80/20 Rule

I am often asked if the 80/20 rule of intensity balance applies to athletes who train at very low volumes. It’s a fair question. We know that low-intensity exercise doesn’t do a lot of good in small amounts, whereas high-intensity exercise does. It is plausible therefore that, below a certain volume threshold, doing less than 80 percent of one’s training at low intensity will yield better results than sticking to the 80/20 rule.

A new study by Luca Festa of the University of Verona and colleagues addresses this question—sort of. The subjects were recreational runners with at least four years of experience. For eight weeks, half of them followed a “polarized” training program in which 77 percent of training was done at low intensity, 3 percent at moderate intensity, and 20 percent at high intensity, while the other half maintained a 40/50/10 intensity split (“focused endurance training”). Volume was adjusted to ensure that the total training load (intensity and volume combined) was equal for the two groups. This required runners in the polarized group to run slightly more than runners in the focused endurance group, though volume was quite low in both groups, averaging out to 3.73 hours per week and 3.1 hours per week, respectively.

Physiological and performance measures were taken on all of the subjects before and immediately after the eight-week training intervention. The table below summarizes the results.

Polarized Focused Endurance
Fat Mass -12.7% -8.6%
VO2max +1.2% +0.9%
Velocity at VO2max +3.2% +4.0%
Running Economy +5.3% +7.0%
Average Velocity in 2K time trial +3.5% +3.0%

As you can see, they’re kind of a mixed bag. The polarized group saw bigger improvements in body composition, VO2max, and (what is arguably the only result that matters) time-trial performance, while the focused endurance group experienced bigger gains in running economy and velocity at VO2max. None of these differences was judged to be statistically significantly, however, so Festa’s team concluded that “Focused Endurance Training obtains similar improvements [as] Polarized Endurance Training[,] saving 17% of training time in recreational runners.”

There you have it: 80/20 training is a waste of time. You get equal results in less time by doing half of your training at moderate intensity, which is precisely the opposite of what 80/20 advocates like me tell athletes not to do.

But wait—there’s another interpretation. Remember the commonly asked question I mentioned at the top of this article? We started out with the premise that it is likely that, below a certain threshold of training volume, an 80/20 intensity balance might not yield optimal fitness benefits. The results of Festa’s study suggest that this threshold is very low indeed, if indeed it exists at all. Members of the polarized group and the focused endurance group ran just 32 minutes and 27 minutes per day, respectively, during the eight-week study period, and improved by roughly equal amounts. So it’s safe to say that you would have to run less than 25 minutes a day, on average, for a more intense training approach to possibly produce better results than the 80/20 method, emphasis on “possibly.”

It’s also worth drawing attention to the fact that the only performance test included in Festa’s study was a 2 km time trial. That’s pretty short. Why 2 km? Because Festa and his colleagues wanted to set up the focused endurance group for success, that’s why! Clearly, a short performance test was going to give the group doing shorter runs the best chance of equaling the improvement of the other group. Even then, though, the polarized group improved slightly more. And although the difference was statistically significant, meaning it could have happened by chance, I’d be willing to bet that if this same experiment were rerun 100 times, the polarized group would improve more with a frequency that exceeded chance, hinting at the beginning of a trend that would only grow as the distance of performance tests increased.

Furthermore, although Festa’s study itself was quite short, its brevity was appropriate in the sense that it doesn’t take long for a training program of such low volume to yield the full measure of its potential benefits. In other words, had the experiment lasted longer, it’s unlikely that either group would have improved much more. But suppose you were to actually follow one of the two programs involved in this study, getting whatever benefit you could squeeze out of it in 8-10 weeks, and then decided that you wanted to improve more going forward.

Here’s what would happen: If you were on the focused endurance plan and you proceeded by gradually increasing the volume of training you did at the same 40/50/10 intensity ratio, you would gain fitness at a gradually decreasing rate for a little while before reaching a point of negative returns at a still fairly modest volume level. That’s because any training done above the first ventilatory threshold—whether moderately intense or highly intense—is significantly more stressful to the body than training done below the VT1, and on this program you’re doing 60 percent of your total running above that threshold. Festa’s team collected data on perceived effort from their subjects but did not report it, and again, I’d be willing to bet that members of the focused endurance group perceived their training to be harder than members of the polarized group perceived their training to be, even though mathematically their training loads were equal.

