High-intensity interval training (HIIT).

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By Dr. Mercola
Whether you seek to lose weight or gain muscle mass, strength or cardiovascular fitness, consider high-intensity interval training (HIIT).
By doing short bursts of very high-intensity drills, you can reduce the duration and frequency of your workouts and still make greater gains than what you'd achieve doing moderate intensity exercises for literally hours longer each week.
Another benefit is that you can do HIIT with just about any activity you can think of, including body weight exercises, biking, swimming, walking, sprinting, rowing, and weight lifting.
The latter is often referred to as SuperSlow weight training, and it is the slow movement that produces the heightened intensity and turns it into a HIIT session. If increased strength is your aim, SuperSlow strength training is by far the fastest, most effective way to achieve it.

Boost Strength by 50 Percent in Two Months

The SuperSlow program was originally developed and popularized by Ken Hutchins, who worked as an equipment designer and educational writer at Nautilus.
It all began in 1982, when he was asked to supervise a Nautilus-sponsored osteoporosis study. As noted by WebMD,¹ the women in the study were so weak and frail, the researchers worried they might get injured lifting weights.
The solution Hutchins came up with was a combination of low weight and slow, controlled movements. The women ended up making dramatic gains in strength.
A decade later, YMCA fitness research director Wayne L. Westcott, Ph.D. decided to test the SuperSlow protocol. He did two informal studies, one in 1993 and another in 1999. In each trial, 75 people were enrolled into a SuperSlow strength training program for eight and 10 weeks respectively.
Their results were compared to groups of people doing a regular strength training routine. As reported in the featured article:²

"The people in Westcott's study did 12 to 13 exercises. The comparison group did 10 repetitions of each exercise, pulling the weight up and lowering it over a period of the usual two seconds in each direction.

The other half did five repetitions, but lifted slowly, 10 seconds on the upstroke and four seconds on the way back down. (Hutchins and others recommend 10 seconds each way.)

That's 20 seconds of muscle contraction for each repetition instead of four seconds. Multiply that by five repetitions and 12 exercises, and you have a killer workout, Westcott says ...

Those doing SuperSlow in both groups experienced a greater than 50 percent gain in strength. In fact, the results were so difficult to believe that Westcott had them verified at Virginia Tech." [Emphasis mine]

Keys to SuperSlow Success

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The key to the SuperSlow weight lifting technique is to remove the momentum. By disallowing muscle rest, you "super charge" muscle growth because your muscle has to continuously work throughout the entire movement.
Another key is to work your muscle to the point of failure, meaning the point at which you simply cannot perform another repetition. Besides building more muscle in a shorter amount of time, there are other benefits to this type of exercise as well.
Despite being more intense, SuperSlow is far safer than regular forms of weight training. As explained by Dr. Doug McGuff, author of "Body by Science," who owns a SuperSlow workout center in South Carolina:³

"With other exercises, to make them more challenging, you usually have to increase the force required — the weight level, whatever — which brings on aches and pains. This makes them more dangerous. With SuperSlow, you can make exercise much more challenging without increasing force."

If you're worried SuperSlow won't improve your cardiovascular fitness, don't fret. The idea that you need aerobic exercise like jogging to improve your aerobic capacity has actually been proven incorrect, because to access your cardiovascular system, you have to work your muscles.
As long as you're doing mechanical muscle work, your aerobic capacity will improve right along with your muscle strength. Moreover, HIIT trains your metabolism to increase energy production by delivering substrate to your mitochondria as fast as possible, and it does so far more effectively and efficiently than traditional aerobic exercise.

Intensity and Duration Are Inversely Proportional When Doing HIIT

One of the foundational concepts of HIIT is that the intensity and amount of time spent working out are inversely proportional. Meaning, the greater the intensity, the less time you have to spend working out. This has been scientifically verified, with studies showing that mere minutes of strenuous exertion can produce the same results as hours of moderately paced exercise.
In one recent experiment^,4,5,6,7 one single minute of intense activity within a 10-minute exercise session was as effective as working out for 45 minutes at a moderate pace.
After doing three workout sessions per week for 12 weeks, the endurance group had exercised for a total of 27 hours, while the HIIT group had exercised for a total of six hours, a mere 36 minutes of which was done at high-intensity. Yet both groups showed virtually identical fitness gains.
As a general suggestion, you only need to carve out about 20 minutes two to three times a week for your HIIT workouts. If you're really pressed for time, you could even get away with less than that. The New York Times' Well Guide⁸ lists HIIT workouts ranging from four to 30 minutes.
What does a four-minute HIIT workout⁹ look like? Basically, to cram a workout into this narrow a time frame, you simply go as hard as you can for the full four minutes.

"In a study, men ran on a treadmill at 90 percent of their maximal heart rate — pretty much all out — for four minutes, three times a week for 10 weeks. Overall, this group improved their endurance, blood sugar control and blood pressure as much as a comparable group of men who did a series of all-out exercise lasting for 16 minutes," The New York Times writes.
"Also, skip the drive to the gym for this workout: It's just not time-efficient. Climb a flight of stairs for four minutes or sprint home from your bus stop. Just make sure you raise your heart rate to a pumping, air-gasping level for four minutes, three times a week."

