Interval training (HIT) involves a combination of high and low-intensity  training within a single workout session. In this session, the individual  alternates between a bout of higher intensity exercise followed by a lower  intensity or “active recovery” bout. This type of training is in contrast to the  more familiar “steady state” exercise where the intensity is much lower but  longer in duration. Interval training is awesome for fat burning and aerobic  conditioning but let’s have a look at some more reasons to use interval training  for your cardio workouts.

What are the benefits of interval training?

1. Intervals vastly reduce boredom. Traditional steady state cardio training  can become quite boring. HIT offers more variety and excitement to your  workouts.
2. Interval training increases post-exercise energy expenditure (calories  burned following exercise) more than steady-state exercise, which means that  more fat is burned. After intense exercise, the body needs extra calories as it  works to repair muscles, replace energy stores (i.e. carbohydrate) and restore  the body to its normal state (e.g. reduce heart rate). As this can take many  hours, you will keep on burning more calories long after the workout is over. In  fact, research shows that metabolic rate is higher for several hours following  interval training compared to steady state exercise.
3. Interval training stimulates the respiratory system, cardiovascular system  and nervous system to a greater degree. Therefore, more fat and carbohydrates  are burned to support the expanding energy demands of the body during, and  after, intense exercise.
4. Interval training increases the activity of enzymes involved in fat  burning. Research has shown that after a bout of interval training there is more  fat in the blood (i.e. free fatty acids), which is an indication of more fat,  being used for energy production.
5. HIT burns more calories. As an example, 30 minutes on an Elliptical  machine using a steady state program will burn roughly 292 calories, whereas 30 minutes of intervals will burn approximately 584 calories!
6. HIT causes a greater increase in VO2max (aerobic capacity). By stimulating  your cardiovascular system to work closer to its maximum capacity for a longer  duration than steady state exercise.
7. HIT allows for better time efficiency. For instance, a typical 30 minutes  steady state run on the treadmill could be reduced to 10 – 15 minutes of HIT due to  its demands on the aforementioned systems.
8. HIT results in increased amounts of circulating growth hormone (GH)  following exercise. This promotes an increase in lean body mass and increased  fat burning. This does not occur to the same extent with steady state exercise.  This is particularly beneficial for those looking to maintain their muscle mass  and at the same time reduce body fat.
9. Interval training makes use of both aerobic (type 1) and anaerobic (type  2) muscle fibres. This is in contrast to steady state exercise that only makes  use of type 1 fibres. By increasing the conditioning of these type 2 muscle  fibres you will greatly increase your capacity to tolerate high-intensity  exercise, which means an increased opportunity to exercise at higher levels that  burns a lot of calories.
10. Because of the high-intensity of this exercise and the increased use of  anaerobic type 2 muscle fibres there is an increased use of the body’s glycogen  (muscle-stored carbohydrates) stores. This is very beneficial for fat loss as  the body will conserve carbohydrate following exercise and thus use fat as an  energy source for the body’s energy requirements. The more glycogen you use  during exercise the more fat you will burn following exercise!

Guidelines for Interval Training

There are a number of variables to consider when planning an interval training workout:

1. Intensity of high-intensity interval
2. Intensity of low-intensity  interval
3. Duration of high-intensity interval
4. Duration of  low-intensity interval
5. Number of Intervals

Because of its versatility, HIT offers thousands of different program variations.  This is great for those looking for variety and change. After all, the body  adapts best to changing stimuli. Furthermore, this type of training can be done  on any cardio machine. Again, switching between machines periodically will  stress your body differently and lead to the best results!

It is recommended that the intensity for the high-intensity interval range  between 75 – 100% of your maximum effort. This will depend on the duration of  the interval, as the longer the interval, the lower its intensity.

The recovery interval should range in the 55 – 65% of maximum effort.

The ratio of work to recovery can be varied and will depend on your fitness  level and desired goal. For instance, I recommend starting at a work : rest  ratio of 1:4 for beginners. As an example, this could represent a high-intensity  (work) interval of 15 seconds followed by a 60 second recovery interval. If you  are more advanced you can play around with this ratio for increased  difficulty.

What you will notice is that over the duration of the interval training  session your average heart rate will tend to drift upward. This is due to the  fact that, depending on the interval protocol and your fitness level, the length  of your recovery bouts will not be sufficient to allow your heart rate to fully  return to rest; thus, you end up working at a greater percentage of your maximum  heart rate even while you recover.

Yuri Elkaim graduated summa cum laude with a Bachelors of Physical Education and Health from the University of Toronto. He is a Certified Kinesiologist, Personal Trainer and Strength & Conditioning Coach based in Toronto. Yuri is the founder and owner of Total Wellness Consulting, a leading health, fitness and wellness company offering health-conscious individuals innovative programs and technologies to help reach their goals of physical and mental well being. He is also very proud to be Head Strength & Conditioning Coach for the nationally ranked University of Toronto Men’s Soccer team. Learn more about Yuri and his fitness programs and products at YuriElkaim.com