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“Your heart and lungs cannot tell whether you’re working your muscles intensely for thirty seconds on a stationary bike or working them intensely on a leg press.” Doug McGuff, MD, and John Little, Body by Science (McGraw-Hill, 2009)
Aerobics, Do You Need It?
Complete Fitness in 12 Minutes a Week
Arthur Jones asserted decades ago that proper strength training makes aerobic exercise unnecessary. “Six weeks of proper strength training can improve one’s cardiovascular fitness to a degree that is impossible with any number of years of aerobics,” he told HIT proponent Drew Baye in 1998 (www.baye.com). Mike Mentzer, Ellington Darden, PhD, and others agreed. No one, however, has argued the point more effectively than Doug McGuff, MD, and John Little in their book, Body by Science (McGraw-Hill, 2009). (Dr. McGuff, an emergency medicine specialist, owns a personal training facility and lectures on exercise science all over the world. Little is a columnist for fitness magazines, operates his own fitness center, and has written 12 books on exercise.)
I would like to summarize their impressive case—I agree with most of it—along with a new study which found aerobic exercise and strength training equally effective in a key area. Finally, I will tell you where and why I part company with McGuff and Little. I hope you’ll stay tuned, because we now know more about this important topic than ever before.
Let’s start with companion studies from McMaster University (Canada) showing the effectiveness of high intensity intervals. This research, in large part, provides the cornerstone of the McGuff-Little case. (For convenience, I’ll refer only to McGuff.)
Sprint Results Set the Stage
The 2005 studies, published in the Journal of Applied Physiology, showed that three to seven all-out sprints on a stationary bicycle (250% of VO2 max), 30-seconds each, with four-minute rest periods, six times over two weeks, are as effective as 90 to 120 minutes of cycling at moderate intensity (65% of VO2 max) six times over two weeks. Both workouts improved endurance capacity by almost 100%, increasing time to fatigue at 80% effort from 26 minutes to 51 minutes. In short, about 15 minutes of hard sprints spread over two weeks produced the same results as nine to 12 hours of moderate intensity effort.
Both the sprinters and the traditional riders showed a substantial increase in citrate synthase, a mitochondrial enzyme that indicates the power to use oxygen, along with increased glycogen (muscle sugar) content. Neither group, however, showed a change in maximum oxygen uptake or anaerobic work capacity.
Talk about bang for the buck or results for effort. WOW!
I wrote about the first study (there were two); you can read the details http://www.cbass.com/Sprintendurance.htm . (The sprints per workout changed from 4 to 7 in the first study to 3-5 in the second study—with essentially the same results.)
Dr. McGuff says this is a big deal—and it is. It suggests that short, hard workouts produce the same endurance changes—and perhaps health and longevity benefits—as long, moderate effort workouts, the type done by most fitness enthusiasts.
Setting the stage for what’s to come, McGuff tells us the “heart and lungs cannot tell whether you’re working your muscles intensely for thirty seconds on a stationary bike or working them intensely on a leg press”—or apparently the seated row, chest press, pulldown, and overhead press, which comprise the recommended “Big-Five Workout.”
McGuff asked the Canadian researchers whether the same results could have been achieved with fewer sprint-intervals, and with even less frequency. (As we’ll see, McGuff suggests far less volume.) The researchers agreed that the required stimulus “might well have been less than what was performed in the study.”
McGuff was happy with that response. He couldn’t expect the Canadians to say more—but he does. McGuff says the required stimulus is simple: “high-intensity muscular effort.”
Continuing to build the case, McGuff goes on to explain “How ‘Cardio’ Really Works.”
Lactic acid, the stuff that makes your muscles burn, is a key part of the explanation. Both interval training and strength training, of course, generate huge amounts of lactic acid.
The Lactic Acid Connection
Dr. McGuff argues that lactic acid unites strength training and cardio—to the extent that cardio actually exists.
Lactic acid build-up—from intervals and strength training—forces the mitochondria to process oxygen (and lactic acid) more efficiently. Let’s see how that works.
