High-intensity interval training
High-intensity interval training (HIIT), also called high-intensity intermittent exercise (HIIE) or sprint interval training (SIT), is an enhanced form of interval training, an exercise strategy alternating periods of short intense anaerobic exercise with less-intense recovery periods. HIIT is a form of cardiovascular exercise. Usual HIIT sessions may vary from 4–30 minutes. These short, intense workouts provide improved athletic capacity and condition, improved glucose metabolism, and improved fat burning.
A HIIT session often consists of a warm up period of exercise, followed by three to ten repetitions of high intensity exercise, separated by medium intensity exercise for recovery, and ending with a period of cool down exercise. The high intensity exercise should be done at near maximum intensity. The medium exercise should be about 50% intensity. The number of repetitions and length of each depends on the exercise, but may be as little as three repetitions with just 20 seconds of intense exercise.
There is no specific formula to HIIT. Depending on one's level of cardiovascular development, the moderate-level intensity can be as slow as walking. A common formula involves a 2:1 ratio of work to recovery periods, for example, 30–40 seconds of hard sprinting alternated with 15–20 seconds of jogging or walking.
The entire HIIT session may last between four and thirty minutes, meaning that it is considered to be an excellent way to maximize a workout that is limited on time.
Peter Coe regimen
A type of high-intensity interval training with short recovery periods was used in the 1970s by the athletics coach Peter Coe when setting sessions for his son Sebastian Coe. Inspired by the principles propounded by the German coach and university professor Woldemar Gerschler and the Swedish physiologist Per-Olof Astrand, Coe set sessions involving repeated fast 200 metre runs with only 30 seconds recovery between each fast run.
A version of HIIT was based on a 1996 study by Professor Izumi Tabata (田畑 泉) et al. initially involving Olympic speedskaters, uses 20 seconds of ultra-intense exercise (at an intensity of about 170% of VO2max) followed by 10 seconds of rest, repeated continuously for 4 minutes (8 cycles). The exercise was performed on a mechanically braked cycle ergometer. Tabata called this the IE1 protocol. In the original study, athletes using this method trained 4 times per week, plus another day of steady-state training, and obtained gains similar to a group of athletes who did steady state training (70% VO2max) 5 times per week. The steady state group had a higher VO2max at the end (from 52 to 57 mL/(kg•min), but the Tabata group had started lower and gained more overall (from 48 to 55 mL/(kg•min). Also, only the Tabata group had gained anaerobic capacity benefits. It is important to note that in the original study from 1996, participants were disqualified if they could not keep a steady cycling pace of 35RPM for the full 20 seconds of work. Implications for popular exercise regimes that advertise as Tabata training should include overall analysis of the original study.
Professor Martin Gibala and his team at McMaster University in Canada have been researching high-intensity exercise for several years. Their 2009 study on students uses 3 minutes for warming up, then 60 seconds of intense exercise (at 95% of VO2max) followed by 75 seconds of rest, repeated for 8–12 cycles (sometimes referred to as "The Little Method"). Subjects using this method trained 3 times per week obtained gains similar to what would be expected from subjects who did steady state (50–70% VO2max) training five times per week. While still a demanding form of training, this exercise protocol could be used by the general public with nothing more than an average exercise bike.
Gibala's group published a less intense version of their regimen in a 2011 paper in Medicine & Science in Sports & Exercise. This was intended as a gentler option for sedentary people who had done no exercise for over a year. It included 3 minutes of warm-up, 10 repetitions of 60-second bursts at 60% peak power (80- 95% of heart rate reserve) each followed by 60 seconds of recovery, and then a 5-minute cool-down.
Jamie Timmons, professor of systems biology at the University of Loughborough, is a proponent of a few short bursts of flat-out intensity. In a BBC Horizon programme in February 2012, he put Michael Mosley on an exercise bike regimen consisting of three sets of about 2 minutes of gentle pedalling followed by 20 second bursts of cycling at maximum effort. This was done three times a week for a total of 3 minutes of intense exercise per week, plus some warm-up and recovery time. Measurable health benefits were reported, including significantly improved insulin sensitivity.
