Lactate Threshold

In last week’s blog post I mentioned that two new studies related to the phenomenon of VO2max had been published recently, and I described one of them, which showed that sustainable power declines more shallowly with increasing time in cyclists with higher VO2max scores. Today I’d like to tell you about the other study I alluded to, which sheds just as much light as the first on the phenomenon in question, but from a different angle.

This one was conducted by Benedito Denadai and Camila Greco of Paulista State University in São Paolo, Brazil, and published in the journal Current Research in Physiology. It was premised on the observation that, in any group of runners of different abilities, VO2max is a very good predictor of performance in races of any distance, whereas in a group of elite runners, VO2max has less predictive power at any distance. More specifically, in any mixed group of runners there will be a wide range of VO2max values, and those with higher values will tend to perform better in races of all distances. But among elite runners, VO2max values are relatively homogenous, and although some elites will perform better than others at either middle distances, long distances, or ultra-distances, few will perform better than others at all distances and the small differences in VO2max values among these runners fail to account for individual superiority at any distance.

This suggests that other components of fitness besides VO2max also make an important contribution to race performance, and that these components differ by race distance. The purpose of Denadai and Greco’s study was to identify these distance-specific contributors to race performance in elite runners. To fulfill this purpose, the two scientists conducted a retrospective analysis of data from past studies using elite runners as subjects. With the aid of sophisticated statistical tools that I don’t understand, they were able to evaluate the relative strength of each fitness component’s contribution to performance in races of various distances.

Here’s what they found: For 1500m specialists, velocity at VO2max (or vVO2max) is the strongest predictor of performance. A high vVO2max comes from having a high aerobic capacity and good running economy. At the 3000m distance, vVO2max and blood lactate response to exercise were coequal predictors of performance. Specifically, the velocity at which a runner’s blood lactate level reached 4 mM predicted performance as accurately as did their velocity at VO2max. This is not surprising, because the ability to attain high velocities at low blood lactate levels is also rooted in aerobic capacity. For runners specializing in the 5000m and 10,000m track events and the marathon, velocity at lactate threshold (2 mM) is the best predictor of performance. While related to velocity at 4 mM, this component of fitness is slightly different, having more to do with the ability to avoid producing lactate through aerobic metabolism at a high rate than the ability to metabolize lactate itself.

Velocity of lactate threshold is also the best known predictor of performance in elite ultrarunners, according to Denadai and Greco, but I say “known” because research on athletes in this category is sparse. I’d be willing to bet that respiratory exchange ratio (RER) is a stronger predictor of performance at ultra-distances than it is at shorter distances. RER is the velocity at which carbohydrate metabolism overtakes fat metabolism as the primary source of muscle energy and it comes from having a high fat-oxidation capacity.

Overall, the findings of this study underscore the need for limited specificity in training. To a great extent, fitness is fitness in running regardless of which race distance you specialize in. We see this in the fact that all elite runners have a high VO2max. Whether you race the 1500, 10K’s, marathons, or ultras, your training should focus on developing your aerobic capacity. However, fitness is not exactly the same across the spectrum of race distances. At each distance, athletes need a little more of certain fitness components, and a little less of certain others, than they do at other distances.

This is where specificity comes in. The hardest workouts a runner does in their heaviest period of training should simulate the specific demands of their event. For 1500m runners, short intervals (1-3 minutes) run at or near vVO2max fit the bill. For 3000m runners, such workouts should be coupled with somewhat longer intervals at a slightly lower intensity. For 10,000 specialists, long intervals and tempo efforts run between critical velocity and lactate threshold velocity are the best peak workouts. Marathoners should couple these workouts with sustained efforts run between half-marathon and marathon pace, and ultrarunners, of course, should make multihour long runs the hardest workouts they do in their heaviest period of training.

Ain’t science neat?

The lactate threshold gets so much attention in endurance sports that, despite its esoteric name, most athletes who have passed beyond the newbie stage are familiar with it. The term “lactate threshold” refers, of course, to the exercise intensity at which lactate, an intermediate product of aerobic metabolism, begins to accumulate in the bloodstream because the muscles are producing it faster than they can use it.

