"Virtually all the body’s adaptive mechanisms are designed to deal with acute, not chronic, stresses. Exercise should mimic the activities of our ancestral existence; we are adaptive organisms that thrive on variety, not machines designed for high volume routine." Arthur De Vany
Probably the funniest explanation of why long duration cardio is not necessarily the optimum training approach came from 'Lights Out: Sleep, Sugar, and Survival' by T. S. Wiley and Bent Formby who concluded that because our ancient ancestors could not outrun a single predator, endorphins, our natural anesthesia, were meant to make our likely mauling a little less horrific. If the one good sprint we had in us didn't outmaneuver the saber tooth, we'd be lunch - commence with the pain killers!
In fact, Wiley and Formby are not the only writers to examine exercise in the framework of evolution, in Paul Chek's 'Cardio Perspective' he writes, "Our next logical question should be, did our ancestors regularly participate in cardiovascular exercise? Not likely. First of all, it would not be energy efficient to run around gathering berries, firewood and nuts in your target zone. Nor would it have been wise to run through the bush trying to get a workout while hunting, since any animal would hear you coming from hundreds of yards away and be long gone by the time you got there."
The entire essay by Art De Vany, Evolutionary Fitness, was built around the very premise that our exercise was and should remain chaotic. In De Vany's words, "Our upright, bipedal posture gives us the mobility to cover the range required of an omnivorous generalist. A large brain is required for hominids to cover the widest range known to any animal species. High value nutrients are essential to the energy-demanding brain and small stomach required for high mobility in a patchy savanna where high value nutrients are variable and fugitive. Our muscle fiber composition reveals that we are adapted to extreme intensity of effort. And the energy sources of these fibers shows that the highly intense activities through which our ancestors ”earned a living” were of short duration (anaerobic metabolism came before aerobic metabolism, which was grafted on later and the quickly exhausted fast twitch fibers are likely to be the most primitive of our sources of movement)." De Vany continues, "Our ability to sweat, our relative hairlessness, our upright and, hence, cool posture, our mobility, as well as our temperature regulation and appetite mechanisms are designed to solve the problem of keeping an energy-hungry, but delicate, brain alive in an energetic body capable of high mobility and peak energy bursts."
"Cardio" for Fat Burning
If, all of this is true, why are so many of us drawn to the low-intensity long-duration training we often refer to as 'Cardio'? The first answer and the one I hear most often, at this time of year especially, is weight-loss or maintenance. With eight years of transient New Year's Resolutioners to study I can tell you that the training approach is often ineffective and, for many, unsustainable. It's why I was delighted to see Alwyn Cosgrove's answer in T-Nation's article which asked prominent coaches and trainers what they believe even if it's unproven. Here's his answer:
"Lower intensity aerobic training is relatively useless for optimal fat loss purposes. Furthermore, for some populations, it's likely to be detrimental."
[Alwyn Cosgrove's] theory (based purely on the observations of my clients' progress) is as follows:
Aerobic training encourages the body to adapt by becoming "energy efficient". This means it will take less fuel to perform the same amount of work. Although an energy efficient body sounds great, it isn't — not if you're trying to lose fat. Energy efficiency just makes the job of losing fat more difficult.
To simplify it as much as possible, fat loss comes down to creating a caloric deficit. The body burns calories primarily by muscular work. Steady state low intensity aerobic training does not require much work from the muscular system and does little or nothing to even maintain muscle tissue.
So, if muscle is "fat burning machinery," then aerobic training makes that machinery smaller and more fuel efficient, which is not what I'm looking for.
So we have an activity that burns calories, but the more you do it, the fewer calories it burns with each subsequent exposure (so to burn the same amount of calories you have to go harder or longer), and in all reality it just doesn't burn that many calories anyway.
Aerobics never helped this fat bastard.
A decent pace for a 180-200lb individual would burn about 10 calories per minute. Thirty minute aerobic sessions will burn around 300 calories. Performed three times per week, with no reduction in work performed (i.e. you keep increasing intensity or time as you adapt), you're still looking at about a pound per month.
If you woke up an hour earlier each day and just sat and watched TV, you'd burn about the same (7 days x 60 mins x 2 cals per minute).
