Understanding Your 80/20 Triathlon Plan

by David Warden and Matt Fitzgerald

Have a structured workout plan? Be sure to read Understanding Your TrainingPeaks.com Structured Workout Plan after reading this article.

A training plan is only as good as its execution. Even the best training plan won’t help you much if you don’t understand it. This document offers guidelines and tips to help you get the most out of the 80/20 training plans.

Anatomy of a Workout

Each workout has three basic elements. The first two are duration/distance (how long the workout is) and intensity (how fast the workout is). The third is structure, which is how the workout is divided into segments of various lengths and intensities.

The workout descriptions you see in the training schedules provide duration/distance, intensity, and structure information in a condensed format. Let’s look at a cycling example:

Cycling Cruise Interval

5 minutes Z1, 20 minutes Z2, 3 x (5 minutes Z3/3 minutes Z1) 5 minutes Z2, 6 minutes Z1

I chose this example because it has a fairly complex structure. Nevertheless, it’s not at all difficult to decode and follow. The workout has three segments: a warm-up, an interval set, and a cool-down.

“5 minutes in Z1, 20 minutes in Z2,” is the warm-up segment. You’ll execute this part by cycling easily for 5 minutes at Zone 1 intensity and then 20 more minutes at Zone 2 intensity.

“3 x (5 minutes in Z3/3 minutes in Z1)” is the interval segment. Cycle for 5 minutes in Zone 2, then slow down and cycle for 3 minutes in Zone 1, and repeat this sequence a total of three times.

“5 minutes Z2, 6 minutes Z1” is the cool-down segment. Like the warm-up, you’ll execute it by cycling easily for 5 minutes at Zone 2 intensity, then finishing for 6 minutes in Zone 1 (the final 6 minutes makes the workout exactly 1 hour).

There is an almost infinite variety of workout structures, but if you understand how to interpret and apply the example we just covered, you can do the same with any other workout. Let’s take a look at a swimming example:

Swimming Speed Play

250 yd Z1, 500 yd Z2, 5 x (50 yd Z4/20″ rest) 500 yd Z2, 250 yd Z1

Like the cycling example, the swim workouts will generally follow the same format of warm-up, interval, and cooldown. Unlike most of the cycling and running workouts, the swim workouts will be based on distance, not time.

“250 yd Z1, 500 yd Z2” is the warmup segment, which also doubles as your drill segment for swimming. Note that while all the swim workouts are measured in yards, you can replace the distance in meters without compromising the overall integrity of the plan.

The interval segment of “5 x (50 yd Z4/20″ rest)” means you will swim for 50 yards (or meters) in Zone 4, followed by 20 seconds’ rest, and repeat that five times.

Finally, “500 yd Z2, 250 yd Z1” is, of course, your cooldown and drill segment.

Getting to Know Your Zones

Perhaps the trickiest part of executing the workouts that are prescribed in a training plan is training at the right intensity in each segment. You will find complete guidelines for using our five-zone intensity scale in our Intensity Guidelines. But simply reading these guidelines alone won’t enable you to fully master the skill of training in the right zones. A certain amount of experience is also required.

Don’t worry: It doesn’t take long to develop a feel for the various zones, so that, for example, when you start a 3-minute interval in Zone 4, you are able to settle into the right effort level even before your heart rate monitor, power meter, or GPS watch confirms that you’re in the correct zone. Here are some specific tips for mastering each individual zone:

Zone 1

Zone 1 is a very low intensity. Staying within it usually requires that you actively hold yourself back to a pace that’s slower than their natural pace. The common exception is when a Zone 1 segment follows a tiring high-intensity effort. The important thing to understand is that it’s almost impossible to go too slow when you’re aiming for Zone 1, whereas it’s very easy and all to common to go too fast.

Zone 2

Zone 2 is fairly broad. You might wonder, “Where exactly within this zone should I be?” As a general rule, I encourage triathletes to go by feel. If you feel strong, execute near the top end of Zone 2. If you feel tired or sluggish, go ahead and allow yourself to exercise near the bottom end.