Simple enough. But when you drill down into the concept of the lactate threshold, things get messy. The first wrinkle is that there are numerous ways of defining the lactate threshold. Among them: the exercise intensity at which the blood lactate concentration reaches 4 mmol/L, the exercise intensity at which the blood lactate concentration begins to increase exponentially, and the exercise intensity at which the rate of blood lactate concentration’s rate of increase is greatest. No single definition of lactate threshold is inherently more valid than the others, and when they are applied to the results of a single lactate threshold test, they set the LT at slightly different levels.

A second wrinkle is that, even when you settle on a particular definition of lactate threshold, the specific testing protocol used to determine an individual athlete’s LT will affect the results. For example, an LT test with 4-minutes stages is likely to yield a slightly different result than an LT test with 2-minute stages.

A third wrinkle is that, because the lactate threshold is a metabolic event, it is affected by a variety of factors other than an individual athlete’s current fitness level, such as diet. If you do an LT test after a day of low-carbohydrate eating, you’ll get a different result than you will from an LT test done the day after high-carbohydrate eating.

Then there’s the question of the LT’s practical relevance. Contrary to pervasive beliefs in the endurance sports community, there is no sudden leap in the rate of fatigue when the lactate threshold exceeded. Athletes can sustain speeds/power outputs slightly above LT almost as long as they can sustain speed/power outputs slightly below LT. Nor is training precisely at LT uniquely beneficial. Training slightly above or slightly below this level produces pretty much the same results.

The ventilatory threshold is a different story. It is defined is the exercise intensity at which the breathing rate begins to increase at a faster rate than it does at lower intensities. The reason this happens is that the brain is required to begin to recruit large numbers of fast-twitch muscle fibers in order to meet the desired level of work output. This makes exercising even slightly above the VT is significantly more stressful to the nervous system than exercising even slightly below it. Consequently, training above the VT generates more fatigue and takes longer to recover from.

Research has consistently shown that endurance athletes at all levels gain the most fitness when they do about 80 percent of their training below the ventilatory threshold. Although supra-VT training is important and beneficial, athletes just can’t handle very much of it, whereas sub-VT training is so much gentler on the nervous system that athletes can handle a whole lot of it and must do a whole lot of it to realize its full benefits. The single most important thing you can do to keep your training on track is to know where your personal ventilatory threshold lies and is this knowledge to stay below it about 80 percent of the time.

Now, you might be wondering: If the ventilatory threshold is so much more reliable and important than the lactate threshold, why are our 80/20 training intensity zones based on lactate threshold? The short answer is “tradition.” The LT and the VT are measured in completely different ways. Direct measurement of the LT requires taking of small blood samples throughout an exercise test, whereas direct measurement of the VT is done through a method known as spiroergometry, which entails collecting and analyzing exhaled gases during exercise. It so happens that the LT was first identified in 1930 and the VT almost three decades later, in 1959. Having gotten a big head start, LT testing has remained the preferred method of quantifying moderate exercise intensity, despite its limitations. Hence, all of the commonly used field tests for establishing individual training intensity zones, including those that the 80/20 scale relies on, are designed to determine LT, not VT.

Because there is a mathematically consistent relationship between the two thresholds, however, LT tests can be used to determine VT as well, and this is precisely what the 80/20 zone scheme is set up to do. A new study conducted by Spanish researchers and published in Frontiers in Physiology found that, in a group of 22 trained male runners, the ventilatory threshold consistently fell slightly below the lactate threshold (actually the maximal lactate steady state, in this case) in terms speed, heart rate, and perceived effort, as shown in the table below (Note that MAS = Maximum Aerobic Speed, VT1 = Ventilatory Threshold, MLSS = Maximal Lactate Steady State, HRmax= Maximum Heart Rate, and VT2= Second Ventilatory Threshold, which is the exercise intensity at which hyperventilation occurs).

