So here’s my conspiracy theory: aerobics were invented in the 1980s solely so that we would buy ugly leotards, shiny tights, and saggy leg warmers. As a kid, I remember slapping in the ol’ cassette by Hanoi Jane, and “feeling the burn” as I did ten thousand leg lifts. She’s a maniac, maniac on the floor!!! *sloosh of bucket of water*
Anyway, the hideous legacy of these times is still with us. Today, cardio (as we now tend to call aerobic activity) is a riddle shrouded in an enigma. We “know” that we’re supposed to do it to be healthy, right? Yet, there are complicated alchemical formulae to follow lest we do something “wrong” and initiate a chain reaction of destructive physiological processes which will end in our kidneys popping out our bellybuttons or something. There is a “target heart rate”, a “fat burning zone”, a “calories-per-minute” measure which requires knowing our body weight…
And let’s be honest, it’s kinda boring to just shuffle on a treadmill for 30 minutes. I see people reading the newspaper on the recumbent bikes at the gym. I’m not so much about rules, but c’mon — you should not be able to read 10 point font about interest rates when you are exercising. I have the urge to whip out a megaphone and start drill sergeant yelling into their ear.
Anyway, between the boredom and the confusion, it just makes you want to say, “Aww, batshit” and forget the whole thing entirely.
In the spirit of giving the finger to pink fuzzy headbands, let’s be destructive. Let’s go through the things that we think we know about cardio and aerobic activity, and then figure out what the real story is. I’ll conclude by discussing how you, yes you, dear reader, can incorporate cardio into your program in a way that is useful, sane, and works with your goals and lifestyle.
what’s “aerobic” anyway?
First, let’s look at what defines aerobic activity. Aerobic, or “with oxygen”, is generally used to refer to activities that increase the heart rate and the intake of oxygen. These are typically understood to be activities such as walking, jogging, dancing, or cycling.
Aerobic activity requires the body to be able to take in and efficiently deliver oxygen to the working tissues. When you perform aerobic activity, your heart rate and stroke volume increase. Your heart beats faster and with more gusto, delivering more of the good stuff with each contraction. Both carbohydrates (glucose and glycogen) along with free fatty acids are metabolized for energy.
Here’s the catch: the body can only do this up to a certain point, and at a certain speed of transmission. You can’t raise the heart rate to 400 beats a minute, nor can you dump huge amounts of blood through the heart instantaneously. The body isn’t able to deliver the oxygen rapidly and effectively enough. The demand is too high. So, for instance, you can jog easily at a slow pace for ten minutes. But you could never full-out sprint for ten minutes. The body can’t keep up with the need to get oxygen and nutrients where they have to go.
When this second type of situation occurs, in which the body’s demand for oxygen outpaces its ability to get it to working cells, the activity is said to be anaerobic, or “without oxygen”.
An example of anaerobic activity is sprinting or squatting. What this usually means in practice is that the intensity of the activity is too high for the body to meet the demands through increasing oxygen intake alone. The body will crank the heart and lungs up anyway, just to help out. But it won’t be enough. Muscles are greedy things. Just like a spoiled screaming brat in a toy store, they want mooooooore!!
So the body will turn to its short-term emergency fuel stores: glucose and glycogen. This is great stuff — it’s what lets you do most weight training activities as well as things like short dashes and jumping — but you don’t get very much of it if you’re really hauling ass and using it up quickly in the process known as anaerobic glycolysis.
Oh yeah, and here’s where “feeling the burn” comes in. If you’ve ever tried doing a high intensity exercise for a period longer than 30-60 seconds, you’ll know the burning sensation that results. This “burn” signifies the buildup of hydrogen ions in the tissues, a byproduct of the body’s production of energy. Hydrogen ions are normally present, minding their own business quietly in the bloodstream, but when the activity intensity is very high, they can’t clear out quickly enough.
However, despite a temporary buildup, they nevertheless clears fairly rapidly after exercise. The soreness you feel the day after training is not lactic acid — that’s a myth.
Speaking of myths, I think it’s just about time to discuss some more.
myth #1: aerobic exercise is the only way to lose fat
On paper, fat loss is relatively simple. All you do is expend more calories than you take in. You do this by adjusting your caloric intake (in other words, changing your diet) and perhaps getting more activity. But more activity doesn’t have to be aerobic activity for fat loss to occur. Many folks are able to lose fat quite well with weight lifting alone, both because of the extra calorie demand of the activity, and because of the retention of muscle which weight training facilitates.
This is not to say that you shouldn’t do cardio when trying to lose weight. Indeed, for women, cardio may play a more significant role in fat loss than men because of hormonal differences in the way that fat is mobilized. But aerobic activity is not the only way to lose fat, and it should be only one part of a fat loss plan.
myth #2: aerobic activity is the only path to good health and longevity
Weight trainers used to be considered terminally unhealthy meat mountains who were immobilized in their steak prison. Snooty joggers and jazzercisers turned up their noses at the iron freaks who were viewed as steroid-laden, narcissistic, and above all, not long for this world.
