Changes

* For people looking to lose weight, HIIT will probably produce a greater reduction in body fat than Continuous Moderate Exercise. Three sessions per week of [[Cycling HIIT For Runners | Wingate HIIT on a stationary bike ]] should help with [[Weight Loss]] and appetite control. The HIIT could be combined with other forms of exercise on the other days, which may further improve weight loss. (HIIT probably more effective than Continuous Moderate Exercise at improving insulin sensitivity.)* Recreationally active people looking for rounded fitness may benefit from including HIIT in their overall training program. Adding 1-3 sessions per week of [[Cycling HIIT For Runners| Wingate or WinTab HIIT on a stationary bike ]] should provide an improvement in fitness. * Athletes focused on improving their performance in endurance races lasting less than an hour will probably benefit from replacing some of their training load with a combination of both traditional HIIT and shorter Wingate or WinTab style HIIT. Up to one traditional HIIT or 1-3 shorter HIIT sessions could be included in a weekly training routine. Care should be taken to increase [[TRIMP| Training Load]] slowly with the additional HIIT and try to avoid increasing [[Training Monotony]]. The traditional HIIT should be performed by running on a track or other outdoor location. For the shorter HIIT, a stationary bike probably has a lower injury risk, but the additional benefits of outdoor running may outweigh the additional injury risk. However, the fast paces of the shorter HIIT should be introduced gradually, building up the pace over a number of workouts. See [[Cycling HIIT For Runners]] for details. * There is no direct evidence to indicate if HIIT will help athletes focused on improving their performance in events lasting longer than an hour. However, it seems reasonable that HIIT would provide some benefits. Including 1 or 2 Wingate or WinTab HIIT sessions per week may be appropriate. Using HIIT followed immediately by endurance training may mimic some of the effects of longer training. As noted in the prior bullet point for shorter duration athletes, care should be taken to monitor [[TRIMP| Training Load]] and [[Training Monotony]]. As with athletes focusing on events lasting less than an hour, the stationary bike has the lowest injury risk, but there may be benefits to other training modes. However, athletes competing in longer duration events typically don't have the same need for the very high paces that are sometimes seen at the end of shorter events.

The [[Tabata]] workout is one of the best -known protocols for HIIT and consists of 7-8 repeats of 20 seconds at 170% of [[VO2max|V̇O₂max]] with 10 seconds rest. The number of repetitions is defined by how long the required intensity can be maintained. An athlete should be able to complete 7-8 intervals; if 9 can be performed, the intensity is increased. However, few people actually follow the [[Tabata]] protocol because it requires specialist equipment to measure [[VO2max|V̇O₂max]], then calculate 1.7x the [[VO2max|V̇O₂max]] workload that should be used. In practice, most people do what I call the WinTab workout (see below). ==4 x 4 (The Norwegian Method)==''Main article: [[Medium Intensity High Volume Intervals]]''   The original Norwegian Method is to perform four intervals, each of four minutes at 90-95% of maximum heart rate, with 3-minute recoveries, often called "4x4". At first glance this appears to be an odd specification, as it's impossible to immediately increase your heart rate to 90% of maximum, and the original definition<ref name="Helgerud-2007"/> talks about trying to get your heart rate to 90% or above in 60-90 seconds, then adjust the effort to keep your heart rate in range. This approach was refined by a more detailed study<ref name="Acala Roche-Willis Astorino 2020"/> that used a range of 85-95% of max heart rate. In that study, the subjects increased their effort rapidly to 85-100% of the effort for their [[VO2max|VO₂max]]. After their heart rate reached 95% of max, the effort was reduced to keep it in the 85-95% range. What's that mean in practice? Given the details below, you need to estimate your [[VO2max|VO₂max]], then either work out your pace or power. * '''Power'''. Use the formula "weight in Kg * [[VO2max|VO₂max]] * 0.097". You then start the 4-minute interval at 85-100% of that power. * '''Pace'''. Luckily, it happens that pace in meters/second is roughly the same as power in watts/Kg. So you can use the formula to "[[VO2max|VO₂max]] * 0.097" to estimate your target pace in meters/second, then use an online converter to change that to min/mile or min/Km. Dropping your effort as the interval progresses may result in a surprisingly large reduction, with the study showing that that most intervals ended at about 60% of the initial power. The study also showed that the second through fourth interval had a lower initial power requirement, roughly 10-15% lower than the first interval. Remember, you can estimate your [[VO2max|VO₂max]] from a race performance using a [[Running Calculator]].(Note that the more recent versions of the Norwegian Method use [[Medium Intensity High Volume Intervals]].)===4x4 Conversion Details===The study had athletes with average [[VO2max|VO₂max]] of 37, average weight of 72 Kg, and average peak power output of 260w, which is 3.6 w/Kg. A [[Stryd]] based study<ref name="stryd"/> showed that there's a linear relationship between [[VO2max|VO₂max]] and peak power. (Peak power at [[VO2max|VO₂max]] varies with protocol). For this study, the peak power in w/Kg is [[VO2max|VO₂max]] * 0.097. ===4x4 Effort Worked Example===Assume your [[VO2max|VO₂max]] is 53 and your weight is 60, then the initial target power is 53 * 0.097 * 60 = 309 watts. So the target range would be 260-309w at the start of the interval. Alternatively, the required pace is 0.097 * 60 = 5.14 meters/second, so the range is 4.37 to 5.14 m/s. That converts to 3:49-3:14 min/Km or 6:08-5:13 min/mile. The power or pace is then dropped to keep your heart rate below 95% max.

