Interval training tops the list of fitness trends. No wonder! It gets the job done quickly – perfect if you’re time-challenged. HIIT training also gives you a reason not to jump on another piece of boring cardio equipment like treadmills and elliptical machine. If you’re like most people, you check the clock every five minutes to see how much tedium you have left. Sound familiar? In contrast, interval training is a dynamic and challenging way to work out that rips you out of your comfort zone and helps you get ripped at the same time. Still, misconceptions exist about this popular form of training, some of which can keep you from getting the full benefits interval workouts offer. Here are five common ones.
Myth One: Longer HIIT Routines Are Better
If you think more is better, you still have a moderate-intensity cardio mindset. The beauty of interval training is its intensity and brevity. With interval training, you can get an effective workout in as little as 10 minutes to 20 minutes. If you’re able to do a 30 or 40-minute interval workout, you’re not pushing yourself hard enough during the active intervals. You should be working out at an intensity of between 16 and 18 on the Borg exertion scale, corresponding to “very hard” or “extremely hard.” At the end of an active interval, you should feel completely “spent.” It’s during the recovery period that you flush lactic acid out of your muscles and recover enough to continue.
Myth Two: HIIT Should Be Your Only Form of Cardio
No doubt, HIIT offers lots of advantages over steady-state, moderate intensity cardio, but there’s still room in your fitness plan for less intense cardio workouts. Due to the vigorous nature of this type of training, it’s not something you should do more than two or three times a week – and you don’t need to do it more than twice weekly to get the aerobic and anaerobic training benefits that HIIT offers. This leaves you ample opportunity to do a lower intensity cardio session. Take advantage of light days. HIIT training, working out at 85% to 95% of your aerobic capacity (V02 max) is too physically taxing to do more than a few times per week.
Myth Three: You Should Do the Same Interval Structure Every Time
Interval training is structured around active intervals followed by rest or recovery intervals, but you can vary the length of the work and rest intervals to best meet your goals. If your goal is to enhance anaerobic capacity so you’re a better sprinter or more skillful at sports that require quick bursts of speed or power, use short work intervals so you can work super hard, and keep the rest intervals long. If your goal is to improve aerobic endurance, lengthen the work intervals and keep the rest intervals short, a ratio of about 4 to 1 work to rest. One of the most popular ways to structure HIIT training is with a 2 to 1 work to rest ratio.
Don’t forget that your body adapts to HIIT training. Just as you use progressive overload to build muscle, to keep challenging your body increase the HIIT training challenge over time by adding a few more high-intensity intervals, increasing the work intervals or decreasing the rest intervals. When high-intensity interval training becomes less challenging, it’s time to up your game. Yes, progressive overload applies to HIIT training too.
Myth Four: HIIT Interval Training Burns Tons of Calories after You Finish
High-intensity interval training creates more of an oxygen debt than moderate-intensity cardio. This forces your body to expend more energy to recover – a good thing for your metabolism. However, the number of extra calories you burn isn’t enormous. Let’s keep it in perspective.
A study published in the Journal of Sports Science found that the after-burn is equivalent to between 6 and 15% of the oxygen cost of a high-intensity workout. So, if you burned 600 calories during an HIIT workout, 15% would add up to 90 calories. It’s something, but it’s not enough to justify a major post-workout splurge. The big advantage is you can burn 600 calories faster with an HIIT training than moderate-intensity cardio. High-intensity interval training is a time expedient way to work out and it enhances anaerobic and aerobic fitness, so it’s better for improving overall fitness.
Myth Five: Moderate-Intensity Cardio is the Best Form of Exercise for Heart Health
For years, physicians and even the American Heart Association recommended brisk walking for 30 minutes a day as a way to prevent heart disease. Now research shows that more vigorous exercise offers greater cardiovascular benefits than moderate-intensity exercise like fast walking. High-intensity interval training reduces cardiovascular risk factors in a number of ways: by boosting aerobic fitness, increasing insulin sensitivity, raising HDL cholesterol, lowering blood pressure, and by lowering body fat. One study showed the risk for cardiovascular disease and all-cause mortality dropped between 8% and 17% for each one-MET in aerobic capacity. Even cardiologists are now recommending supervised high-intensity interval training for some people after a heart attack.
Of course, everyone, even healthy adults, should develop a baseline level of fitness before doing HIIT workouts. One way to integrate HIIT into your schedule, if you’re just starting, is to do a few intervals at the end of your current cardiovascular workout and gradually transition to mostly HIIT. If you do have heart disease, talk to your physician before starting high-intensity interval training.
HIIT training is one of the best forms of exercise for blood sugar control, making it an ideal form of training for diabetics. A study published in Diabetes Care showed interval exercise improved blood sugar control in diabetics more than continuous walking with an equivalent energy expenditure.
The Bottom Line
High-intensity interval training offers too many benefits to ignore. Keep these myths in mind, though. The key is to get the most benefits without driving yourself so hard that you’re exhausted for a day or two afterwards. The best approach to HIIT training is to make it part of a balanced workout, not your only workout style. Everything in moderation, including HIIT.
Ask Men. “Metabolism Myths: Part 2”
Vigorous Versus Moderate-Intensity Exercise. Len Kravitz, Ph.D. (2006)
Diabetes Care February 2013 vol. 36 no. 2 228-236.
J Cardiopulm Rehabil Prev. 2010 Jan-Feb;30(1):2-11. doi: 10.1097/HCR.0b013e3181c56b89.
Circulation. 2003; 107: e2-e5 doi: 10.1161/01.CIR.0000048890.59383.8D.
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