high intensity intervals

Interval Training: Mistakes Cyclist Make with High Intensity Intervals


By Jim Rutberg,
CTS Pro Coach,
co-author of “Ride Inside
and “The Time-Crunched Cyclist

Despite the current frenzy around Zone 2 training, coaches and athletes have long known they need to train the full range of intensities to improve performance. Even proponents of large volumes of easy aerobic training incorporate high intensity intervals into their training programs when it’s time for athletes to get ready for racing. We’ve been fans of high-intensity intervals (HIIT workouts) for a long time. The “Time-Crunched Cyclist” is based on the premise that hard intervals play an important role for cyclists who cannot put in long hours. The most effective training combines long Zone 2 riding with appropriate intensity from intervals. Unfortunately, high-intensity intervals are easy to mess up, so make sure you’re not making the mistakes in this article.

(If you’re new to cycling interval training you may want to read our guide on including interval training in your training plan.)

Too Little Warm Up Before HIIT Intervals

Let’s say you have a few sets of ten 20-second max efforts separated by 40 seconds of recovery. What we often see is that some or all of the first set ends up being more of a warm-up exercise than a true high-intensity interval set. The total time-at-intensity during these workouts is pretty low, maybe 12-16 minutes, and losing 20-30% of that potential time-at-intensity is a big deal. If the data from your first set of short, high-intensity intervals is a mess compared to the rest, try spending more time warming up, even if it means cutting your cool down a little shorter.

High Intensity Intervals That Aren’t Hard Enough

The next mistake we see from cyclists is not committing to full efforts. The effectiveness of high-intensity intervals is based on hitting those high power outputs and pushing your cardiovascular system hard. A one-minute effort that’s “almost” really hard isn’t going to do it. Worse yet, you’re doing a lot of work, but it’s not productive.

To clarify, many high-intensity intervals are prescribed as “all out” or “max effort”. This can be confusing because the power output associate with your maximum effort for repeated 20-second efforts separated by 40-second recoveries will be different than your output for a maximum effort lasting one minute or two minutes. Then, there’s varying purposes behind certain interval durations. Repeated 45-second all-out sprints can be an effective workout for increasing anaerobic capacity, but only when these intervals are separated by 4-5 minutes of recovery. That’s a very different “max effort” than Speed Intervals, in which an 8-minute set consists of repeated 30-second efforts with 30 seconds recovery between them.

As a reader noted, you could also consider that the anaerobic capacity intervals (45 second sprints) could be thought of as “maximum” at the repetition/interval level, and Speed Intervals could be thought of as maximum at the set level (i.e., full recovery between sets). Philosophically, all intervals are done at the maximum intensity you can maintain for the duration. Functional Threshold Intervals are 10-20 minutes long because that’s how long you should be able to sustain the power if it is prescribed appropriately. In other words, the intensity defines the duration and the physiological target, not the other way around.

Lack of focus

What the previous point comes down to is primarily lack of focus. You can just go out for a ride and think through that work or relationship problem you’re having. In fact, those long rides can be really helpful for that! High intensity intervals require focus. It’s not time for problem solving. You can’t take a call in the middle of it. Be present, deliberate, and disciplined.

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Doing High Intensity Intervals Too Frequently

If you’re doing HIIT workout correctly, you won’t be physically able to do them well 5-6-7 days a week. Please don’t try. Any idiot can crush themselves; you need to be smarter. Give yourself the recovery time necessary to adapt to the training stress and alleviate the fatigue so your next HIIT workout builds on your prior work instead of burning it to the ground. Two HIIT workouts in a week is plenty for new cyclists. Three per week is a sweet spot for most time-crunched cyclists. And four in a week (not every week) is manageable – sometimes – for advanced athletes.

HIIT Workouts That Are Too long

Time-at-intensity is a big deal for the effectiveness of a workout. When you do long threshold or tempo intervals you might be trying to accumulate 30-45 minutes of time at a specific intensity. With high-intensity intervals workouts, the time-at-intensity could be 10-20 minutes total. Adding more intervals to an HIIT workout doesn’t necessarily increase its effectiveness. More often, the anticipation of the longer workout leads athletes to hold back in the beginning and then still get tired before the end. Stop trying to be the last person standing (or pedaling); there’s no award for most exhausted.

Acute and Chronic Dehydration

HIIT workouts are often executed indoors because they are time-efficient and more engaging than indoor endurance rides. The result is often a swimming pool of sweat on the floor. (Side note: Take the time to clean or prevent sweat from coating your bike and eating through bolts, aluminum handlebars, etc.) During indoor cycling, you can sweat out 1.5 liters of fluid, perhaps more if the room is warm.