This style of HIIT is based around the Wingate test, which is used to measure peak anaerobic power and anaerobic capacity<ref name="Vandewalle-1987"/>. ===The Wingate Test===The Wingate Test typically uses a warmup of 10 minutes easy cycling, followed by 2-3x 15 second sprints to get used to the speed. Then the test is normally 30 seconds all out sprinting, though some researchers use a longer period of 40-120 seconds. ===The Test on a Smart Trainer===The test is performed on a mechanically braked cycle ergometer, often a Monarch model. This makes converting the settings to a smart trainer tricky. The Monarch uses a weight to provide the resistance, and the Wingate Test uses 7.5% of your body weight. The formula for working out Watts for the Monarch is the resistance in Kg multiplied by the cadence. So, if you weigh 60 Kg, 7.5% is 4.5Kg, and at a cadence of 80 rpm is 360 watts. Setting your smart trainer's resistance so you get about 360 watts at 80 rpm is a good starting point for the test. ===The Wingate as HIIT===The Wingate HIIT uses 30 seconds of 'all out' intensity, followed by ~4 minutes of recovery, repeated 4-6 times. A similar warmup procedure as the test seems reasonable, with 10 minutes easy, then 2-3x 15 second sprints.

High intensity Interval Training has been in use since before the [[Tabata]] study made the term popular. The Jack Daniel's 'R' paced workouts are a classic example of this tradition of anaerobic interval training. The Jack Daniel's 'R' intervals are performed at around mile/1500m pace<ref name="JD"/>, which is generally close to 100% [[VO2max|V̇O₂max]]. The 'R' workouts are 12-40 repeats of 30-60 seconds with 1-4 min rests<ref name="JD-P132"/>. Jack Daniels mentions once having his athletes perform over 1,000 repetitions of one -minute HIIT (4 -minute rest) in a 14 -day period, with two male athletes averaging 5:00 min/mile pace and therefore covering 250 miles<ref name="JD-P132"/>.

There are various ways that HIIT could be performed, each with their own pros and cons. As this site is dedicated to running, my assumption is that you're a runner primarily. If that's not the case, then you'll have to interpret the pros and cons slightly differently.

| [[Cycling HIIT For Runners | Stationary BikeHIIT]]

* A stationary bike is much safer than writing outdoors at extreme intensities.* The vast majority of many studies have used a stationary bike to perform HIIT.* Riding out of the saddle is closer to moderate running in terms of muscle usage than riding seated.

| Outdoor Bike

| Runningon the flat

* For runners, roughly the right muscle groups are trained.* With [[Stryd]] it's possible to get a good measurement of pace, and even an estimate of power output. (The estimate of running power is not equivalent to cycling power, which can actually be measured rather than estimated.)

* At high Intensity, the movements involved in running become dramatically different, requiring a greater range of motion. This difference creates a significant risk of injury. Running uphill reduces some of this stress (hill based HIIT is not uncommon<ref name="active.com-hills"/>)It also changes the muscles used compared with running at submaximal intensity.

|-| Running up hill| * Even with Running uphill generates a [[Footpod]] and much higher intensity at a [[Best slower pace. This means that the biomechanical changes are not so extreme, reducing the risk of injury.| * Running Watch| good uphill uses somewhat different muscles to running watch]] iton the flat, so the training stress is not identical.* It's hard to measure pace accuratelyfind a hill that's long enough to do a high intensity interval training session that includes only partial recovery.* Getting the right incline is a tricky balance. Too shallow, and GPS is useless for you may as well be running on the short intervals often used in HIITflat. Too steep and your biomechanics become exaggeratedly different. |-| Running on with extra drag| * It's possible to use a track [[Running Parachute]], or other known distance may be slightly easierdrag a tire behind you to increase intensity at a slower pace.* The slower pace means a less extreme stride length and biomechanical changes, but it's still not trivialreducing risk of injury from those changes.| * The additional track creates radically different muscle recruitment patterns. (This is not * For a problem for 'all out' style full list of HIITdownsides see [[Running Parachute]]s.)

<ref name="activeHelgerud-2007"> J. Helgerud, K. Høydal, E. Wang, T. Karlsen, P. Berg, M. Bjerkaas, T. Simonsen, C. Helgesen, N. Hjorth, Aerobic high-intensity intervals improve VO2max more than moderate training., Med Sci Sports Exerc, 39 !!V̇olume!!, issue 4, pages 665-71, Apr 2007, doi [http://dx.doi.org/10.1249/mss.0b013e3180304570 10.1249/mss.0b013e3180304570], PMID [http://www.ncbi.nlm.nih.comgov/pubmed/17414804 17414804]</ref><ref name="Acala Roche-hillsWillis Astorino 2020"> How Justin J. Acala, Devyn Roche-Willis, Todd A. Astorino, Characterizing the Heart Rate Response to Complete Highthe 4 × 4 Interval Exercise Protocol, International Journal of Environmental Research and Public Health, publisher MDPI AG, volume 17, issue 14, date 2020-07-Intensity Interval Hill Workouts15, ISSN [http://www.activeworldcat.org/issn/1660-4601 1660-4601], doi [http://dx.doi.org/10.3390/ijerph17145103 10.3390/ijerph17145103], page 5103</ref><ref name="stryd">https://blog.stryd.com/running2019/12/Articles06/Howhow-to-Completeuse-Highstryd-Intensitypower-Intervalto-calculate-Hillyour-Workoutsvo2/, How to use Stryd power to calculate your VO2, Accessed on 24 February 20132023-08-21</ref>