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Originally Posted by Marie2006
Rivcook, I still have to set everything up regarding my weight lifting workout, I'll do it tonight, but regarding the cardio, it'll be 20' HIIT 3 times a week AM on empty stomach + 30' brisk walk at night. And I'll add swimming sessions on other days too. |
Well, you can
try to do HIIT 3 times a week on an empty stomach, but you might want to re-think that plan after reading some interesting facts. Based on my own research, I have come to the conclusion that ANY intense form of exercise in a fasted state only encourages a catabolic response. New studies are indicating that individuals that are fed prior to training, make significantly greater improvements over the same amount of time as fasting individuals. The following article, written by Alan Aragon (google for his bio) was originally posted on a bodybuilding website. I am posting it here for your reference.
Alan Aragon credentials:
Bachelor's and Master's degrees in nutrition.
Standard & Advanced Personal Training Certifications of the National Academy of Sports Medicine.
Accredited continuing education provider:
- Commission on Dietetic Registration / American Dietetic Association
- American Council on Exercise
- National Strength & Conditioning Association
- National Academy of Sports Medicine
Myths Under The Microscope: The Low Intensity Fat Burning Zone & Fasted Cardio By Alan Aragon, © 2006
Part 1
STEADY STATE AEROBICS –VS- INTERVAL TRAINING
"In recent years, there has been quite the overpopularization of the concept of interval training, along with a rather major backlash against traditional forms of aerobic training, for fat loss. It's not uncommon to read how low intensity aerobics is useless for fat loss, everybody should just do intervals, regular aerobics makes you lose muscle, etc. I have seen it claimed that aerobics will make you fatter, stress the adrenals, and all manners of fascinating claims. Nevermind that, over the decades, bodybuilders have gotten into contest shape with (often endless amounts of) cardio, runners, cyclists and swimmers are extremely lean, etc. Somehow, aerobic training has gotten a bad rap.
I think what happened is that for about 2 decades, aerobic training has been (over) emphasized over all other kinds of activity. As well, people got the absolutely wrong idea about how to use it for fat loss so you have people trotting along on the treadmill at an intensity that is just slightly higher than sitting on the couch, burning a couple of hundred calories in an hour and wondering whey they aren't losing fat.
So folks, usually with a heavy resistance training bias or background, overreacted. And the backlash began. Basically, people get a little over-enthusiastic about a certain type of training (or eating), take it to some absurd extreme, get into problems, find an alternative and decide that the first type of training is useless, overrated, etc, etc, blah, blah, blah and they jump to the opposite extreme. They jump from one extreme to the other until, hopefully, they come back to some happy medium.
Well, I'm a happy medium kind of guy and I try to avoid that kind of binary either/or thinking; I find it more useful to examine training tools in terms of their pros and cons, benefits and disadvantages. So let's examine both steady state aerobics and interval training for fat loss (endurance performance is a separate topic) in that fashion. In part 1, I'm going to define some terms and examine both types of activity; in part 2, I'll talk about how to decide which is best depending on the specifics of the situation.
Some definitions
Steady state training: Any form of aerobic/cardiovascular training where some reasonably steady intensity is maintained for an extended period. So this might be something akin to 20-60 minutes at a steady heart rate of 140-150 (could be higher, could be lower). I'm just going to call this cardio or aerobics, even though I know some people get into longwinded semantic arguments about it. I'm sure everybody knows what I'm talking about.
Interval training: Essentially any form of activity that alternates higher intensity activity (such as 30-60 seconds almost all out) with periods of lower intensity activity. The rest interval can be passive (sit on your butt) or active (keep moving at a low intensity). While weight training can technically be considered interval training, I'm going to restrict this article to interval training done with standard cardio modes (i.e. running, cycling, stairmaster, etc). A typical interval workout for fat loss might be a short warmup followed by 5 repeats of 60 seconds near maximum intensity alternated with 60-90 seconds of very low intensity activity, followed by a 5' cool down. This is often referred to as high intensity interval training (HIIT) which differentiates it from aerobic interval training discussed immediately below.