But if instead you went through the same process on the 80/20 program, you would continue to improve for a very long time, albeit at a diminishing rate, not reaching the point of negative returns until you’re doing a ton of running. And that’s because training below the first ventilatory threshold is so gentle on the body that even the average athlete can handle (and benefit from) massive amounts of it. I would only add that, whereas in this study almost all of the 20 percent of training done above the VT1 was done at high intensity, a runner training at ever-increasing volumes would be wise to gradually shift minutes from the high-intensity bucket to the moderate-intensity bucket as volume grew.

Festa and his colleagues admit that it is a well-established fact that an 80/20 intensity balance provides the best possible results for athletes who train a lot, writing, “several studies have shown that it allows them to achieve greater improvements in performance,” and that “this distribution is necessary for athletes who perform a large volume of training, to prevent overtraining or steady state of performance.” What this new study shows is that the 80/20 approach is also at least as effective as a more intense training approach at a very low training volume of around 30 minutes a day. In other words, the title of this article is a joke.

Originating in ancient Samaria more than 4,000 years ago, the seven-day week has become a standard calendrical feature throughout the world. Most athletes in most sports adhere to this convention as well. I recall noting this during my time with the HOKA Northern Arizona elite professional running team in 2017. Unlike the majority of us, who have to balance training with school attendance, office jobs and such, the gifted young members of this club didn’t have to do their long runs on Saturday or Sunday, yet they did anyway.

The number seven is not arbitrary. By this I don’t just mean that seven days is the length of each of the four lunar phases. After all, the ancient Samarians didn’t have to base their calendar on the moon. One “sabbath” every seven days is also about the right frequency of rest to keep laborers from breaking down or going crazy. (Two-day weekends are a relatively new convention, remember.)

Endurance sports training is another kettle of fish, however. In the labor realm, the goal is to get by, resting often enough to keep muddling along through life. With endurance sports training the bar is higher. The goal is not only to rest with optimal frequency for physiological recovery but also to expose the body to the various types of training stimuli with the optimal frequency to maximize event-specific fitness for competition. Who’s to say that once every seven days is the optimal frequency for long runs, for example?

Well, real-world evidence suggests that, with appropriate attention to the details, a seven-day microcycle can work extremely well. At the elite level, virtually every great performance ever achieved in endurance sports was achieved by an athlete who trained on a seven-day microcycle. There are exceptions, such as Paula Radcliffe’s recently eclipsed marathon world record of 2:15:25, which capped a training cycle made up of Paula’s preferred eight-day microcycles. But these exceptions are certainly no basis to conclude that longer microcycles are somehow better.

Aging endurance athletes who find they don’t recover from big workouts as quickly as they once did often wonder whether they should lengthen their microcycles as a way to spread these workouts out a bit, and some actually follow through. But there are other options. At age 49, I myself do not recover from big workouts as quickly as I once did. What’s more, as a self-employed work-from-home type, I have the freedom to do any type of workout on any day of the week. Yet I’ve chosen to keep doing my longest rides and runs on the weekend, for the most part, and am adapting my training to my changing body not by lengthening my microcycles but by doing smaller big workouts.

For example, recently I did the following session: 2-mile warm-up, 3 x 1 mile descending on 1:00 rest, 2-mile cooldown. In the past, any time I did mile repeats I did at least six of them. My thinking was that if my body wasn’t up to doing six to eight times one mile fast, then it wasn’t up to doing mile repeats at all. But I’ve since discovered, through trial and error, that a little bit of speed work is way better than none, and also that, the older I get, a little speed work is also better than a lot! I still do some giant workouts, but sparingly, and almost always on the weekend.

The general point I’m trying to make is that there are enough other levers to pull that virtually any runner of any age can make a seven-day microcycle work more or less optimally. But this is not to say that an extended microcycle can’t work just as well or better in certain cases. For those whose life schedule permits it, a nine-day cycle in which each a hard session of any type is followed by two easy days establishes a nice, sustainable rhythm. Not infrequently, I hear from masters athletes who have purchased one of our 80/20 training plans and report feeling overwhelmed by its seven-day microcycles. “How do I extend my weeks without spoiling the 80/20 intensity balance?” they ask. An impish impulse inside me always imagines the following exchange before I answer for real:

Q: How do I turn this pizza into a cake?

A: Throw out the pizza and bake a cake.

