By Dr. Mercola
Being short on time is no longer an excuse for avoiding exercise, as some of the most effective exercises also require the least amount of time.
As you may have guessed, we're talking about high-intensity interval training (HIIT) and the high-intensity version of weight training, commonly referred to as super-slow weight training.
In the featured video,1 Damien Blenkinsopp, host of The Quantified Body, interviews Dr. Doug McGuff, an emergency room physician and fitness center owner who's also an expert on HIIT. He's been doing HIIT for 37 years, and has trained clients on how to do it for the past 17 years.
HIIT can significantly reduce the amount of exercise you need to do, cutting your hour-long workouts down to 15 minutes once a week or less.
Basic Concepts of HIIT
One of the key 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 spend working out.
Moreover, as intensity goes up, you also need longer recovery times in between sessions, so the frequency of your workouts also goes down. At most, you might be able to do HIIT three times a week. Any more than that will likely be highly counterproductive.
McGuff's "Body by Science" program is typically done just once every seven to 10 days, and focuses on super-slow weight training, which turns strength training into a high-intensity exercise.
The same formulas apply here, so when you're doing super-slow weight training, it becomes very easy to over-train, and care needs to be taken to make sure you sufficiently recover.
Recovery needs will vary depending on your personal situation. On the one extreme you have people who recover very easily and quickly, and they may only need 48 hours' worth of recovery.
On the other end of the spectrum, those who do not recover well may need as much as 14 days or even longer before they're ready for another session. According to McGuff, the average recovery time is somewhere between four and nine days, with seven days being the mean "normal."
How to Get Results in 15 Minutes a Week
McGuff's program takes about eight to 15 minutes, and as mentioned, most people will only do it once every seven to 10 days (depending on their recovery needs).
Typically, the program involves just one set of five super-slow movements. Each set is performed in such a way that your muscle is under continuous load. The super-slow movement disallows you from using momentum to move the weight, and this ensures your muscle will reach maximum fatigue.
There's also a minimum amount of time in between each exercise. McGuff notes that the way you can tell whether you've sufficiently recovered between workouts is by keeping track of your sessions and noting the actual time needed to reach muscle failure for each movement.
The easiest way to do this is to have a buddy use a stop watch to time each set. If you notice a drop in performance, this is a tipoff that you're not fully recovered. If you've recovered well, you should be able to repeat your previous performance or see a slight improvement over your previous session.
Timing each set in the session will also help you determine your optimal load or weight. According to McGuff, some people can reach their full genetic potential in as little as 12 weeks when using this program. For others, it may take years.
Still, it's a very efficient form of exercise that can reap exceptional results in a short amount of time when compared to other forms of exercise. On a side note, Tim Ferriss' book, "The 4-Hour Body," is based on this very program, and McGuff was consulted during the writing of that book.
Why High-Intensity Exercise Is Needed for Aerobic Conditioning
You've likely heard the terms anaerobic, aerobic and cardiovascular training. Many believe that in order to improve your aerobic capacity, you need an aerobic workout, such as jogging or taking a Zumba class. But this is actually incorrect.
As explained by McGuff, in order to access your cardiovascular system, you have to work your muscles. As long as you're doing some form of mechanical work with your muscle, your aerobic capacity will improve. And HIIT forces your aerobic metabolism to run as fast as it possibly can.
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 like jogging.
By reaching peak intensity, you're also maximizing the stimulus for muscle growth and strength for each exercise, which makes your workout as a whole more efficient.
HIIT Sprinting Versus Super-Slow Weight Training
Now, you can perform HIIT using a recumbent bicycle, a treadmill, or by sprinting, for example. Or you can use weights, which is what McGuff prefers. One of the primary reasons for that is because it's far safer. As the intensity goes up, the forces actually diminish when you're doing super-slow weight training.
When doing HIIT on say a bicycle, you increase your risk of injury simply because the intensity required also creates increased force through acceleration.
Force is mass times acceleration. When you deprive yourself of the acceleration, you deliver virtually no punishment to your joints, so there's no repetitive use injury. Also, at the peak of intensity, when you're at your weakest, super-slow weight training therefore becomes safer rather than more risky.
Still, at the end of a 12-minute super-slow weight lifting routine, you will feel as if you just ran an all-out 440 meter dash; you'll be breathing very rapidly and heavily and your ears will likely be roaring. As noted by Dr. Guff, this program provides total conditioning, even without the traditional aerobic component.
