As a fitness professional, you have known for years that interval training can meet the goals and needs of your members and class participants. Interval training has become such a popular type of training - mainly because students enjoy the constant moving and changes of intensities. Mixing things up by alternating bouts of high intensity with bouts of moderate/low intensity can be very motivating, as well as efficient. So, how well do you know the science of interval training and how to effectively incorporate it into your group fitness class?
Though Interval training has been around for decades, it’s only recently gained enough popularity to grab the attention of fitness enthusiasts around the world. So much so, that it has been given names based on its intensity and those that have researched it well – HIIT (High Intensity Interval Training), and Tabata (named after Professor Izumi Tabata), just to name a few. As the darling of fat loss and improved aerobic conditioning, you can choose to do it right...and gain the credibility and following of your students. Or you can choose to do it wrong...and lead your students down a path of injuries and muscle loss.
Let’s take a look at a sampling of some common interval types and how they are differentiated:
- Tabata Intervals – In 1996, researcher Dr. Izumi Tabata studied high intensity intervals, working at a high intensity (well-over participants’ VO2 max), and found increases in both cardiovascular endurance and fat loss.
- Gibala Method - In 2009, Dr. Martin Gibala, from the McMasters University Department of Kinesiology, reported improvements in body composition, strength and power from his 60 second work and 75 second rest intervals.
- Turbulence Training – Researcher and Exercise physiologist, Craig Ballantyne, found similar success alternating heavy strength training with light cardio.
The chart below lists additional components of each training option:
||20 seconds high intensity followed by 10 seconds rest
||8 cylces = 4 minutes
||60 seconds high intensity followed immediately by 75 seconds easy.
||12 cycles = 27 minutes
||8 reps heavy strength training, followed by 1-2 easy cardio
||Maximum of 45 minutes
In the simplest sense, interval training is nothing more than a method of exercise that alternates periods of work and rest. The complicated part of interval training may be figuring out how to implement it. How much work do I do? How hard should I do it? How long should I rest before I do it again? Knowing that these interval ratios have been tested and shown effective, the chart above can provide a framework and sampling of how you can incorporate interval training in your classes today. In addition, consider all of the following when designing your interval based format:
- Intensity of work interval – To monitor the intensity of the workout, students can use RPE (Rating of Perceived Exertion) or heart rate monitors. On a scale of 1-10, a student’s rating of perceived exertion should be between 8 -10 for high intensity. If you are using heart rate monitors and zone training, heart rates should be at or above AT (typically 85% of max heart rate).
- Duration of work interval - The duration is often governed by students’ abilities to maintain the intensities. In a group environment, students will fall off early and lose motivation if you push them for longer than 1-2 minutes at a time. Start with easy bouts of 20 seconds to 1 minute. Remember, longer isn’t always better. As soon as a student can no longer maintain the intensity, they slow down and end up working aerobically. The goal is to push them into anaerobic metabolism, allow for rest, and repeat.
- Duration of rest or recovery interval - This can be tough to structure in a group fitness environment, especially one that is dictated by the music and choreography. If you are using RPE or HR, ask your students to begin the next interval when they reach a 2-3 RPE or a Zone 2 (60% max HR). In order for this to work as a true interval of work and rest, the students have to be allowed that rest. Keep in mind that if a student is de-conditioned, their heart rate may not come down as quickly as a well-conditioned student. Your job is to encourage and educate. Remind them that by waiting until their heart rate is down to an appropriate level, it will allow them to perform well on the next interval, therefore burn more calories throughout the workout.
- Number of repetitions of each interval - I liken this to the number of sets for each exercise or pair of intervals. Keep muscle balance and innovation in mind when designing these sets. For example, you might balance equal sets of upper and lower body exercise, total body exercises with core, etc.
Once you’ve determined how many bouts of intervals you will run, and how long each interval and rest period will last, it’s all about the movements. After all, everyone from the high level athlete to the beginner will want to take your class and challenge themselves with high intensity intervals. But remember, what is high intensity to one student, is easy to another - it all depends on the student’s cardiovascular fitness, coordinated ability, and anaerobic strength. The best way to ensure the success of each student is to have a base movement in mind, along with a modification and a progression. Some examples are provided here:
|Modification (level 1)
||Base Movement (level 2)
||Progression (level 3)
||Plank to Squat Thrust
|Plank to Squat
||Single Leg Burpee
|High Knee March
Remind your students that once their body adapts to the stress of the interval, their fitness level improves along with muscle function. They will then have to work harder to achieve a high intensity or perform a progression of the movement. It’s recommended that interval workouts are done every other day at most. This allows for the necessary rest and recovery needed for hard-working muscles.
Knowing that lack of time and lack of results are the top reasons why people give up exercising, your guidance with interval training can be the boost your students need for finding fitness success!
- Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism, vol. 43, no. 7, July 1994
- Talanian JL, Galloway SD, Heigenhauser GJ, Bonen A, Spriet LL. Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women. J Appl Physiol. 2007
- Gibala MJ, Mcgee SL. Metabolic adaptations to short-term high-intensity interval training: a little pain for a lot of gain? Exerc Sport Sci Rev. 2008
- Tjonna AE, Lee SJ, Rognmo, et al. Aerobic interval training versus continuous moderate exercise as a treatment for the metabolic syndrome: a pilot study. Circulation. 2008
- Perry CG, Heigenhauser GJ, Bonen A, Spriet LL. High-intensity aerobic interval training increases fat and carbohydrate metabolic capacities in human skeletal muscle. Appl Physiol Nutr Metab. 2008;33
- Meckel Y, Eliakim A, Seraev M, et al. The effect of a brief sprint interval exercise on growth factors and inflammatory mediators. J Strength Cond Res. 2009
- Ace Fitness Journal, Healthy Living Fit Facts, April 2013
- Gibala, Martin J; Jonathan P. Little, et al.(September 15 2006)." Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance". Journal of Physiology 575 (3): 901–911.