David Warden – 80/20 Endurance

David Warden

…but you can make it tell the truth. 

The Performance Management Chart in TrainingPeaks is an amazing tool. As early as 1975, physiologists have been attempting to quantify, and ultimately predict, the relationship between training and endurance performance. Coaches and athletes wanted to know if you put in X units of training, could you predict Y units of performance? Variations of this impulse-response model were proposed, until the late 1990s when Dr. Andrew Coggan introduced the Performance Manager. It was a brilliant, easy to use application to quantify the impulse-response relationship, and is used to this day within TrainingPeaks as the Performance Management Chart (PMC).

In regard to your understanding of the PMC, you probably fall into one of two categories. You’re either a die-hard daily PMC consumer, or puzzled by the beautiful colors of this strange chart in your TrainingPeaks dashboard. Without deliberating too long on how the PMC works (which often takes an entire book), I’ll give a brief summary. Each workout you complete is assigned a Total Stress Score (TSS). That score is relative to your personal threshold, where a score of 100 TSS is the output from your own 1-hour time trial. All other workout scores orbit around this fitness polestar. An easy 30-minute ride might be a TSS of 25, but a marathon could be 250. In theory, the easy bike ride was 25 percent as stressful to your body as your 1-hour time trial, and the marathon was 2.5 times as stressful. Your average daily TSS over a period of 6 weeks becomes your Chronic Training Load (CTL), and CTL is considered your quantitative fitness. In the PMC world, a higher CTL is always better. Theoretically, if you start an event with a CTL of 100, you will perform better than at a CTL of 90. Because TSS is always relative to the individual’s threshold, CTL is always relative. An individual with a CTL of 100 may not out-perform an individual with a CTL of 90 if the latter has a higher threshold to begin with.

After 15 years of using the PMC for myself and athletes, I’ve determined that by default, the PMC is lying. The good news is that you can tame this psychedelic graph once you understand its risks, limitations and strengths.


The PMC Promotes Wrong Behavior

In many circles, the CTL is a badge of honor. Athletes are in awe of the elite triathlete with a CTL of 130 and seek to emulate. When not used socially, it’s used as an individual “white whale” to be pursued. “If I reached a CTL of 80 last year, I have a goal for a CTL of 90 this year.” This CTL-based agenda impacts each and every workout, where the athlete, either consciously or unconsciously, tries to achieve as high a TSS as possible from the workout, spends significant time at moderate intensity, which in turn provides that higher CTL. In our books 80/20 Running and 80/20 Triathlon, Matt and I identify this “moderate intensity rut” as the primary roadblock to improved performance. Ironically, in many cases that higher CTL results in a decrease in real fitness. The CTL is up, but fatigue and stagnation keep the actual race-day result disappointingly low.


CTL Does Not Reflect Fitness

To demonstrate how the CTL can be deceiving, let’s look at two hypothetical age-group athletes, Rebecca and Rachel. They are the same age, same weight, same thresholds, same experience level, and training for the same event. Both use the PMC to track their fitness. Rebecca trains by feel, but Rachel discovered and implemented 80/20 training early in her season.

In a sample week, Rebecca and Rachel both train for 10 hours. Rebecca falls into the classic moderate-intensity rut and performs 50% of her training at low intensity, but Rachel follows her 80/20 plan closely and spends 80% of her time at low intensity. Their respective intensity distribution for the week looks like this:

Rebecca’s 10 Hours

2 hours in Zone 1 (80 TSS)

3 hours in Zone 2 (150 TSS)

3 hours Zone X (248 TSS)

1.5 hours Zone 3 (105 TSS)

0.5 hours Zone 4 (20 TSS)

Total: 603 TSS

Rachel’s 10 Hours

2.5 hours Zone 1 (100 TSS)

5.5 hours Zone 2 (275 TSS)

1.5 hours Zone 3 (140 TSS)

0.25 hours Zone 4 (25 TSS)

0.25 hours Zone 5 (30 TSS)

Total: 570 TSS

Should Rebecca and Rachel continue a similar pattern for the remainder of their plan, Rebecca will have a CTL 5-10 percent higher than Rachel. Based on the PMC alone, Rebecca should outperform Rachel at their event. Much to Rebecca’s surprise, Rachel has the better performance on race day.

