An instant H.I.I.T.

HIIT refers to training intensely for short bursts followed by similar periods of low intensity. HIIT workouts are usually short but intense and burn a large number of calories in a short period of time.

In 1994, an important study was conducted over a 20-week period with 17 test subjects. One group was instructed to perform between 30 to 45 minutes of steady-state cardio. They began the program exercising at 60% of their target heart rate and increased this to 85% over the 20 weeks. The second group performed 30 minutes of HIIT training. They would warm up at 70% of target heart rate, then perform intervals of 10 seconds at lower heart rate and 90 seconds at higher heart rate, followed by a less intense period allowing their heart rate to drop before beginning the next interval. Interestingly, the second group expended less energy during their training sessions. However, over the 20-week period, they lost almost three times as much fat. This fat loss was specifically underneath the skin (subcutaneous fat).

HIIT training creates a demand for Excess Post-exercise Oxygen Consumption (EPOC). In order to restore the body to a resting state and adapt to the load of the exercise, the body must use excess oxygen after the workout is completed. This effect can last for hours and even days. In a 2002 study (Schuenke, M.D., Mikat, R.P., McBride, J.M. Effect of an acute period of resistance exercise on excess post-exercise oxygen consumption: implications for body mass management, European Journal of Applied Physiology 86:411-417, 2002) a measurable increase in resting metabolic rate was found two (2) days after the exercise was performed.

These findings have important implications for training and specifically fat loss. First, you may burn more fat underneath your skin performing HIIT sessions than traditional 'steady-state' sessions such as long runs or bike rides. Second, you may be able to create a measurable positive impact on your metabolism. For people who are restricting calories to lose weight, this means more calories will be available to consume without hindering fat loss. Finally, those with a hectic schedule can burn fat without spending hours in the gym. In fact, most HIIT workouts last only 20 minutes or less - despite potentially burning more fat than longer sessions lasting an hour or more!

To create your own HIIT workout, keep the following parameters in mind:

1. The workout should include short, intense bursts of activity
2. These should be followed by periods of active recovery - you will still be exercising, but at a lower intensity to allow your heart rate to return to normal
3. HIIT sessions typically should not last more than 20 - 30 minutes

One popular variety of HIIT involves using several intervals. To construct the program, follow these steps:

1. Pick a pace that is very comfortable for you - you are exercising but are able to carry on a normal conversation. Call this '50%'.
2. Pick another pace that is almost 'all-out' (like a sprint) and call this '100%'.
3. Now, build your intervals based on these percentages

You'll perform 2 - 5 minutes of a warm-up at level 50%. Then, spend 1 - 2 minutes at level 60%, followed by 1-2 minutes at 70%, then 80%, then 90%. Repeat this several times and finish with an extra minute or two at 100%, followed by a 2 - 5 minute cool down at 50%.

As an example assume you are comfortable warming up at 8 kilometers per hour and feel your 100% is 14 kilometers per hour.

Your first week of workouts may look like this:

5 minutes at 8 kph
The sequence:
1 minute at 9 kph
1 minute at 10 kph
1 minute at 11 kph
1 minute at 12 kph
Repeat the sequence 3 times
1 minute at 14 kph
5 minutes at 8 kph

This workout would only take 23 minutes. The next week you might either increase the speed, or add another sequence to make the workout 27 minutes. Eventually, you could even double the intervals and create an intense 45 minute workout.

Another variation on this might be to ramp down instead of dropping suddenly. For example:

1 minute at 9 kph
1 minute at 10 kph
1 minute at 11 kph
1 minute at 12 kph
1 minute at 11 kph
1 minute at 10 kph
1 minute at 9 kph

Another form of HIIT involves just two intervals. You might start by sprinting for 20 seconds and then jogging for 100 seconds. This would create a two-minute cycle that you repeat several times. Increase the number of intervals until you are training for 10 - 15 minutes (if you are truly doing an all-out sprint, you won't be able to train long than this - in fact, your initial workouts may involve only 2 or 3 cycles). After 3 - 4 weeks, change to 30 seconds of sprinting of 90 seconds of jogging. This increases the sprint and shortens the recovery time. Work up to a final cycle of 40 seconds sprinting and 80 seconds jogging and see for yourself the results after 12 solid weeks of HIIT training.

The final variety involves using a heart rate monitor or being able to take your pulse. Finding your pulse is beyond the scope of this article but if you are familiar with how to take a reading using your wrist or neck you can count for 6 seconds then multiply by 10 for a good estimate. Using this method, you'll spend 30 - 90 seconds going 'all out' or performing the workout at the highest intensity possible. Then, instead of resting for a fixed interval, you perform light work until your heart rate drops about 20% - 30% (for example, if you complete the interval with a 180 heart rate, you will wait until it drops to between 130 - 140 before starting the next intense interval). Repeat the high intensity bout, repeat the recovery, etc. You'll find that your rest intervals will increase each cycle. However, over time, your total rest should actually shorten as your body gets in better shape.

Many people advocate training on an empty stomach. While some research suggests this may help improve the fat burning effect of the workouts, you can just as easily obtain stellar results doing this later in the day or after a balanced meal that has been given ample time to digest. Decide for yourself - if you feel weak or hungry, don't train on an empty stomach! One of the major benefits of HIIT training is that it takes so little time. It makes sense to schedule your sessions when they are most convenient and you feel you'll have the most energy to complete them. One important thing to consider is that HIIT training does place a lot of stress on your system so you should start slowly with only 2 - 3 sessions per week. Some people work up to 4 - 5 sessions but the risk of injury is greatly increased when performing HIIT consecutively for several days, especially if you increase too quickly.

HIIT is a great way to fit a lot of training into a short period of time. Because most hotels and local gyms have treadmills and stationary bikes it is also a form of training that can be done while traveling. The short, intense intervals leave you with a strong feeling of accomplishment at the end of the training session. The workout time flies quickly and is more interesting because you're constantly looking to the next interval. Integrate some interval training into your own fitness program and see for yourself if it's an instant H.I.I.T.