Zone X

Zone X is the trap that most triathletes fall into, and avoiding it is one of the key objectives of the 80/20 training approach. Just easy enough to not be uncomfortable, but just hard enough to make you think you’re getting a good workout, this lukewarm intensity provides minimum value in increasing fitness, while generating fatigue that interferes with recovery and performance in subsequent intense workouts. Avoiding Zone X allows you to go harder on the hard days and gain more fitness. For half and full Ironman athletes, Zone X is used sparingly in the Specific phase of training to prepare you for your event, as Zone X does overlap with race intensity for those longer distances.

Zone 3

Zone 3 corresponds to lactate threshold intensity. Thinking in “threshold” terms can help you find this zone and stay in it by feel. The feeling of running in Zone 3 is often described as “comfortably hard,” or as the fastest speed that still feels relaxed. When you perform a Zone 3 effort, imagine there’s a cliff edge in front of you that represents the feeling of strain that accompanies faster speeds. Always stay one or two steps back from that precipice when training in Zone 3.

Zone Y

While Zone Y is not as detrimental to the athlete as Zone X, this narrow intensity gap simply isn’t targeted by any of the tried-and-true workout formats. It’s a little too fast for threshold workouts, which traditionally target Zone 3, and a little too slow for high-intensity interval workouts, which offer more fitness bang for your workout buck when done in Zones 4 and 5.

Zone 4

Zone 4 is the narrowest training Zone. Mastering this zone is a matter of connecting the pace and/or heart rate numbers that define the zone with what it feels like to train at that pace or heart rate, so that you are able to reliably start each zone 4 effort at the right intensity. If you mess it up the first few times, either going too slow or too fast, don’t sweat it. In fact, getting it wrong today is the best way to get it right tomorrow.

Zone 5

Zone 5 is almost always used in interval workouts similar to the one given as an example earlier in this article. This intensity zone ranges from the highest speed you can sustain for a few minutes all the way to a full sprint. So how fast should you actually run Zone 5 efforts?

Tailor your pace to the specific format of the workout. The rule of thumb here is to run closer to the bottom end of Zone 5 when these efforts are longer and closer to the top end when the intervals are shorter. For example, if a workout asks you to run a bunch of 90-second intervals in Zone 5, you’ll want to control your pace so that you are able to run all of the intervals at the same speed without slowing down. But if a workout prescribes a set of 20-second intervals, you’ll want to run them as relaxed sprints.

Perfection Is Overrated

While it’s important to execute workouts as they were intended to be done, it is not necessary that you execute every workout perfectly, and you shouldn’t beat yourself up when a given workout is not done to the letter. If the 2 hours ride on your schedule for today ends up being a 1:57:30, no big deal.

There’s a well-known story about a legendary running coach who always had his athletes run 187-meter hill repetitions. Another coach who admired this legendary coach emailed him to ask about this very precise distance. “Why 187 meters?” he asked, assuming there must be some deep physiological rationale for it. But the legendary coach came back with this answer: “Why 187 meters? Because that’s how long the hill closest to our training camp is!”

Keep this story in mind as you execute the training plans on this website. As with horseshoes and hand grenades, close is good enough.

The Importance of Listening to Your Body

There are some times when executing the workouts in your training plan to the very letter is a bad idea. For example, if you get three intervals into a nine-interval workout and you feel absolutely terrible, you should probably stop, or replace the remaining intervals with an easy jog. A helpful guideline to follow is this: If your interval pace or power is >3% less than it was in the previous interval, terminate the interval set and complete the remaining time in Zone 1 or 2. Similarly, if you wake up one morning with a really sore foot that hurts even to walk on, you should not run that day.

A training plan is really an attempt to predict the future. The many workouts that comprise a training plan represent what you should do if everything goes perfectly—that is, if there are no days when you feel really lousy or have an alarming sore spot. But things seldom go perfectly all the way through a training plan. It’s important that you listen to your body at every step of the process and make adjustments as necessary based on what your body is telling you.

