Have They Found the Perfect Interval Formula?

In the fitness world, buzzwords come and go almost monthly. One that seems to have some real staying power, though, is high intensity interval training, or HIIT. Although it’s not really a new idea, HIIT has really gained ground in the past few years with the rise of standardized forms like Crossfit, Tabata and the Little method. Even with these programs, though, a universal formula for an effective HIIT workout has been sorely lacking.

A group of Danish researchers set out in 2012 to define the perfect formula for HIIT and their work produced some intriguing results worth considering.

The 10-20-30 Study

At the beginning of their research, the team, led by Dr. Thomas Gunnarsson experimented with different ratios that are already at use in other HIIT methods.

Starting with 30-second sprinting bouts, which is a common approach, they found that, although this produced powerful results in their subjects, it’s also a very demanding. Eventually, through trial-and-error, the team fell on 10-second intervals.

It’s not really surprising that the 10-second sprints produced benefits but the exact depth of those improvements has caught many experts off-guard.

Over the course of the 7-week study, veteran 5K runners cut a full minute off their time and 1500-meter runners reduced their time by an average of 23-seconds. And these reductions all happened while slicing their weekly mileage by half. As an added selling-point, these highly effective workouts only took about 20 to 30 minutes.

Workout Details

At its core, the 10-20-30 program is modeled after the Fartlek approach by involving short bursts of running with the speed adjusted by how you’re feeling.

A typical workout following this new protocol would look like this:

  1. A 10-minute warmup. The runners in the original study ran just 3/4 of a mile for their warmup, with no regard to time.
  2. Jog for 30 seconds, run for 20 and then sprint for 10. Repeat this same pattern four more times, follow this routine for five straight minutes.
  3. Walk or jog for 2 minutes as an active rest.
  4. Repeat steps 2 and 3. Cycle through these intervals two or three times. Runners in the study eventually worked their way up to four of these sets.

The original study didn’t list any sort of cool-down but a 10-minute walk is generally recommended to wrap-up your workout.

Because this approach allows you to adjust the speed of each interval, whether it be jogging, running or sprinting, and the number of times you repeat the pattern, it’s easily adapted to your fitness level.

Expert Reception

In general, most experts who reviewed the research found no problems with the study methodology or the program that the study produced. A few authorities have questioned the effectiveness of this type of workout for elite-level athletes.

Others have expressed doubts regarding the trustworthiness of the touted benefits since the subjects used were all experienced runners. These detractors feel that those benefits are to be expected by runners who suddenly shift to an easier training method.

Overall, however, both anecdotal and expert reports have supported the use of 10-20-30 intervals.

Have you been able to incorporate 10-20-30 into your workouts? Please share your experience in the comments.




Time-Crunched Treadmill Workouts

Ask Coach Jenny

 Q: I struggle this time of year to get in my workouts and I’m limited to the treadmill. Do you have any suggested workouts for the time-crunched runner?  ~Jessica

A: Hi, Jessica. You’re not alone. In fact, this time of year is when activity falls by the wayside in lieu of parties, shopping and busy schedules. The good news is you’re right on target in terms of how to stay on track this holiday season. It is better to get in short, frequent workouts than cancel because you can’t get in your normal 45 minutes. The key is to maintain momentum and make the most of the time you have.

Before we discuss the workouts, here are a few key rules to know before you go.

Always invest the allotted time to warm up by walking. You’ll start with a brisk walk, transition to a power walk, then run to fully prepare your body for the high-intensity workout ahead. This will make for a more pleasurable and optimal workout experience.