The reason is simple: by spending sufficient time at low intensity using the 80/20 method, Rachel can recover quickly and gain new fitness from higher intensities using those fresh legs. Rebecca churns out more raw TSS, but remains mired in moderate-intensity training where recovery is compromised and, as a result, quality high intensity is rare.


CTL Does Not Matter. Speed Does

As demonstrated in the two sections above, CTL can be misleading. Ultimately, CTL is also irrelevant. None of us arrive on race day, show the race director our 130 CTL, and request a podium award before the race even begins. CTL may be an indicator of our individual relative fitness to a previous period, but in the end we have to earn results on the asphalt. The ultimate measure of the effectiveness of a training plan is demonstrated in the field with racing and periodic testing. Regardless of what the CTL says, if you are getting faster, your plan is working.


The PMC Requires Significant Maintenance

Even Dr. Coggan would agree that the PMC is a harsh boss. Every workout must be recorded. Every workout must be recorded accurately. Your threshold is constantly changing (as it should in an effective plan) which means you must constantly change your threshold in the PMC. Device runs out of battery on a 3 hour ride? Good luck in guessing the TSS. Using HR for TSS one month and Pace the next? A recipe for PMC disaster. Do you include strength training? How do you enter a TSS for that? (I use 35 TSS, a colleague uses 70) I once spent 45 minutes calculating a TSS score for an athlete who participated in a tennis match. An accurate PMC requires a complete understanding of the methodology and daily commitment to ensuring the inputs are accurate. In this scenario, it’s not a matter of the PMC lying to you, it’s a matter of you lying to the PMC.

The biggest mistake athletes make with the PMC it to just let TrainingPeaks automatically manage it for them. TrainingPeaks will guess your threshold, and then it will guess your future TSS to then guess your future CTL. It’s a guess from an estimate wrapped in a presumption. The only accurate PMC is a micro-managed PMC.


CTL is Always Relative: Even To You

As mentioned earlier, TSS is always relative, and therefore so is CTL. Rachel’s brother-in-law, Brad, has also started 80/20 training, and he will be participating in the same event as Rachel. Both Rachel and Brad adhere to their 80/20 training plan, and both arrive on race day with a CTL of 80. Why would Rachel still outperform Brad if they have the same CTL? Instinctively, we know why, that these are very different athletes, but let’s quantify it anyway.

Brad has a running threshold pace of 7:30 per mile. Rachel has a threshold pace of 7:00 per mile. Brad runs one hour in mid-Zone 2 and achieves a TSS of 60. Rachel runs one hours in mid-Zone 2 and also achieves a TSS of 60. But Brad’s mid Zone 2 is 9:10 per mile and Rachel’s is 8:30 per mile. Rachel is just faster than Brad, even though they achieve the same TSS for each workout, and ultimately, the same CTL.

But here’s what’s scary: CTL is not only relative athlete to athlete, it’s relative to you as well. Let’s say Brad is fed up with Rachel scorching him at races. So, he continues to follow 80/20 training and soon finds that his threshold pace is 6:50 per mile. Brad completes a 1 hour run in mid-Zone 2, or 8:25 per mile, only to discover his TSS score is (you guessed it) still 60. That’s because (if Brad manages his PMC correctly) the relative stress for Brad running for an hour in mid-Zone 2 compared to his threshold pace has not changed. Your 1-hour time trial TSS should always be 100, even as the raw speed continues to climb. Old Brad’s stress (or TSS) from running an hour at 9:10 with a threshold pace of 7:30 is the same as New Brad’s stress running 8:25 for an hour with a new threshold pace of 6:50.

The bottom line is that with a properly managed PMC, your CTL will not change for a set amount of volume and intensity distribution as a percent of threshold pace even if your threshold speed does increase. CTL can only increase with an increase in total training duration or change in intensity distribution. What often happens is that athletes don’t manage their PMC, and so as their fitness improves, the TSS score is artificially inflated until the athlete changes their thresholds for future workouts, and retroactively changes their threshold for past workouts.


TrainingPeaks Has Some Bugs

TrainingPeaks is the best platform, but like all software, it has some issues. One issue has to do with the calculations TrainingPeaks uses to predict future CTL. One of the most common questions I get is, “why does my predicted CTL get lower when I apply an 80/20 plan?” In addition to the issues listed above, there are some quirks with the platform itself.

