The Science Of Interval Training

Interval training, is it science or hype? The true answer is both.

In today’s current culture it becomes increasingly difficult to discern between when we are being informed and when we are being hoodwinked into buying hype. The “hype” in the health and fitness world today is this “new”, “revolutionary” training style called HIIT (High Intensity Interval Training). HIIT may also be called HIT (High Intensity Training), HIIE (High Intensity Interval Exercise), SIT (Sprint Interval Training), The 10 Minute Workout or, better yet, The 7 Minute Workout. All these programs are based on interval training. Beware; some of the claims being made by people selling these programs are misleading. I am here to help you wade through the hype and find the true science. I have reviewed multiple articles from New York Times Magazine to body building websites and followed their references back to the scientific studies. After diligent review of the 10 most cited studies this is the skinny on interval training.

The first misleading statement is that this style of training is “new”. Interval training was first documented in the early 1900’s and became a staple of performance training in the 1950’s. The only way this is new to your training is if you have never been training properly.


The second misleading claim is that interval training replaces traditional steady state cardiovascular training. Interval training is a fabulous way to train and see results, but by no means should it replace your cardio training. You can cut back on how much steady state cardio you are doing, but a complete replacement is not suggested, at least not on a long term basis. After I share the science with you I will give you a couple goal specific program options for your training.

Then there is “The 7 Minute Workout” , this is very misleading. It is not possible to effectively meet your cardiovascular, strength and flexibility needs in twenty one minutes per week. Even when incorporating intervals you should be investing 150 minutes a week into the wellness of the only body you will ever receive.

The Science and Application

Now, let’s discuss the truths about interval training. If your goal is to be a leaner, healthier you, and possess a high level of performance, then interval training is a must in your program. Interval training produces physiological effects that are unique to training at maximal or near maximal effort. The most beneficial effect of interval training is its effect on mitochondria production in skeletal muscle cells (Daussin et al. 2008).

Mitochondria are the power plants of muscle cells. The higher the density of mitochondria in your muscles the more oxygen you can utilize. Utilizing oxygen burns fat!! The greater your ability to use fats and oxygen for energy, the higher your level of performance!! This effect of high intensity intervals is what you are after. The other wonderful benefit of interval training is that you can increase cardiovascular health with less training time. K.A. Burgomaster’s study, published in 2008, showed that three workouts per week of 4-6 intervals of 30 seconds “all out”, 100% VO2Max, with 4.5 minutes of active rest at 65% VO2Max, yielded the same cardiovascular benefits as 40-60 minutes of 65% steady state cardio five days per week. So, high intensity intervals did in 1.5 hours per week what low intensity cardio did in 4.5 hours per week. You can definitely trade intensity for time!! So, make some of your cardio workouts interval workouts. Don’t replace them all with intervals because variety in your training is still the second most important part of your exercise program. Just do some interval days and some lower intensity days. The most important part of your exercise program is consistency!!! Make it a point to be active every day.

Let’s dive a little deeper into interval training. Depending on your goals there are different intensities at which you perform your intervals.

Cardio Intervals

If your goal is to increase your cardiovascular performance and burn a little more fat your intervals should be performed at a 9 on a 1-10 intensity scale, or 90% maximal effort, and allot for a good recovery between intervals(Billat et al.2001) . Start with a four minute warm-up, and then work hard at your 90% for one minute, after your minute relax back to 65-70% your max effort for four minutes. Repeat this cycle 4-6 times. As you advance make the work intervals longer and the rest intervals shorter, until you are performing three minutes of work to three minutes of active rest. To really make your training program effective use a heart rate monitor. Then you know exactly how your body is responding to your exercise and how to properly adjust it for maximal results. To factor your heart rate simply use this equation;

Gellish; 207-(.67 x your age) = Theoretical Maximum Heart Rate (TMHR)

If you are 40 years old; 207 – (.67 x 40 = 26.8) = 180.2 bpm is your TMHR

To factor your training %’s take your THMR and multiply it by your desired %

180 x .9 = 162bpm = 90% exertion

A 40yr old needs to work at 162-165bpm during their intervals and is ready to sprint again when they get back down to 117-126bpm. Now, that’s scientific!

Fat Burning / Metabolic Training

If your goal is ultimate fat reduction then perform whole body exercise intervals at a level 10 on a 1-10 intensity scale, 100%, and hold that intensity for a minute. Dig deep and work hard!! Then do an easier exercise for 1-2 minutes, making sure you have recovered enough to get another full minute of “all out” exertion. “Walk it off” if you need to, but never sit down!! Then hit it again!!You are trying to dig a big metabolic deficit so your body is in recovery mode (burning fat) for as long as possible. You are trying to take advantage of your EPOC (Excess Post-exercise Oxygen Consumption). Repeat these intervals for 20-30 minutes then do five minutes of cool down and stretching. Please consult a fitness professional if you have any questions about being ready for this level of intensity. Injury is a sure fire way for your exercise program to fail.

Example intervals;

1. Perform 20 alternating walking lunges then immediately do 10 burpes, walk for 1-1.5 minutes then repeat

2. Perform as many pull ups as possible then do jump squats until you can’t stand it. Recover with 1 minute of slow, full range crunches on a bosu. Remember to keep your abs engaged (Kegel) at all times.

3. Do 15 push-ups then 10-15 kettle bell swings, recover and repeat.

4. My personal favorite 10 tire flips and 10 tire rows!!!

(You can find these exercises online or consult a training professional)

If you are using a heart rate monitor (suggested), you want to max out, then let your heart rate recover by 30bpm, and then max it out again. When your heart will no longer recover 30 beats in two minutes, your workout is coming to an end. Your workout will be approx. 20-30 minutes. Clean up and come back in 48 hours. Do an easier workout on the days in between, light cardio, rotator cuff/hip/core workout or rest.



2. Make sure you have built the proper fitness base to start applying this very demanding stress to your body.

3. Make sure you always warm up and cool down after every workout.

4. The 7 Minute Workout three times a week is not going to yield your desired results!! A 20 minute workout three times per week will get you headed in the direction you want to go.

5. DIET!!! You need to eat within 30 minutes of completing your training to maximize muscle retention and growth.



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For questions and/or help with exercise suggestions and form please contact me at

La Jolla’s Finest Training
565 Pearl Street
La Jolla, CA 92037