On the 80/20 intensity scale, the lactate threshold corresponds to the top end of Zone 3, which puts the ventilatory threshold in Zone X, which, in turn, ensures that when you train in Zones 1 and Zone 2—as you will do about 80 percent of the time when you follow one of our 80/20 training plans—you are at low intensity.

Having said all of this, I will also say I am hopeful that one day soon we will be able to develop a complementary alternative intensity scale that is anchored directly to ventilatory threshold testing. Currently I am trying out a wearable device that is capable of measuring the VT through accelerometer technology, specifically by measuring the rate and degree of lung expansion and contraction. Bending to tradition, though, the makers of this device are currently using the device’s VT estimates to determine LT. I’d like to talk them into providing users with their VT value instead, or additionally. Stay tuned.

I’m currently coaching a runner, we’ll call in Dylan, who’s training for the Berlin Marathon. Recently he asked me why I’ve had him run his recent marathon-pace efforts at 6:51 per mile (2:59 marathon pace) when he hopes and (more or less) expects to run closer to 2:50 in Berlin. His concern was that I judged his goal to be out of reach.

I assured Dylan that I do believe his goal is realistic, but that, for the most part, workout pace targets should be based on a runner’s current fitness, not on his goal time. Aiming for pace targets that are based on your goal is a bit like doing your workouts with another runner who’s a little fitter than you and trying consistently to keep up. Assuming the workouts this other runner is doing are appropriately challenging for him or her, then they are almost by definition too challenging for you. Sure, you may survive a few of them by treating them as quasi-races, but in the long run you’ll overcook yourself.

I then told Dylan a story that Ben Rosario told me when I was training under him in Flagstaff last summer. It came from Ben’s time as a member of the Brooks-Hanson team. In the leadup to the 2004 Olympic Trials Marathon, Ben and his teammate Trent Briney were in a small group of athletes aiming for the Olympic B standard of 2:18 (both Ben and Trent had marathon PR’s of 2:21 at the time). Training went especially well for Trent, and a few weeks before the race he asked coaches Keith and Kevin Hanson if he could move up to the 2:15 group, which included Clint Verran and Brian Sell. Feeling that Trent had earned it, the brothers approved the request. Trent’s training continued to go well and in Birmingham he shocked the running world by blasting a 2:12:34, finishing fourth.

Ben told me he was convinced that Trent would not have run this fast if he had trained for a 2:12 all along, nor perhaps even if he’d trained for a 2:15 from the beginning. It was because he was always chasing targets that were appropriate to where he was at each step that he scored his breakthrough. The reason he told me this story was that Ben intended to take the same approach with me during the 13 weeks I trained under him in Flagstaff. I willingly submitted to the plan, felt terrific through the entire process, and ran my own breakthrough marathon at the end of it.

So, that’s the principle: Train as the athlete you are today, not as the athlete you hope to be on race day. The devil, of course, is in the details. Putting this principle into practice requires that you have an accurate knowledge of your current fitness level on which to base workout pace targets. There are three general ways to gain this knowledge: experience, testing, and on-the-fly. They are not mutually exclusive.

Experience: If you’ve been running competitively for a while, you have at least a pretty good sense of where you are fitness-wise at all times. You can use this self-knowledge to estimate your current performance capacity and select appropriate workout pace targets. For example, suppose you’ve just come off a training cycle that culminated in a PR 3:27:43 marathon, taken a week off, spent two more weeks slowly easing back into training, and are now ready to begin ramping up for another marathon PR attempt. In this case, based on your knowledge of how much fitness you’ve given up in past scenarios of this type, you might estimate your current marathon performance capacity to be in the 3:42 range and base your initial workout pace targets on this estimate (using either my 80/20 Zone calculator or Greg McMillan’s Running Calculator).

Testing: Alternatively (or additionally), you can measure your current fitness level more formally by performing a time trial, going in for a lactate threshold test, getting a lactate threshold or VO2max estimate from a device such as a Garmin Forerunner, or racing. Bear in mind that it’s generally not a good idea to race too early in a new training cycle and that testing-based measurements become outdated as your fitness improves, so you will need a means of adjusting them that does not entail doing a race or time trial every weekend! To that end, keep reading.