The most significant is a known problem in TrainingPeaks for HR-based workouts. The auto-calculation for predicted TSS for HR-based workouts has two main issues. First, the predicted TSS value will only increase in units of 10. If you have one run that should have a TSS of 41 and another run that should have a TSS of 49, TrainingPeaks will round down and calculate both as a predicted TSS of 40. Second, for a given amount of planned workout time, and regardless of the planned intensity, TrainingPeaks uses a minimum value. For example, if there are two runs of 30 minutes, one performed at 75% of LTHR and the other performed at 90% of LTHR, both will have a predicted TSS of 40. Thus, TrainingPeaks systematically miscalculates predicted TSS, and therefore predicted CTL, for HR-based structured workout plans.

This particular issue is limited to the predicted TSS and predicted CTL for HR-based plans only, and does not impact TSS or CTL for completed workouts, nor Pace or Power-based workouts. TrainingPeaks reports they are looking into the issue.

Even with Pace and Power-based workouts, TrainingPeaks assumes that you will be running in the upper quartile of the zone range when predicting average Pace or Power (and therefore TSS). For example, if your Zone 2 run pace was 7:00 to 9:00 minute per mile, TrainingPeaks will assume that you will run an average of 7:30 per mile for a Zone 2 segment when predicting pace, when in reality you could be running as slow as 8:55 per mile and still be following the workout correctly. The inevitable result of Zone training is that your intensity for the day could fall anywhere within a broad range, therefore, the predicted TSS will almost always be incorrect.


How To Use and Interpret the PMC Correctly

Despite the articulated issues, I use the PMC for myself and my athletes. There is a way to effectively take advantage of this useful tool, which includes the following steps and insights.

  1. Change your PMC chart start date to the day you started 80/20 training. Anything pre-80/20 is not valid.
  2. Don’t compare your CTL to other people.
  3. Accept that your new 80/20-era CTL is going to be lower than your pre-80/20 CTL. In most cases, your CTL will be 20% lower using 80/20 and you’ll get a PR in your next race.
  4. Do change your thresholds in TrainingPeaks after each threshold test. This is critical in maintaining an accurate PMC.
  5. Use results, not CTL, to gauge your improvements.
  6. Micro-manage your PMC, don’t delegate to TrainingPeaks.
  7. Unless you manually override the predicted TSS of every future workout in your plan, TrainingPeaks will not provide an accurate predicted CTL.

Once you have an accurate PMC and understand how to use it, the PMC can be used to compare your fitness to previous periods and predict performance. At this point, your individual CTL of 90 will result in better performance than your old CTL of 80. Increasing volume is the best way to achieve this CTL improvement, as your intensity balance should remain 80/20.

Sometimes, the people we love lie to us. That doesn’t necessarily mean we cut them out. We set boundaries and reform them. The PMC can be an essential part of your training, as is it for me and my athletes. If you apply the above principles, you can change your current PMC into a real PMC (a Properly Managed Chart).

I remember my first heart rate monitor. A Polar S720i. It used infrared to download data. Infrared! The first time I wore it, it felt like magic. The device was a key to unlock secrets about my body I could have never observed before. I wore it when I exercised, I wore it all day, I wore it all night for the first week. Of course I knew my average heart rate for actives like cycling and running, but I knew it even for mundane activities like doing the dishes (61 bpm).

Since the first commercial heart rate monitors were introduced in 1982, using heart rate to monitor intensity remains the method of choice for the plurality of recreational athletes. Of all our 80/20 plans use sold in the past year, 41 percent choose a heart rate-based plan, with the remaining 59 percent almost evenly split between pace and power. Why does heart rate remain so popular after 36 years, even with the advent of more sophisticated technology? Because heart rate training is cheap and easy. It is the original “plug-and-play” device, with reliable and simple setup, and at a cost often less than 10% of power meters.

But that 41 percent is declining. We estimate that pace and power sales will each eclipse heart rate training by the end of 2019. As the cost of pace and power devices comes down, athletes have already begun to shift to these alternatives. But it’s not just cost that drives this decision. Athletes increasingly recognize that despite the advantages of heart rate training, it has significant drawbacks. The most glaring drawbacks being reliability and consistency.