Studies by Tabata, Tremblay and others have explored the effectiveness of this method compared to traditional endurance training methods. A 2008 study by Gibala et al. 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, 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. 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." Around 20% of participants in Timmons' 2010 study showed less than 5% improvement in aerobic capacity. Conversely, about 20% of participants were described as "high-responders". A complex mixture of genes are involved, but differences in 11 single-nucleotide polymorphisms alone could predict 23% of the total variance in VO2max. Timmons was able to demonstrate that about half of the responsiveness of aerobic capacity to HIIT was genetically determined.
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 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.
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 has shown 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' 3x20-second HIIT regimen, exactly in line with Timmons' larger studies. Gibala's group reported a 35% increase in both insulin sensitivity and muscle oxidative capacity among seven sedentary people after just two weeks on the lower-intensity regimen outlined above. Timmons believes that this response is due to HIIT using 80% of muscles in the body, compared to 40% for gentle jogging and cycling. Similarly, 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. HIIT may therefore help to prevent Type-2 diabetes.
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".
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.
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."
- Perry, Christopher G.R.; Heigenhauser, George J.F.; Bonen, Arend; Spriet, Lawrence L. (December 2008). "High-intensity aerobic interval training increases fat and carbohydrate metabolic capacities in human skeletal muscle". Applied Physiology, Nutrition, and Metabolism 33 (6): 1112–1123. doi:10.1139/h08-097.
- Laursen, P.B.; Jenkins D.G. (2002). "The Scientific Basis for High-Intensity Interval Training: Optimising Training Programmes and Maximising Performance in Highly Trained Endurance Athletes". Sports Medicine 32 (1): 53–73. doi:10.2165/00007256-200232010-00003.
- Talanian, Jason L.; Stuart D. R. Galloway; George J. F. Heigenhauser; Arend Bonen; Lawrence L. Spriet (2007). "Two weeks of high-intensity aerobic interval training increases the capacity for fat oxidation during exercise in women". Journal of Applied Physiology 102 (4): 1439–1447. doi:10.1152/japplphysiol.01098.2006.
- "High-Intensity Interval Training (HIIT): The Ultimate Fat Incinerator".
- Van Dusen, Allison (October 20, 2008). "Ten ways to get more from your workout". Forbes. Retrieved December 14, 2008.
- Coe, Sebastian (2013). Running My Life. Hodder. pp. 38, 39. ISBN 978-1-444-73253-5.
- Tabata I, Nishimura K, Kouzaki M, et al. (1996). "Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max". Med Sci Sports Exerc 28 (10): 1327–30. doi:10.1097/00005768-199610000-00018. PMID 8897392.
- "Abstract - Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and VO2max". Retrieved 13 March 2013.
- "Interview with the founder of the world-renowned Tabata Protocol". Ritsumeikan University. Retrieved 30 January 2013.
- Tabata I, Irisawa K, Kouzaki M, Nishimura K, Ogita F, Miyachi M (March 1997). "Metabolic profile of high intensity intermittent exercises". Medicine and Science in Sports and Exercise 29 (3): 390–5. doi:10.1097/00005768-199703000-00015. PMID 9139179.
- Little, Jonathan P; Adeel S. Safdar; Geoffrey P. Wilkin; Mark A. Tarnopolsky; Martin J. Gibala (2009). "A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle: potential mechanisms". Journal of Physiology 588 (Pt 6): 1011–22. doi:10.1113/jphysiol.2009.181743. PMC 2849965. PMID 20100740.
- Hood, MS; Little, JP; Tarnopolsky, MA; Myslik, F; Gibala, MJ (Oct 2011). "Low-volume interval training improves muscle oxidative capacity in sedentary adults.". Med Sci Sports Exerc. 43(10): 1849–56. doi:10.1249/MSS.0b013e3182199834. PMID 21448086.
- "How To Get Fit With 3 Minutes Of Exercise A Week: BBC Doc Tries "HIT"". Medical News Today. 6 March 2012.
- Tremblay A, Simoneau JA, Bouchard C (1994). "Impact of exercise intensity on body fatness and skeletal muscle metabolism". Metabolism: Clinical and Experimental 43 (7): 814–8. doi:10.1016/0026-0495(94)90259-3. PMID 8028502.
