Tortoise vs the Hares: The truth about Interval Training

I started interval training at Shred415 class about 3 months ago and it was love at first run. Shred415 is  a "total body workout that is based off of high intensity interval training". I began raving about Shred415 to friends. One of my friends, Nicole, informed me that they began a 'shredded' class at David Barton Gym. Luckily I found a Gilt City to a month membership at DBG, solely to take advantage of their many interval training classes :)

So what is all this hub-bub about interval training and why is every gym offering it?

Interval training is the method of increasing and decreasing the intensity of your workout. The workout consists of switching between aerobic and anaerobic exercises. Aerobic exercises are light --> moderate ( < 65% of your heart rate max) like walking, the elliptical, running at a steady pace. In these exercises you are steadily using your bigger postural muscles, such as core, quads, hamstrings, etc. Anaerobic exercises (> 80% of heart rate max) are heavy --> intense exercise, such as jumping, sprinting, stairs. Anaerobic exercises require power and speed so your smaller muscles are more active because they have to work at a quick speed. The heavy intensity is requiring immediate recruitment of you energy and stresses your cardiovascular system. Aerobic and anaerobic exercises have a tendency to utilize different energy resources. For your aerobic exercises your body primarily relies on your carbs (carbohydrates) because your body can steadily break those down. With anaerobic exercise you require more energy than that, so you burn more fat, and require more protein in order to repair the stress that has been done. 

By switching the intensity you are essentially switching between the fuels (carbs vs fat) that you to turn into energy. With increased intensity levels you are increasing fat burn which can mean that you can go further before tapping into carbohydrate stores. Your are also tapping into your carbohydrates with your moderate--> lower intensity activity. This is helpful because it allows us to lose weight or avoid gaining it because your fat storage is your hardest to burn. Many people who are consistently doing the same workout without challenging their bodies are commonly just utilizing the carbohydrate fuel source. So interval training is advantageous to burning fat aka that extra cushion.

Additionally interval training helps improve your cardiovascular system. You stress your heart muscle by alternating the intensity of your heart rate. Your heart is being stressed because it is pumping faster each minute in order to get enough oxygen to all those tinier muscles you are working in high intensity. Whenever you stress a muscle you cause it to strengthen. By strengthing your heart you will be able to endure increased intensity exercises for longer periods of time. According to a New York Times article,  "A study found that after just two weeks of interval training, six of the eight college-age men and women doubled their endurance, or the amount of time they could ride a bicycle at moderate intensity before exhaustion". So not only does interval  training strengthen but it increases your endurance. Increased endurance allows you to participate in activities for a longer period of time without fatigue. Fatigue is a challenge for overcoming plateaus or baselines. But by building up your endurance you can lower your baseline for fatigue and endure activities longer that will burn more calories and increase strength. However it is important to note, interval training isn't appropriate for everyone. If you have a chronic health condition or haven't been exercising regularly, consult your doctor before trying any type of interval training. Strenous exercise can results in injury so it is important to start slow and build up your stamina.

Where to begin with interval training?

At Shred415 works you alternate between cardio work on top of treadmills and weight-training, it's a fast-paced workout typically consisting of  four 15-minute sessions. The ideal result is in one hour you average a performance of maintaining a high heart rate, 70% of the maximum heart rate, Similarly, David Barton's, Shredded, you are also alternating between cardio and weight training but not at 15-minute intervals. The switch between the treadmills/cardio and weight training is the switch between aerobic and anaerobic.  This switch allows participants to to burn more fat and carbs while building strength and endurance. Additionally interval training is also something you can do at home. My friends, Dan and Kate, have an interval timer and they use it and switch between exercises such as jump rope, sprints, burpies, kettleball movements, squats, mountian climbers, rowing machines, squat jumps, etc. So jump on the bandwagon and get involved. Interval training will help you torch those calories, improve your aerobic capacity, and potentially decrease your boredom with the variety of exercises that it offers!

References

Mayo Clinic Staff. Interval training: Can it boost your calorie-burning power? Mayo Clinic. Feb 6, 2010, Available at http://www.mayoclinic.com/health/interval-training/SM00110

Jaret P. A Healthy Mix of Rest and Motion. The new york times. May, 3 2007. Available at http://www.nytimes.com/2007/05/03/fashion/03Fitness.html?pagewanted=all

Weil R. Interval Training. MedicineNet.Com. June 6, 2008. Available at http://www.medicinenet.com/interval_training/article.htm