How to Determine Your Ideal Workout Frequency

As intensity goes up, you also need longer recovery times in between sessions, which means the frequency of your workouts goes down as well. At most, you might be able to do HIIT three times a week. Any more than that will likely be highly counterproductive.
McGuff's SuperSlow program is typically done just once every seven to 10 days. Some may even need as much as 14 days of recovery before they're ready for another session. As a general rule, by the time your next workout comes along, you should be rearing to go. If you feel tired or exhausted, you're not ready for another session. Telltale signs that you've not sufficiently recovered and need to decrease the frequency of your SuperSlow workouts include the following:

• A drop-off in performance, i.e. the time it takes you to reach muscle fatigue for the given set of exercises will decrease. You can track this by having a buddy use a stop watch to time each set. When properly recovered, you should be able to repeat your previous performance or see a slight improvement over your previous session.
• The day after your workout, you feel run down; flu-like symptoms may be present. Ideally, when you're well recovered, you should feel slightly fatigued the following day, but overall invigorated with a sense of well-being.
• In the longer term, you feel at or below baseline more days than you feel invigorated and well. Over the course of the 7 to 10 days between workouts, you should be feeling well and energized more days than not.

If Weight Loss Is Your Goal, Dietary Changes Are Required

Studies and anecdotal experience alike agree that exercise alone is rarely sufficient to produce significant weight loss. For this you really need to address your diet. As reported by The Guardian:¹⁰

"Exercise alone is not enough to lose weight because our bodies reach a plateau where working out more does not necessarily burn extra calories, researchers have found. The team is the latest to challenge obesity prevention strategies that recommend increasing daily physical activity as a way to shed the pounds.

In a study,¹¹ published in Current Biology ... they suggest that there might be a physical activity 'sweet spot', whereby too little can make one unhealthy but too much drives the body to make big adjustments to adapt, thus constraining total energy expenditure."

To reach this conclusion, the researchers measured the daily activity levels and corresponding energy expenditure of more than 330 adults. If you're like most people, you'd think that the more you move the more calories you'll burn, but that's not what they found. There's a point at which energy expenditure levels off, even though you remain active.
Compared to the most sedentary people, those with moderate activity levels burned about 200 calories more. But those who had the highest activity levels did not have dramatically higher energy expenditure than the moderate activity group. According to the featured article:

"The results could help explain why people who start exercise programs with the aim of shedding pounds often see a decline in weight loss — or even a reversal — after a few months.
In light of their findings, the authors suggest revision of World Health Organization guidance on how to prevent weight gain and obesity, which suggests 150 minutes of activity a week for adults ... They say it should 'better reflect the constrained nature of total energy expenditure and the complex effects on physical activity on metabolic physiology.'"

Dr. Aseem Malhotra, a cardiologist and advisor to the U.K.'s National Obesity Forum takes it even further, noting that:¹² "We know exercising in the right way has many health benefits but weight loss isn't one of them. We need to disassociate obesity with exercise altogether. If we're going to combat obesity, it's going to happen purely from changing the food environment."

Intermittent Fasting — A Potent Way to Rev Up Your Metabolism

A major part of the problem and the reason why it can be so difficult to lose weight is because once your body has adapted to burning sugar as its primary fuel, it down-regulates enzymes that utilize and burn stored fat. This is another reason why exercise alone won't cut it in most cases. If you eat too much sugar — and especially if you graze all day long — your body's ability to access and burn stored fat is severely inhibited. By shifting what you eat and when you eat, you can turn this situation around.
When it comes to shedding unwanted pounds and reworking your fat-to-muscle ratio, HIIT combined with intermittent fasting is a winning combination that is hard to beat. Intermittent fasting involves cutting calories in whole or in part, either a couple of days a week, every other day, or even daily as in the case of the scheduled eating regimen I recommend for those with insulin resistance (overweight, high blood pressure, diabetes, or taking statin drugs).
This eating schedule involves restricting your eating to a specific window of time each day, ideally a window of eight hours or less. This means no calories at all during your non-eating window. You can have water, tea, and coffee, but no milk or sugar added. This is one of the most aggressive intermittent fasting regimens, so you'll likely notice results far sooner than with some other eating schedules.
Once your insulin resistance improves and you've reached your goal weight you can start eating more frequently, as by then you will have reestablished your body's ability to burn fat for fuel — that's really the key to sustained weight management. This is what happened to me. I was losing far too much weight on one meal a day and had to increase to two meals to not lose too much weight.

Shifting Your Nutrient Ratios May Be the Answer You've Been Seeking

Also pay careful attention to your food choices when you do eat. Focus on eating real food cooked from scratch (or eaten raw). To optimize your mitochondrial function, aim for the following nutrient ratios.

• 75 to 85 percent of your total calories as healthy fat (monosaturated, saturated, polyunsaturated (PUFA), and omega-3/omega-6). Limit PUFAs to less than 10 percent. At higher levels, concentration in the inner mitochondrial membrane makes it far more susceptible to oxidative damage from the reactive oxygen species generated there. Also avoid exceeding 5 percent of your calories as omega-6 fats. Combined, your omega 6/omega 3 fats should not exceed 10 percent, and the omega 6:3 ratio should be below 2.
• 7 to 10 percent of your calories as protein (high-quality grass-fed or pastured meats and animal products)
• 8 to 15 percent as carbs, which should be twice as many fiber carbs (vegetables, seeds and nuts) as non-fiber carbs (sugar/fructose, refined grains and starchy foods)

SuperSlow Strength Training Can Help You Gain Muscle and Lose Fat

Considering the fact that muscle uses more energy than fat, increasing muscle mass is an effective way to boost weight loss, and SuperSlow weight training is by far the most efficient way to increase your muscle mass. Combined with appropriate diet changes and intermittent fasting, your chances of meeting your weight loss goals are about as optimal as it can get.
Remember, if an intermittent fasting regimen doesn't appeal to you long-term, you don't have to stay on it forever. But it's a great way to help your body make the shift from burning sugar to burning fat as its primary fuel. Not only is this key for sustained weight management, it also helps optimize mitochondrial function, which is crucial for longevity and disease prevention in general.