On-the-fly: The on-the-fly method of setting workout pace targets consists of always doing workouts of a given time at the same effort level and allowing your numbers to slowly improve as you gain fitness. For example, early in a training cycle you might choose to target a pace of 6:56 per mile in a set of lactate threshold intervals based on either experience or testing. An appropriately designed and executed lactate threshold intervals session will feel “comfortably hard” and leave you tired but not exhausted. If you pay attention to your perception of workout and allow it to regulate your pace appropriately in all such workouts, you may automatically do the next workout of this kind in the cycle at 6:53 per mile, the next at 6:51, and so on.

Make sense?

We live in a highly individualistic society, a situation that has both pluses and minuses. On the plus side, our children tend to grow up with a sense of freedom to choose their own path in life. On the minus side, a growing percentage of us are burdened by feelings of loneliness and isolation that make us unhappy and have proven consequences for our physical health.

As an endurance coach and nutritionist, I see our society’s hyperindividualism manifest in a sense of exaggerated specialness and uniqueness. Take the “I can’t eat that” phenomenon, for example. Although food allergies, intolerances, and sensitivities are real, these conditions are claimed far more often in some societies and groups than in others—specifically in the most individualistic societies and groups. Asserting the need for a special diet is in many cases a way of asserting personal specialness.

Individualized approach to Endurance training

I see individuality overemphasized to some extent in the training realm too. In the 35 years I’ve been involved in endurance sports, I’ve observed a growing receptiveness to the notion that individual athletes training for the same event (e.g., a marathon) should do so in different ways based on genetic differences that affect how their bodies respond to various training stimuli. Contributing to this trend are studies such as one that was conducted by Canadian researchers and published on the online journal PLoS One in 2016, which found that when subjects were placed on an all-low-intensity exercise program for three weeks and, separately, on an all-high-intensity exercise program during a second three-week period, some subjects exhibited improved fitness only after the former and others only after the later, while only a few improved on both programs and no subject failed to improve on both.

Should we conclude from such findings that individual athletes should indeed take radically different approaches to training for races? I think not. The problem with a radically individualized approach to endurance training is that in essence it amounts to training for what you’re good at rather than training to be good at the specific event for which you are preparing. To return to our earlier example, a marathon is a very long race undertaken at a low to moderate intensity. No matter what your genetic makeup is, you won’t be optimally prepared to run a marathon unless your training features lots of running and frequent prolonged efforts at low to moderate intensity. Training for a marathon with a heavy emphasis on short, high-intensity intervals because you happen to be highly responsive to this type of training is only slightly less absurd than training for a marathon exclusively by chopping wood because testing has demonstrated that you are most responsive to this type of training.

But wait: If your body simply doesn’t adapt to low-intensity exercise, as the above-mentioned study suggests is the case for some individuals, then what benefit can these folks get from this type of training even if it is a marathon they’re preparing for? Good question, the answer to which is that of course every athlete really is capable of adapting to high-volume low-intensity exercise. The Canadian study cited above measured a few select variables such as VO2max and lactate threshold. But a marathon is not a VO2max test. So-called non-responders to low-intensity exercise who do not experience an increase in VO2max in response to this type of training but who do a bunch of it any way will undergo a host of other adaptations, including increased fat-burning ability and heightened resistance to impact-related muscle damage, that are crucial to marathon performance.

This is to say nothing of the neural and psychological adaptations. A runner who routinely does long training runs at low to moderate intensity will see improvements in central fatigue resistance and inhibitory control that he couldn’t gain any other way. Physiology aside, the experience of going long is an essential contributor to the capacity to go long.

The same principle holds for supposed non-responders to high-intensity exercise. A runner of this type who includes a small amount of high-intensity exercise in his training despite deriving no boost in aerobic capacity from it is sure to come away with other benefits, such as increased perceived effort tolerance, that will translate into better performance in real-world competition.

