High intensity interval training (HIIT) is a short, intense workout. A popular form of training, HIIT might just live up to the hype. Not just a passing fad, HIIT is a super useful form of training and well worth exploring.
HIIT involves performing periods of high intensity work intensity work interspersed with brief periods of recovery. For example, you might row 300 meters as fast as humanly possible and then rest for 90 seconds before doing it all over again, and again, and again until you have completed six to eight repeated efforts.
HIIT can be applied to a great many exercise modalities. Basically, anything that you can do at a fast pace for 30 to 90 seconds that leaves you winded and tired (work interval) and is alternated with brief periods of rest (recovery interval) that are about 2 – 4 times longer than the work interval. Sprinting, doing burpees, jumping rope, swinging a kettlebell, tossing and chasing a medicine ball, hitting a punch bag or simply using an exercise bike can all be HIIT workouts.
The basic premise of HIIT is that you work as hard as you can and get to the point where you switch from aerobic to anaerobic energy usage. Depending on how hard you are working, this could be as little as 20 seconds to closer to 90 seconds. This results in the production of lactic acid (the stuff that makes your muscles burn). The brief rest allows your heart and breathing rate to slow and your lactic acid levels to drop enough to allow you to complete another high intensity work interval.
THE BENEFITS OF HIIT
So, why do HIIT at all? Clearly it’s harder than just going for a jog and all that lactic acid makes for a painful workout. In addition to appealing to masochists, HIIT offers some legitimate benefits and advantages over regular slow and steady cardio.
1. Time Efficiency
A normal cardio workout will probably last close to an hour – especially if you go to a group exercise class. Conversely, an HIIT session will take no more than around 30 minutes and in many cases considerably less. Lots of people say they don’t have time to exercise – HIIT could be the solution.
2. Improves fitness
In exercise, the law of specificity rules the roost. That is to say, you are fit for what you do. If you run a long way slowly, your body will develop in such a way to improve your slow distance running ability.
In other words, if you only ever run ten-minute miles, that‘s exactly how fit you are going to be. If, however, you push the pace and work much harder, your fitness will have to improve to the level at which you are working. If you want to see your fitness levels soar (and in less time) HIIT could be the answer.
3. Targets Fast-Twitch Muscle Fibers
Regular cardio works your heart and lungs but also emphasizes your type IA slow-twitch muscle fibers which are generally thin, weak and have no capacity for size or strength. On the other hand, HIIT uses those type IIB fibers and will actually maintain or even increase their size and strength much like lifting weights would do.
4. HIIT Adds Variety
Short, sharp workouts really get your adrenalin flowing and the wide variety of suitable exercise modalities you can use means that HIIT workouts are lots of fun and needn’t be boring – ever.
Imagine, instead of spending 40 minutes on a treadmill staring at the TV, you could run at high intensity for 30 seconds alternated with 2 minute rests. Twenty minutes later, your workout is done, your stress levels are zero and you’ve also had a great workout.
HOW TO DO HIIT
HIIT offers lots of benefits but it’s not without drawbacks. High intensity means heard work and not everybody’s body is up to the strain. Newbies and those with low levels of fitness should build a solid base of aerobic fitness by doing regular cardio before trying HIIT.
Once you have decided to jump on the HIIT train, start with short intervals and relatively long rests. Keep the number of repeats relatively low and only increase your workload gradually week by week.
Finally, don’t get carried away with the whole HIIT ethos of “go hard or go home” – while HIIT means working hard, you must still do your exercises using good form otherwise you risk suffering an injury.
HIIT could make a valuable addition to your fitness regimen but remember, it is just one of many tools you can use to get in shape. Just because it’s a fitness industry buzzword right now, doesn’t mean that other forms of exercise have suddenly become obsolete. HIIT is just one of many ways you can get fit, stay fit and be healthy.
- Kohn TA, Essén-Gustavsson B, Myburgh KH. Specific muscle adaptations in type II fibers after high-intensity interval training of well-trained runners. Scand J Med Sci Sports. 2011;21(6):765-72. doi: 10.1111/j.1600-0838.2010.01136.x.
Astorino TA, Edmunds RM, Clark A, King L, Gallant RA, Namm S, Fischer A, Wood KM. High-Intensity Interval Training Increases Cardiac Output and V˙O2max. Med Sci Sports Exerc. 2017 Feb;49(2):265-273. doi: 10.1249/MSS.0000000000001099.
- ACE (American Council on Exercise). 8 Reasons HIIT Workouts are So Effective. Available from: acefitness.org/education-and-resources/lifestyle/blog/5073/8-reasons-hiit-workouts-are-so-effective/