.2 MCT1 is found on the outer edges of muscle membranes where it can come into direct contact with lactate. As MCT1 concentrations advance, lactate-disappearance rates increase correspondingly, and running velocity at lactate threshold also improves.3 Thus, MCT1 optimization should be a key goal of lactate-threshold training. MCT1 levels are so important that MCT1 concentration in the muscles can actually be an excellent predictor of resistance to fatigue and endurance performance.4 (Don’t worry, though. We won’t add it to our already rather extensive list of seven key performance enhancers.)
Running Science Page 38