What If You Miss Workouts?

Things happen. Busy days at work, out-of-town visitors, snowstorms, tendonitis, sharknados, the flu. What should you do if you miss one or more workouts due to one of these factors, or for some other reason?

The answer is that it depends very much on the specific cause and context of the interruption. As a rule of thumb, its best not to try to “make up” missed workouts. If you miss just one or two and you’re healthy, just pick up the schedule where you are. If you miss a bunch of workouts—especially for reasons of injury or illness—you should take at least a few days to ease gently back into training before you return to the schedule. And there may come a point where you’ve missed too much training to ever be able to safely return to the training plan. At that point you just need to hit the “reset” button and start a new plan when you’re ready.

Glossary of Workout Codes

Acronym Sport Long Name Description
CAe Cycle Cycling Aerobic Intervals This cycling aerobic interval set is intended to prepare the athlete for the specific intensity and stress of half and full Ironman racing. The Zone 2 intervals should be done at the expected intensity of the athlete’s next half or full Ironman. For new athletes, this will be low to mid Zone 2. For more experienced athletes, this intensity will take place in upper Zone 2. For advanced athletes, these intervals can even include Zone X, a rare exception to the 80/20 system.
CAn Cycle Cycling Anaerobic When executed properly, this anaerobic interval set is the most effective method at increasing an athlete’s VO2max. While VO2max is only one component an athlete’s success, it is a direct predictor of endurance performance. Additionally, VO2 intervals have been proven to be more effective at improving overall economy than submaximal (threshold) or supramaximal intervals. Thus, a successful integration of these intervals in the General phase of training places the athlete in an advantageous position for the upcoming Specific phase, and ultimately their endurance performance results. These intervals are challenging, and the athlete must take great care to not perform them at a Zone 3 or Zone 5 intensity. The unusually high rest period compared to a Zone 3 work reflects the difficulty of the interval. The 80/20 principle is fundamental to executing these anaerobic intervals, as the athlete has deliberately trained easy 80% of the time in order to have the form necessary to maintain this repeated Zone 4 intensity. These anaerobic intervals are permission to go very hard. Be bold, but measured. A successful anaerobic interval set will have the athlete’s output (pace, speed, power) be almost identical for each interval, in Zone 4, and without fade.
CCI Cycle Cycling Cruise Intervals Muscular endurance is arguably the most important ability an endurance athlete can develop, and no other interval improves muscular endurance better than the cruise interval. The application of the cruise interval is broad. The only interval type appropriate for both the General and Specific phase of training, its benefit spans all triathlon distances. The 80/20 principle makes the cruise interval possible, by ensuring the athlete is sufficiently rested in order to achieve the required Zone 3 intensity. The cruise interval is the antithesis of Zone X. A successful cruise interval set has the output for each interval nearly identical to the previous, while maintaining solid Zone 3 intensity. Consider reducing the rest time from 3 minutes to 2 minutes and then 2 minutes to 1 minute if previous cruise intervals sets have been successful.
CF Cycle Cycling Foundation Discipline is required for the cycling foundation set. If rested, the temptation is to drift into Zone X. However, save your energy for the 20% of the 80/20 plan, and stay in Zone 1-2 for this workout. High cadence. Avoid group cycling that will tempt you to go beyond Zone 2.
CFF Cycle Cycling Fast Finish One of the few workouts designed with the intensity scheduled for the end of the workout, the intent is to expose the athlete to high intensity while slightly fatigued.
CFo Cycle Cycling Force Because the cycling force intervals are so short, the athlete will have to often use perceived effort to gauge intensity, as HR may not reach Zone 5 prior to the interval ending. This workout is an excellent time to go very hard, but aim to have each interval with a similar output and avoid fading near the end of the interval. If hills are unavailable, the athlete can simulate by reducing cadence to 65-75rpm and occasionally standing.
