Intervals for Cardio


High Intensity Interval Training


What exactly is High Intensity Interval Training (HIIT)?  This term gets thrown around a lot without much explanation.  I always asked myself what percentage of maximum heart rate (Max HR) is considered to be high intensity and how hard should I be exercising?  Interval training is considered to be high intensity when you cross over from aerobic to anaerobic training which is called the anaerobic threshold.  You have to be working hard during the work intervals to reach the anaerobic threshold and it occurs around 85% of Max HR.  Therefore, interval training around or above 85% of Max HR is considered to be high intensity.  Moreover, you should not exceed your Max HR during HIIT.

There are 2 ways to perform HIIT

 1. You can gradually work your way up to or above 85% of Max HR during the work intervals.
 2. If your warm up is intense enough you can perform all the work intervals at or above 85% of Max HR.

A Word of Caution

HIIT is not recommended for individuals with risky health issues or unfit obese people.  Only experienced and suitably fit people should train with high intensity.  If you are not conditioned for HIIT I assure you that you will be lying on the floor in the fetal position by the end of the workout.  You greatly increase your risk of injury if you are unfit so make sure you slowly build up your conditioning before attempting HIIT.  Beginners should perform HIIT with caution and should immediately lower the intensity of the intervals or quit the training session all together if the intervals become too strenuous.

Exercise Intensity correlated with the Target Heart Rate Zone:

 Target Zones  Percentage of Max HR  Exercise Intensity
 Healthy Heart Zone  50% - 60%  Very light to light
 Temperate Zone  60% - 70%  Light to moderate
 Aerobic Zone  70% - 80%  Moderately hard
 Anaerobic Zone  80% - 90%  Hard
 Red Line Zone  90% - 100%  Very hard

Now that we have covered all the bases, let's give HIIT a try.  This HIIT program involves 6 sets of 30 second work intervals followed by 15 second rest intervals.  The object of HIIT is to push yourself hard during the high intensity work intervals and back off during the rest intervals.  If you truly exert yourself HIIT is a challenging workout.  Interval training can be performed on a variety of cardio equipment or with any suitable physical activity.  Always warm up before performing intervals and cool down afterwards.

Interval Chart:

 HIIT Intervals  Sets  Time

 30s High intensity work interval + 15s Rest interval

 6  4.5 min.

Another Example

The Tabata Protocol, known as the “World’s greatest fat burning workout," is a very popular form of HIIT.  It's a short but intense 4 minute interval workout split between 8 sets of 20 second high intensity work intervals followed by 10 second rest intervals.  Give these Tabata intervals a shot for you next interval workout.

Interval Chart:

 Tabata Intervals  Sets  Time

 20s High intensity work interval + 10s Rest interval

 8  4 min.