How to Optimize High-Intensity Interval Training for Cyclists

No matter what type of high-intensity intervals you choose to do, there are several keys to getting the most out of your sessions.

There is a complicated mythology surrounding high-intensity interval training (HIIT) for cyclists. On one hand, the “no pain, no gain” mentality that has been so pervasive for so long has convinced many cyclists to believe that they must go really deep to see any benefits. So they do it too often, to their detriment.

On the other hand, there are so many interval types and workout prescriptions that it can be overwhelming to know which to do and when—to the point that some of us give up and just ride, or we create overly complicated training sessions that are challenging or impossible to properly execute.

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Let me simplify the myth: high-intensity intervals have significant benefits, but we don’t need many to see big gains. Think of them as the icing on the cake, or the pinch of salt you add to soup to give it that final burst of flavor. Overdo it and you spoil the whole meal.

As influential physiologist Dr. Stephen Seiler likes to say, when you’re near your peak fitness, think of yourself as fresh fruit:

“A lot of athletes are interested in doing these super high-intensity intervals. You can get a big improvement, a 10 percent improvement or so, in as few as four workouts, if they’re well executed. But they’re costly. And they’re ‘fresh fruit’ because that adaptation is what I would call a soft adaptation.”

By that, Dr. Seiler refers to complex biochemical changes that come on quickly, and disappear just as fast.

“It’s some proteins in your blood and in your intracellular space, it’s some changes in buffering, it’s stuff that both comes pretty fast, but it goes away pretty fast,” he says.

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With that in mind, instead of focusing on which intervals are the best, how to work them into your overall training plan, or what energy systems they each work, let’s focus on proper execution, so that no matter what you choose to do, you get the most out of every session.

Focus on execution

Many times, the most important aspect of interval training is not the “what” (as in what interval you’re doing), but the “how,” or the way you’re doing it. Without proper execution, you may not generate the required training stress to produce an adaptation.

For example, in the case of 8-minute threshold intervals in which you hope to stress the aerobic energy system, if you complete the first one at an average of 250 watts, the second at 225 watts, and the final interval at 200 watts, the composition of each interval is changing. The contribution from the anaerobic energy system is dropping, and you’re never fully stressing the aerobic system. Thus, you’re not satisfactorily completing the workout as intended.

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A good set of threshold intervals means that you are averaging your threshold repeatedly, to accumulate time at that physiological mark. Hitting the mark time after time takes practice, which leads to the second key.

Consistency is critical

If you regularly try to complete different intervals—the temptation for variety is natural—there is a downside. You risk reducing the effectiveness of the adaptation by only partially taxing the various energy systems. Thus, you never fully subject one energy system to enough work to elicit that supercompensation you desire.

It’s better to select a routine and stick with it for several weeks. The higher the interval intensity, the more quickly you see adaptations. Short intervals, such as sprints, produce benefits in as few as three to four sessions. Anaerobic capacity work takes about six to eight sessions, and threshold work can take eight to 14 weeks to produce full gains.

As mentioned, proper execution takes practice, so kill two birds with one stone by picking an interval you like and sticking to it for a predetermined number of weeks. This will not only help you maximize the adaptation of the energy system you’re working, but it will also improve the quality of each session as you improve execution. This leads to the final point.

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Quality over quantity

For certain cycling disciplines—for example, stage races—there are benefits to doing some HIIT sessions in a fatigued state. This helps you produce power on the fifth day of a weeklong race, for instance.

But, generally speaking, to optimize the adaptations you get from high-intensity work, the intervals should be performed when you are rested. This helps you go as deep as intended and, thus, reap the full reward. For very hard workouts, rest or, at most, do a recovery ride the next day.