To illustrate this, think of measuring exercise intensity like you do with your car, and imagine that in addition to the various gauges on your dashboard your car has a gauge measuring horsepower. Your car’s horsepower is an output, the speed is an outcome, and the engine temperature is an indicator. These measurements line up with using power, pace and heart rate, respectively, to measure intensity when training. Engine temperature (heart rate) does not actually represent any output or outcome. It is simply an indicator of how the car is responding to the input and environment. Your car’s engine temperature needle can be through the roof when idling at a stoplight in summer, or resting near the bottom when driving at 50 mph on a cold day (Honest, officer! I wasn’t speeding! My engine temperature was super low).

Likewise, your heart rate will respond very differently based on environmental conditions, even when the output is identical. For example, an athlete running on a treadmill set to 14kph at a room temperature of 70 degrees F may have a bpm of 160, but a bpm of 180 if the room temperature is increased to 90 degrees F. The output is the same at 14kph, but the data on the indicator is much different.

Temperature is only one factor that can influence heart rate. Evening workouts have a bpm 4 beats higher than the same output during a morning workout. When and how much you last ate can increase hear rate by up to 10 bpm when exercising. Sleep and stress can cause wild fluctuation in heart rate. Indoor training training tends to be 5 to 10 beats lower than the same output for outdoor training. It is these, and other factors that make heart rate training less reliable and less consistent than power or pace.

Contrast that to using power as a measure of intensity. A watt is a watt, regardless of temperature, time of day, or stress. Pace also has drawbacks, but is reliable when performed on a relatively flat surface. And for most of us, isn’t the outcome (pace) the whole point when racing? There are no awards for highest heart rate in a race, it goes to the individual with the best pace.

But I’m not here to bury heart rate, I’m here to praise it. Despite the drawbacks, heart rate can play an important role as a secondary measure when training and racing. Using pace in hills is foolish, but having heart rate in your toolkit can help you find an appropriate pace. A watt may be a watt, but heart rate is indeed a key to unlock secrets about how your body is responding to the stress of training and racing. It may be that heart rate is the angel on your shoulder telling you to slow down when pace and power devils are telling you that you’re just fine. A combination of monitoring pace plus heart rate or power plus heart rate will always be superior than relying on any single measurement.

Heart rate monitoring may be losing popularity, but it isn’t dead. It isn’t even dying. I’ll be the first to recommend power and pace as primary measures of intensity, but I haven’t done a workout or race without a heart rate monitor as well in years.

Besides, there will never be a pace and power intensity measure for doing dishes.

If you already have an 80/20 plan that uses heart rate and want to try pace or power, we offer a free switch to any other measure of intensity or level within your purchased plan distance. Contact us and we’ll make that happen.


This season I’m doing my first marathon, first olympic tri, and first ironman. I am super stoked to get to do these workouts! I really love how organized your program is and I used your website to set up all my zones and stuff and it makes a ton of sense. I trained for the marathon blind and wish I would have found your program before I started it.

If you have any just basic tips I would love to hear them if you have time. Thank you again for taking the time to help me out with this!



Dear K,

I’ll give you my top six training tips (that I can think of at this particular moment…)

1- Adherence to the plan is important, but missing workouts should not cause anxiety. 90 percent adherence to the plan will get you 98 percent of the results.
2- Workouts done first thing in the morning have a significantly higher chance of actually getting done (100 years from now this statement will be as popular as Wayne Gretzky’s, “You miss 100% of the shots you don’t take.”)
3- Go hard on the hard days and easy on the easy days. This is fundamental to 80/20 training, and is integrated into your training plan.
4- Practice nutrition early, on any run workout longer than 1.5 hours and any bike/brick longer than 3 hours. Race-day nutrition should be nailed down for the last 4 weeks of your training.
5- Add strength training to your plan with our free strength training plugins (these will be published by this week-end, check the 80/20 website under Free Plans). If you have to replace some of the easy workouts with 1-2 sessions a week, you’ll actually get better results. Doing both the plan plus the strength training is best.
6- The biggest mistake that first time Marathon and IM athletes make is going out too fast. If you are tapered properly (which the 80/20 plans will do), you’ll feel like a caged tiger. Hold back and save it for the second half.


Hello David,

Hope you are well. I purchased the 80/20 level three plan back in June and used it to train for my first marathon. I loved it! It helped me to a 3:24 in NYC. I am looking to shave some time off and am running my second in March. I know there is no “Level 4” but do have any suggestions on how to tweak the plan to help get me to my goal?