There are two primary energy systems: aerobic and anaerobic. Both systems burn carbohydrate in the form of glucose (blood sugar) and glycogen (muscle sugar). The main difference between the two systems is the presence of oxygen—and the end product. Moderate exercise is mostly aerobic, with oxygen; it’s clean burning, so there is no end product. When exercise becomes more intense and the aerobic system can’t provide enough oxygen, the anaerobic system kicks in to provide energy, without oxygen. The end product of anaerobic exercise is lactic acid. (Intervals and strength training are both anaerobic.)
The two energy systems have been thought to operate as separate and distinct systems. Lactic acid was considered the enemy of aerobic metabolism, with the power in sufficient accumulations to bring it to a halt. As we learned on this website a while back, that’s old thinking. It is not true.
“It was one of the classic mistakes in the history of science,” says UC Berkley integrative biology professor George A. Brooks.
Here’s the bottom line from Professor Brooks: “The world’s best athletes stay competitive by interval training. The intense exercise generates big lactate loads, and the body adapts by building up mitochondria to clear lactic acid quickly. If you use it up (as an energy source), it doesn’t accumulate.”
The job of the athlete is to train in a way that causes the mitochondria to process lactic acid faster and more efficiently.
Lactic acid is a fuel. To improve your capacity to use it as a fuel, you must increase the lactic acid load very high during training. (For more details, see my earlier article: http://www.cbass.com/Lacticacid.htm )
Dr. McGuff is on top of this new thinking. He says that high-intensity intervals and high-intensity strength training both perform the same function: they improve aerobic function by forcing the mitochondria to burn lactic acid more efficiently.
“It is during ‘recovery’ from high intensity exercise that you’re actually getting an increased stimulation of the aerobic system equal to or greater than what you would get from conventional steady-state ‘aerobic’ exercise,” McGuff writes.
“If you have been subjected to proper physical training, you can actually make good use of the lactic acid that is produced. If you are intent on improving your aerobic capacity, it’s important to understand that your aerobic system performs at its highest level when recovering from lactic acidosis,” McGuff adds. “It is also important to understand that since muscle is the basic mechanical system being served by the aerobic system, as muscle strength improves, the necessary support systems (which include the aerobic system) must follow suit.”
To improve the ability of your aerobic system to use lactic acid as a fuel, McGuff says: Lift weights. And then, let your mitochondria take over from there. Get your aerobic benefit on the “drive home from the gym or off to lunch or back to work.”
For McGuff, productive exercise begins and ends with strength training. THE key stimulus for strength—and aerobic fitness—is high-intensity muscular effort.
To see and hear Dr. McGuff explain, in 5:50 minutes, just about everything we’ve talked about so far—and why he believes ‘cardio’ really doesn’t exist—visit You Tube: http://www.youtube.com/watch?v=RiHhc7eLpQY
I promised to tell you about a new study comparing aerobic exercise and strength training. Let’s do that now. Then I’ll be ready to tell you my view on the need for aerobic exercise. Is McGuff-type strength training enough?
Resistance Exercise Versus Aerobic
Many studies have shown that exercise significantly improves blood flow (endothelial function). For example, see http://www.cbass.com/Everymealcounts.htm Little is known about the effectiveness of different forms of exercise, however. M. Vona, MD, a researcher from Switzerland, and colleagues compared three different forms of exercise: aerobic training, resistance training, and a combination of the two. (There was also a control group that did no training.) The results are reported in the journal Circulation (online March 16, 2009).
All three exercise groups trained 4 times a week for 4 weeks, and then stopped training for an additional month. The aerobic training group (52) did 40 minutes of cycling at 75% of heart rate maximum (with 10 minute warm-up and cool-down); the resistance training group (54) did 4 sets of 10 exercises with 60% of maximum contraction; and the combination group (53) did two days of aerobic training and two days of resistance training each week. All subjects were tested for flow-mediated dilation (FMD) before the exercise sessions began, when the sessions ended, and again after a month without training.
FMD improved about the same for all three exercise groups, and returned to baseline after detraining. The control group showed no change. “Exercise training was associated with improved endothelial function independently of the type of training, but the effect disappeared after 1 month of detraining,” the study authors wrote.