CLI Cycle Cycling Long Intervals Highly intense and rarely used, these heavy Zone 4 intervals mimic their fraternal twin, the anaerobic intervals (code CAn). The extended Zone 4 duration and reduced recovery interval reserve this workout for advanced athletes.
CMI Cycle Cycling Mixed Intervals An exceptionally challenging workout. Half and full Ironman athletes may question the necessity for the suffering caused by this particular workout, but the raw increase in FTP will pay off in subsequent workouts and on race day. Used only in the General phase for half and full Ironman, it (unfortunately) spans into the Specific phase for Spring and Olympic training. Pacing is critical in the first Zone 3 interval, start in low Zone 3 and work your way up.
CRe Cycle Cycling Recovery Take advantage of this day with active recovery. Avoid even Zone 2. High cadence.
CSI Cycle Cycling Short Intervals Unlike the very similar cycling force interval (CFo) the cycling short interval is done with a high cadence and seated. Feel free to go hard.
CSP Cycle Cycling Speed Play Not to be confused with the Zone 5 cycling short interval (CSI), the cycling speed play is done in Zone 4 with much shorter recoveries. If done in Zone 5, the athlete will fade.
CT Cycle Cycling Tempo The cycling tempo workout does an excellent job at muscular endurance, and should be used as a method to either verify or re-establish current HR Zones. A difficult workout, pacing is key. Start slightly lower and finish stronger. Some brief forays into Zone 4 are acceptable.
RAe Run Running Aerobic Intervals This running aerobic interval set is intended to prepare the athlete for the specific intensity and stress of half and full Ironman racing. The Zone 2 intervals should be done at the expected intensity of the athlete’s next half or full Ironman. For new athletes, this will be low to mid Zone 2. For more experienced athletes, this intensity will take place in upper Zone 2. For advanced athletes, these intervals can even include Zone X, a rare exception to the 80/20 system.
RAn Run Running Anaerobic When executed properly, this anaerobic interval set is the most effective method at increasing an athlete’s VO2max. While VO2max is only one component an athlete’s success, it is a direct predictor of endurance performance. Additionally, VO2 intervals have been proven to be more effective at improving overall economy than submaximal (threshold) or supramaximal intervals. Thus, a successful integration of these intervals in the General phase of training places the athlete in an advantageous position for the upcoming Specific phase, and ultimately their endurance performance results. These intervals are challenging, and the athlete must take great care to not perform them at a Zone 3 or Zone 5 intensity. The unusually high rest period compared to a Zone 3 work reflects the difficulty of the interval. The 80/20 principle is fundamental to executing these anaerobic intervals, as the athlete has deliberately trained easy 80% of the time in order to have the form necessary to maintain this repeated Zone 4 intensity. These anaerobic intervals are permission to go very hard. Be bold, but measured. A successful anaerobic interval set will have the athlete’s output (pace, speed, power) be almost identical for each interval, in Zone 4, and without fade.
RCI Run Running Cruise Intervals Muscular endurance is arguably the most important ability an endurance athlete can develop, and no other interval improves muscular endurance better than the cruise interval. The application of the cruise interval is broad. The only interval type appropriate for both the General and Specific phase of training, its benefit spans all triathlon distances. The 80/20 principle makes the cruise interval possible, by ensuring the athlete is sufficiently rested in order to achieve the required Zone 3 intensity. The cruise interval is the antithesis of Zone X. A successful cruise interval set has the output for each interval nearly identical to the previous, while maintaining solid Zone 3 intensity. Consider reducing the rest time from 3 minutes to 2 minutes and then 2 minutes to 1 minute if previous cruise intervals sets have been successful.
Rest Rest Rest Athletes can consider adding a strength workout to this day, and beginner swimmers can consider adding a swim. However, rest is a critical element of improving fitness. Adding activity to this rest day is a high risk decision. Very few athletes, of any ability level, can maintain a 16+ week training program without regular days off.