Now granted, there are exceptions. Complete beginners, obviously, and precontest bodybuilders (or those wanting to go "beyond lean"), but for most people it's an extremely inefficient fat loss modality.
Anecdotally, you only need to stand at the finish line of a marathon and look at the physiques of the masses. These people developed the joint integrity and muscular and cardiovascular endurance to run 26.2 miles — some of them running in the 3-4 hour range — yet they haven't created enough of a metabolic demand to create significant fat loss.
Effective fat loss hinges on burning as many calories as possible during the workout, and elevating metabolism so that we burn more calories per minute, all day long. Aerobic training fails on both counts
So why has aerobic training become so popular?
In the past, fitness professionals and researchers have looked at how much fat is burned during the exercise session itself. This is extremely short-sighted.
As my colleague Alan Aragon said: "Caring how much fat is burned during training makes as much sense as caring how much muscle is built during training." Think about that. If we looked at a weight training session that started at 9AM and finished at 10AM, how much muscle would we see built if we stopped looking at 10AM? None.
In fact, we'd see muscle damage. We could make the conclusion that weight training does not increase muscle; in fact it decreases muscle, right? It's only when we look at the big picture — and look at the recovery from the session — that we find the reverse is true: weight training builds muscle.
Fat loss training is the same way. Someone talking about the benefits of the "fat burning zones" or "fasted cardio" is a sure sign that the individual has stopped looking at the end of the exercise session. They have come to the conclusion that fasted, lower intensity steady state exercise burns the most fat and made a massive leap of faith to suggest it is best for real world fat loss.
Using that same logic these same people would suggest you avoid weight training if you want to grow muscle.
This is where I'd leap out of my theater seat, clap wildly, wipe a tear and look with adoration at the speaker who had the eloquence to speak these words. It's what I've yearned to say every time someone asks me about the 'fat burning zone' on the elliptical - a machine that's useful in developing human athleticism only when dragged or pushed across the floor manually. It has little application otherwise.
De Vany explains Cosgrove's theories in the following way, "The body uses fat in the aerobic (Slow Twitch and lower Intermediate Twitch) zone. So, linear thinking suggests that to burn fat you should operate in that zone," thus the snazzy little diagrams on the cardio equipment illustrating 'fat burning' zones. "It would not surprise someone trained to understand the adaptive capabilities of the human body that if you burn more fat the body will find a way to produce more. And this is just what happens when you energy flows over the aerobic pathway—your body releases hormone messengers that signal higher fat production." The hormone De Vany is talking about here is cortisol which is the 'fight or flight' hormone we hear so much about in late-night weight loss miracle pharmaceuticals. As your exercise increases in duration your production of anabolic (muscle building) hormones drops off and your production of catabolic (muscle burning) hormones increases.
In De Vany's words, "You burn more calories and more fat in total when you train at high intensity. And you do not open the metabolic pathways that cause your body to make more fat. Energy that flows over the anaerobic pathway signals your body to make more muscle and to burn fat. You incur an oxygen depth that raises metabolism for days after a high intensity session. Above all, you bring adaptations that burn fat. As the body remodels in response to the adaptive challenge presented by a brief, high-intensity session, it preferentially burns fat. In addition, you put on lean muscle mass that burns energy continuously. From 60 to 70 per cent of the energy you burn is at your basal metabolic rate. If you gain lean muscle mass you raise your basal metabolic rate and, thus, burn more energy 24 hours a day."
Clarence Bass reported the following study by Angelo Tremblay, Ph.D., and his colleagues at the Physical Activities Sciences Laboratory, Laval University, Quebec, Canada in his article on interval training, "The Canadian scientists divided 27 inactive, healthy, non-obese adults (13 men, 14 women, 18 to 32 years old) into two groups. They subjected one group to a 20-week endurance training (ET) program of uninterrupted cycling 4 or 5 times a week for 30 to 45 minutes; the intensity level began at 60% of heart rate reserve and progressed to 85%. (For a 30-year-old, this would mean starting at a heart rate of about 136 and progressing to roughly 170 bpm, which is more intense than usually prescribed for weight or fat loss.) The other group did a 15-week program including mainly high-intensity-interval training (HIIT). "
"Much like the ET group, they began with 30-minute sessions of continuous exercise at 70% of maximum heart rate reserve (remember, they were not accustomed to exercise), but soon progressed to 10 to 15 bouts of short (15 seconds progressing to 30 seconds) or 4 to 5 long (60 seconds progressing to 90 seconds) intervals separated by recovery periods allowing heart rate to return to 120-130 beats per minute. The intensity of the short intervals was initially fixed at 60% of the maximal work output in 10 seconds, and that of the long bouts corresponded to 70% of the individual maximum work output in 90 seconds."