Aerobic interval training: For completeness, I want to mention a third, sort of hybrid, form of training that is usually referred to as aerobic interval training. This is a type of training often used by very untrained beginners who are simply unable to perform 20 minutes or more of continuous aerobic activity. So they might perform 5 minutes of low intensity aerobic activity prior to taking a short break, followed by another 5 minutes of low intensity aerobic training, until they accumulated 20-30 minutes of activity. Over their first several weeks of training, they would try to increase the duration of each aerobic interval session while decreasing the rest interval. Additionally, many strength and power athletes do a type of aerobic interval training usually referred to as extensive tempo running: this is a low intensity type of aerobic interval training done in short bouts. So a sprinter might run 10 repeats of 200 meters but at a very low intensity (aerobic intensity) with 100 meters of walking in-between. In this article, I'm not talking about aerobic interval training when I compare and contrast traditional aerobic training and interval training; aerobic interval training is sort of a third category that doesn't apply to this discussion.
Moving on
Ok, so now that we're on the same page definition wise, I want to compare and contrast aerobic and interval training in terms of potential pros and cons. This will allow us, in part 2 to look at how to integrate the different types of training into real world workout schemes.
Steady state aerobics
Pros:
1. Depending on the intensity, steady state aerobics tends to burn more calories during the exercise bout than interval training.
2. More appropriate for beginners.
3. Can be done more frequently, daily or more often (if desired) although this depends on the duration, intensity and frequency as well as the setup of the rest of the training program.
4. Some research finds suggests that regular exercise helps people stick to their diet better. In that interval training can't (well, shouldn't) be performed daily, low intensity activity may help people stay on their diets.
Cons:
1. Most indoor aerobics modes tend to be boring, especially for long durations. Exercise can, of course, be done outdoors but this raises a whole separate set of issues (bicycle safety, running outdoors, traffic, etc) that are beyond the scope of this article. This is a big part of why gyms have music and televisions; I have seen one with a cardio movie theater.
2. An excess of endurance training, especially at higher intensities (too close to lactate threshold, a topic for another newsletter) seems to cause muscle loss, decrease strength and power, and cause overtraining. This is major issue for bodybuilders and strength/power athletes but can be avoided by keeping the intensity under control.
3. Too much repetition of the same mode of aerobics can generate overuse injuries, both runners and cyclists are prone to knee problems, swimming causes rotator cuff issues (and the cold water tends to increase hunger), etc. This can be avoided by non-endurance athletes by rotating the type of activity being done.
4. Unless people are tremendously aerobically fit, it can be difficult to burn a huge number of calories unless the duration of each workout is just ridiculous. So, at moderate intensities, the average person might burn 5-10 calories/minute; a 145 lb person burns about 100 calories per mile walking or running. So over an hour aerobic session, you might achieve 300-600 calories burn. While this can certainly add up if done daily, it's still a fairly small expenditure. The people trotting along on the treadmill or spinning on the bike at low intensities, often for only 30 minutes, are burning jack all calories. Which are usually more than compensated when that person figures that they must be burning at least 1000 calories and rationalizes that cheeseburger and milkshake because of it. This is one of those weird ironies: very high caloric expenditures through aerobics are reserved for trained endurance athletes, and they typically don't need it. The people who need to be burning a lot of calories through aerobic activity usually aren't able to, at least not initially.
Before continuing, I should probably bring up one of the more idiotic arguments against steady state aerobics here. The argument goes something along the lines of "Aerobic training is useless because, as you adapt and become more efficient, the same workout that burned a significant amount of calories over 40 minutes takes 60 minutes because you're getting more efficient." This is about as logical as saying that weight training is ineffective because the same weight that was difficult for 12 repetitions is now too light, and you have to do more repetitions with it. Except that, in the case of weight training, the suggestion would be to add weight to the bar. And the same exact thing can be done with aerobic training: as the body adapts (and you become fitter), you can increase your caloric expenditure by increasing the intesity of your workout. So say that you were doing the stairmaster at level 8 and a heart rate of 140 beats per minute for 40 minutes. Now you've adapted and level 8 is only a heart rate of 130. Well, you could go to an hour, or you could increase the intensity to level 9 and burn more calories during those same 40 minutes. In addition, exercise efficiency doesn't vary that much; in cycling for example, it varies between about 20-25%. So even if you increase your efficiency by 5%, this would only change the caloric expenditure for a given exercise bout by that same 5%. A 400 calorie workout becomes a 380 calorie workout. This is hardly a change worth decrying steady state aerobics before.