So glad to hear about your success! 3:24 in your first marathon is a solid result.

Although we don’t yet have a Level 4 plan Marathon plan, if/when we do build it, I would create it in this manner:

1. An increase of 20% total volume from the L3 plan. If the weekly schedule called for 7 hours of running, I would up that to 8.4 hours. That could be achieved by simply adding 20% to each run, or adding another 1.5 hours over 2-3 runs.
2. Add 1 interval segment to every other interval run. For example, if Monday called for 3×2.5 in Zone 4 on 5 minutes rest, make that 4×2.5. Make no modification to the next interval run, then add an interval to the third interval run.
3. Increase the long week-end runs by 2 miles. This would be done in conjunction with #1 above.



I sometimes have to do the workout for a particular day in a different order than specified in the plan. For example, today calls for a swim, then a run. Due to my schedule today I need to do the run and then the swim. How big a deal is that?

I know some of the days where there is a bike and a run they specifically say it’s not a brick and to not do them together, etc…

Thx for your feedback,



The daily workout order in your plan is based what we feel is best for a typical triathlete, but there are exceptions and it is not a problem to make some changes. To answer your direct question on swimming, for example, most triathletes have swimming as a weakness, and typically that weakness is caused by technique. Swimming when completely fresh will usually lead to better technique, swimming when fatigued can reinforce poor technique. Strong and experienced swimmers don’t have this problem and con usually swim well under almost any conditions. Or, if the swim is separated by hours and hours of rest, fatigue is less likely to impact your swim technique.

On days with both a bike and run workouts, we schedule and recommend that you split them up morning and evening. If you can’t, then perform the workout with the most intensity first so that you can gain maximum fitness during those tough intervals. For example, if you run for an hour right before your interval bike ride, that fatigue from the run means you’re less likely to build fitness on the bike. An exception is the scheduled or optional bricks in your plan, where we do want you to run when fatigued in order to simulate the stress of racing.



I am pushing through first weeks with Garmin + Stryd to track it. I noticed that my power zone 2 running results in running in HR zone X calculated on your calculator for threshold HR delivered by my Garmin fenix 5. Would it be a clear sign that I overstated my threshold Power?

Is alignment (on rather flat terrain) of 1-2 power zones with 1-2 HR zones sign of properly defined zones?




Great question. Because HR is easily influenced by external factors, Power and HR will only ever align under ideal conditions, and is also why Power and Pace are superior measures of intensity.

Using an automobile as an example is helpful in this regard. A car can measure horsepower, speed, and temperature very accurately. Horsepower is an output, speed in an outcome, and temperature is an indicator. Sometimes these measurements line up perfectly and predictably, but often they do not. We can be traveling at 65 miles per hour at 250 horsepower with an engine temperature of 180 degrees Fahrenheit OR traveling at 30 miles per hour at 200 horsepower with an engine temperature of 230 degrees. We can’t really use temperature (an indicator) to accurately judge intensity (an output).

When we train, we have similar options. Power is our output, Pace is an outcome, and HR is an indicator. HR is not actually measuring any kind of result, it is simply indicating how our body is reacting to the stress we are applying. And, all kinds of environmental factors play into how the heart responds to exercise, including:

– Temperature
– Time of day
– Indoors vs. Outdoors
– When you last ate
– Chronic fatigue
– Stress
– Sleep

As a result, we can perform the exact same workout with the exact same power output and get completely different HR results. I once witnessed a test with a runner on a treadmill locked in at 6:00 per mile in a room maintained at 70 degrees Fahrenheit. The average HR was 160. A week later the same runner, same room, same treadmill, same speed (and therefore the same power output), but the temperature was maintained at 95 degrees. Average HR was 185 in the second test.

Pace is obviously influenced by terrain, but that is the only practical limitation, and Power is not influenced by terrain nor the pitfalls of HR.

In summary, the 80/20 HR Zones were created based on ideal conditions. I would say that most runners on a rest week, with good sleep, in the morning, on an empty stomach, outside on a flat surface, with low humidity at 65-70 Fahrenheit would have 80/20 Power, Pace, and HR zones all line up nicely. Because we probably won’t train ideal conditions, the most consistent results will come from Power and Pace.

