Why High-Intensity Interval Training is Best For Weight Loss
I’m going to start this article bluntly:
Unless you just love going for long jogs, there’s absolutely no reason whatsoever to do steady-state cardio instead of high-intensity interval training (HIIT).
By the end of this article, I think you’ll agree.
Let’s begin.
High-Intensity Interval Training and Burning Fat
Cardio machines often show pretty graphs indicating where your heart rate should be for “fat burning” versus “cardiovascular training.”
You calculate this magical heart rate by subtracting your age from 200 and multiplying this number by 0.6. If you keep your heart rate at this number, as the story goes, you’ll be in the “fat burning zone.”
There’s a kernel of truth here.
You do burn both fat and carbohydrates when you exercise, and the proportion varies with the intensity of exercise.
A very low-intensity activity like walking taps mainly into fat stores, whereas high-intensity sprints pull much more heavily from carbohydrate stores. At about 60% of maximum exertion, your body gets about half of its energy from carbohydrate stores and half from fat stores (which is why many “experts” claim that you should work in the range of 60–70% of maximum exertion).
Based on the above, you might think that I’m actually arguing for steady-state cardio, but there’s more to consider.
The first issue is total calories burned while exercising. If you walk off 100 calories, 85 of which come from fat stores, that isn’t as effective as spending that time in a moderate run that burns off 200 calories with 100 coming from fat. And that, in turn, isn’t as effective as spending that time doing sprint intervals that burn off 500 calories with 150 coming from fat.
Calories burned while exercising isn’t the whole story, though.
Studies such as those conducted by Laval University, East Tennessee State University, Baylor College of Medicine, and the University of New South Wales have shown that shorter, high-intensity cardio sessions result in greater fat loss over time than longer, low-intensity sessions.
A study conducted by The University of Western Ontario gives us insight into how much more effective it really is. Researchers had 10 men and 10 women train 3 times per week, with one group doing 4-6 30-second treadmill sprints (with 4-6 minutes of rest in between each), and the other group doing 30-60 minutes of steady-state cardio (running on the treadmill at the “magical fat loss zone” of 65% VO2 max).
The results: After 6 weeks of training, the subjects doing the intervals had lost more fat. Yes, 4-6 30-second sprints burns more fat than 60 minutes of incline treadmill walking.
Although the exact mechanisms of how high-intensity cardio trumps steady-state cardio aren’t fully understood yet, scientists have isolated quite a few of the factors:
Increased resting metabolic rate for upwards of 24 hours after exercise.
Improved insulin sensitivity in the muscles.
Higher levels of fat oxidation in the muscles.
Significant spikes in growth hormone levels (which aid in fat loss) and catecholamine levels (chemicals your body produces to directly induce fat mobilization).
Post-exercise appetite suppression.
And more…
The bottom line is that high-intensity interval training burns more fat in less time than steady-state cardio.
But wait, there’s more…
High-Intensity Interval Training and Your Muscles
In most people’s minds, cardio and muscle growth don’t go together very well. And there’s some truth in this.
While I recommend that you always include some cardio in your programming regardless of whether you’re bulking or cutting (and I detail why here), there are right and wrong ways to do it.
For instance, research has shown that combing both strength and endurance training (concurrent training) can hinder your strength and muscle gains when compared to just strength training alone. This is why I recommend that people split their cardio and strength training into two separate workouts.
But, even if you do this, cardio can still have a negative impact on your muscle-related gains.
Research has shown that the longer your cardio sessions are, the more they impair strength and hypertrophy. That is, the shorter your cardio sessions are, the more muscle you preserve.
Thus, keeping your cardio sessions short is important when we’re talking about maximizing your gains in the weight room, and preserving your muscle. Only high-intensity interval training allows you to do this while still deriving significant benefits from the exercise.
The Best Form of High-Intensity Interval Training
I often get asked about what my favorite HIIT routine is, and my answer is cycling (recumbent cycling to be specific).
Why?
Well, not only is it convenient that I can bring my iPad and read or watch a show or movie while doing my cardio, it turns out that cycling itself has special benefits for us weightlifters.
These benefits were demonstrated in a particularly interesting study conducted by Stephen F Austin State University.
What researchers found is that the TYPE of cardio done had a profound effect on the subjects’ ability to gain strength and size in their weightlifting. The subjects that did running and walking for their cardio gained significantly less strength and size than those that cycled.
Why?
Researchers concluded that it was because cycling involves the use of more of the muscles used in hypertrophy movements (squats, for instance) than running or walking does. That is, it more closely imitates the motions that result in hypertrophy, and thus doesn’t impair hypertrophy.
Therefore, I recommend cycling for your high-intensity interval training (the next-bext choice would be sprinting, as this too involves many of the same muscles), and I recommend keeping your sessions relatively short (20-30 minutes).
In terms of an exact protocol, here’s what you can do.
You start your workout with 2-3 minutes of low-intensity warmup on the lowest resistance.
You then bump the resistance up to 4-5, and pedal as fast as possible for 30 seconds.
You then reduce the resistance to its slowest setting and pedal at a moderate pace (about 100 RPM) for 60-90 seconds. If you’re new to HIIT, you may need to extend this rest period to 2-4 minutes.
You repeat this cycle of all-out and recovery intervals for 20-25 minutes.
You do a 2-3 minute cool-down at a low intensity.
Have you tried high-intensity interval training before? Do you find it more effective than steady-state cardio? Let me know in the comments below!
