I believe regular movement and exercise is essential to health. As Stephan Guyenet pointed out in a recent blog post, our paleolithic ancestors had a different word for exercise: “life“. They naturally spent a lot of time outdoors in the sun, walking, hunting, gathering, and performing various other physically-oriented tasks. They had no concept of this as “exercise” or “working out”. It was just life.
But while exercise contributes to health in several different ways, it’s not very effective for weight loss. Or, more specifically, I should say that low-intensity, “cardio” – which is how most people exercise – is not effective for weight loss.
Why Cardio Doesn’t Work
How could this be? There are three main reasons:
- caloric burn during exercise is generally small;
- people who exercise more also tend to eat more (which negates the weight regulating effect of exercise); and,
- increasing specific periods of exercise may cause people to become more sedentary otherwise.
In an example of the first reason, a study following women over a one-year period found that in order to lose one kilogram (2.2 pounds) of fat, they had to exercise for an average of 77 hours. That’s a lot of time on the treadmill just to lose 2 pounds!
In an example of the second reason, a study found that people who exercise tend to eat more afterwards, and that they tend to crave high-calorie foods. The title of this study says it all: “Acute compensatory eating following exercise is associated with implicit hedonic wanting for food.” I love it when researchers have a sense of humor.
In an example of the third reason, one study assigned 34 overweight and obese women to an exercise program for 8 weeks. Fat loss at the end of the study was an average of 0.0kg. Not very impressive. But the researchers noticed that some women did lose weight, while others actually gained. What was the difference?
If you’re still not convinced, the Cochrane group did a review of 43 individual studies on exercise for weight loss. Study length ranged from 3 to 12 months, and exercise sessions lasted on average 45 minutes with a frequency of 3-5 times per week. The results? On average, the additional weight loss from exercise averaged about 1 kg (2.2 pounds). Meh. Assuming they worked out for 45 minutes 4x/wk over 6 months, that means they had to exercise 69 hours to lose that 1 kg.
The purpose of this rather long introduction is simply to point out that low-intensity, “cardio” exercise is spectacularly ineffective for weight loss. But that doesn’t meal all types of exercise aren’t effective.
High-Intensity Intermittent Training (HIIT)
HIIT is a type of exercise performed in short bursts (intervals) at high-intensity. Several studies have been done comparing HIIT to low-intensity, steady-state (“chronic cardio”, as Mark Sisson calls it) exercise, and HIIT has been shown to be superior in nearly every meaningful marker.
In this study, one group was assigned to “chronic cardio”, while the other was assigned to intervals of 8-second sprints. After 15 weeks, the researchers concluded:
Both exercise groups demonstrated a significant improvement (P less than 0.05) in cardiovascular fitness. However, only the HIIE group had a significant reduction in total body mass (TBM), fat mass (FM), trunk fat and fasting plasma insulin levels.
A pair of studies done at McMaster University found that “6-minutes of pure, hard exercise once a week could be just as effective as an hour of daily moderate activity“, according to the June 6, 2005 CNN article reporting on the study.
The study itself was published in the Journal of Applied Physiology, and it revealed that HIIT resulted in unique changes in skeletal muscle and endurance capacity that were previously believed to require hours of exercise each week.
A follow-up study confirmed the results. Despite the fact that the more conventional endurance exercise group spent 97.5 percent more time engaged in exercise, both groups of subjects improved to the same degree. The group that exercised 97.5 percent more received no additional benefit whatsoever from doing so. Considering the wear-and-tear and increased risk of injury associated with that much more exercise, there’s absolutely no point to doing “chronic cardio” when you can receive the same benefits with a fraction of the time and risk by doing HIIT.
The Cochrane study I linked to earlier in the article also found that high-intensity exercise was superior to “chronic cardio”. In particular, the researchers found that high-intensity exercise led to a greater decrease in fasting blood glucose levels than low-intensity exercise.
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Why High-Intensity Exercise Is Better
In his excellent book on high-intensity strength training, Body By Science, Dr. Doug McGuff explains that high-intensity training is superior to chronic cardio because it produces a greater stimulus and thus more effectively empties the muscles and liver of glucose. This stimulus can last several days with HIIT, as opposed to just a few hours with low-intensity training.
High-Intensity Strength Training: Best of All?
Both high-intensity running or bicycling sprints and high-intensity strength training are effective. But I believe high-intensity strength training is probably a better choice for most, simply because the wear-and-tear and risk of injury is lower – especially if the strength-training is performed using weight machines as described in Body By Science.