Seriously, though, microcycle length is such a fundamental ingredient of training plan design that it’s almost impossible to retrofit a plan built with microcycles of one length to accommodate extended weeks. I mean, you can do it, but to do it right you have to change so much that you really are just starting over the hard way. But let’s say for the sake of argument that you’ve purchased a plan and you find that, although you can handle even the most challenging workouts, they come at you too quickly for you to stay on top of your recovery, and for whatever reason you insist on adapting the plan you have rather than starting over. In this scenario, I would suggest rearranging the workouts in the plan to fit into the following framework:

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 Day 9
High Intensity Easy Easy Moderate Intensity Easy Easy Endurance Easy Easy

From here, the devil is in the details. For example, after taking this step, you may find that you recover more quickly from moderate-intensity workouts than from high-intensity workouts, and/or that you can handle bigger moderate-intensity workouts than you can high-intensity workouts, hence that your plan requires additional fine-tuning to yield optimal results for you.

If you’re a triathlete who trains in three disciplines and exercises twice a day some days, you will have some decisions to make about how to make the above framework accommodate these exigencies. I would recommend as a starting point that you count all swims as easy sessions, because they really are, and alternate hard days between cycling and running, as in this example:

Day 1 Day 2 Day 3 Day 4 Day 5 Day 6 Day 7 Day 8 Day 9
High Intensity Bike Easy Run Swim Moderate Intensity Run Easy Bike Swim


Endurance Bike Easy Run Swim

Any additional easy rides or runs you might wish to do can slot in wherever. Or you can just hired me to create a custom training plan for you with extended microcycles, which I would be more than happy to do.

The question that serves as the title of this article is one that comes up often in discussions of the 80/20 method of endurance training. It’s a natural question to ask. Common sense suggests that a person can make up for exercising little by exercising hard. Heck, there’s no bigger proponent of the 80/20 approach than me, and even I would admit that if you’re only going to exercise for five minutes at a time, three times a week, you’d be wise to spend most of that time at high intensity.

But what about more realistic scenarios? As far as I know, there are no endurance athletes who train just five minutes a day, three times a week. There are, however, some who train less than everyone else. Is it right to advise these athletes to follow the same 80/20 approach that is known to work best for moderate- to high-volume athletes? 

Science has not yet pinned down this threshold definitively. The best evidence we have comes from a 2014 study conducted at the European University of Madrid, which found that recreational runners who trained just under four hours per week for 10 weeks improved their 10K time more with an 80/20 intensity balance than they did with a more intense training program. These results indicate that if there is a threshold of training volume below which an 80/20 intensity balance is less effective, it’s probably lower than 33 minutes of exercise per day.

Just for the sake of argument, let’s say the bar is only slightly lower—perhaps 25 minutes a day. I’ve got to say it, folks: If you’re not willing to train 25 minutes a day, why the heck do you even want to be an endurance athlete? I’m sorry if this sounds snarky, but I really mean it. The World Health Organization recommends that people get at least 150 minutes of vigorous physical activity per week if they wish to maximize the basic health benefits of exercise. So, even if you have no interest in participating in endurance races but simply want to live a long and healthy life, you should be working out about 21.4 minutes per day (give or take). And, for all we know, even at that level you will gain the most fitness from an 80/20 intensity balance.

While we wait for science to nail down the threshold below which an 80/20 intensity balance is no longer optimal, we have real-world evidence to hold us over. You don’t have to have been coaching as long as I have to realize that there’s only so much improvement you can gain from training harder versus more, and that a ball-busting 20-minute interval workout can’t really substitute for a 20-mile run. But don’t take my word for it. There’s no greater expert on this subject than Stephen Seiler, the exercise physiologist who discovered the 80/20 rule. Recently I emailed Stephen to ask the question that serves as the title of this post, and here’s how he responded:

Yeah, that is a good question, meaning that I have no data to throw down here. I think when you get down in that two to four training sessions per week range, there are a number of ways to optimize. For example, at three days a week, I would shoot for two low-intensity and one high. But I would really try to stretch the duration as much as possible on one of those low-intensity workouts. So, for a lot of people, that itself would make that low-intensity session pretty tough.

At four days a week, I would experiment with three low and one high versus two low and two high(-ish). My gut says that at four days a week (Monday, Wednesday, Friday, Saturday, for example), the athlete might benefit from doubling up and making that Friday some kind of HIT session, then doing a “long” low-intensity session the next day. That would perhaps help to optimize the adaptive signal of that long session due to muscle glycogen levels being still depressed.

