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There are a million different ways to do an interval workout on the bike. And that’s just the problem. With so many formats to choose from, how do you decide which workout is the best workout for you today? And next week? And the week after that?
Relax. Choosing the perfect interval workout for you now is not so important. In fact, there is no such thing as the perfect interval workout for a given athlete at a particular time. Any of a number of different formats will yield more or less the same benefits. What’s more important than the specific format of each interval workout is the direction defined by the sequence of interval workouts you do. The right direction has two aspects: Your interval training should be progressive and should become increasingly race-specific.
Within these parameters, your interval training can be anything else you want it to be, and I recommend that you also keep it simple. It can be tempting to think that a more complex interval workout progression is somehow more scientific and effective, but this is not necessarily so. The advantages of using a simpler interval workout progression are that doing so makes it easier to ensure that your training is moving in the right direction, and easier to monitor your improving fitness.
A sequence of interval workouts is progressive if each workout entails a greater workload than the last, except for scaled-back interval sessions performed within recovery weeks. You can make interval workouts more challenging by increasing the number, duration or intensity of intervals in it. If you have a power meter, you can ensure that the workload of your interval workouts is increasing from session to session by downloading your ride data onto a software application such TrainingPeaks WKO+, which assigns a “Training Stress Score” to the workout based on its duration and intensity relative to your current functional threshold, which is the maximum power output you can sustain for one hour. This handy tool allows you to make apples-to-apples comparisons among all works, even when the number, duration and intensity of intervals differ.
A sequence of interval workouts becomes increasingly race-specific if the intensity and total amount of work performed move closer to the intensity and duration of your race. In practical terms, this means that the sequence begins with intervals that are shorter and much faster than race intensity and culminates in longer intervals that are only a little higher than race intensity.
This progression should not be perfectly linear, however. Once every three or four weeks you should reach back and perform a set of shorter intervals to maintain the speed and power you developed through your initial focus on them. Also every three or four weeks, as suggested above, you should perform a lighter set of intervals to facilitate recovery. It is sensible to combine these two ways of “stepping back” by doing a lighter set of shorter intervals every third or fourth week.
Traditionally, triathletes incorporate cycling intervals into their training only during the “build” and “peak” phases of their training. More recently, however, there has been a movement toward including interval work throughout the training cycle. The rationale for doing interval work in the base phase of training is that the base phase is the best time to build a foundation of speed and power through very short, very high-intensity intervals that can then be developed into a capacity to sustain speed with the use of progressively longer intervals in the build and peak phases. Personally, I favor this approach, but I don’t think it matters too much either way.
Following is an example of a 16-week cycling interval progression for triathletes that is similar to the progression I am currently using in my preparations for Ironman Arizona. You can use it in training for triathlons of any distance because high-intensity interval training is not meant to be specific to race intensity. Instead, it is meant to boost your peak power and maximum short-term sustainable power so that you can sustain your target power output for any race distance more easily.
The longest intervals in this progression are five minutes. You can perform five-minute intervals at a power output level that is significantly higher than your race power output level. Few triathletes ride this hard consistently, but it is extremely beneficial, especially when combined with regular threshold work and long rides in a cycling program. Indeed, these interval workouts are not the only hard rides you should do. You should do a second high-intensity ride each week with more sustained efforts at threshold to race intensity.
The total ride duration for your interval workouts can be anywhere from 30 to 60 minutes. They should never be longer than about 90 minutes, as the duration of the ride will start to affect the quality of your intervals beyond this point. The numbers in parentheses in the right column of the table below represent suggested spinning recovery durations. Ride the intervals in each workout at the fastest pace you can sustain through the end of the last interval without losing power. Note your average power output within the intervals in each workout and try to match or slightly beat it every time you do intervals of the same duration.
Finally, note that it is much more convenient to do these workouts on an indoor trainer than outdoors. I use a CycleOps PT300 with a built-in PowerTap.
1 6 x 0:20 (2:00)
2 8 x 0:20 (2:00)
3 8 x 1:00 (2:00)
4 6 x 0:20 (2:00)
5 10 x 1:00 (2:00)
6 12 x 1:00 (2:00)
7 6 x 2:00 (3:00)
8 8 x 1:00 (2:00)
9 8 x 2:00 (3:00)
10 4 x 3:00 (3:00)
11 5 x 3:00 (3:00)
12 6 x 2:00 (3:00)
13 4 x 4:00 (3:00)
14 4 x 5:00 (3:00)
15 5 x 5:00 (3:00)
16 8 x 0:20 (1:00)