Interval training
Pros:
1. For a given time investment, interval training leads to a greater fat loss and this occurs despite a smaller calorie burn during activity. This is because interval training generates a much larger EPOC (excess post-exercise oxygen consumption) which are the calories burned post exercise.
2. Interval training may improve the muscle's ability to use fat for fuel more effectively than aerobic training (note: recent studies have also suggested that interval training can generate very rapid improvements in endurance performance in a very short period but this is beyond the scope of this article).
3. Time efficient: Not everybody has the time to devote to an hour (or more) of aerobic training per day. A properly set up interval workout may only take 15-20 minutes.
4. Time seems to pass faster: Compared to regular aerobics, which can be mind numbingly dull (especially if done indoors), the change in intensity with intervals seems to make the workout pass faster.
Cons:
1. The intensity of intervals makes them inappropriate for beginners. One exception is a style of training called aerobic intervals which I mentioned above. But high intensity interval training is simply inappropriate for beginning exercisers, for the same reason that high intensity weight training is inappropriate.
2. Intervals are high intensity training, this has implications for the overall training setup (discussed in more detail in part 2) and integration with the rest of your program (i.e. weight training). Simply put: if you think you can train legs in the weight room 2-3X/week and do intervals an additional 2-3X/week on alternate days, you are incorrect unless you are deliberately trying to overtrain or get injured.
3. Higher risk of injuries: this depends somewhat on the type of activity with high impact activities such as sprinting carrying a higher injury risk (especially for heavier individuals) than intervals done on the bike or stairmaster.
4. Limited in how many days they can be performed. Two to three days per week is about the maximum for interval training, most endurance athletes won't do intervals more than twice/week. Have I heard of people trying to interval daily? Yes. Do I think it's a good idea? No.
5. Intervals hurt, especially intervals in the 60-90 second range where muscular acid levels are very high. If you're not willing to push yourself, you won't get much out of interval training. You know the warnings on most aerobics machines, that tell you to stop if you feel signs of exhaustion or fatigue; that's what a properly done interval program should feel like. Sensations of burning in your legs (from high acid levels in the muscle) along with extreme discomfort are not only common but expected. Some people also report nausea initially, this can be made worse if they have eaten too close to training.
Part 2
THE “FAT BURNING ZONE” ON TRIAL
Substrate Utilization 101: Origin of the myth
Dietary variables aside, the body’s proportional use of fat for fuel during exercise is dependent upon training intensity. The lower the intensity, the greater the proportion of stored fat is used for fuel. The higher the intensity, the greater proportional use of glycogen and/or the phosphagen system. But this is where the misunderstanding begins. Common sense should make it obvious that although I’m burning a greater proportion of stored fat typing this sentence, Getting up and sprinting would have a greater impact on fat reduction despite its lesser proportional use of fat to power the increased intensity. Alas, sufficient investigation of the intensity threshold of maximal net fat oxidation has been done. In what’s perhaps the best designed trial of its kind, Achten & Jeukendrup found peak fat oxidation to occur during exercise at 63% VO2 max. This peak level got progressively less beyond that point, and was minimal at 82% VO2 max, near the lactate threshold of 87% [1].
Misunderstanding is perpetuated in fitness circles
It has been widely misconstrued that a greater net amount of fat is burned through lower to moderate intensity work, regardless of study duration and endpoints assessed. In addition the confusion of net fat oxidation with proportional fat oxidation, the postexercise period is critically overlooked. No distinction is ever made between during-exercise fat oxidation, recovery period fat oxidation, total fat oxidation by the end of a 24-hr period, and most importantly, a longer term of several weeks.. Thus, the superiority of lower intensity cardio continues to be touted over the more rigorous stuff that takes half the time to do. Fortunately, we have enough research data to gain a clear understanding. Let’s dig in.