"Intensity on both was increased 5% every three weeks. As you might expect, the total energy cost of the ET program was substantially greater than the HIIT program. The researchers calculated that the ET group burned more than twice as many calories while exercising than the HIIT program. But (surprise, surprise) skinfold measurements showed that the HIIT group lost more subcutaneous fat. "Moreover," reported the researchers, "when the difference in the total energy cost of the program was taken into account..., the subcutaneous fat loss was ninefold greater in the HIIT program than in the ET program.""
"In short, the HIIT group got 9 times more fat-loss benefit for every calorie burned exercising. Dr. Tremblay's group took muscle biopsies and measured muscle enzyme activity to determine why high-intensity exercise produced so much more fat loss. I'll spare you the details (they are technical and hard to decipher), but this is their bottom line: "[Metabolic adaptations resulting from HIIT] may lead to a better lipid utilization in the postexercise state and thus contribute to a greater energy and lipid deficit." In other words, compared to moderate-intensity endurance exercise, high- intensity intermittent exercise causes more calories and fat to be burned following the workout. Citing animal studies, they also said it may be that appetite is suppressed more following intense intervals. (Neither group was placed on a diet.) "
"Cardio" for Aerobic Conditioning
The idea of aerobic training as the only pathway to cardiovascular health is yet another oversimplified concept. Paul Chek goes back again to our evolution, "First, let’s look at the issue from a perspective of natural history. Our evolution into the human species from our ape ancestors is thought to have occurred some 2.8 million years ago." Chek continues, "Spanning the duration of this vast period, it should strike you as interesting that the first reported heart attack in the U.S. occurred in 1920, only 12 years after the grain industry began hydrogenating plant and grain oils. Now, I personally find it interesting that there is such hype over cardiovascular exercise as necessary prevention for heart attack or even heart disease, when such diseases were relatively nonexistent less than 100 years ago. That’s but a flash in the pan of human evolution." At very least, you should consider the possibility that many miles on a treadmill is not actually getting you anywhere.
Clarence Bass compares aerobic with anaerobic conditioning and their impact on cardiovascular health using the research of Dr. Izumi Tabata and his colleagues at the National Institute of Fitness and Sports in Tokyo, Japan. "This study used accumulated oxygen deficit to measure anaerobic energy release, and is one of the first to measure the effect of training on both aerobic and anaerobic capacity. Notice that the duration of the moderate-intensity and the high-intensity protocols are drastically different: (excluding warm-ups) one hour compared to only about 4 minutes per training schedule Tabata's moderate-intensity protocol will sound familiar; it's the same steady-state aerobic training done by many (perhaps most) fitness enthusiasts."
"Here are the details (stay with me on this): In the moderate-intensity group, seven active young male physical education majors exercised on stationary bicycles 5 days per week for 6 weeks at 70% of V02max, 60 minutes each session. V02max was measured before and after the training and every week during the 6 week period. As each subject's V02max improved, exercise intensity was increased to keep them pedaling at 70% of their actual V02max. Maximal accumulated oxygen deficit was also measured, before, at 4 weeks and after the training. A second group followed a high-intensity interval program. Seven students, also young and physically active, exercised five days per week using a training program similar to the Japanese speed skaters. "
"After a 10-minute warm-up, the subjects did seven to eight sets of 20 seconds at 170% of V02max, with a 10 second rest between each bout. Pedaling speed was 90-rpm and sets were terminated when rpms dropped below 85. When subjects could complete more than 9 sets, exercise intensity was increased by 11 watts. The training protocol was altered one day per week. On that day, the students exercised for 30 minutes at 70% of V02max before doing 4 sets of 20 second intervals at 170% of V02max. This latter session was not continued to exhaustion. Again, V02max and anaerobic capacity was determined before, during and after the training. "
"In some respects the results were no surprise, but in others they may be ground breaking. The moderate-intensity endurance training program produced a significant increase in V02max (about 10%), but had no effect on anaerobic capacity. The high-intensity intermittent protocol improved V02max by about 14%; anaerobic capacity increased by a whopping 28%. Dr. Tabata and his colleagues believe this is the first study to demonstrate an increase in both aerobic and anaerobic power."
