As was mentioned in an earlier post, High Intensity Interval Training (HIIT) is simply repeated periods of time spent conditioning with periods of recovery.  The hard part is trying to figure out how long to recover and how long to perform the interval.

There are two ways to construct your own interval training program.  The first way involves using a work to rest ratio that is based on the amount of time that you spend conditioning. Typical work to rest ratios are 1 – 2, 1 – 3.  In some cases where the work interval is longer, for example 1 minute or more, the ratio is 1-1.  This is the classic method of doing intervals, but the problem with it is that the rest interval is a bit arbitrary.  It doesn’t take into account the fitness level of the individual or their ability to recover during the work out (presumably you should take longer to recover between each interval as fatigue levels increase).  Typically the shorter and more intensive the work interval, the longer the rest interval.  Therefore sprints of 10 – 20 seconds may incorporate rest intervals of 20 seconds to a minute.  Longer intervals of work such as 1 mintue  would use a 1-1 ratio in this case a 1 minute rest period.  Better conditioned people will not require that long of a rest interval and may feel ready to go at 30-45 seconds.

The second method of implementing recovery periods is to use a heart rate monitor or simply take your pulse.  The monitor is easier to use and more accurate as you may find it hard to get your pulse and count it as you are gasping for air.  Heart rate and intensity level of exercise are closely related and as such we can use heart rate to track both the work intensity and the recover-ability of the body.  In order to do this you need to know what your estimated maximum heart rate is (HRmax), and then take a percentage of that HRmax.  In the literature 60 – 65% of maximum heart rate is assumed to be the low end of the aerobic threshold and is typically used in hear rate recovery methods.  The only problem here is that using a simple percentage of HRmax as an indicator of when to go again is not accurate.  The formula for finding your maximum heart rate is assumed to be 220 – age.  This works for only about 30 percent of the population and has an accepted error of + or – 10 to 12 beats per minute.  In addition there is a smaller percentage (30%) of the population where the error is larger, as much as + or – 20 beats per minute.  This can have a profound effect on the work out of a person that falls into one of these categories when using the HRmax percentage method.   A more accurate method of predicting your HRmax was published in the journal Medicine & Science in Sports & Exercise.  The formula used is: 206.9 – (0.67 x age).

Now that you have your HRmax you can use it to predict your recovery HR. Use the Karvonen method also known as the heart rate reserve method.  It is more accurate as it takes into account the reduction in maximum heart rate with age as well as  current fitness level indicated by a resting heart rate.  The formula  for a person who is 20 years old with a resting heart rate of 65 would look like this:

HRmax = 206.9 – (0.67 x 20 (age)) = 193 beats per minute (bpm)
193 – 65 (resting heart rate) = 128
128 * 65% (low end of the aerobic “zone”) = 83
83 + 65 (resting heart rate) = 148
The recovery heart rate for this person would be 148.  At this point they would begin thier next work interval.

This is a much better indicator of recovery between work boughts.  You may find that as you are training with your heart rate monitor that your recovery times will increase as you progress through your work out.  This is normal.

Using fitness expert Michael Boyles’ recommendations for interval training using rest periods instead of heart rate, a typical session may look something like this:

Interval 1 – 30 sec sprint, 30 sec recovery

Intervals 2 and 3 –  30 sec sprint, 45 sec recovery,

Intervals 4, 5 and 6 – 30 sec sprint, 1 min recovery.

Depending on your fitness level you may elect to do a second and is some cases a third  bought of intervals once your heart rate has recovered to pre exercise levels or after a 5-8 minute rest.  Again, using heart rate is the most accurate measure of recovery.

High Intensity Interval Training vs. Long Distance Running

Interval training is a method of conditioning the body that uses brief periods of work interrupted by periods of rest.  For years, intervals have been used by athletes to prepare their bodies for sports. On the other hand, long slow distance running has long been billed as the best way to “burn fat”, burn calories and “get in shape”. So this begs the question; which method is the best?

Recent research in to this question has with out a doubt labeled high intensity interval training (HIIT) superior to long slow distance training (LSD).  In a study conducted by Martin Gibala, an Associate Professor of Kinesiology at McMaster University in Canada, Gibala looked at the differences between interval training and long slow distance training.  Two groups were studied.  The interval training consisted of 20 minutes of work in which the participants had to peddle all out for 30 seconds and then peddle slowly for 4 minutes.  The long slow distance training consisted of 90 to 120 minutes of steady paced work in the “heart rate zone”.  In essence, two to two and a half minutes of hard work versus 90 – 120 minutes of lower intensity work.

The results of the study were surprising.  Each group had about the same improvement in oxygen utilization after two weeks.  Each group trained three times per week.  The interval group spent one hour per week training.  The distance group spent four to six hours per week training.  If time is a limiting factor for you to get in shape, why would you pick distance running?

 When you look at the time investment, overall health and sports performance benefits, HIIT wins every time. HIIT produces the same or better results in fat loss, aerobic endurance and anaerobic endurance with out the huge time investment that is required for LSD.  According to fitness expert Michael Boyle, the main benefit of LSD may be to prepare the body for interval training.  He reccomends about two weeks of LSD to prepare for interval training if you are just getting started. One last strike against LSD is that most injuries in distance runners come from over use, or high volumes of work. In fact, statistics estimate the injury rate to be as high as 60% for those begining a running program.  So tell me, why do you still want to go out for that 30-60 minute run when you can get the same or better fitness benefits from HIIT in less time?