HR still has it’s place as a secondary measure. For example, if you don’t have a running power meter, HR is very helpful in hilly terrain where Pace becomes invalid.


Matt and I periodically publish anonymously your inquiries to us, particularly when the answer may benefit the community. Have a question about 80/20 training or training in general? Feel free to e-mail me. David W.

Dear David W,

I’m going to buy your plan for the level 3 half marathon plan. I have a race (in Madrid, Spain) on April 8 which by my calculations will have me starting Dec 31/Jan 1… I had a bike wreck in a triathlon a few months ago that resulted in broken bones, concussion, etc. So I’m just now starting to get back into where I can work out 4-5 times a week. So I’m on pace to be at least to the proper starting place for your program.

I am a gadget guy. I supported Stryd on Kickstarter and upgraded to the footpad at the first opportunities. I record my power on my runs, but it is just another interesting bit of data that I review at the end of some of my runs. So I’ve never really done much with it. That is why I’m so intrigued by this [the 80/20 power-based run plans].

So that leads me to my questions: When should I do the power test? I would assume fairly close to the start of the program so that my numbers are pretty accurate for that time. As my training increases and my thresholds change, will I be doing more tests during the training plan?


Dear DH,

I wish you the best of luck on your recovery.

You are exactly right, particularly where you are coming back from low fitness, your power thresholds will constantly change (improve). The run plans have RT (run tempo) workouts scheduled every recovery week, which is every 3rd or 4th week. Those RT workouts are designed to confirm or re-establish your zones. Therefore, you’ll be testing regularly anyway with an 80/20 plan.

It would be good to do a test before your start your regular training. We have a suite of tests in our Intensity Guidelines for Running document on our 80/20 Resources page. Some of the tests are brutal (30-minute time trial) and some are easier, if slightly less accurate. I would do the easy test at first. Make sure to see the section on RT workouts at the bottom of that guide.

Also consider that HR zones will change very little. Your output for a given HR will, but early on, consider using HR as a secondary (or primary) measure of intensity until your power zones level off.

Finally, we offer a Level Guarantee. If you buy the Level 1 plan and find that 8 weeks later it is too easy, come back to me and I’ll get you the L2 plan for free. This applies to leveling up or down on all of our plans.


Matt and I periodically publish anonymously your inquiries to us, particularly when the answer may benefit the community. Have a question about 80/20 training or training in general? Feel free to e-mail me. David W.

Hi Matt,

I just finished reading your book 80/20 Running. I liked the basic idea and I also have experienced my biggest fitness gains with mostly slow exercising. But I have one question that I did not find an answer – but maybe there was..

As a triathlete I currently do hard and slow workouts in all three sports, but how should I schedule them. I mean if I do 5 runs, 4 swims and 3 bike rides a week, if I do high intensity workouts in each of them, that could mean that I either do 3-4 ”hard days” (meaning there is a high intensity in some of the sports) or I do hard swims and hard runs on the same day and maybe only have 2 hard days per week. Now I usually have a hard bike on tuesdays, a hard run on thursdays and hard swimming on wednesdays and sundays. But according to the 80/20 philosophy: what is optimal?

And one ”common knowledge” is also that one can do more high intensity in swimming than in other sports, but according to you that is false.

Thank you for good books. I also have the Racing Weight books from you.


Dear TE,

Thanks for reading 80/20 Running! Matt and I expect to publish the book 80/20 Triathlon sometime next year which will address your questions as well.

To answer your direct questions, the 80/20 intensity distribution measured in elite athletes has always been observed at a macro level. Some days or even weeks might vary from 80/20, but over a given season the best athletes maintain that ratio. Therefore, you do not need to do high intensity in each sport each day, in fact that would be discouraged, as it interferes with the necessary recovery to continue high intensity on another day. In general, our triathlon plans follow a hard/easy approach with 3-4 days of workouts that include intense intervals, and 2-3 days of workouts exclusively at low intensity. Our plans target 80/20 distribution for each week.

Swimming, as you point out, is an exception. We target 75/25 when swimming by distance. We also allow for much more frequency of swim session that include intense swimming because of the recovery issue. While our plans almost never include an interval bike and run on the same day (excluding race-specific bricks) we often have an intense swim on the same day as an intense bike or intense run.