"What's more, in an e-mail response to Dick Winett, Dr. Tabata said, "The fact is that the rate of increase in V02max [14% for the high-intensity protocol - in only 6 weeks] is one of the highest ever reported in exercise science." (Note, the students participating in this study were members of varsity table tennis, baseball, basketball, soccer and swimming teams and already had relatively high aerobic capacities.)"
"The results, of course, confirm the well-known fact that the results of training are specific. The intensity in the first protocol (70% of V02max) did not stress anaerobic components (lactate production and oxygen debt) and, therefore, it was predictable that anaerobic capacity would be unchanged. On the other hand, the subjects in the high-intensity group exercised to exhaustion, and peak blood lactate levels indicated that anaerobic metabolism was being taxed to the max. So, it was probably also no big surprise that anaerobic capacity increased quite significantly."
"What probably was a surprise, however, is that a 4 minute training program of very-hard 20 second repeats, in the words of the researchers, "may be optimal with respect to improving both the aerobic and the anaerobic energy release systems." That's something to write home about!"
In support of interval training, Dr. Stephen Seiler was busy doing research of his own. In his research Seiler used three groups of rats from the same litter and, as he explains, "One group sat around in cages, ate rat chow and got weighed periodically. A second group was gradually adapted over 4 weeks (several months in rat years) to running on a treadmill until they were running for 60 minutes, 5 days a week at an intensity that was equal to about 75% of VO2 max. The third group was adapted to an interval running program. These guys would run two minute bouts at a speed that required just over 100% of VO2 max, then slow down for two minutes, and so on for 10 bouts (after four weeks of buildup). The total running distance was the same for the two groups, only the intensity differed. To evaluate cardiac performance, I develped a surgical procedure under anesthesia (the rats, not me) that allowed me to directly and constantly measure cardiac output, intraventricular pressure development, heart rate etc., while subjecting the heart to a volume overload with saline infusion. What I found and reported at a meeting of the American College of Sports Medicine was this. In these previously untrained rats, 8 weeks of interval training was superior to 8 weeks of steady state training as an inducer of enhanced maximal cardiac performance. Interval trained hearts achieved higher peak stroke volumes during overload."
Art Devany has also come to the same conclusion regarding interval training, but approaches the question from the perspective of human design. He challenges modern training idealogy and the resultant steady-state exercise prescription with the explanation that, "These programs model the body as a machine, not as an adaptive organism. Consequently, they prescribe a regime in which the body is under-fed and over-trained. They are not based on adaptation, but on steady state analysis. These models assume the body is a linear process that maintains a steady state. In fact, all bodily processes are highly non-linear and these non-linearities must be exploited in any effective fitness program. The key to exploiting the highly non-linear and dynamic adaptive metabolic processes of the human body is to achieve the right mixture of intensity and variety of activities. "
The mastermind behind CrossFit, Coach Greg Glassman, explains how randomized training methodologies utilize two of the three waves of adaptation to endurance training in the CrossFit Journal article entitled 'What is Fitness', "The first wave is increased maximal oxygen consumption. The second is increased lactate threshold. The third is increased efficiency. In the CrossFit concept we are interested in maximizing first wave adaptations and procuring the second systemically through multiple modalities, including weight training, and avoiding completely third wave adaptations. Second and third wave adaptations are highly specific to the activity in which they are developed and are detrimental to the broad fitness that we advocate and develop. A clear understanding of this material has prompted us to advocate regular high intensity training in as many training modalities as possible through largely anaerobic efforts and intervals while deliberately and specifically avoiding the efficiency that accompanies mastery of a single modality."