DISSECTING THE RESEARCH
Mixed study protocols + mixed results = plenty of mixed-up bodybuilders
As with all research involving applied physiology, the highly mixed set of results is due to a wide variation of study designs in terms subject profile, dietary manipulation, energetic balance, and actual intensities used. Nevertheless, the body of exercise-induced fat oxidation research can be easily deciphered by stratifying it into 3 subgroups: Acute effect (during exercise & immediately after), 24-hr effect, & chronic effect (results over several weeks).
Acute effects spawn ideas for further research
In addition to measuring fat oxidation during exercise, most acute effect trials look at fat oxidation at the 3 to 6 hr mark postexercise [2]. Fat oxidation during exercise tends to be higher in low-intensity treatments, but postexercise fat oxidation tends to be higher in high-intensity treatments. For example, Phelain’s team compared fat oxidation in at 3hrs postexercise of 75% VO2 max versus the same kcals burned at 50% [3]. Fat oxidation was insignificantly higher during exercise for the 50% group, but was significantly higher for the 75% group 3 hours postexercise. Lee’s team compared, in college males, the thermogenic and lipolytic effects of exercise pre-fueled with milk + glucose on high versus low-intensity training [4]. Predictably, pre-exercise intake of the milk/glucose solution increased excess postexercise oxygen consumption (EPOC, aka residual thermogenesis) significantly more than the fasted control group in both cases. The high-intensity treatment had more fat oxidation during the recovery period than the low intensity treatment. This implicates pre-fueled high-intensity training’s potential role in optimizing fat reduction while simultaneously setting the stage for quicker recovery.
24-hr effects come closer to reality
You can call it Murphy’s Law, but the promise of greater fat oxidation seen during and in the early postexercise periods of lower intensity cardio disappears when the effects are measured over 24 hours. Melanson’s research team was perhaps the first to break the redundancy of studies that only compared effects within a few hours postexercise [5]. In a design involving an even mix of lean, healthy men & women aged 20-45, identical caloric expenditures of 40% VO2 max was compared with 70% VO2 max. Result? No difference in net fat oxidation between the low & high-intensity groups at the 24 hr mark.
Saris & Schrauwen conducted a similar study on obese males using a high-intensity interval protocol versus a low-intensity linear one [6]. There was no difference in fat oxidation between high & low intensity treatments at 24 hrs. In addition, the high-intensity group actually maintained a lower respiratory quotient in postexercise. This means that their fat oxidation was higher than the low-intensity group the rest of the day following the training bout, thus the evening out the end results at 24 hrs.
Chronic effects come even closer
Long-term/Chronic effect studies are the true tests of whatever hints and clues we might get from acute studies. The results of trials carried out over several weeks have obvious validity advantages over shorter ones. They also afford the opportunity to measure changes in body composition, versus mere substrate use proximal to exercise. The common thread running through these trials is that when caloric expenditure during exercise is matched, negligible fat loss differences are seen. The fact relevant to bodybuilding is that high-intensity groups either gain or maintain LBM, whereas the low-intensity groups tend to lose lean mass, hence the high intensity groups experience less net losses in weight [7-9].
The body of research strongly favors high-intensity interval training (HIIT) for both fat loss and lean mass gain/maintenance, even across a broad range of study populations [9-12]. A memorable example of this is work by Tremblay’s team, observing the effect of 20 weeks of HIIT versus endurance training (ET) on young adults [9]. When energy expenditure between groups was corrected, HIIT group showed a whopping 9 times the fat loss as the ET group. In the HIIT group, biopsies showed an increase of glycolytic enzymes, as well as an increase of 3-hydroxyacyl coenzyme A dehydrogenase (HADH) activity, a marker of fat oxidation. Researchers concluded that the metabolic adaptations in muscle in response to HIIT favor the process of fat oxidation. The mechanisms for these results are still under investigation, but they’re centered around residual thermic and lipolytic effects mediated by enzymatic, morphologic, and beta-adrenergic adaptations in muscle. Linear/steady state comparisons of the 2 types tends to find no difference, except for better cardiovascular fitness gains in the high-intensity groups [13].