Matt and I periodically publish anonymously your inquiries to us, particularly when the answer may benefit the community. Have a question about 80/20 training or training in general? Feel free to e-mail me. David W.

Hi David,

I hope you are well. I was excited to receive your email about the addition of 80/20 ironman plans with running power targets. I’m currently using the level 3 Pace and Power ironman plan, but would love to try the power and power plan. Is there a way to get access to this without having to pay the full price of the new plan? Perhaps I could pay half, for the addition of the running power structured workouts?

Also I was wondering if you had any guidelines/advice in regards to electrolyte supplementation during an ironman (e.g. an hourly electrolyte target during)? I’m 62kg, 174cm, I think an average to high sweater, and my exercise clothes do generally have white salt marks after a session, particular when it is hot. Any advice/guidance you can give me would be greatly appreciated.

Warm regards,


Dear LH,

Great to hear from you. I’m really pleased that we have these triathlon Run Power and Bike Power plans available. All of your 80/20 plans allow for a complimentary switches between levels and intensity types, so you can have this one for free. Please use coupon code [redacted] for a 100% discount off of the IM L3 Power and Power plan.

Regarding electrolytes, I have a short answer and a longer answer. Short answer: 300-500mg per hour on the bike is a safe dose. The electrolytes in your nutrition probably already have something close to this and additional supplementation may not be necessary.

Longer answer: There is no empirical evidence that electrolyte supplementation is helpful for endurance athletes, and no evidence that it reduces the risk of cramps or improves performance (see http://tri-talk.com/74/). There is also no evidence electrolytes in moderate doses are detrimental, so feel free to try it.

To illustrate, attached is an example of electrolyte concentrations and IM performance. In this particular study, there was no statistically significant difference in electrolyte concentrations between Ironman crampers and non-crampers (controls). Also consider Tim Noakes phenomenal book, Waterlogged for more on the subject.


Matt and I periodically publish anonymously your inquiries to us, particularly when the answer may benefit the community. Have a question about 80/20 training or training in general? Feel free to e-mail me. David W.

Dear David,

I think I’m falling in love with my mail carrier. I can’t afford all the unnecessary orders I’m making just to have more packages delivered (with signature required!) I need to take this to the next level. How can I ask her out?


1st Class Male

Dear 1st Class,

I recommend the 10K Level 2 plan.


Hi Guys,

I am planning buying 80/20 program (not sure in 1/2 marathon or marathon) but I want to prepare myself for it, as I am out of shape to start it now. On my first run after long break I noticed that pace to HR ratio decreased over the course of 5k, where in the end I had to almost walk to have it in aerobic zone. I have read that such ratio dropping is sign of lack of aerobic base. And my question is while building base do I always keep myself in aerobic space? And secondly is there a benefit to push longer and slowing the pace, or rather stop once HR starts spiking despite constant or even decreasing pace.


BTW: are all 80/20 plans the structured workout version on training peaks? (so I can download automatically on Fenix 5?)


Dear M,

Great question!

In our 80/20 plans, you’ll find that 80% of the workouts are done in Zone 1 and Zone 2. This is the “easy” 80 percent. The other 20 percent is moderate to high intensity. It is possible that at the beginning of your training you will have trouble staying in Zone 1 when Zone 1 is called for. That is OK. As long as you stay in Zone 1 or 2 when the workout calls for Zone 1 or 2, you’ll improve faster. If the workouts calls for Zone 2 but you are tired that day and stay in Zone 1, that is ok. If the workout calls for Zone 1 but your slowest run pace puts you at Zone 2, that is ok. As long as the combination of Zone 1-2 is 80%.

It is of course better to spend the time in Zone 1 and 2 exactly as the plan is prescribed, but you’ll be able to do that after a month of training.

When using HR, I would only walk in between hard intervals. If you are running a long Zone 2 session (and there are many of these) and your HR spikes above Zone 2, don’t walk, just run as slow as you can.

However, this HR problem does not exist if you use Pace or Power are an intensity guide. If your Zone 2 workout calls for a pace of 6 minutes per kilometer, you can your HR. If the plans calls for Zone run of 200 watts, then just hold 200 watts and ignore HR. Our plans support both Pace and Power and translate Zones to pace, power, and HR. In fact, when you purchase our plans, you choose HR, Pace, or Power as your measure of intensity.