RF Run Running Foundation Discipline is required for the running foundation set. If rested, the temptation is to drift into Zone X. However, save your energy for the 20% of the 80/20 plan, and stay in Zone 1-2 for this workout. Avoid running with individuals who will tempt you to exceed Zone 2.
RFF Run Running Fast Finish One of the few workouts designed with the intensity scheduled for the end of the workout, the intent is to expose the athlete to high intensity while slightly fatigued. An excellent simulation of a triathlon finish.
RHR Run Running Hill Repeats Because the run hill repeats are so short, the athlete will have to often use perceived effort to gauge intensity, as HR may not reach Zone 5 prior to the interval ending. This workout is an excellent time to go very hard, but aim to have each interval with a similar output and avoid fading near the end of the interval. If hills are unavailable, a treadmill is recommended. If neither option is available, the prescribed intensity and duration can still be met.
RLI Run Running Long Intervals Highly intense and rarely used, these heavy Zone 4 intervals mimic their fraternal twin, the anaerobic intervals (code RAn). The extended Zone 4 duration and reduced recovery interval reserve this workout for advanced athletes.
RMI Run Running Mixed Intervals Complex in execution, the reward is high. This workout is best done pre-programmed into a watch (such as a Garmin).
RR Run Running Recovery Take advantage of this day with active recovery. Avoid even Zone 2.
RSI Run Running Short Intervals Unlike the very similar running hill repeats (RHR) the running short interval is done on a flat surface. Feel free to go hard.
RT Run Running Tempo The running tempo workout does an excellent job at muscular endurance, and should be used as a method to either verify or re-establish current HR Zones. A difficult workout, pacing is key. Start slightly lower and finish stronger. Some brief forays into Zone 4 are acceptable.
Rta Run Running Taper Brief, but fast intervals to promote the taper.
SAe Swim Swimming Aerobic For half and full Ironman athletes, these intervals can be used to simulate the intensity of race day swimming at upper Zone 2, with perhaps some intensity in Zone X. For Sprint and Olympic athletes, best to keep these at mid Zone 2, and use the more intense Zone 3+ workouts to prepare for racing.
SCI Swim Swimming Cruise Intervals Designed to increase Critical Velocity, these intervals are done at upper Zone 3. Be careful not to get sloppy, form should not be sacrificed for what feels like more power. These are an excellent way to test different techniques, as the athlete can compare the effect of slight conscious changes to the swim stroke on each interval.
SF Swim Swimming Foundation For half and full Ironman athletes, these workouts can be used to simulate the intensity of race day swimming at upper Zone 2, with perhaps some intensity in Zone X. For Sprint and Olympic athletes, best to keep these at mid Zone 2, and use the more intense Zone 3+ workouts to prepare for racing.
SMI Swim Swimming Mixed Intervals Consider using different strokes for this workout. The purpose is intensity, and therefore the athlete is not limited to freestyle.
SRe Swim Swimming Recovery Consider using multiple strokes for this recovery swim. Easy pace.
SSI Swim Swimming Short Intervals This extremely high intensity and frequency will test your ability to maintain form at high speed.
SSP Swim Swimming Speedplay This set should ultimately help improve Critical Velocity, and provide a significant challenge that helps the workout fly by!
ST Swim Swimming Tempo The “big brother” of the swim cruise interval (SCI), take care not to start too fast and fade. Target your Z3 Critical Velocity and hold on to your form.
STa Swim Swimming Taper If possible, in open water at the race venue or similar environment. Brief, but fast intervals to promote the taper.
STT Swim Swimming Time Trial This set is designed to confirm or reestablish your Critical Velocity. Suppose you swim your four-hundred-yard test in 5:55 (5.92 minutes) and your two-hundred-yard test in 2:50 (2.83 minutes). Your critical velocity, then, is (400y – 200y) ÷ (5.92 min. – 2.83 min.) = 64.7 yards/ min. It is customary to express critical speed in the form of time per hundred yards. To make this conversion, divide one hundred by your critical velocity. In this example, 100 ÷ 86.6 = 1.55, or 1 minute 33 seconds.