The obvious take home message: Exercise and don’t stop. The surprise is that the resistance trained groups did just as well as the aerobic exercise group. “The present study demonstrates that all types of exercise (aerobic, resistance, and their combination) are safe and effective,” the researchers concluded.
Well, how about that?
“The all important question is why…the effect of resistance training on FMD was similar to that of aerobic training and combined training,” the researchers wrote in the “Discussion” portion of the report. After considering several possibilities, they decided that similarity in training volume was the likely explanation. Here’s what they wrote: “It has been speculated that the volume of exercise could influence vascular reactivity. In our study, the total number of sessions was identical in all trained groups; this identical volume of exercise could explain the identical results on endothelial function.”
Interestingly, the average heart rate during training sessions for all three exercise groups was essentially the same: 100, 99, and 101, respectively. Intensity was monitored and increased as fitness improved in all three exercise groups. The resistance trainers did 10 to 12 reps per exercise, for a total 40 sets and about 440 reps per workout, or 160 sets and 1760 reps per week.
What stands out is that the training volume in the study and the volume recommended by McGuff and Little are miles apart. Their routine calls for one set of 5 exercises every 7 days. McGuff would probably argue that the McMaster studies show that you don't need as much volume if the muscular effort is high enough. Yes, but is 5 sets spread over 5 different body parts each week sufficient?
That brings us to the question at hand. Is the Body by Science training routine adequate for complete fitness?
Let’s be clear. Moderate aerobic exercise has proven value; see Miracle of Movement: http://www.cbass.com/MiracleMovement.htm
That’s not the issue. If moderate aerobic exercise is all you’re willing or able to do, keep doing it.
The query is whether the McGuff-Little routine is better or more efficient. Is it a stand-alone regimen, as they claim?
McGuff and Little recommend the “Big-Five Workout” once every seven days—12 minutes a week. To fully understand what they suggest (and why) you’ll need to read Body by Science. You can get a pretty good idea what’s involved, however, by watching (online) a 5-min session overseen by Dr. Ellington Darden: http://www.drdarden.com/readTopic.do?id=459177 As you can see, this kind of training requires effort. The only thing moderate about it is the time it takes.
Dr. McGuff demonstrates the “Body by Science Big 5 Workout” in a 4-part video on You Tube. He acknowledges that the only fun is when your done. The results are well worth the unpleasantness, he says. It’s hard. You have to be plenty motivated to do it on a regular basis. Some people, perhaps most, won’t want to do it—at least not as recommended.
Others, however, may be willing to exercise—hard—12 minutes a week, and no more. More power to them.
For those still in doubt, here’s my opinion.
First, I believe you can skip traditional aerobic workouts—if you are willing and able to do high-intensity intervals once or, at most, twice a week. (Walking or at least staying active on off days is also advisable.) We’ve already seen from the McMaster studies that sprint intervals dramatically increase endurance capacity in a fraction of the time required for conventional steady-state aerobic training. Intervals are also more effective/efficient for burning fat and probably for overall health. For studies in point, see Intervals for (Almost) Everyone: http://www.cbass.com/IntervalsEveryone.htm
Hard intervals have proven value that has not been shown for resistance training, especially very short, hard routines. Until we have evidence that strength training—any kind—will do as well, I’m going to keep doing intervals.
Dr. McGuff’s concept of total body conditioning may be correct. His demonstration on You Tube suggests that the 12-minute routine does indeed have a “global metabolic effect.” If you try it, I believe you’ll agree. For people who are busy and motivated, it may work very well when combined with walking (or some other form of physical activity) on most non-workout days. (We will have an article next month on the importance of staying active between workouts.)
I do believe that one hard set (after warm-up) is the best—certainly the most efficient—way to build strength and muscle. I don’t favor rushing from one exercise to the next, however; it dampens effort and creates an aversion to training. And I’m not convinced that one set is enough for complete fitness. Until we have convincing evidence to the contrary, I believe you need resistance training and some form of endurance training.
I’m sorry I can’t provide a more definitive answer. I don’t believe anyone can at this point. The best approach may simply be to do what you find most appealing.
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