The 80/20 Rule Of Triathlon Training Intensity

The 80/20 rule has, in the past few years, acquired quite a few press mentions for its role in maximizing performance with the most efficient training plan. If you haven’t heard of it, here’s a brief overview from Stephen Seiler, an exercise scientist who researched and popularized this phenomenon.

Don’t want to watch the whole video? That’s okay. Essentially, Seiler analyzed the training logs of world-class cyclists, skiers, runners, and triathletes, and found that they did approximately 80 percent of their training at low intensities, and the other 20% at moderate to high intensities. Hence, the 80/20 rule, sometimes also referred to as “polarized training”. Some of the athletes adhered to this principle purposefully, but he found many instances of elite athletes who had discovered this through trial-and-error and fell into this ratio based on what their bodies were telling them each day.

The fundamental variables of triathlon training are discipline, volume, and intensity. Discipline is the type of workout you’re performing (swimming, cycling, running, weight training, etc.), volume is the amount you’re doing (for example a two-hour bike ride or a five mile run), and intensity is how hard you do the workout (commonly measure in zones 1-5).

Here is a brief description of each zone, taken from

The point of the 80/20 ratio is to keep you at either zones 1-2 (slow and easy) or zones 4-5 (intense), and avoid the “grey zone” of zone 3. Many recreational athletes know enough to push themselves out of zones 1-2, but aren’t comfortable with the discomfort of zones 4-5, and so end up doing the bulk of their training in zone 3, which unfortunately results in the worst of both worlds. The result is chronic fatigue, with no light days necessary for recovery, and no high-intensity days which have been shown to increase performance even for endurance races.

Instead, your optimal training should be approximately composed as follows:

Zone 1 and 2: 80 to 85 percent
Zone 4: 10 to 15 percent
Zone 5: 2 to 5 percent

In your day-to-day workouts, keep in mind that unless you’re specifically doing a high intensity section, you should be breathing comfortably hard but not panting. For example, if you can’t say the phrase “Old Macdonald had a farm” in one breath without gasping at the end, you are likely going too fast. (Side note: don’t do this in the middle of a group run or you may get some strange looks.) For more details on the 80/20 rule, read the excellent “80/20 Running: Run Stronger and Race Faster By Training Slower” by Matt Fitzgerald.

80/20 Running: Run Stronger and Race Faster By Training Slower by [Fitzgerald, Matt]

^Read it

One way to stick to the 80/20 plan is to incorporate a heart rate monitor into your workouts. The purpose of this is simple: keep your easy days easy and your hard days hard. While it’s worthwhile to learn to listen to your body, a heart rate monitor can be an invaluable tool for initially teaching you what each zone feels like. If you do go this route, remember that each person’s body is different, and there’s no one single formula you can use to find your resting or maximum heartrates. Also remember that your heartrate can be impacted by day-to-day factors such as the hydration, caffeine intake, and the previous night’s sleep quality.

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