To maintain workout quality you have to go into it well hydrated, otherwise, core temperature rises too much and power output drops off. The problem is worse than with moderate-intensity indoor workouts because many athletes don’t have the desire to drink when working very hard. And after losing all that fluid, you have to focus on replenishing it – over a period of hours, not just one big bottle all at once) so you can recover and get ready for the rest of the day and your next training session.

High-intensity intervals can be the salvation for Time-Crunched Cyclists who want to make the most of limited training time, but only if you pay attention to what you’re doing on and off the bike, as well as before and after your workout.

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Comments 39

  1. I’m a little unsure of how to improve my warmup. At times, one of the workouts I do that I love to hate is 5 minute intervals. I tend to do 6 of them, but always find the first is lower power etc than the rest, and I’ve come to classify it as a sort of warm up interval. Is there a way to improve this besides gaining the mental fortitude to push myself through it?

  2. I’m alittle confused about this article……
    20sec all out efforts with 40sec rest.

    In another article we’re doing 30sec all out efforts with 4-5 minutes of rest between the efforts.

    Doesn’t make sense to me.


    1. This is why it annoys me when I see a coach say “all out effort”, without clarifying what that means. In general, “all out” means “as hard as you can go, and still finish all the intervals at that power”.

      20 second intervals with 40 seconds rest are FRC intervals. Figure 150% – 200% FTP.

      30 second intervals with 4-5 minutes of rest (and really, 7-8 minutes rest is better) are PMax/FRC intervals. These are 30 seconds sprints with full recovery, and should be more like 300% FTP. Really, as hard as you can go.

    2. Post

      Michael’s response is correct. I would add, in response to his statement about using the term “all out” rather than prescribing a target power output relative to FTP, that from a practical standpoint we want you to go as hard as you can sustain for the duration of the interval. If there’s a target power, you’ll aim for that when perhaps you could do more. The target power outputs for these short efforts are more useful in the post-workout analysis to evaluate how consistent the efforts were and how much power was generated.

      This is particularly true for athletes doing 30-second intervals or 20/40s on a smart trainer. These are not well suited to ergometer mode because we don’t want you to limit yourself to a target power output. Rather, put the trainer on “resistance” or “level” mode so it mimics the resistance curve of a fluid or wind trainer.

      – Jim Rutberg, CTS Pro Coach, co-author of “The Time-Crunched Cyclist” and “Ride Inside”.

      1. Jim, that really doesn’t clarify the confusion raised by a generalized prescription of “all-out” or “max”. The common workout of 3x13x(30-15) is usually done all-out, but not at the rep or set level but at the workout level. An anaerobic capacity workout of, say, 4x5x(30-30) can be done max at the set level (full recovery between sets), but is only seated max at the rep level. A Pmax/FRC workout of 30-50s all-out sprints with full recovery is just that: max at the rep level. Please – when you say “max” let your readers know if the max is at the rep, set or workout level (it might be obvious to you, but it isn’t to everyone).

        1. Post
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  4. “HIIT workouts are often executed indoors because they are time-efficient and more engaging than indoor endurance rides”

    This is supposed to be “…than outdoor endurance rides”

    1. Disagree 2 hour indoor trainer endurance rides are boring and hard to complete but I can easily enjoy an outdoor 3-4 hour endurance ride and not be bored

  5. Great article Coach! Keep the hard hard and the easy easy. Going fast on a bike takes suffering and these HIIT intervals are critical. Thanks for the reminder!

  6. It sounds like you’re saying that if you go hard enough to be in the power range for the workout, you’re OK. And, you should be able to complete the workout in that range or within ___% of that range (percentage is?).

    Can I also assume that (1) you use Average Power for short intervals, not normalized power?, and (2) you want as consistent as power as possible and not a huge beginning surge above the range with completion below the range (which would still average you in the range for the overall interval)?

    One problem that I find with automatic range calculations is that coming off of winter, my Zone 2/3 conditioning exceed the calculated ranges but my Zone 5/6 conditioning is below the calculated ranges. Do I allow my self some number of lower power HIIT workouts while my body acclimates to the demands or do I increase my rest time between repetitions?


      1. sports science is about overthinking to improve the “done” thing. 30 years ago no one was doing it now you would be hard pressed to find a pro not doing HIIT. If you don’t want to improve don’t do it and sit down for a 4 hour ride every day of the week.

  7. I have found a no cost HACK for Garmin users that want an estimate of relative power while doing climbing training. When climbing at slower speeds, simply add percent slope and MPH. If your bike plus body weight remains constant , the wattage needed for 7 mph up a 8% (i.e. 7+8 =15) slope is rather close to 9 mph up a 6% slope (also 15). You quickly learn how hard you can climb for how long an interval, be it 60 seconds or 15 minutes. Obviously, if you lose weight or ride a lighter bike, you will climb faster at the same wattage.

