graphic of man running, B/W illustration

Our bodies are designed for movement. There are many different ways to move, each good for us for different reasons. Most people know about cardio workouts, exercise that pumps up your heart rate. Stretching is another and, important as it is, maybe the only kind of exercise that is over rated. Although less popular, most people are still aware of strength training, and some even know that balance training is a good idea. The power that exercise, in whatever form, has to transform our health and our bodies is practically magical.

Unfortunately, perhaps the most magical type of exercise is the most often overlooked. The great majority of you are missing out on this form of exercise. You should change that because this kind of exercise turns out to have uniquely beneficial effects and those effects are gained very quickly. Ok, what am I talking about? The answer is High Intensity Interval Training (HIIT). Even those who know something about HIIT nearly always have the wrong impression. The worst mistake is that they assume HIIT is only for strong athletes. That is completely wrong.

HIIT has long been a part of serious athletic training. When I was a high school soccer player, we began our two-a-day summer trainings by jogging down the street a mile to the soccer field at an elementary school. In those days soccer was displaced by the football team that got all the fields on campus. Every practice session ended with a dreadful set of interval sprints, the point of which seemed to be as much about proving that the coach was in charge as it was about any fitness boost we might achieve.

If you watch the movie, “Miracle On Ice”, the story of the USA gold medal hockey team of 1980, you can experience (thankfully from the comfort of your couch) the “Herbie” intervals that tormented the USA players.  This style of HIIT was, not so lovingly, named after their brilliant and determined coach, Herb Brooks. History shows that worked out pretty well.

As I am certain many of you with athletic pasts can recall, intervals were NOT fun. That does not need to be the case. Actually, I find HIIT particularly useful for the very individuals one would think would have the biggest reasons not to do it – people with serious joint trouble and other fitness limitations. That probably doesn’t make sense, so I need to explain a bit more.

What exactly is HIIT?
HIIT stands for High Intensity Interval Training. Some call it High Intensity Intermittent Training. No worries. The idea is exactly the same.

Following a short warm up for a very short time, a person works really, really hard. Then the person slows down their pace to recover. That is one cycle. Typically the cycle is repeated three or four more times.

You can use this approach with any kind of exercise, swimming, cycling, running, whatever. If you have healthy joints you might even be able to combine HIT with strength training as you can see on my website. They key is to work HARD, back off, and then repeat.

Nuts and Bolts, How Long, How Hard, How Often
How long should the intervals be? That is an important question and just of the questions about HIIT that we haven’t answered very well yet.

The first studies used protocols that lasted around 25 minutes. After a five minute warm up, the subjects exercised as hard as they could for three minutes, rested or moved slowly for one minute, and then repeated the cycle three more times.

Stunned by the dramatic improvements in cardiovascular fitness over just a few weeks, researchers have been working since then on learning more about the specifics. I remember a packed session on HIIT at the American College of Sports Medicine’s big annual meeting, where I was surprised that some of researchers were discovering benefits from HIIT even with heart rate elevations that would be rated as low as 13 (“somewhat hard”) on a scale of 1-20. (19 is “extremely hard” and 20 is “maximally hard”). A rating of 13 is like a moderate walk, but even this low level HIIT had a surprising impact.

Since then, we have learned that higher intensity HIIT is surprisingly as potent as it is efficient.

For me, the real groundbreaking early study was when researchers tested patients hospitalized with heart failure. The patient tried walking on a treadmill slowly for 40 minutes and compared that to walking as fast as they could for a couple of minutes, alternating that with slow walking for 25 minutes. There were two key findings. One was that patients who did the intervals improved their heart function much more than the slow walkers. The other discovery was that patients preferred the intervals over the long, slow walks. So, HIIT was a double winner.

On the practical side, the interval duration remains the most confusing element. One recent study found significant benefits for people who excised five cycles that were each only ONE minute long. The subjects worked very hard for 20 seconds, easy for 40 seconds and then repeated the cycle four more times.

The most available and compliant experimental subject at my disposal is me. After five lower extremity joint surgeries, multiple broken bones, dozens of assorted injuries and a nasty family history of heart disease, I always need to be creative with my exercise regimen. When I started using HIIT myself over a decade ago, I ran ten minutes to warm up, then one minute as hard as I could, followed by three minutes at a slower pace waiting for my heart rate to drop from 90-95% of my heart rate maximum down to 70%. I repeated this cycle nine more times. That was my regimen twice a week. It was very challenging. Now we know that was more than necessary and maybe even too much to achieve the best results.

The twice a week part I got right. Recent studies tell us that doing HIIT more than three times a week appears to backfire, reducing a person’s capacity instead of increasing it. That is probably due to overwork.

After erring on the side of pushing myself too hard (my usual MO) and getting older, I was eager to try the five cycles in five minutes routine. My verdict? It is okay, but it doesn’t feel like it does as much for me as longer intervals do.

HIIT Take Home Messages
1- HIIT is for every body.
2- Do it 2-3 times a week.
3- Figure out how to do it safely. Don’t run down stairs. Don’t do it on a “bad day”.
4- Warm up first.
5- Start out with SHORT intervals. Even 20 seconds will be good for you. Make the intervals hard enough so that you are looking forward to the end of that interval.
6- Go easy between the intervals for a length of time necessary to recover a bit.
7- Repeat the cycles more times when the intervals are short, but at least three cycles.

Finally, adapt your HIIT regimen to your circumstances. In our hilly locale, it is easy to turn a walk into a HIIT session by pushing yourself uphill. Cycling, swimming, dancing, elliptical machines, etc. can all be used for HIIT workouts. Some activities like downhill skiing, soccer, basketball and tennis naturally incorporate HIIT. Strength training can become a HIIT workout, but that can also be risky, as a loss of good form will lead to injury.

Written by 

Michael Carlston, MD is an internationally recognized authority in the integration of conventional and complementary medicine in clinical practice, as well as medical education, research and organizational consulting. Practicing in Santa Rosa, California, Dr. Carlston was voted “Best General Physician In Sonoma County, California” by readers of the Sonoma County Independent newspaper and also named one of the outstanding physicians in the Bay Area by San Francisco Focus Magazine. With 30+ years in private practice, his expertise is in nutrition, homeopathy and sports medicine.