3 Mistakes You’re Probably Making in Your Interval Workouts

Every runner knows that interval workouts are highly beneficial. But not all HIIT sessions are equally beneficial. If your coach asks you to do an interval workout that’s either too hard or too easy for you, it won’t do much for your fitness. Likewise, if your coach gives you a workout that’s just right on paper but you make it too hard or too easy by running faster or slower than you’re supposed to, you won’t benefit as much as you would have if you’d been more compliant.

As you see from these examples, there are two basic requirements for effective interval training. The first is planning, and that’s on the coach. Whenever I plan an interval workout for an athlete, I ensure it presents just the right level of challenge. The second requirement is execution, and that’s on the athlete. When you take your planned workout to the track, trail, or road, you must try your best to avoid common mistakes that compromise the effectiveness of interval work.

RELATED: How to Get Better at Pacing (and Why It’s Worth the Effort)

In the nearly thirty years I’ve been coaching endurance athletes, I’ve seen three mistakes made repeatedly in the execution of HIIT sessions. Let’s look at them and how you can make your coach happy with flawless interval workout execution.

DID YOU READ? How to Use Heart Rate Zones to Improve Your Running

Intervals Mistake #1: Slowing Down within Intervals

The image you see below is a pace graph of an interval workout done recently by one of my athletes. You’ll notice that the line representing her pace slopes downward in all eight intervals. This means she started too fast each time and lost steam as the interval unfolded. Although her average pace came out close to the target I gave her, she spent very little time actually running at this pace, instead starting faster and finishing slower.

Correct execution of interval sets like this one entails running at a steady pace from beginning to end. When I see perfectly flat lines in pace graphs, I smile, because I know the athlete has earned the physical benefit of spending time at the targeted intensity as well as the mental benefit of exerting excellent control over their effort.

RELATED: Get Better Faster: Master the Fundamentals Before Seeking “Marginal Gains”

Intervals Mistake: #2 Slowing Down Between Intervals

The second most common mistake made in interval workouts is slowing down from one interval to the next. Sometimes this happens in conjunction with mistake #1 (i.e., the athlete fades both within and across intervals); other times it happens on its own (i.e., the athlete does a good job of holding steady within each repetition yet their average speed drops as the workout goes on). Either way, mistake #2 is really just another version of mistake #1, which is starting out too fast.

It's important to understand that slowing down out of necessity in a workout—whether it occurs within or across intervals—is a form of failure, and runners should not practice failing. This is why I always call out my athletes when they lose steam in a workout. It might seem harmless, but it’s not. Athletes who lose steam in workouts do the same in races, and that’s not good.

RELATED: What’s the Best Way to Measure Your Run Intensity?

Intervals Mistake #3: Slowing Down in Active Recoveries

Suppose you avoid both mistake #1 and mistake #2 in your next interval workout. A+ for execution, right? Not necessarily. The third most common mistake made in interval workouts is getting slower in the active recoveries between intervals. If you can’t run your last active recovery at the same pace as your first active recovery and still manage to run your last interval as fast as your first interval, then you’ve run intervals are too fast, plain and simple.

Most runners think of recovery periods as the unimportant part of interval workouts, but in fact they are just as important as the intervals themselves. A major portion of the fitness benefit you get from doing HIIT comes from challenging your body to recover quickly from intense efforts while still moving. Maintaining a steady pace across recovery intervals ensures you maximize this benefit and also keeps you from pushing too hard within intervals.

RELATED: How to Increase Your VO2 Max

As Easy as 1-2-3

Don’t be intimidated by all this talk of mistakes. You don’t need luck to perform interval workouts flawlessly and thereby maximize their benefits. You just need to make an honest effort to start out at a pace you can sustain throughout all of the prescribed intervals without slowing down within intervals, across intervals, or during active recoveries between intervals. When you successfully avoid the three most common mistakes in high-intensity interval training, your workouts are actually easier than when you make one or more mistakes. That’s good news!