This is, in fact, the method of training I’ve been doing since April of this year. I admit I was somewhat skeptical about it all before I read Body By Science. But the research and the physiology was convincing, so I decided to give it a try.
The results have been incredible. My workout varies in length between 5 and 9 minutes a week. That’s right, I said minutes. With only a few exceptions, I’ve increased the amount of weight I can lift, the time I can lift it, or both, with each successive workout. My strength has increased and my physique is, if anything, better than it was when I was lifting 3x/week for much longer periods.
Aside from the Body By Science (BBS) weight workout which I perform once a week, I stay active on a daily basis. I ride my bike or walk to work or to do errands, and rarely drive my car. I go on walks in the woods or on the beach. I surf when time permits. But I don’t do anything else for “exercise”. This routine not only feels great, it fits very well with my lifestyle and it is completely sustainable. It doesn’t feel like an effort at all.
If you’re interested in this kind of training, I’d recommend picking up a copy of Body By Science and checking out their excellent blog. You can post your weekly workout results and get help and suggestions from the very knowledgeable community there – including both authors of the book, Doug McGuff & John Little, and other experienced trainers and enthusiasts.
Another option that may be more accessible for some is Fred Hahn’s The Slow Burn Fitness Revolution. Fred also has a website and blog worth checking out.
Final note to slackers: the popular excuse of “I don’t have time to exercise” is no longer valid. You’ve got 6 minutes a week to do this. I know you do.
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Jessica,
It makes sense to be skeptical of what someone says if it promotes what that person is selling, but saying “you’re lying because you might make money if people believe you” isn’t always valid, and is kind of a lazy argument in general. If you want to show that someone is wrong, use the evidence that is available from science, or at least show that the person’s claims are not based on science.
Hey Chris, great post!
I’ve been incorporating hiit into my regular exercise for a while now but only recently have I made it the primary form of my exercise routine and I have to say I’ve seen some great results. I think one of the hardest parts of hiit is finding a way to do them that doesn’t require special equipment, etc. I’m a grad student, thus poor and can’t afford a gym membership. I also just like working out at home. I’ve been using exercises from Mark Lauren’s book, “You are your own gym” (http://amzn.com/0971407614) and also more recently, I’ve been doing body weight workouts from http://www.bodyrock.tv/, great workouts! Zuzana post new workouts on her blog everyday with modifications for beginners, they are always fun and intense!
Just some ideas, especially for people who are just starting out. I think starting hiit can be a little intimidating.
Thanks again for all your great post!
_Power of 10_ by Adam Zickerman is another great book of this genre: http://www.amazon.com/Power-10-Once-Week-Revolution/dp/B00034P80K/ref=pd_sim_b_1
One thing I really like about this book is that it includes several different routines. Also it includes specific core muscle work, which can be important.
One of my favourite contributions from BBS is the concept of Time Under Load, which I much prefer over just a particular rep rate.
Amber: thanks for the tip on that book. I wasn’t aware of it. Looks like it’s worth checking out, and maybe more user friendly for the general population.
STG-the point is not change what you already do, but to add in a short HIT program to enhance what you already do. If 6-12 minutes a week can do that (and it can), its totally worth it. Skiing and hiking are great activities and I wouldn’t stop or decrease that either.
STG: I didn’t suggest people stop doing activities like that, and never would. At the end of the article I mentioned that I enjoy riding my bike, walking in the woods and on the beach, surfing, and more recently, kiteboarding. Being outdoors and in nature is essential to health and well-being.
Adding a 6-minute strength training routine like this is not intended to take the place of those activities, but to complement them. It will also improve your conditioning and performance of those activities, if that’s something you’re interested in.
I will not be changing my exercise program based on this article. Here is why: the kind of exercise I do, backcountry skiing, hiking and backpacking are more than just physical conditioning acitivities. They connect me with nature allowing me to observe animals (saw a black wolf this fall), see majestic places and experience serenity. Morever, the physical sense of skiing untracted powder snow is amazing! One cannot get these experience in 6 minutes or in a gym.
Stu: I agree and the great thing about body-weight training is that it can be done wherever you are. It’s also possible, of course, to do the push-ups, chin-ups and squats in a HIIT style.