If I could only train two times a week, I would probably end up combining some high intensity and low-intensity work in both sessions, aiming to try to stimulate every muscle fiber I could, as much as I could!

All of this sounds pretty sensible to me, and if you turn Stephen’s ideas into percentages, you’ll find that only at two days per week are we looking at an intensity balance that doesn’t hew pretty close to 80/20. And again, if you’re only going to practice your sport twice a week, may I suggest golf or skiing rather than long-distance running or triathlon?

Unless you fell onto this blog through a trapdoor and you have no clue what you’re doing here, you know that I am a proponent of the 80/20 training method, which entails spending about 80 percent of your training time at low intensity and the rest at moderate and high intensities. This does not mean that I believe every athlete should always do exactly 80 percent of his or her training at low intensity. There are more general, non-quantitative ways of stating my core philosophy of endurance training that do a better job of getting at its essence. For example:

Intensity balance is the single most important variable in endurance training. The single most beneficial thing you can do in your training is to consistently maintain an intensity balance that is heavily weighted toward low intensity yet does not neglect high intensity. The single most common and costly mistake that endurance athletes make in training is to spend too much time at moderate intensity, way too little time at low intensity, and also too little time at high intensity.

These statements are strongly supported by both real-world evidence and scientific research, and the last of them in particular has gotten further scientific support from a cool new study published in The Journal of Strength and Conditioning Research. Conducted by a team of researchers at Belgium’s Ghent University led by Jan Boone, the study involved 11 recreational cyclists training for a mountain-climb event. Over a 12-week period, each subject trained as he or she saw fit while wearing a heart rate monitor to collect data that was then passed on to the researchers. Before and after this 12-week period, all of the subjects underwent testing to assess various aspects of their fitness level.

The main purpose of the study was to test the power of certain ways of measuring training load to predict changes in fitness. Training load is a function of both the volume and the intensity of training. Because there was a great deal of variation in the volume and intensity of the training that the 11 cyclists involved in this study did in preparation for the mountain-climb event, it was expected that there would also be significant inter-individual differences in the amount of fitness they gained. What remained to be seen was how well the four ways of quantifying training load that were being put to the test in the study were able to account for these differences.

I don’t want to get too deep into the mathematics involved. If you’d like to go deeper on your own, open up a web browser and run a Google search on training impulse (TRIMP), of which there are four competing versions. These four methods of calculating TRIMP were the specific tools used by Boone’s team to quantify training load. What’s important to know is that all four of them allow athletes to achieve equal training loads, hence equal levels of predicted fitness, through different combinations of volume and intensity. For example, a cyclist who increases the average intensity but not the volume of his training might end up with the same TRIMP score as a cyclist who does the reverse. The Ghent researchers questioned the validity of this allowance, and the results of their experiment justified their skepticism. While the cyclists did demonstrate improvements in power output at the aerobic and anaerobic threshold and in maximum power, these improvements correlated weakly with changes in TRIMP values.

In addition to tracking TRIMP, Boone’s team calculated the relative amounts of time each athlete spent at low, moderate, and high intensity. Interestingly, this data proved to be a better predictor of fitness gains. In particular, those athletes who spent the least time at moderate intensity exhibited the greatest improvements in power output at the anaerobic threshold. Combining the data on training intensity distribution with the data on training load accounted for almost all of the inter-individual variance in fitness improvement. The authors concluded that the TRIMP formulas should be modified to factor in training intensity distribution.

The lesson for you, as an athlete who cares most about your fitness improvement, is that increasing your training load won’t do you a heck of a lot of good unless you’ve got your intensity balance right. By taking some of the time you’re currently spending at moderate intensity and moving most of it into the low-intensity bucket and the rest into the high-intensity bucket, you will feel and perform better without increasing your training load. And by continuing to apply the 80/20 rule as you add minutes to your weekly training, you will ensure that those minutes aren’t partially wasted.

Trail running is becoming more and more popular—statistics say so. But I don’t need statistics to know that increasing numbers of runners are taking to the trails. I can tell by the emails I receive from advice-seeking athletes, a rising percentage of which are sent by trail runners.

The question that is most frequently asked by this cohort is a version of the following: “I do most of my training in the mountains and I find it difficult to keep my heart rate in Zone 2, especially on steep climbs. How do I obey the 80/20 Rule as a trail runner, or does it not apply to me?”

