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For the past few decades, people have been told that long, steady cardio workouts like jogging, running and cycling are a must-have in each person’s workout regime. Of course, people followed suit, and a lot of us have now formed a habit to do cardio regularly, be it on a treadmill, or jogging with our dedicated workout buddy.

In the last decade, a new workout gained popularity at such a pace, that it seemed that the days of cardio reign were over. HIIT stepped into the world of fitness and turned everything we knew about exercise upside down. Suddenly, the fitness world has started buzzing about how 20 minutes is more than enough for a complete workout and how that’s even better than doing an hour on a treadmill. People were conflicted because a lot of them had great results by doing just cardio, while other swore that their fitness success was completely due to regular HIIT. Naturally, people began wondering what is the best workout to do? Is there even a clear winner between cardio and HIIT? The debates are hot, passionate and ongoing, but hopefully, some fitness experts and sports scientists can shed some light and solve the 10-year long dilemma. 

For those that aren’t familiar with the concept of high-intensity interval training, it’s a workout regime that includes two phases: the intense phase, in which exercises are performed at 90-100% of a person’s maximum heart rate (this phase can last from 10 seconds up to 60 minutes, depending on our level of fitness) and the recovery phase, in which the exercises are performed at 30-40% of our maximum heart rate. The whole HIIT workout can last for up to 30 minutes (a lot of people claim that there are 45 minute or 60-minute HIIT workouts, but those are either moderate-intensity or very dangerous).


Experts Weigh-In

According to some health and fitness experts, cardio is actually the least efficient form of exercise. Why? because cardio isn’t metabolic, meaning it doesn’t have the sought-for ’afterburn’ effect; in other words, people who do steady state cardio do not burn calories after the workout is finished, unlike those who do strength, resistance training and HIIT.

However, the afterburn effect is just one aspect of the workout benefits, and there are a plethora of other positive effects of exercise. So, clinically speaking, is HIIT better than cardio?

Neel Chokshi, MD, MBA, director of Penn’s Sports Cardiology & Fitness Program has a somewhat different take. He says that Interval training has gained interest lately because research has suggested that you make similar gains in cardiovascular fitness as you would with traditional endurance exercise regimens, but with shorter periods of exercise. So, if you do not have time for the traditionally recommended 150 minutes of moderate intensity exercise each week, this may serve as a substitute. The 'better' exercise regimen is arguably the one that is consistent and sustainable to see gains over time.“

A lot of other experts have agreed that there isn’t one exercise that’s better on all accounts than any other. Rather, the best exercise is the one a person actually sticks with, according to Kyle Meyer, DO, a Sports Medicine fellow at Penn Medicine.

Meyer, Chokshi and Chris Kusmiesz, MS, an exercise physiologist with the Penn Sports Cardiology and Fitness Program all agree that HIIT has been shown to provide better results in cardiorespiratory fitness, and could be thought of as more efficient.“

Indeed, a 2014 study has found that HIIT significantly increases cardiorespiratory fitness by almost double, compared to moderate-intensity continuous training. HIIT can also improve VO2Max and testosterone levels. Increased VO2Max improves the capability of the heart and lungs to deliver oxygen to the muscles, and testosterone is a hormone that helps the body to synthesize proteins and build muscles faster as a result.

Truly, HIIT has been vital to the success of a number of athletes throughout the decades. But how useful can it be for a recreational athlete or a casual fitness enthusiast?

Kristopher Fayock, MD, associate program director of Primary Care Sports Medicine Fellowship and an assistant professor of Clinical Family Medicine and Community Health thinks that the explosive exercises, like sprinting, in HIIT would probably predispose a person more to muscle pulls, strains and tears. On the other hand, the longer, more repetitive activities in traditional cardio (jogging and distance running) would more likely predispose people to overuse skeletal injuries, like stress fractures.“


The ’Verdict’

As you can see, the experts seem to think there isn’t a clear winner here, especially because in the weight loss department (which is possibly the primary reason why recreational athletes exercise), both HIIT and cardio have shown to produce results when coupled with a healthy diet.

A pound of fat equals to about 3500 calories, so in order to lose that fat, one must create a caloric deficit. This deficit is achieved primarily through making changes to our diet. If we were to just create the caloric deficit through exercise, we would have to do 350 to 450 minutes of cardio per week to see results. 

On the other hand, if we do make changes to our diet in order to make it more healthy and create a caloric deficit, research shows that any form of exercise has a beneficial effect to our overall health. Be it HIIT, cardio, weightlifting, yoga, dancing or just walking – they can all improve our blood pressure, fat metabolism, and insulin sensitivity.

In the end, the main thing to do in order to choose the right workout for you is to listen to your body. If you really happen to like your morning jogs, don’t stress – there’s a number of studies that show that cardio can help reduce the risk factors associated with cardiovascular disease. 

However, there are certainly more efficient and effective ways of training depending on your goals. For example, if your goal is to lose weight and you struggle with time then HIIT and strength training is by far the most effective way to train. Find what works best for you and stick to it.