What really IS High Intensity Interval Training
You hear all the time these days about the HIIT training (which is actually a redundant phrase as HIIT stands for High Intensity Interval Training). Do you know what it really is, what it’s purpose is, and how to achieve it? Many people think they do, but a high percentage of those people would be wrong.
HIIT is a type of hybrid training that involves fast twitch and slow twitch muscle training. It was originally designed to increase athletic performance and to increase something called the anaerobic threshold and localized muscular endurance. What does this mean? basically it means that you train for shorter periods doing almost any activity type, but at a far higher rate of performance than you would during long bouts of cardio.
Some of you may be thinking “so what’s the difference between HIIT and weight training then, since they are doing similar muscular activity?” While it’s true the goal of HIIT is to fatigue the muscle quickly, there is a very important difference between HIIT and weight training to failure. Where weight training (if performed correctly) is designed to push a specific muscle past the point of load that it can perform, essentially forcing a muscle to adapt and grow, HIIT training doesn’t push any one muscle past it’s work threshold all at once, it does it more gradually, while still being used anaerobically (see my post on weight training for the beginner exerciser here for more info https://bankshealth.wordpress.com/2011/07/11/weight-training-for-the-beginner-exerciser-and-technical-failure/). This means that while we are still looking for a failure point, we are achieving that failure for different reasons with HIIT than we do with weight training. Where weight training is looking to engage all of the muscle fibers in a muscle group and fatigue them quickly, HIIT is looking to draw all of the potential chemical energy out of a muscle site, using up all the oxygen and glycogen at a muscle site, this forces the body to adapt and allow for larger stores of glycogen, more efficient mitochondrial reaction (higher oxygen efficiency) and essentially better performance in that muscle group. To compare that with regular steady state cardio, with regular cardio, you should never become anaerobic, your body should always be able to replace oxygen and glucose reserves to keep you going at the increased metabolic rate.
For the reasons stated above, HIIT training has a very specific purpose, it’s designed to work muscle groups hard and fast. HIIT training sessions should be 10 to 40 minutes maximum, depending on how your endurance levels are, and the type of activity. The working to resting periods should be 20 and 40 seconds (respective) for beginners and as low as 30 and 15 seconds for highly trained athletes (that means 30 seconds of very hard work, coupled with 15 second rest periods) for anywhere from 4 repetitions to 20 repetitions. This means that a normal HIIT training routine will last anywhere from 10 to 30 minutes if done right.
The difference between HIIT training and Weight training is that you CAN perform HIIT training next to cardio and not sustain any noticeable hormonal drawbacks as the hormones produced from HIIT training are similar to a moderate cardio routine, in other words feel free to do a 15 minute HIIT session followed by 30 or 40 minutes of cardio.
Who should be doing HIIT training? Well, anyone who wants to increase athletic performance, specifically people who need explosive movements coupled with long-term activity, for instance, hockey players, football players (both american and otherwise), basketball players, volleyball players, swimmers, moderate distance runners. HIIT training will allow for better muscle coordination along with the localized muscular endurance increases. HIIT training generally will NOT increase either workload of a muscle (I.E. you generally won’t become physically stronger with HIIT training) nor will it increase overall cardiovascular endurance (much, maybe small gains), it’s designed to work a localized muscle group, allowing you to perform at peak levels for longer periods and more periods, giving you that “burst” of energy even after an extended period, like a runners kick, or a better example would be a hockey player being able to put on a burst of speed to reach a puck in the 3rd period after a full game of hockey. That’s what HIIT training is really about.
Side effects and benefits of HIIT training are abundant. HIIT training is hard on the joints, be sure you’re physically able to perform HIIT training before you try it. Also anyone with cardiovascular or bone problems should consult a qualified medical professional before attempting HIIT. Of course, HIIT training will burn calories at a higher rate than straight cardio, but that is somewhat balanced by the fact that you can’t perform as long. Normally, a 20 minute HIIT training session with a 5 minute warm up and a 5 minute cooldown is the same caloric expense as about 50 to 60 minutes of moderate cardio. HIIT training (and any anaerobic activity) will create oxygen debt, which means that your metabolic rate will be raised for a time period post exercise (called EPOC or Exercise Post-exercise Oxygen Consumption), this means a slightly higher metabolic rate for a time after the exercise, anywhere from 30 minutes to 8 hours depending on the individual. HIIT training is NOT something you should perform every day, it’s hard on the body and long-term you could increase the likelihood of injury or arthritis, give your body plenty of rest days (or regular cardio) between, and make sure you stretch and cooldown after a HIIT session. There are other side effects of HIIT training, and in general it’s a great addition to any active and fit persons regimen, but it isn’t all you need to be athletic, nor should it be overused. If you have questions, please contact me.