In case you are unaware, the 80/20 Rule is the idea that endurance athletes in all disciplines and of all ability levels gain the greatest amount of fitness when they do approximately 80 percent of their training at low intensity. On my 80/20 intensity scale, the top of Zone 2 corresponds to the upper limit of low intensity, so in practical terms, applying the 80/20 Rule means keeping your heart rate and/or pace and/or power below the top end of Zone 2 four-fifths of the time when running.

Due to the effect of gravity, runners must slow down to maintain the same physiological intensity when running uphill. Athletes with low to moderate levels of fitness may even have to dial all the way back to a walk to stay in Zone 2 on steeper climbs. Before I move on to talk about what these individuals should do to avoid falling into the all-too-common “moderate-intensity rut” as trail runners, let me first point out that runners at higher levels of fitness need not make any special modifications to their training as trail runners to stay in line with the 80/20 Rule.

I’ll use myself as an example. At my present level of fitness, my Zone 2 tops out at about 6:54 per mile. According to a certain online calculator, the effort level that is associated with running 6:54 per mile on level ground is equivalent to the effort level associated with running 9:32 per mile on a steep hill with a 10 percent gradient. So all I have to do to avoid creeping into moderate intensity in a hilly run that is intended to be done entirely at low intensity is keep my pace slower than 9:32 per mile on 10 percent inclines and make similar adjustments on hills with other degrees of slope. It’s just a matter of being aware and disciplined.

Now, I grant that most runners cannot ascend a 10 percent hill in Zone 2 without shifting to walking. So, then, what should you do if you’re in this group? My first suggestion is that you use a run power meter such as Stryd to monitor and control the intensity of your runs. This tool will give you a more reliable picture of how you are distributing the intensity of your training than will either pace or heart rate. Unlike your pace at the top end of Zone 2, your power at the top end of Zone 2 doesn’t change with topography. If your Zone 2 power tops out at, say, 220 watts, it does so regardless of whether you’re running uphill, downhill, or on level ground.

It’s true that your Zone 2 heart rate range also does not change with topography, but the trouble with heart rate is that it lags behind changes in intensity, so when you’re running on highly varied terrain your heart rate monitor is continually giving you yesterday’s news, so to speak. It can work, but not as well as a power meter.

My other bit of advice is that you match your workouts with your training venues so that you avoid spending more than 80 percent of your training time above Zone 2. One way to do this is to avoid challenging trail routes when doing runs that are intended to be done entirely at low intensity. A second, and complementary, way to achieve the same objective is to budget “unavoidable” time above Zone 2 into your weekly allowance of moderate- and high-intensity running. For example, suppose you like to run up a mountain and back down once a week and you’re above Zone 2 during the ascending portion of the run no matter how slow your pace is. Let’s supposed further that it takes you about one hour to get to the top and 35 minutes to come back down. There’s no reason you can’t include this workout in your weekly training schedule provided that the 60 minutes you spend above Zone, combined with any other moderate- to high-intensity running you do during the week, does not represent more than 20 percent of your total training time for the week.

There, I’ve taken away any and all excuses you might have had for falling into the moderate-intensity rut as a runner who trains primarily on trails.

If I could clone myself a few times for the sake of taking different paths in life, I would definitely dedicate one of my clones to the pursuit of sports science. This being impossible with current technology, I choose instead to live vicariously through the individual sports scientists who are tackling the questions I would be most interested in tackling if I had my own lab.

One such question (or line of questioning, more accurately) is this: If you could do only one

thing right in your training as an endurance athlete, what should it be? In other words, what is the single most beneficial training practice you could employ as an endurance athlete seeking improved performance? And if you were already doing this one thing, what then is the next most impactful method you could incorporate?

If we were to pursue this line of questioning all the way through to the end, we would end up with a sort of hierarchy of endurance training needs. How useful that would be! Well, guess what? This hierarchy already exists, created by one of my very favorite sports scientists, Stephen Seiler, who drew upon his encyclopedic knowledge of research on endurance training practices to perform the exercise I just described. With a nod to Abraham Maslow’s famous hierarchy of psychological needs, Seiler’s Hierarchy of Endurance Training Needs ranks eight fundamental training practices in order of proven impact. If there’s a more helpful tool for understanding the big picture of endurance training, I haven’t seen it. So, let’s go through the hierarchy (see Seiler’s own graphical summary at the end of this post):Hierarchy of Endurance Training Needs by Stephen Seiler

1. Total Frequency/Volume of Training

According to Seiler, the single most beneficial thing you can do to improve your performance in endurance racing is to train a lot. The fine print is that in training a lot, you must be sure not to train too much, and you can train more without training too much if you train at low intensity, so what Seiler really means here is that the single most beneficial thing you can do to improve your performance in endurance racing is do a lot of low-intensity training.

