Benefits of HIIT

Benefits

Aerobic benefits

Studies by Tabata,^[8] Tremblay^[14] and others have explored the effectiveness of this method compared to traditional endurance training methods. A 2008 study by Gibala et al.^[15]demonstrated 2.5 hours of sprint interval training produced similar biochemical muscle changes to 10.5 hours of endurance training and similar endurance performance benefits. According to a study by King,^[16] HIIT increases the resting metabolic rate (RMR) for the following 24 hours due to excess post-exercise oxygen consumption, and may improve maximal oxygen consumption (VO₂ max) more effectively than doing only traditional, long aerobic workouts.^{[17][18][19][20]} Tabata's 1997 study concluded that "intermittent exercise defined by the IE1 protocol may tax both the anaerobic and aerobic energy releasing systems almost maximally."^[10] Around 20% of participants in Timmons' 2010 study showed less than 5% improvement in aerobic capacity.^[21] Conversely, about 20% of participants were described as "high-responders".^[13] A complex mixture of genes are involved, but differences in 11 single-nucleotide polymorphisms alone could predict 23% of the total variance in VO₂max.^[21] Timmons was able to demonstrate that about half of the responsiveness of aerobic capacity to HIIT was genetically determined.^[21]

High-intensity interval training has also been shown to improve athletic performance. For already well-trained athletes, improvements in performance become difficult to attain; increases in training volume may yield no improvements. Previous research would suggest that, for athletes who are already well-trained, improvements in endurance performance can be achieved through high-intensity interval training. A 2009 study by Driller and co-workers^[22] showed an 8.2 second improvement in 2000m rowing time following 4 weeks of HIIT in well-trained rowers. This equates to a significant 2% improvement after just 7 interval-training sessions. The interval-training used by Driller and colleagues involved eight 2.5 minute work bouts at 90% of vVO₂max, separated by individualized recovery intervals.

Metabolic benefits

Long aerobic workouts have been promoted as the best method to reduce fat, as it is popularly believed that fatty acid utilization usually occurs after at least 30 minutes of training. HIIT is somewhat counterintuitive in this regard, but has nonetheless been shown to burn fat more effectively. There may be a number of factors that contribute to this, including an increase in resting metabolic rate. HIIT also significantly lowers insulin resistance and causes skeletal muscle adaptations that result in enhanced skeletal muscle fat oxidation and improved glucose tolerance.

Timmons' group showed that two weeks of HIIT can substantially improve insulin action in young healthy men.^] In the aforementioned Horizon documentary, Michael Mosley, a borderline diabetic, saw a 24% improvement in insulin sensitivity after 4 weeks of Timmons' regimen, exactly in line with Timmons' larger studies.^[13] Gibala's group reported a 35% increase in both insulin sensitivity and muscle oxidative capacity among seven sedentary people after two weeks on the lower-intensity regimen outlined above.^[12] Timmons believes that this response is because HIIT uses 80% of muscles in the body, compared to 40% for gentle jogging and cycling.^[13] In young women, HIIT three times per week for 15 weeks compared to the same frequency of steady state exercise (SSE) was associated with significant reductions in total body fat, subcutaneous leg and trunk fat and insulin resistance.

Cardiovascular disease

A 2011 study by Buchan et al. assessing the effect of HIIT on cardiovascular disease markers in adolescents reported that "brief, intense exercise is a time efficient means for improving CVD risk factors in adolescents". A meta-analysis by Weston et al. (2013) has identified that HIIT has more physiological benefits than moderate intensity continuous training (MICT) in patients with lifestyle-induced chronic disease. Indeed, the improvements in cardiorespiratory fitness after HIIT are almost double that of MICT.

Utilization of HIIT training

HIIT technique can be applied either as a separate exercise plan in case that you are in a hurry, or as an intense complement to your existing plan. HIIT training can literally have hundreds of forms. Depending on your objectives, combine exercises, tools and time intervals to obtain the optimal result.

For example: 20 seconds of intensive workout and 10 seconds of rest. Whole process shall be repeated for 4 minutes.

Benefits of moderate intensity exercise

In one study of participants who were obese and sedentary, researchers compared the benefits and results of sustained cardiovascular exercise at the moderate intensity thought optimal for fat oxidation with results from a eucaloric interval training program (one that burned the same number of calories). They found the sustained moderate intensity workouts were more effective in burning fat: "A continuous exercise training protocol that can elicit high rates of fat oxidation increases the contribution of fat to substrate oxidation during exercise and can significantly increase insulin sensitivity compared with a eucaloric interval protocol."

http://en.wikipedia.org/wiki/High-intensity_interval_training