- Gibala, Martin J; Jonathan P. Little, Martin van Essen, Geoffrey P. Wilkin, Kirsten A. Burgomaster, Adeel Safdar, Sandeep Raha and Mark A. Tarnopolsky (September 15, 2006). "Short-term sprint interval versus traditional endurance training: similar initial adaptations in human skeletal muscle and exercise performance". Journal of Physiology 575 (3): 901–911. doi:10.1113/jphysiol.2006.112094. PMC 1995688. PMID 16825308. Retrieved 2008-07-23.
- King, Jeffrey W. A Comparison of the Effects of Interval Training vs. Continuous Training on Weight Loss and Body Composition in Obese Pre-Menopausal Women (M.A. thesis). East Tennessee State University.
- Smith TP, Coombes JS, Geraghty DP (2003). "Optimising high-intensity treadmill training using the running speed at maximal O(2) uptake and the time for which this can be maintained". European Journal of Applied Physiology 89 (3–4): 337–43. doi:10.1007/s00421-003-0806-6. PMID 12736843.
- Rozenek R, Funato K, Kubo J, Hoshikawa M, Matsuo A (2007). "Physiological responses to interval training sessions at velocities associated with VO2max". The Journal of Strength & Conditioning Research 21 (1): 188–92. doi:10.1519/R-19325.1. PMID 17313282.
- Helgerud J, Høydal K, Wang E, et al. (2007). "Aerobic high-intensity intervals improve VO2max more than moderate training". Medicine and Science in Sports and Exercise 39 (4): 665–71. doi:10.1249/mss.0b013e3180304570. PMID 17414804.
- Esfarjani F, Laursen PB (2007). "Manipulating high-intensity interval training: effects on VO2max, the lactate threshold and 3000 m running performance in moderately trained males". Journal of Science and Medicine in Sport 10 (1): 27–35. doi:10.1016/j.jsams.2006.05.014. PMID 16876479.
- Timmons et al (Jun 2010). "Using molecular classification to predict gains in maximal aerobic capacity following endurance exercise training in humans.". J Appl Physiol. 108(6): 1487–96. doi:10.1152/japplphysiol.01295.2009.
- Driller Matthew, Fell James, Gregory John, Shing Cecilia, Williams Andrew (2009). "The effects of high-intensity interval training in well-trained rowers". International Journal of Sports Physiology and Performance 4: 1.
- Boutcher SH (2011). "High-intensity intermittent exercise and fat loss". Journal of Obesity 2011: 868305. doi:10.1155/2011/868305. PMC 2991639. PMID 21113312.
- Babraj J, Vollaard N, Keast C, Guppy F, Cottrell G, Timmons J (2009). "Extremely short duration high intensity interval training substantially improves insulin action in young healthy males". BMC Endocrine Disorders 9: 3. doi:10.1186/1472-6823-9-3. PMC 2640399. PMID 19175906.
- Trapp EG, Chisholm DJ, Freund J, Boutcher SH (April 2008). "The effects of high-intensity intermittent exercise training on fat loss and fasting insulin levels of young women". International Journal of Obesity 32 (4): 684–91. doi:10.1038/sj.ijo.0803781. PMID 18197184.
- Buchan DS, Ollis S, Young JD, et al. (2011). "The effects of time and intensity of exercise on novel and established markers of CVD in adolescent youth". American Journal of Human Biology 23 (4): 517–26. doi:10.1002/ajhb.21166. PMID 21465614.
- Venables, Michelle. "Endurance Training and obesity: effect on substrate metabolism and insulin sensitivity". Edgbaston, UK: School of Sport and Exercise Sciences, The University of Birmingham. PMID 18379212.
- Gibala MJ, Little JP, Macdonald MJ, Hawley JA (January 2012). "Physiological adaptations to low-volume, high-intensity interval training in health and disease". J Physiol 590 (Pt 5): 1077–84. doi:10.1113/jphysiol.2011.224725. PMID 22289907.
- Burgomaster KA, Howarth KR, Phillips SM, et al. (January 2008). "Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans". J. Physiol. (Lond.) 586 (1): 151–60. doi:10.1113/jphysiol.2007.142109. PMC 2375551. PMID 17991697.
- Tabata Protocol in swimming