2. High-Intensity Training

 Although doing a lot of training exclusively at low intensity will make you fitter than doing a small amount of any other kind of training, you will get fitter still if you combine a little high-intensity training with a lot of low-intensity training. Seiler rates this fact as “well established” in the scientific literature.

3. Training Intensity Distribution

Seiler made a name for himself by discovering the 80/20 Rule of endurance training, which posits that endurance athletes improve the most when they do roughly 80 percent of their training at low intensity and the remaining 20 percent (give or take) at moderate to high intensity. So, the next most impactful thing you can do in your endurance training—if you’re already doing a lot of low-intensity training and a little high-intensity training—is to fine-tune the balance of intensities to bring your training in line with the 80/20 Rule.

Let me add here that applying the 80/20 Rule is usually the first change that I make to the training of the athletes I coach. The reason is that the average recreational endurance athlete does close to 50 percent of his or her training at moderate intensity—way too much. Training more won’t help an athlete who is caught in the moderate-intensity rut because it only exacerbates an existing problem. There is much more to be gained from redistributing the training he or she is already doing and then taking advantage of the reduced stress and fatigue levels resulting from this shift to train more.

4. General Periodization Details (Annual)

 Periodization refers to the practice of evolving one’s training over the course of the year in specific ways intended to cause fitness to continually increase. Seiler rates this practice as “likely overrated.” By this I don’t think he means that training shouldn’t evolve over the course of the year but rather that the details don’t matter much. If that’s the case, then I agree wholeheartedly. What does matter is that 1) the overall training workload (which is a function of both the volume and the intensity of training) increase and 2) your most challenging race-specific workouts come later on, when your fitness is near peak levels and it’s getting close to time to race. But the relevant research has shown that within these broad parameters, different periodization practices yield similar results. In other words, where periodization is concerned, there’s more than one way to skin a cat.

5. Sports-Specific and Micro-Periodization Schemes

 According to Seiler, the particular ways in which endurance athletes chose to sequence workouts from day to day and week to week has a “likely modest” effect on fitness. In other words, it doesn’t matter too much whether you schedule recovery weeks every third week or every fourth week. Of course, it’s vitally important that you balance hard work and rest/recovery in such a way that your body neither accumulates fatigue over extended periods nor detrains between challenging training stimuli, but as with macro-periodization, there’s more than one way to achieve this balance.

6. Training-Stimuli Enhancement

“Training stimuli enhancement” refers to practices such as training at high altitude and training in a glycogen depleted state. Seiler believes that such things are worth doing but that the effects are “individual and condition specific.”

7. Pacing Training

Fitness is not the only determinant of race performance. To get the most benefit from any level of fitness in competition, an athlete must pace himself or herself effectively, and this objective is aided by practicing pacing in training, which may also serve to stimulate pace-specific fitness adaptations. Seiler rates this practice as “potentially decisive if everything else is done right.”

8. Training Taper

Although your fitness level won’t change much in the last week or two before a race, no matter what you do, what you do in the last week or two before a race can have a big impact on how you perform nevertheless. Tapering is the art (Stephen Seiler might say science) of altering your training prior to competition to ensure that you’re rested—but not too rested—and physiologically primed for a maximal effort. Science has shown clearly, for example, that endurance athletes race better when they include high-intensity work in their taper than when they do everything at low intensity. Seiler rates tapering as “potentially decisive if you have one isolated competition. . . and everything else is done right.”

Learn more here: https://www.researchgate.net/profile/Stephen_Seiler/publication/310725768_Seiler%27s_Hierarchy_of_Endurance_Training_Needs/links/583590c208ae004f74cc51f5/Seilers-Hierarchy-of-Endurance-Training-Needs.pdf


$ubscribe and $ave!

  • Access to over 600 plans
  • Library of 5,000+ workouts
  • TrainingPeaks Premium
  • An 80/20 Endurance Book


30 day money back guarentee

For as little as $2.32 USD per week, 80/20 Endurance Subscribers receive:

  • 30-day Money Back Guarantee