    1. Based on physics fundamentals, a better power metric would be to multiply percent slope and speed instead of adding them. This metric and your additive approach both neglect drag so they are more applicable to steeper gradients where climbing speeds are less.

    2. Ahh — the Rule of 15!
      I have long used this, not as a replacement for power, but as a gauge of effort that I can follow in a long ride, to keep from going too hard or falling too far off pace. For me it falls apart for grades above 12 or below grades of a few %. And some days it is the rule of 16, or 13.5, if I’m in less awesome shape.

  8. Smart trainers made the difference for me between hitting my interval targets or not, so of course my coach has capitalized on this by giving me intervals which can feel impossible. In order to get through them I use all the distractions I can. I especially like music which has a cadence that matches the target cadence for the interval. Once I realize I’m going to be able to complete a daunting workout (usually by the end of the first third of the session) I feel a lot more confident and the workout becomes a lot more fun. Blues are great for 55-65 rpm, btw.

  9. A technique that I learned from an older CTS training video is to incorporate one 30 – 60 second hard interval into your warm up, but give yourself time to recover before you start your true interval sets. This has really helped me to get warmed up in less time, so I can knock out a good session without spending too much time on the warmup.

      1. I recall these easy spin/recovery periods. When I was much younger my indoor trainer warm up was shorter compared to now where I take 20 minutes before harder efforts.

    1. Yeah I remember it well from the old climbing/tt dvd’s. Works great, seem to remember it was high power low cadence around 50/55. It gets those legs buffering early in the workout hey.

    1. Me too, my gauge on hiit intervals is if I can feel my pulse in my forehead and my butthole is trying to suck in air, then i’m slightly above lactate threshold. I get distracted by gadgets, much prefer rpe scale.

    2. I agree, that’s how I race, go hard, worry about the power, cadence, HR, etc etc later. It’s a distraction and can be a little dangerous. Your power doesn’t define your race, or your value as a person, for that matter. You have more fun that way too. I love it when people tell me their Garmin said their ride had no benefit.

  10. To back up a point that Chris brings up but most folks ignore – clean your “trainer slave” bike! I work in a bike shop and we replace 2-3 bars each year due to sweat-induced failure. What happens is you sweat all over your bars, the sweat works its way under the bar tape and corrodes the aluminum to the point where it eats through the bars and they break, usually right behind where the shifters attach. That can cause some interesting results if it happens during a sprint interval. 🙂

    1. This is why I use my TT bike indoors. My carbon base bar and extensions were easy to wrap in plastic wrap, then using plastic wrap-the stuff shippers use to hold pallets together- I wrap the steerer, headset, and the top and bottom tubes. Further, at the beginning of winter I will unthread my BB and apply a thick layer all over my bb and shell to prevent sweat incursions into my ceramic bearings. I have also found, i went to a “gym” and ended up with one of those 1/3 size towels, I put that drapped over the extensions between my elbows pads and it catches 90% of my sweat, if it does start dripping then it drips on the floor not my front wheel.

      1. Devon,
        That is an amazing solution! I have sweated through a bar before and killed at least 3 headsets, my chainring bolts, and put a massive hole in my handlebar, and I don’t want to think about what would have happened if it had come apart at 50 mph on a downhill. Can I use Saran or some kind of regular home cling wrap to do that?

  11. I race Masters 50+ Cat4. This is my 2nd year after taking 7 years off. During that time off I still rode but did not train/race. I train indoors with power but outdoors with no power. Meaning my trainer has a power meter. How do I figure out my HiiT HR training zones for the outdoors? I tried using my indoor zones outside and well not even close. Right now I cannot afford a power meter so I have to go by hr and feel. I love your articles and I’m on the TCC plan.

    1. Dan, I also found outside power meters quite expensive but did find a workable one called Power Pod from http://www.ibikesports.com/

      I was skeptical since it was around $400 but after learning how to pair it, it has worked on two separate bikes and it parallels pretty good on more expensive stain based systems.

      Hope that helps on your quest for outside FTP and training zones.

      1. I have a PowerPod and it works great for my level – it also can be put into ‘indoor trainer mode’ and will then output ‘virtual power’ to your headunit – this means I can use power-based thresholds for indoor training.

    2. Dan – if you are interested in a PowerPod I have a used one that is in good working condition that I would like to sell.

      Here is an in-depth review of it https://www.dcrainmaker.com/2016/03/powerpod-depth-review.html

      Contact me at bobandla@yahoo.com if you would like to talk.

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