How HIIT Helps Battle Chronic Fatigue
In terms of health effects, anecdotal reports suggest HIIT can improve a number of biomarkers associated with improved metabolic activity and good health, including:
- Improved insulin sensitivity and reversal of type 2 diabetes
- Normalized cholesterol, eliminating the need for statin drugs
- Reversal of bone mineral loss and reversal of osteoporosis
- Improved C-reactive protein levels (marker for inflammation)
Interviewer Damien Blenkinsopp also offers his own anecdotal story. He suffered from chronic fatigue, and in an effort to battle it he tried CrossFit, along with various dietary changes, like going Paleo. None of it made any positive difference. Then he found McGuff's program. He decided to take the long road, and began working just one set of body parts — such as legs — every 12 days.
That finally did the trick, and he slowly but surely began regaining his energy levels. There's a good reason why HIIT would work for this kind of recovery, as Dr. McGuff explains:
"[Forcing it] really does not work because first you have to have the capacity, and that capacity has to be brought out through intelligent programming that respects your body's need for intensity and recovery ... [O]nce you have given someone the metabolic capability and the muscular strength to function at a higher level, then their activity levels will spontaneously rise ...
[P]eople that have chronic fatigue, fibromyalgia; I really do believe that is a metabolic illness that involves mitochondrial down regulation, the ability to generate citrate through the mitochondria is just down regulated over time because of dietary and activity issues. And that can be cured with an intelligent application of exercise, but it cannot be fixed by saying 'okay, I am just going to man up and bring a sledgehammer to this process.' Because that will backfire on you."
How to Determine Optimal Recovery
One approach for determining whether you've sufficiently recovered between sessions was already mentioned. If you've not fully recovered, you'll notice a marked drop-off in performance, i.e. the time it takes you to reach muscle fatigue for the given set of exercises will decrease. You may find you reach failure very suddenly, and/or faster than before. Other telltale signs that you've not sufficiently recovered include the following:
- 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 seven to 10 days between workouts, you should be feeling well and energized more days than not
- By the time your next workout comes along, you should be feeling ready to go. If you feel tired or exhausted, you're not ready for another session
Again, by aggressively working your muscle to fatigue, you're stimulating the muscular adaptation that will improve the metabolic capability of the muscle and cause it to grow. McGuff recommends using the following five basic compound movements for your exercise set.
- Pull-down (or alternatively chin-up)
- Chest press
- Compound row (A pulling motion in the horizontal plane)
- Overhead press
- Leg press
These exercises can be done using either free weights or machines. The benefit of using a quality machine is that it will allow you to focus your mind on the effort, as opposed on the movement. Here's a summary of how to perform each exercise:
- Begin by lifting the weight as slowly and gradually as you can. The first inch should take about two seconds. Since you're depriving yourself of all the momentum of snatching the weight upward, it will be very difficult to complete the full movement in less than seven to 10 seconds. (When pushing, stop about 10 to 15 degrees before your limb is fully straightened; smoothly reverse direction).
- Slowly lower the weight back down.
- Repeat until exhaustion. Once you reach exhaustion, don't try to heave or jerk the weight to get one last repetition in. Instead, just keep trying to produce the movement, even if it's not "going" anywhere, for another five seconds or so. If you're using the appropriate amount of weight or resistance, you'll be able to perform four to eight repetitions.
- Immediately switch to the next exercise for the next target muscle group, and repeat the first three steps.
Done in this fashion, your workout will take no more than 12 or 15 minutes. While this may sound ridiculously short, once you've tried it, you'll likely realize that it's really all you can muster. This super-slow movement allows your muscle, at the microscopic level, to access the maximum number of cross-bridges between the protein filaments that produce movement in the muscle.
Move More, Exercise Less
I believe a HIIT program such as this, done once or maybe twice a week, or even every 10 days, is an excellent way to optimize your fitness and boost longevity. While not specifically mentioned in this interview, one of the great benefits of HIIT is the fact that it naturally increases your body's production of human growth hormone (HGH), aka "the fitness hormone." HGH is also associated with weight loss, improved muscle growth, longevity, and improved vigor in general.
In between sessions, I urge you to become more active on an hour-to-hour basis. Research has demonstrated that six hours of uninterrupted sitting counteracts the positive health benefits of one hour of exercise, so the foundation for good health is relatively constant or regular movement.
This means avoiding sitting down as much as possible, because even just standing up produces beneficial biological effects. Movement is also crucial so make sure you get a minimum of 7,000 steps a day and seek to exceed 10,000.