  • Post workout, cool down and let your heart rate and circulation return to their resting rate. In most cases, two to three minutes of easy-effort walking will do the trick.
  • Listen to your body. Avoid the trap of running by pace, and go by how your body is feeling instead. Some days this will be faster, and some days slower – but when you run by your body on a given day, you’ll gain the most for your effort.
  • If you’re new to high-intensity workouts, start with one of these workouts per week and see how your body responds. You can fill in the gaps with short, easy- effort runs in the meantime. This will help you maintain your momentum, recover optimally and progress to running more frequent high-intensity workouts per week.
  • Note to newbie exercisers: If you are new to the active life, make sure to develop a solid base of regular walking or running at least three times per week for 30-60 minutes each before weaving these workouts into your schedule. You’ll progress faster with a lower risk of injury and burnout.

Here are three, 30-minute workouts that are fun, functional and will keep you fit through the crazy-busy holiday season.

The Music Mix Mash-Up

Move to the rhythm of your own beat.

  • Create a music mix by alternating a slow-to-moderately paced song, like “Just the Way You Are” by Bruno Mars, with a fast-paced song, like “Beautiful Day” by U2.
  • Warm up by walking for 3 minutes at a brisk effort level.
  • For 25 minutes, alternate slow and fast songs, matching your effort level to each.
  • Run at an easy pace to slow music. After the warm up, run for the duration of the first song (slow-to-moderate) at a comfortable effort level where you can talk while you’re moving.
  • Run hard to fast music. Pick up the pace to a comfortably hard level where you can hear your breathing and you’re just outside your comfort zone for the entire duration of the fast-paced song.
  • Continue to alternate easy and hard efforts with the alternating songs on your custom playlist.
  • Cool down by walking 2 minutes at an easy effort.
  • Soon you’ll find that the time flies by quickly when you’re jamming to your favorite tunes!

The Mountain Climber

Moving up and down hills strengthens your legs and your stamina.

Changing the incline on the treadmill is just like strength training for your legs. The added resistance is a great way to increase the intensity, burn a ton of calories and utilize a variety of muscles. (Cut and paste this workout and tape it to the treadmill).

Warm up

  • Walk at a brisk pace for 3 minutes at 0% incline.
  • Start running at 0% incline for 5 minutes at an easy effort level (conversational pace).

Set 1

  • Keeping the speed the same, increase the incline to 1% and run for 1 minute.
  • Decrease incline to 0% for 2 minutes to catch your breath.

Set 2

  • Increase the incline to 2% and run for 1 minute.
  • Decrease to 1% for 1 minute.
  • Decrease to 0% for 2 minutes to catch your breath.

Set 3

  • Increase the incline to 3% for 1 minute.
  • Decrease to 2% for 1 minute.
  • Decrease the incline to 1% for 1 minute.
  • Recover with 2 minutes at 0%.

Set 4

  • Increase the incline to 4% for 1 minute.
  • Decrease progressively, 3% for 1 minute, 2% for 1 minute and finally 1% for 1 minute.
  • Recover with 2 minutes at 0%.

Cool Down

  • Finish running at 0% incline for 2 minutes at an easy effort level (conversational pace).
  • Finish your cool down walking 2 minutes at an easy effort.

The Pyramid

Time flies when you move at the speed of light. Alternating the speed of your workout with fast and slow intervals boosts cardiovascular fitness and running form.

Warm up

Walk 3 minutes at a brisk effort level.


Run 8 minutes at an easy effort level (conversational). Then alternate the following:

  • 30 seconds at a comfortably hard intensity, 1 minute at an easy effort to catch your breath
  • 30 seconds at a comfortably hard intensity, 1 minute at an easy effort to catch your breath
  • 60 seconds at a comfortably hard intensity, 2 minutes at an easy effort to catch your breath
  • 90 seconds at a comfortably hard intensity, 3 minutes at an easy effort to catch your breath
  • 60 seconds at a comfortably hard intensity, 2 minutes at an easy effort to catch your breath
  • 30 seconds at a comfortably hard intensity, 1 minute at an easy effort to catch your breath
  • 30 seconds at a comfortably hard intensity, 1 minute at an easy effort to catch your breath

Cool down

Finish with 2 minutes of easy-paced walking or running and cool down.

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