Great article and I’ve read both Dr. McGuff and Fred’s books. I’m firmly convinced that resistance training trumps cardio every time if done with intensity. A 60-90 second set of squats will send anyone’s heartbeat soaring. Official guidelines keep focusing on duration of exercise when the real answer is intensity.
I just want to point out that a simple body weight circuit of push ups, chin ups and squats will improve the health of most people. It’s just such a simple, boring solution that it’s easily ignored but I think it should be every ones start state. I’m interested in your opinions on this.
Stu
Chris highlighted this already, but it’s worth repeating. The absolute best thing about BBS/HIT or HIIT, other than the great results they deliver, is the efficiency. You simply get more bang (gains) for your buck (in this case, time spent exercising) with the least side effects (I know way too many runners who have screwed up hips, knees, ankles and backs-and continue to run for psychological reasons). It’s by far the best way to train for this reason alone. You probably wont get the bodybuilder physique training this way, but most people wont ever achieve that anyway.
One of the reasons I think HIIT may be a better choice than steady-state “cardio” for many is that it probably has a negligible effect on cortisol rhythms over days and weeks. It will certainly affect cortisol on workout days, but throughout the week the effect would be less than if you were working out several times a week. Still, there’s something to be said for taking time off if your adrenal fatigue is severe. It’s difficult for me to know without knowing more about your case.
I am a fan of interval training and have found great success with losing fat using this method. However, I am now suffering from adrenal fatigue and have been told to only do mild walking and yoga. Do you have any thoughts as to how HIIT would affect my cortisol levels?
Your heart and lungs do not know if they are getting cardio from training your muscles with resistance or running long distances. Logically it makes more sense to get your cardio from training that does not stress your tendons, ligaments and joints the way running does.
I have been doing deep tissue sports massage for twenty years and have worked on ALL types of athletes. The runners by far have the most complications including arthritic hips and knees, every over use injury on the planet and most alarming heart irregularities. Trust me, you do not want the body of a 70 year old runner who has been at it since his youth.
In contrast, the “gym rats” are the most well rounded group and spend less time doing it. I’ll take the body of a 70 year old gym rat who lifts twice a week and stays active the rest of the time any day.
If you don’t think you can get cardio benefits that running offers doing resistance training, go outside and do 50 non-stop burpees. How did that feel? Did you finish? Puke? All in about 2 minutes with minimal wear and tear.
Make the switch now, you will be glad you did.
The one lasting effect from my days as a runner are knees that have a nasty habit of complaining when I ask them to work! The more I learn about the nasty effects of running, the ‘happier’ I am that I had to stop a few years ago because of heel spur syndrome.
The most running I do now is some sprinting, and even those I am more inclined to do as swim sprints. You get lots of low level-cardio from walking (I walk a lot) and great high-level cardio from BBS-type weight training, intense yoga practices, and HIIT bodyweight routines. My bodyweight has never been more stable and I have never felt stronger than in the last year or so while adopting and following this type of routine.
For instance:
http://www.bmj.com/content/308/6923/231.full
“Athletes from all types of competitive sports are at slightly increased risk of requiring hospital care because of osteoarthritis of the hip, knee, or ankle. Mixed sports and power sports lead to increased admissions for premature osteoarthritis, but in endurance athletes the admissions are at an older age.”
Fred, I’ve heard good stuff about your work.
I’d be interested in the research that makes you believe that. So far what I’ve read for the case against “chronic cardio” from Mark Sisson and Art De Vany has been very unconvincing.
Running seems to have some unique benefits to health, mentioned in my previous comment, which I’ve not seen replicated by any other form of exercise.
Tuck – Strength training does indeed offer the same benefits of traditional cardio and a lot more.
I just wanted to point out that with your three reasons cardio doesn’t work, the study you cited for point 1 concludes the opposite of what you say for point 3 (which it was designed to study). Interesting contrast.
Lou: Body By Science. The book I mentioned in the article.
Where could I find a good strength workout that would last me 5-9 minutes and hit all of the muscles I need to hit?
I don’t buy the blanket argument against “chronic cardio”.
There are a number of epidemiological links between running and lower instances of disease: you’re at a lower risk of arthritis, lower risk of diverticulitis, and, according to the Stanford study, at a lower risk of all-cause death and disability if you’re a runner. HIIT or weight-lifting does not offer any of these benefits, although it may offer benefits to those solely interested in losing weight.
I do agree that running won’t do a darn thing to help in losing weight. I tried that avenue for years, with no luck. Switching my diet to the sort you recommend did the trick in a couple of months.