Summing up the research findings
• In acute trials, fat oxidation during exercise tends to be higher in low-intensity treatments, but postexercise fat oxidation and/or energy expenditure tends to be higher in high-intensity treatments.
• Fed subjects consistently experience a greater thermic effect postexercise in both intensity ranges.
• In 24-hr trials, there is no difference in fat oxidation between the 2 types, pointing to a delayed rise in fat oxidation in the high-intensity groups which evens out the field.
• In long-term studies, both linear high-intensity and HIIT training is superior to lower intensities on the whole for maintaining and/or increasing cardiovascular fitness & lean mass, and are at least as effective, and according to some research, far better at reducing bodyfat.
FALSE HOPES FOR FASTED CARDIO
The bandwagon is lead by blind horses
Many trainees pigeonhole weight training as an activity exclusively for building muscle, and cardio exclusively for burning fat. On the contrary, weight training can yield very similar results to cardio of similar intensity when 24-hr energy expenditure and macronutrient oxidation is measured [14]. The obvious advantage of weight training is the higher potential for lean mass and strength gains. In the bodybuilding context, cardio should be viewed as merely an adjunctive training mode to further energy expenditure and cross-complement the adaptations specific to weight training. As far as cardio being absolutely necessary for cardiovascular health, well, that depends upon the overall volume and magnitude of your weight training - another topic for another time.
Chaos theory strikes again
On the surface, it seems logical to separate carbs from cardio if you want a maximal degree of fat oxidation to occur during training. But, there’s the underlying mistake - focusing on stored fuel usage during training instead of focusing on optimally partitioning exogenous fuel for maximal lipolytic effect around the clock. Put another way, it’s a better objective to coincide your carb intake with your day’s thermic peaks, where insulin sensitivity & lean tissue reception to carbs is highest. For some reason, this logic is not easily accepted, nor understood. As we know, human physiology doesn’t always cooperate with logic or popular opinion, so let’s scrutinize the science behind the claims.
LET THE RESEARCH SPEAK
Carbohydrate ingestion during low-intensity exercise reduces fat oxidation
As far as 3 decades back, Ahlborg’s team observed that carb ingestion during low-intensity exercise (25-45% VO2 max) reduced fat oxidation compared to fasted levels [15]. More recently, De Glisezinski’s team observed similar results in trained men at 50% VO2 max [16]. Efforts to determine the mechanism behind this phenomenon have been made. Coyle’s team observed that at 50% VO2 max, carbohydrate availability can directly regulate fat oxidation by coordinating hyperinsulinemia to inhibit long-chain fatty acid transport into mitochondria [17].
Carbohydrate’s effect on fat oxidation during moderate-intensity exercise depends on conditioning level
Civitarese’s team found glucose ingestion during exercise to blunt lipolysis via decreasing the gene expression involved in fat oxidation in untrained men [18]. Wallis’ team saw suppressed fat oxidation in moderately trained men & women when glucose was ingested during exercise [19].
In contrast to the above trials on beginning and intermediate trainees, Coyle’s team repeatedly showed that carb ingestion during moderate-intensity (65-75% VO2 max) does not reduce fat oxidation during the first 120 min of exercise in trained men [20,21]. Interestingly, the intensity margin proximal to where fat oxidation is highest was unaffected by carb ingestion, and remained so for the first 2 hours of exercise.
Horowitz’ team examined the effect of a during-training solution of high-glycemic carbs on moderately trained men undergoing either low intensity exercise (25% VO2 max) or high-moderate intensity (68% VO2 max) [22]. Similar results to Coyle’s work were seen. Subjects completed a 2-hr cycling bout, and ingested the carb solution at 30, 60, and 90 minutes in. In the low-intensity treatment, fat oxidation was not reduced below fasted-state control group’s levels until 80-90 min of exercise. In the 68% group, no difference in fat oxidation was seen whether subjects were fasted or fed throughout the trial.
