If you want to lose body fat and are looking for better results from your fitness efforts, then you must increase your exercise intensity. Often I see exercisers walking on a treadmill at a very leisurely pace for 60 minutes or more and expecting results in fat loss. If you've been training regularly in a moderately intense cardio activity like fast walking, jogging, or bicycling, then it may be time to take your cardio training to the next level and add High Intensity Interval Training (HIIT) to your exercise program
Recent research indicates that HIIT is more effective in helping people lose body fat than conventional cardio training. To illustrate my point, let me give you the results of a 15-week study done by researchers at the University of New South Wales, Sidney, Australia.
Two different groups were studied. One group did HIIT cardio for a 20 minute session, three times a week. The other group did steady state Long, Slow Distance (LSD) cardio for a 30-40 minute session, three times a week. The HIIT cardio group lost 3 times more body fat than the LSD group and the HIIT group spent approximately 43% less time exercising than the LSD group.
HIIT is an intense, but shorter duration, form of cardio training. Therefore, if you have a previous heart condition or have risk factors for heart disease like high blood pressure, high cholesterol, diabetes, chest pains (angina), shortness of breath, arrhythmias, etc., then you should get your physician's approval before beginning this training protocol.
During High Intensity Interval Training, you alternate between periods of intense anaerobic activity (Peak Effort) followed by a Rest Period in the aerobic state. Typically, the Peak Effort anaerobic activity lasts 30-60 seconds and the aerobic Rest Period lasts 60-120 seconds. You can achieve an anaerobic state by walking, jogging, running, swimming or cycling 50-100% faster than you do in the aerobic Rest Period. Your intensity level during the Peak Effort period should be hard enough that you could not continue at your pace beyond 30-60 seconds. Your heart beat and breathing rate should be very high at the end of your Peak Effort period.
This anaerobic and aerobic cycle is repeated 6-8 times during a 30 minute interval training workout. Initially, I recommend setting the Peak Effort time at 60 seconds and the Rest Period time at 120 seconds (2 minutes) for 8 cycles. You may have to experiment to find the optimum speed ranges and time periods to achieve a sufficient intense Peak Effort and a suitable Rest Period.
During the Peak Effort anaerobic activity you're burning carbohydrates – in the form of glycogen stored in the muscle. During the Rest Period aerobic activity you're burning fat and carbohydrates. After the HIIT training session is completed, your body recovers and goes into the "afterburn" mode and burns mostly fat in the aerobic state for several hours.
This post exercise energy expenditure (or "afterburn") is significant. Some studies have reported up to 15% increase in the resting metabolic rate up to 24 hours after the HIIT workout. In another study, the "afterburn" of the HIIT trained group was 160 calories higher than the conventional cardio trained group.
The increased energy expenditure during the HIIT exercise and the additional "afterburn" energy expenditure is the reason why HIIT helps you to lose body fat faster than conventional cardio. So, if you want to lose body fat, then give High Intensity Interval Training a try. This training, coupled with a sensible diet and resistance training 2-3 times per week will yield significant body fat reductions from your hips, upper thighs and waistline.