Interval Training Mistakes That Keep You from Maximizing Your Speed and Power Gains
High-intensity interval training a.k.a. HIIT—when you alternate hard and easy cycling bouts—is a tried-and-true approach for boosting speed and power.
By breaking up higher-intensity intervals with brief rest periods, you can train at efforts you can’t normally maintain for long periods of time. “The higher-intensity interval helps to increase the work output you can sustain, which is also known as your functional threshold power, or FTP,” says Dean Somerset, C.S.C.S., an exercise physiologist who works with cyclists. The higher your FTP, the faster you’ll be able to cycle and the better you’ll be able to charge up hills or sprint on flats.
Whether you follow a busy racing schedule or like to take your bike out on weekends, interval workouts can help you ride faster and longer without tiring.
However, many cyclists make some miscalculations that prevent them from maximizing the benefits of interval training. To avoid falling into that trap, watch out for these common HIIT mistakes.
Mistake #1: Not Taking Enough Time for Recovery
Taking adequate recovery between intervals is just as important as the intervals themselves. If you shortchange your recovery, you’ll shortchange your progress.
The energy systems your body uses to power high-intensity efforts—primarily carbs and creatine phosphate—deplete quickly and take a while to recover. In fact, the higher the intensity, the longer it takes your energy systems to return to pre-interval status. “An anaerobic interval above FTP may only take two to five minutes of recovery to reproduce the same level of power, whereas sprint work that lasts less than a minute might take 10 to 20 minutes of recovery to do again,” Somerset says.
If you don’t give yourself enough time to recover between bouts, you’ll go into your next high-intensity interval with little gas in the tank. You’ll tire out quickly and wind up dropping your intensity to keep going. “This is like having to take weight off the bar when strength training,” Somerset says, and you won’t see the performance improvements you hoped for from your workout.
How to Fix It
Recovery intervals should last long enough to allow your heart rate or power time to drop back down. For longer intervals (around three to five minutes), this might take one to five minutes, Somerset says. Depending on your fitness level and/or how intensely you work, you can either stop cycling or ride at a very low effort level while you recover. Keep tabs on your heart rate while you recover—if it returns to a pre-interval state, you’re ready to pick up the pace again.
However, heart rate won’t tell you enough about your recovery in a workout that involves shorter (less than a minute), and more intense intervals. “This is because the higher output of work will require recovery of more than just your heart rate,” Somerset explains. You also need to replenish fast-burning fuel sources like creatine phosphate and flush out byproducts that build up from high-intensity efforts, “which can take a bit more time,” he notes.
The best way to tell if you’ve recovered from a shorter interval is to check that you can match the power output in your next interval. “This is sort of a trial by fire in that you have to do the interval to see if you were recovered enough,” Somerset says. “If you can’t maintain power output for the same duration, you need longer to recover in the next phase before trying again.”
Mistake #2: Doing Too Many Interval Workouts
You have to do interval workouts often enough to see performance improvements. But there comes a point where more isn’t necessarily better, especially if you do too many interval workouts in a row.
“Doing too many interval workouts back to back could be a disservice because you’re not giving your body enough time to recover between workouts,” says John Thornhill, a cycling instructor with Barry’s in New York City.
This recovery time is essential because it’s when your body makes the adaptations that ultimately help you cycle faster and more powerfully. Without recovery, your body won’t adapt. Moreover, it’ll eventually break down, causing a drop in performance and potential injury.
How to Fix It
Separate your interval workouts by at least one day. Depending on how hard you go during your interval workout, it might be a good idea to make your next workout lighter intensity or switch modes entirely (i.e., strength training or mobility), Thornhill says.
There’s no hard-and-fast rule as to how many interval workouts you should do per week, Thornhill continues. However, the general recommendation is anywhere from two to four, depending on your fitness level, goals, and how quickly you recover.
Mistake #3: Skipping a Warmup or Cooldown
The warmup and cooldown offer unique perks that you don’t want to miss.
Thornhill says that warming up is essential for getting your muscles ready to work at a higher intensity. A warmup gradually increases your body temperature and primes your nervous system for hard intervals, making your movements smoother and safer.
Meanwhile, a cooldown helps flush blood and waste products from your legs, allowing your body to return to its pre-exercise state. “This will assist in recovery,” says Tiffany Berenberg, a cycling instructor with Life Time Plymouth.
If you skip the warmup and cooldown, you’ll increase your injury risk and potentially prolong your postworkout recovery. Either way, the end result is the same: Fewer benefits from interval training.
How to Fix It
Before you begin your intervals, spend several minutes pedaling at an easy pace. Berenberg suggests aiming for an effort between two and four on the rate of perceived exertion (RPE) scale, where 10 is the equivalent of working at your maximum.
Once you finish your interval workout, take a few minutes to pedal at an easy intensity to bring your heart rate back down. Then, hop off your bike and stretch out your lower back, quads, inner thighs, hamstrings, glutes, and hip flexors, Thornhill says.
Mistake #4: Not Pushing Hard Enough During Work Intervals
Interval workouts aren’t a time to get lulled into steady-state efforts—they should make you uncomfortable. If you don’t push yourself, you won’t make progress.
The intensity you’re working at will determine which energy system gets targeted and, ultimately, the improvements you see.
For example, if your goal is to nudge your FTP higher, you might work at zone 5 of your cycling power zone, or an intensity that lasts about three to five minutes and hits slightly above your FTP and targets your VO2 max. The goal is to maintain that zone 5 effort throughout the entire interval (and then recover after).
To boost speed and power, you might work at power zone 6, or a high enough intensity to last for only 60 to 120 seconds, an effort significantly greater than your FTP that uses quick-burst fuel sources like creatine phosphate and carbohydrates. And full-force sprint intervals that build power and use only creatine phosphate should be done at zone 7 and may only last 10 to 20 seconds, Somerset says.
The key with each interval is actually maintaining that effort so it matches and helps you reach the overall goal of the workout.
How to Fix It
Keep tabs on your effort levels during work intervals. “You want to push yourself in your interval to an RPE of eight or nine,” Berenberg says, for most interval sessions. In other words, you should be ready for that recovery when your timer goes off. If you’re not breathless and panting, step up the intensity.
Keeping tabs on your training zone (whether you’re using a heart rate monitor or power meter) will also help make sure you’re hitting the right intensity. If you want to push your VO2 max, you want to make sure you hit zone 5 of your cycling power zone. If you’re looking to elevate your lactate threshold, you might want to work in zone 4.
Determining the goal of your interval session ahead of time, then following a workout to hit the goal will help you pinpoint the target zone, and then help you stick to the intensity it requires.
Mistake #5: Doing Intervals That Are Too Long
You need to work hard during your intervals, but you also need to match your efforts to the duration of the interval. If your work interval lasts too long, you’ll gas out early and slog through your workout.
The rule to keep in mind: The higher the intensity, the shorter the working interval. That’s because the energy systems that fuel intense exercise get depleted more quickly than those that support steady-state efforts, Somerset notes.
How to Fix It
Time your intervals to align with your performance goal.
To improve speed, keep your intervals in power zone 5 for anywhere between three to five minutes. For speed and power, work in power zone 6 for intervals of 60 to 120 seconds. To maximize your power, go to zone 7 and limit your efforts to 10 to 20 seconds.
Remember, you can always target a different goal with each interval workout (i.e., speed on Monday, speed and power on Wednesday, power on Friday).
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