High Intensity Interval Training

Method

HIIT is a cardio technique which has the subject alternating between high intensity and very high intensity intervals lasting typically from 5 to 20 minutes (with an additional 5 min warmup and cooldown). An example of HIIT would be alternating between 30 seconds of running and 30 seconds to 1 minute jogging on a treadmill. The goal is to keep the heart rate very high. This causes the body to increase its oxygen uptake post exercise (thus increasing metabolic rate) [1,2,3,9], and in fact causes a greater overall calorie burn than either moderate interval training or steady state training due to this increase in O2 consumption [4,7,8].

Prefuel your cardio session with adequate carbohydrates and protein to cover calories burnt during the HIIT session. Remember that the goal is to increase overall metabolism, and to not use cardio as a direct means of burning fat. This prevents the use of muscle as a fuel source for the cardio.

Do not perform this cardio technique before getting approval from your doctor for high intensity activity.

HIIT Induces Greater Fat Loss than Moderate Cardio

A study by Yoshioka et al reinforced previous studies by demonstrating that high intensity exercise increases oxygen consumption (ie. increases metabolic rate) and fat burning significantly as measured post-exercise post-meal [5]. An earlier study showed that a 15 week HIIT cardio program resulted in greater weight loss than a 20 week moderate intensity program in which the cardio was burning twice as many calories [4]. It has also been demonstrated that previously obese subjects on a high intensity program are more likely to maintain their loss and not return to pre-program weight [6].

References

[1] Effect of intensity of exercise on excess postexercise O2 consumption, Bahr R, Sejersted OM, Metabolism. 1991 Aug; 40(8):836-41.

[2] Energy metabolism during the postexercise recovery in man, R Bielinski, Y Schutz and E Jequier, American Journal of Clinical Nutrition, 1985; 40: 69-82.

[3] Postexercise energy expenditure and substrate oxidation in young women resulting from exercise bouts of different intensity, J. F. Phelain, E. Reinke, M. A. Harris and C. L. Melby, Journal of the American College of Nutrition, 1997; 16(2): 140-146.

[4] Impact of exercise intensity on body fatness and skeletal muscle metabolism, Tremblay A, Simoneau JA, Bouchard C. Metabolism. 1994 Jul;43(7):814-8.

[5] Impact of high-intensity exercise on energy expenditure, lipid oxidation and body fatness, M Yoshioka, E Doucet, S St-Pierre1, N Almeras, D Richard, A Labrie, JP Despres, C Bouchard and A Tremblay. International Journal of Obesity. 2001; 25: 332-339

[6] Long-term maintenance of weight loss: do people who lose weight through various weight loss methods use different behaviors to maintain their weight?
M T McGuire, R R Wing, M L Klem, H M Seagle and J O Hill International Journal of Obesity. 1998 June; 22(6): 572-577

[7] A Comparison of the Effects of Interval Training vs. Continuous Training on Weight Loss and Body Composition in Obese Pre-Menopausal Women Jeffrey W. King. 2001 May. Master's Thesis. Department of Physical Education, Exercise, and Sports Sciences. East Tennessee State University

[8] A comparison of interval vs. steady-state exercise on substrate utilization in overweight women. King, J; Broeder, C; Browder, K; Panton, L FACSM, Medicine & Science in Sports & Exercise: Volume 34(5) Supplement 1 May 2002 p S130

[9] A role for high intensity exercise on energy balance and weight control. GR Hunter, RL Weinsier, MM Bamman and DE Larson. International Journal of Obesity 1998; 22: 489 - 493