HIIT (High Intensity Interval Training) consists of short bursts of intense exercise followed by a brief recovery period. This enhanced fitness program is designed to burn significantly more calories in less time compared to a steady cardio workout.
Requires Less Time
While steady cardio is better than no exercise at all and fine for those with enormous amounts of spare time devoted to physical fitness, circuit training (HIIT) is crucial for maximum results in a limited amount of time. It is the workout of choice for top athletes, like Finnish Olympic runner Hannes Kolehmainen.
Burns More Fat
HIIT workout routines create an after burn effect (known as EPOC) which makes them an excellent fat burning workout. The body’s metabolic rate is relative to its oxygen supply. Intense exercise followed by a rest phase peaks oxygen quantity and greatly increases metabolism. This after burn effect aids in shedding superfluous fat in noticeably less time. Researchers at the American College of Sports Medicine, Florida State University (Tallahassee) found that individuals following a HIIT program lost 10% more fat and burned more calories than those who exercised steadily for the same amount of time i.
Additionally, Researchers at the East Tennessee State University reported that individuals subjected to eight weeks of High Intensity Interval Training had a significant drop in body fat compared to none at all in subjects who spent more time on a treadmill ii.
Decreases Fat Enzymes
HIIT reduces the fat synthesizing enzyme, fatty acid synthase, which converts supplemental energy into fat. A study by the Norwegian University of Science and Technology demonstrated that individuals subjected to 16 weeks of HIIT training sessions reported a 100% decrease in fat producing enzymes compared to those who followed steady state exercises iii.
HIIT is better than sustained cardio exercise for heart health. Research shows that high intensity workouts cause a 13% greater increase in the incidences of heart contractility and 12% heart mass iv.
Skeletal Muscle Adaptations
Muscles contain mitochondria (a structure within cells) that use oxygen to extract energy by the breakdown of fats and carbohydrates. When the body endures intense physical activity, the number of mitochondria increase to meet the energy demands of muscles. Research shows that HIIT exercises increase mitochondrial density as compared to sustained cardiovascular exercise so skeletal muscles of individuals who follow endurance training adapt to high density mitochondria. This helps gain lean muscle mass at the expense of fat loss.
If you still haven’t incorporated some aspect of HIIT into your workout routine, perhaps it’s time to consider doing so.
i Meuret, J.R., et al. A comparison of the effects of continuous aerobic, intermittent aerobic, and resistance exercise on resting metabolic rate at 12 and 21 hours post-exercise. Medicine & Science in Sports & Exercise 39(5 suppl):S247, 2007.
ii King, J.W. A comparison of the effects of interval training vs. continuous training on weight loss and body composition in obese premenopausal women (thesis). East Tennessee State University, 2001.
iii Tjonna, A.E., et al. Superior cardiovascular effect of interval training vs. moderate exercise in patients with metabolic syndrome. Medicine & Science in Sports & Exercise 39(5 suppl):S112, 2007.
iv Micah Zuhl, et al. HIIT vs Continuous Endurance Training: Battle of the Aerobic Titans. Retrieved from https://www.unm.edu/~lkravitz/Article%20folder/HIITvsCardio.html