HIIT training: How to perform high-interval training

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What is High-Intensity Interval Training?

High-Intensity Interval Training (HIIT) has become a popular form of exercise in recent years for improving cardiovascular fitness. Since 2014, this training method has topped the list of most popular fitness trends according to the American College of Sports Medicine’s annual survey of health and fitness industry trends (5). A lot has happened in HIIT research since 2014, and it has evolved from being seen as a trend to becoming a well-established form of exercise in the world of health and fitness.

A New Type of Training

HIIT is often referred to as a “new” fourth category of training that complements endurance training, strength training, and sprint/speed training. It can also be described as a hybrid of all three of these traditional categories. Generally, HIIT is defined as training that includes repeated high-intensity intervals, ranging from about 90% of maximum heart rate to maximal exertion. Between each working interval, active or passive rest is performed.

The Effects of High-Intensity Interval Training

In addition to being an effective way to improve fitness—specifically, your maximal oxygen uptake (VO2max)—HIIT has also been shown to provide health benefits such as reduced blood pressure, improved insulin sensitivity, and better body composition (1, 7). Studies have demonstrated that within six weeks, HIIT can improve VO2max by 15% by training three times a week and performing two all-out 20-second intervals on a cycle ergometer, with five minutes of rest between each (2). This effect is even more impressive when compared with studies using traditional endurance training (e.g., 45 minutes at 70% VO2max) (3, 6). While the improvements in VO2max are comparable, the time required for HIIT is only a fraction of what is needed for long-duration endurance training. This finding is not unique—recent research has firmly established that HIIT is just as effective as classical endurance training, despite the much shorter duration (4).

Why Is High-Intensity Interval Training So Effective?

The exact reasons why HIIT is so effective are not fully understood yet, but there is a solid theoretical foundation. In order for the body to develop central and peripheral adaptations to training, the stimulus must be intense enough to trigger an adaptation process. This is why both strength and endurance training tend to be more effective when performed over longer periods. Here are some arguments for why you should include HIIT in your training:

  • More time-efficient – the high intensity makes sessions shorter

  • A larger portion of muscle mass is recruited

  • Muscle cells are forced to generate large amounts of energy in a short time

  • Blood volume is increased due to the high energy demand (plasma is pushed into the muscle, stimulating blood volume expansion)

How to Perform HIIT Workouts

You can do HIIT using running, cycling, rowing, or skiing—just make sure to warm up properly beforehand. A good rule of thumb is to warm up for 5–15 minutes. If it’s cold outside or if you’re a bit older (over 60), you should warm up for at least 15 minutes. The warm-up should gradually increase in intensity and finish at about 15–16 on Borg’s Rating of Perceived Exertion (RPE) scale.

 

Referanser:
  1. Little JP, Gillen JB, Percival ME, Safdar A, Tarnopolsky MA, Punthakee Z, Jung ME, Gibala MJ. Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. J Appl Physiol 111: 1554–1560, 2011. doi: 10.1152/japplphysiol.00921.2011.
  2. Metcalfe RS, Babraj JA, Fawkner SG, Vollaard NBJ. Towards the minimal amount of exercise for improving metabolic health: beneficial effects of reduced-exertion high-intensity interval training. Eur J Appl Physiol 112: 2767–2775, 2012. doi: 10.1007/s00421-011-2254-z.
  3. Metcalfe RS, Koumanov F, Ruffino JS, Stokes KA, Holman GD, Thompson D, Vollaard NBJ. Physiological and molecular responses to an acute bout of reduced-exertion high-intensity interval training (REHIT). European Journal of Applied Physiology 115: 2321–2334, 2015. doi: 10.1007/s00421-015-3217-6.
  4. Milanović Z, Sporiš G, Weston M. Effectiveness of High-Intensity Interval Training (HIT) and Continuous Endurance Training for VO2max Improvements: A Systematic Review and Meta-Analysis of Controlled Trials. Sports Medicine 45: 1469–1481, 2015. doi: 10.1007/s40279-015-0365-0.
  5. Thompson WR. Now Trending: Worldwide Survey of Fitness Trends for 2014. ACSM’s Health & Fitness Journal 17: 10–20, 2013. doi: 10.1249/FIT.0b013e3182a955e6.
  6. Vollaard NBJ, Constantin-Teodosiu D, Fredriksson K, Rooyackers O, Jansson E, Greenhaff PL, Timmons JA, Sundberg CJ. Systematic analysis of adaptations in aerobic capacity and submaximal energy metabolism provides a unique insight into determinants of human aerobic performance. J Appl Physiol (1985)106: 1479–1486, 2009. doi: 10.1152/japplphysiol.91453.2008.
  7. Wisløff U, Støylen A, Loennechen JP, Bruvold M, Rognmo Ø, Haram PM, Tjønna AE, Helgerud J, Slørdahl SA, Lee SJ, Videm V, Bye A, Smith GL, Najjar SM, Ellingsen Ø, Skjaerpe T. Superior cardiovascular effect of aerobic interval training versus moderate continuous training in heart failure patients: a randomized study. Circulation 115: 3086–3094, 2007. doi: 10.1161/CIRCULATIONAHA.106.675041.