I don’t want to overstate my case. It is undeniably true that each athlete is unique and responds somewhat differently than do other athletes to the same training stimuli. But this individuality is itself overstated in some quarters, and again, even to the extent that athletes are different they must consider the specific demands of the event they’re preparing for before they consider their particular athletic type in deciding how to train.

The proper way to individualize training, therefore, is not to start from scratch with each athlete, inventing from whole cloth the method that is uniquely optimal for that individual. Rather, all athletes should begin by training with the methods that have proved most effective with athletes generally (80/20, etc.) and then fine-tune their formula based on how their body responds to these methods. And fine-tuning never means replacing running with chopping wood.

Most runners target a single intensity in all of their workouts. Either it’s an easy run or long run at a slow and steady pace or a tempo run with an effort at lactate threshold intensity sandwiched between a warm-up and a cool-down or an interval session featuring a set of a certain number of repetitions of uniform length or duration all done at the same high intensity or—you get the idea. But there is something to be said for doing the occasional workout that includes a range of different intensities.

First of all, multi-pace workouts are a literal change of pace, and as such they’re an effective way to keep your training fun and interesting. Multi-pace workouts are also a good way to get appropriate doses of different intensities. For example, if you’re at a point in your training where you can benefit from a little work at VO2max intensity—but only a little—why set aside an entire workout for it when you can incorporate that work into a session focused on an intensity you need more of—say, lactate threshold intensity?

Yet another benefit of multi-pace workouts is that they help teach effective pacing. Can you shift accurately from half-marathon pace to 10K pace to 5K pace by feel? Most runners can’t, but runners who do workouts that include efforts at all three of these paces can. Finally, multi-pace workouts that put the fastest work at the end develop the capacity to dig deep and finish strong in races.

Here are three multi-pace workouts to try:

3 Multi-pace workouts to try

Intervals + Time Trial

This type of workout serves most of the purposes mentioned above. The interval segment provides the primary training stimulus and it should target a high aerobic intensity close to the lactate threshold. The closing time trial should be fairly short in order to serve the purpose of providing a modest exposure to VO2max and to get you suffering a bit. As a whole, an Intervals + Time Trial workout is very taxing and you shouldn’t attempt them very often. The specific session described below is one I did with NAZ Elite during my time in Flagstaff.

1-3 miles of easy jogging

Drills and strides

7 x 1 km @ lactate threshold pace with 1:00 standing recoveries (2:00 after the last rep)

1500-meter time trial

1-3 miles of easy jogging

30-20-10 Run

A few years ago, a team of Danish researchers led by Jens Bangsbo set out to see if they could come up with a high-intensity interval workout that was more enjoyable than standard formats without being less effective. They tested a variety of designs before settling on one that fulfilled their hopes: the 30-20-10 Run. After learning about it, I gave it a try, made a couple of tweaks, and started incorporating the workout into the training plans I create for my clients. I like to schedule 30-20-10 runs during recovery weeks and during the final weeks of preparation for longer races as a way to expose athletes to a range of intensities without making them go to the well. This workout is also a great way to teach better pacing. Here’s the basic format:

1-3 miles of easy jogging

5 x 1:00 with the 30 seconds at marathon pace, the next 20 seconds at lactate threshold pace (i.e., the fastest pace you could hold for one hour), and the last 10 seconds at a relaxed sprint. No recovery—just cycle right into the next interval until you’ve completed all five.

Complete three cycles of five 30-20-10 intervals with 5 minutes of jogging after each.

1-3 miles of easy jogging

Tempo + Sprints

As a long-distance runner, you should sprint, but not a lot. Because any sprinting you do in a race is likely (one hopes) to occur at the very end of a race when you’re tired, it makes sense to sprint on tired legs in training. In the Tempo + Sprints workout, you will do just that.

1-3 miles of easy jogging

Drills and strides

20:00 at lactate threshold pace

2:00 standing recovery

8 x 200-meter relaxed sprints with recovery by feel (i.e., go again when you’re ready)

1-3 miles of easy jogging

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