High Intensity Interval Training 101

By Tom Bunn, L.Ac.

dreamstime_11806256Boulder, Colorado, where I live and practice Chinese Medicine, is a Mecca for all sorts of athletic training: running, cycling, swimming, triathlon, rock climbing, martial arts… you name it. There are more gyms than coffee shops. If you add up the all the yoga, Pilates, dance, and martial arts studios, they outnumber the grocery stores. Then there’s all the multi-use paths and hiking trails.

Every day, I treat people (men and women, young and old) who are trying to lose weight, improve their fitness, recover from injuries, and generally look and feel their best. As you can imagine, I field a lot of questions about how to get there.

Here’s what I tell my patients: There’s no one-size-fits-all magic pill — especially when you factor in age, injuries, lifestyle, body composition, general health, and overall fitness level. And that’s OK. Thankfully, you don’t need to be Tarzan or Jane (or look like them) to receive all the physiological, psychological, and emotional benefits of exercise.

Regardless of your age, physical condition, or schedule, you can still receive a huge benefit from exercise in about an hour a week. And no, I’m not trying to sell you the latest home fitness gizmo that fits under the bed when you’re not using it.

High Intensity Interval Training (HIIT)

The idea behind high intensity interval exercise dates back to the Stone Age. Our ancestors (whose physiological prototype we’re still walking around in today), were the “hunter/gatherers” most of us learned about in elementary school. They spent the majority of their time walking from place to place as they gathered things to eat: plants, roots, seeds, nuts, eggs, fruit, insects, whatever they could get their hands on. They also sprinted in short bursts while chasing after prey (or more importantly) avoiding becoming the prey of some other animal.

Not surprisingly, the benefits of combining low-intensity exercise like walking with high-intensity exercise like sprinting has millenniums’ worth of data to support it.

Depending upon your schedule and where you live, you can do the low-intensity exercise while taking a walk around the neighborhood before work or after dinner — maybe with your partner, your children, your dog, or just by yourself. In addition to walking, gentle hiking, yoga, or bike riding at an easy pace are all good ways to get low-intensity exercise.

When it comes to high intensity interval training (HIIT), there is no master formula. Instead, there are a lot of variations on a central theme. Here is a sample of five different formulas:

  1. 60 seconds of HIIT, followed by 2 minutes of active recovery
  2. 30 seconds of HIIT, followed by 45 seconds of active recovery
  3. 30 seconds of HIIT, followed by 60 seconds of active recovery
  4. 30 seconds of HIIT, followed by 90 seconds of active recovery
  5. 20 seconds of HIIT, followed by 10 seconds of active recovery

As you can see, it’s a flexible system. The pattern with all of these formulas is short bursts of intensity followed by short periods of active recovery (moving slowly while you breathe vigorously to repay your “oxygen debt” and your heart rate comes back down).

The beauty of HIIT is you can take advantage of its benefits regardless of your age, fitness level, or schedule. The particular formula of high intensity interval training I advocate takes 16 minutes per workout and can be done while using any of the following equipment:

  • elliptical cross trainer (arms and legs)
  • rowing machine (arms and legs)
  • elliptical glider (legs)
  • exercise bike (legs)
  • stair-stepper machine (legs)

Doing an HIIT workout on a treadmill is not recommended because of the potential for falling as you focus your attention on adjusting the controls. (Remember: First, do no harm.)

HIIT can also be done while:

  • running
  • cycling
  • swimming
  • cross-country skiing
  • climbing stairs
  • calisthenics
  • speed walking
  • or whatever exercise modality works best for you

The format is simple: 30 seconds of the highest level of effort you can maintain for the full 30 seconds followed by 90 seconds of active recovery.

Each cycle takes two minutes, and you repeat the cycle eight times — for a total of 16 minutes. Add in a few minutes to warm up before and a couple to cool down after, and you’re done in 20-25 minutes.

Ideally, you want to perform this workout (all eight cycles) three times a week; however, unless you are a well-trained athlete, you will need to work up to that level of intensity.

I recommend starting with one HIIT workout for the first week. I also recommend that you start slowly with only one to four of these two-minute cycles during that first workout. During the second week, you can increase the number cycles. Depending upon your fitness level, it may take you a couple of weeks before you feel up doing to all eight cycles. That’s normal.

