The Truth Behind 5 Common Myths About HIIT

You've probably heard again and again that high-intensity interval training (HIIT) gets people amazing results in fat loss and fitness training. For the uninitiated, HIIT pairs high-intensity exercise intervals with low- to moderate-intensity exercise recovery phases.

HIIT has earned its spot as a here-to-stay fitness trend. But as with many other popular fitness and nutrition trends (such as CrossFit or the paleo diet), there are plenty of myths out there about HIIT. Make sure you don't fall victim to any of these misconceptions.

Just like you would not run a marathon — or even a half-marathon — without training, you also probably shouldn't go all out on your very first HIIT workout.

"Beginning with HIIT may increase the chance for injury and muscle soreness," wrote Len Kravitz, PhD, professor at the University of New Mexico and Micah Zuhl, assistant professor at the Central Michigan University, in a 2012 Idea Fit article on endurance training.

It's important to start any new exercise program carefully. Begin with low-intensity aerobic exercise until you can run for 30 consecutive minutes at a moderate intensity before trying HIIT, Kravitz and Zuhl advise.

Read more: How to Do a HIIT Workout at Home

Many people are actually doing supramaximal interval training (SMIT) and mistakenly calling it HIIT. HIIT involves performing high-intensity exercise intervals, interspersed with low- to moderate-intensity exercise. SMIT, by contrast, involves performing all-out bursts of exercise, interspersed with full rest periods, or no activity.

Confusion and mislabeling aside, SMIT could be a more effective training method. A 2013 study published in the European Journal of Sport Science looked at the endurance and sprint benefits of high-intensity and supramaximal interval training. The researchers found that SMIT led to greater improvements in performance than HIIT or continuous running. SMIT also provided the greatest benefits for physically active people, especially for women.

You can't always do SMIT training, as your body will become adapted to the type of stimulus, making your effort less effective. Plus, you're also more likely to lose interest when you're doing the same type of conditioning. That's where HIIT comes in. Try incorporating both SMIT and HIIT training to make your workouts more comprehensive, effective and interesting.

Read more: 4-Minute Tabata-Inspired Fat-Blasting Workout

A well-designed strength-training program can significantly increase strength, power, athletic performance and physical appearance. But what many people don't realize is the importance of muscle in the fat-loss process.

Put simply, muscle is metabolically active tissue, as it is the physical place in your body where fat is burned (i.e. used as energy). The more lean muscle tissue you have, the more calories/fat you'll burn throughout the day, even while you sleep ─ because more muscle tissue requires more energy.

Your body is like your car: If you put a bigger motor in your car, you'll burn more fuel while driving. With this analogy in mind, having more muscle will help make your interval training efforts more effective by helping you burn more calories. This is why strength training and maintaining muscle with proper training and eating strategies is absolutely critical for fat loss. The winning workout plan combines interval training with a comprehensive strength-training plan.

Like the name suggests, high-intensity interval training is intense and pushes your body hard, so it's important to allow for plenty of recovery time between workouts. You don't want to do too much throughout the week. Using high-intensity interval training three times per week will give you the best results while limiting the risk of injury.

Read more: 6 Low-Impact HIIT Workouts That Won't Hurt Your Back, Knees or Ankles

With the popularity of high-intensity interval training, the standard 30-minutes of steady-state aerobic training seems to have fallen out of favor with some fitness fans. Steady-state cardio is often demonized for interfering with and even killing muscle gains from strength training.

However, a small August 2012 study published in the International Journal of Sports Medicine found that adding low-impact aerobic exercise, such as cycling, will not jeopardize gains in strength or muscle size. And, of course, cardio training increases your aerobic fitness. Light to moderate cardio is a great method to use on recovery days — between the more intense anaerobic interval training days.

Keep in mind it's important to add variety and diversity to your workout routine. Each type of training — strength training, high-intensity, supramaximal and steady-state cardio — have their unique benefits and limitations. Using only one of them is like eating only fruits and no vegetables.