Please see our Zone Calculator to see the different ways to measure intensity. Also please see https://8020endurance.com/8020-run-plans/marathon-plans/ to read about the three different types of intensity plans for the marathon.

All of our 80/20 plans come in either structured workouts or original plans. The two types are identical, but you really want the structured workouts as they will indeed export and sync automatically to supported devices, including the Fenix 5.

Finally, we offer a Level Guarantee for our plans. If you buy the Level 0 plan and find it is too easy after a month, come back to me and I’ll get you the Level 1 plan for free, and if Level 1 becomes too easy, I’ll get you the Level 2.


Matt and I periodically publish anonymously your inquiries to us, particularly when the answer may benefit the community. Have a question about 80/20 training or training in general? Feel free to e-mail me. David W.

Hi David,

I’ve recently purchased a 5k plan for trainingpeaks.com

It’s the level 3 plan, so it contains some days with two sessions: firstly, I was wondering should these, or should they not be run back to back? or is the intention that one would be done early in the day and the other later in the day?

I’d like to do a more advanced plan, but I’m not sure I could commit to these two sessions per day; what’s your advice: should I just try and do them when I can, or should I drop down to a lower plan?



Dear R,

Thanks for purchasing our plans. I’ve just added a new paragraph to our Understanding Your 80/20 Run Plan to further clarify two-a-days. You may also find the section in that document named Cross-training to be helpful as well. Be sure to review all our 80/20 documentation while you are at it. I’ve included the two-a-day addition for your convenience below.

I think you’ll have better performance with an L3 where you do 50% of the two-a-days than an L2 where you do 100% of the two-a-days. Therefore, I would recommend sticking with the L3. However, you can switch to the L2 anytime, just let me know.


In the advanced 80/20 run plans, some days have two workouts scheduled in the same day. These are always scheduled with the first workout as a Run and the second as a Run or Cross-train. Regardless of whether you choose to run or cross-train the second workout, the two workouts would ideally be done in the AM and PM, or at least as far apart as possible. In extreme circumstances, the two workouts can be combined together, but preferably the second workout is simply moved to another day of the week.


Matt and I periodically publish anonymously your inquiries to us, particularly when the answer may benefit the community. Have a question about 80/20 training or training in general? Feel free to e-mail me. David W.

Hi David

I am looking at following the 80/20 ironman training plan (probably level 2) and have downloaded the free Ironman plan

I have a few questions:

1. When cycling I noticed I can keep in zone 1-2 for heart rate but when I analyse I see my power is spread more over all zones including 4-5. Is power a better measure and more preferred way for cycling?

2. What kind of performance gains would you expect during a 4 week period? If there is no improvement in pace and power would that indicate an issue in my training?

3. Does the plan contain longer cycle and runs towards the end of the plan?

Thanks, C

Dear C,

Thanks for looking into our plans! Responses below.

1. Power is commonly recognized as a superior way to measure intensity. Heart rate (HR) is affordable and convenient, but HR has several disadvantages. The root of these disadvantages is that HR is an indicator not an output. Like your car, your engine temperature (an indicator) might be directly related to your horsepower (output) and speed (outcome), but often they are not in sync at all.

Your power zones are also most likely not yet calibrated correctly, almost certainly too low. Consider our Intensity Guidelines for Triathlon document for some protocols on how to retest your power zones.

2. This is tough to answer. I regret that genetics plays such an out-sized role that the results are all over the map. What I can comfortable say is that the best athletes in the world use an 80/20 intensity distribution, and you’ll have the best chances of success with that format. If I were to commit to a “typical” triathlete without a strong background in cycling, I often see a 10-15% percent improvement in the first year, another 5-10% the second year, and diminishing but continued returns from year 3-5. The monthly improvements would be some fraction of those annual estimates. Genetics could double or half those “typical” results. Be patient, sometimes you’ll go months without seeing an improvement, and then you’ll get a 5% bump overnight.

3. Yes, the free plans are just the first two weeks of each plan. We use the empirically proven method of progressive overload in all of our plans, the weekly volume caps out at 2-3 times what you see in the first 2 weeks.


Matt and I periodically publish anonymously your inquiries to us, particularly when the answer may benefit the community. Have a question about 80/20 training or training in general? Feel free to e-mail me. David W.