Further supporting the evidence in favor of fed cardio in trained men, Febbraio’s team investigated the effects of carb ingestion pre & during training in easily one of the best-designed trials on this topic [23]. Subjects exercised for 2 hrs at an intensity level of 63% VO2 max, which is now known as the point of maximal fat oxidation during exercise [1]. Result? Pre & during-training carbs increased performance - and there was no difference in total fat oxidation between the fasted and fed subjects. Despite the elevated insulin levels in the carb-fueled groups, there was no difference in fat availability or fat utilization.
Summing up the research findings
• At low intensities (25-50% VO2 max), carbs during exercise reduce fat oxidation compared to fasted trainees.
• At moderate intensities (63-68% VO2 max) carbs during exercise may reduce fat oxidation in untrained subjects, but do not reduce fat oxidation in trained subjects for at least the first 80-120 minutes of exercise.
• Carbohydrate during exercise spares liver glycogen, which is among the most critical factors for anticatabolism during hypocaloric & other conditions of metabolic stress. This protective hepatic effect is absent in fasted cardio.
• At the established intensity level of peak fat oxidation (~63% VO2 max), carbohydrate increases performance without any suppression of fat oxidation in trained subjects.
DISCUSSION
The current facts have been presented, and the bases for conclusion should be self-evident. Let me clarify that HIIT and linear high-intensity cardio are not the best and only ways to go. Many folks have perfectly legitimate orthopedic, cardiac, and even psychological reasons to avoid them. Not only that, I sincerely believe that both low and high-intensity cardio have unique benefits unto themselves. Optimally, both types should be done on either a phasic or rotational basis. Saying that one is bottom-line superior to the other for improvement in body composition is as false as blanketly saying 5 reps per set is superior to 15. On the contrary, there is well-established benefit in periodizing training variables, or as they say in the trenches, “mixing it up”.
I’ve heard it mentioned that high-intensity cardio shouldn’t be done concurrently with high-intensity weight training due to excessive stress on the central nervous system. Perfect excuse. My primary response is, there’s no solid proof of that danger. Certainly there’s no evidence of it in my observations as a professional in the field, working with bodybuilders, and all types of other competitive athletes such as gymnasts, sprinters, boxers, etc (you know, athletes whose incredible physiques have nothing to do with weights + high intensity cardio). It’s true that some folks regard a precociously low carb intake as a legit reason to keep intensity low. However, if your nutritional program doesn’t adequately support productive training, then you’ve designed it ass-backwards, painting yourself into a corner of compromised adaptation.
Fasted cardio is not optimal for reasons spanning beyond its questionable track record in research. There’s unavoidable positive metabolic synergy in fed (read: properly fueled) training, regardless of sport. This effect increases with intensity of training; even in untrained subjects, whatever fat oxidation is suppressed during training is compensated for in the recovery period by multiple mechanisms, many of which are not yet identified.
Bodybuilders are known for their gravitation towards self-sacrifice, but some rely on hearsay, while others rely on science. Did you know that way back in the 60’s, it wasn’t uncommon for coaches to tell athletes in various sports to avoid drinking water before and during training? No comment needed. Good thing researchers questioned it, and enough data surfaced to validate claims of the skeptics. Sometimes counterproductive dogma indeed dies, thank goodness. However, the myths addressed here are admittedly more subtle than the water example. Even on sub-optimal protocols, bodybuilders all over the world still inch along, although not at optimal rates, and not necessarily to optimal levels.
I’ll end off by challenging you to diligently review the facts before blindly latching onto the myths… Maybe someday in the near future, natural bodybuilding contests won’t look like they’re missing a pool."
I hope you will find this article useful in planning your fat loss and exercise routines and I wish you the greatest success in meeting your goals.
Linear Mode