Once you start to see results (improved stamina, weight loss, mental clarity, and an overall feeling of wellness), I hope you’ll find that the level of exertion in these exercises becomes sweet pain — or at least not drudgery. (Note: As with all strenuous exercise, it’s more fun if you have a workout partner or a personal trainer to help you stay motivated.)

When you can do all eight cycles without excessive muscle soreness or fatigue (during or after), I recommend moving up to two HIIT workouts per week. When your body gets more comfortable with that level of exertion, you’re ready to move on to three HIIT sessions per week. Don’t be surprised if it takes your several weeks or even months to reach three sessions per week.

Because HIIT is a flexible system, there is a built-in allowance for those days when going “flat out” eight times in a row is not in the cards (lack of sleep, not enough to eat, too much fun the night before, whatever the reason). On those days, pick two cycles in the middle of the eight that you are only going to do at 80 percent (instead of all out). I recommend numbers five and six, which allows you to go hard on cycles one through four, ease up on five and six, and then finish strong. You could also alternate between fast and 80 percent if that pattern works better for you on those “off” days.

A few words of caution about overtraining and injuries

First and foremost, listen to your body. Even though you might be really excited about experiencing the benefits of HIIT, your body may are not on the same page. Instead of rushing in and possibly hurting yourself, go slowly and allow your body to dictate the pace and intensity of your training. As you adapt to this new form of exercise, your body will reap the benefits, and allow you safely move further into the zone of high-intensity training.

If you have injuries that flare up either during the 30-second high-intensity portion of these exercises or after the workout, you either need to make some modifications that allow you to workout without pain or find a different exercise modality that doesn’t cause problems for your injured areas. The 30-second segments of this workout are painful enough as it is; you don’t need the extra baggage of additional aches and pains on top of that.

While this type of high-intensity exercise isn’t easy, the benefits are amazing. Let’s take a look at what the experts have to say.

Fitness, Health, and Human Growth Hormone

Efficient: One of the reasons sports physiologists and coaches believe HIIT works better than traditional long, slow exercise is because all the muscles in your body are involved in an all-out effort — you are pumping your arms and legs as fast as they can go. One 2006 study found that 2.5 hours of HIIT produced similar bio-mechanical muscular changes as 10.5 hours of traditional endurance training. (That’s the same results in ¼ of the time.)

Heart Health: Numerous HIIT studies have shown improved serum lipid profiles, reduced blood pressure, and inflammatory markers, as well as reduced risk of stroke, acute coronary syndrome, and overall cardiovascular mortality. For a summary of this information, click here.

Lung Function: According to Dr. Al Sears, MD (the founder of PACE training), by the time most people reach the age of 50, they have lost 40 percent of their lung function, which increases the risk of heart disease, stroke (first-time and fatal), and death from all causes. This chronic lack of oxygen leaves people feeling weak, fatigued, light headed, and out of breath. HIIT not only restores lung function, it also burns fat.

Fat Burning (aka weight loss): The high-intensity portion of an HIIT workout (especially when the high-intensity portions last longer than 20 seconds) burns the stored carbohydrates (glycogen) in your muscles. After the workout is over, the body switches to fat-burning mode as it replaces the glycogen that your muscles just used.

HIIT also lowers insulin resistance and burns fat more effectively than longer, slower workouts. Several studies have demonstrated an increase in insulin sensitivity (24 -34 percent improvement) after four weeks of HIIT training. “Insulin sensitivity” is the measure of how much of the pro-inflammatory hormone insulin is required to move glucose from the bloodstream and into the body’s cells. Reducing insulin levels in the bloodstream is a positive marker for lowering both cellular and systemic inflammation, which are pre-conditions for diseases such as diabetes, cancer, and heart disease.

Human Growth Hormone: Research from fitness expert Phil Campbell, the author of Ready, Set, Go, shows that a 20-minute HIIT workout can increase HGH levels 771 percent for up to two hours after the workout. If it weren’t for the fact that you feel so tired after a HIIT workout, that should be considered doping.

Gets Results (even for well-trained athletes): A 2009 study by Driller et al. reported an 8.2 second improvement in 2000 meter rowing times following 4 weeks of HIIT in well-trained rowers. A 2010 study in Cell Metabolism demonstrated that DNA gene expression changed in a way that increased VO2Max (maximum oxygen consumption) in the muscles of healthy but inactive people who took part in HIIT training. Several of these affected genes are involved in fat metabolism (fat burning).

The take home message is that high intensity interval training improves health, diminishes disease, and burns fat. I recommend you give it a try. Please let us know how it works for you.