Current research now shows us that the fountain of youth may be iron after all. Study after study shows that weight training has benefits for young and old, athletes and plain folks, rehab and recreation. Indeed, recent theory suggests that large amounts of endurance-type cardio provoke oxidative processes which lead to eventual degeneration and decay. Additionally, higher intensities but shorter durations of cardio-type activity are turning out to be superior to lower intensity, long duration bouts for both fat loss and overall conditioning (Tremblay et al; Metabolism 43: 814-818 (1994)).
Again, this is not to say that lower intensity, long duration cardio shouldn’t be done, or shouldn’t be a part of one’s fitness program. After all, many people (like me) start out doing what they can do, which includes gentle activities such as walking. Lower intensity cardio is great for rehabilitating injuries and conditions such as lower back pain. There is also some evidence that traditional cardio has benefits for mood stabilization.
But aerobic activity should be applied intelligently, should be tailored to individual goals, and should be only one aspect of a well-rounded regime. For older people, loss of flexibility and strength is a more significant problem affecting quality of daily life than cardiovascular endurance, and thus weight training should be a fundamental part of any good fitness initiative.
myth #3: cardiovascular endurance should be the goal of all aerobics programs
I won’t dwell too much on this point because I think the problem of applying one goal to everyone should be self-evident. As I indicate in the article on sport-specific training, different people have different needs. Sure, an endurance athlete, such as a distance runner, should indeed train her endurance capabilities. However, endurance-type work comprised of long sessions of low intensity is not the only type of cardio activity that can be done, and may not always be the best choice.
You can adjust both length and intensity of the session, as well as vary activity choice and rest intervals. Short bursts of cardio-type activity may be as effective for your goals as longer sessions. In fact, I would go so far as to say that unless you are an endurance athlete or starting at a low level of fitness, you would be better off working on increasing the intensity of your cardio, rather than the duration.
Even activities which don’t seem like “official” aerobics, such as shoveling snow or chopping wood, can provide cardio benefits. Try shoveling snow as quickly as you can, and you’ll see what I mean. The bottom line is: train for what you need. If you don’t need endurance, then don’t train for it as a primary objective. And even endurance athletes can benefit from doing more intense training. Distance runners and other endurance athletes incorporate sessions of higher intensity into their training to build speed and lactate threshold tolerance.
myth #4: endurance cardio in the “fat burning zone” is best for bodyfat loss
I don’t get pissy easily, but this one really steams me up because it’s so patently contrary to demonstrated evidence. There are many, many athletes who do no endurance cardio at all, and who are ripped. Of course what elite athletes look like doesn’t necessarily apply to us average folks, but again, the research seems pretty clear that endurance cardio is not best for bodyfat loss.
To understand this, let us consider the physiological processes behind the contention. How many times have you heard people say, “Keep your heart rate within 65-75% of your max, otherwise you’re not burning fat?” The notion of the fat burning zone is based on a rather poor understanding of how the body burns fuel for energy.
To put it in a simplified way, as I mentioned earlier, the body burns different kinds of fuels in an order of preference, depending on the intensity and duration of the activity. You can only do a high intensity activity like sprinting for a short time, whereas you can walk for hours without stopping. The body uses a mix of fuels for energy at all times; sometimes it’s primarily fat-based fuel, sometimes it’s glucose (sugar) based fuel. The lower the intensity, the greater the likelihood that you’ll be using a larger percentage of fat for energy. So that part is sort of right.
BUT here’s the part people miss in promoting the fat burning zone: just because you’re burning more fat as a percentage of fuel during a certain activity doesn’t mean that you’re going to burn more fat overall. You burn the most fat, relatively speaking, while sleeping! Now don’t get me wrong; if someone could figure out a good way to burn fat while sleeping 14 hours a day, I’d be first in line to buy it. Just because you’re burning fat at a given moment does not mean that you’ll burn more fat in general.
What really matters for fat loss are two things: metabolic demand (i.e. does the body have a need to use fat for energy?) and long-term energy balance (in other words, calories in versus calories out). Let’s say you create a deficit of 300 calories doing an hour of high intensity cardio, and 150 calories doing an hour of low intensity cardio. Now let’s say you do this every day. At the end of a week, you’ve created a deficit of 2100 calories with the high intensity stuff, and barely more than 1000 with the low intensity stuff. Which do you think will be more important in the long run? Which leads me to one of the big apparent paradoxes of fat loss: interval training, which uses periods of high intensity alternated with periods of low intensity cardio, is the most effective form of cardio for fat loss, even though while you’re sprinting like hell you’re not burning primarily fat for fuel!
myth #5: circuit training is a good way to do cardio
Circuit training was popularized as a way to gain the benefits of both strength and cardio training. It involved doing a “circuit” in which one moved from weight machine to weight machine rapidly, doing high-rep sets with low weight and short rest intervals. This was supposedly to keep heart rate up as well as strength train. Unfortunately this did not really develop either capability. In fact, it proved a significantly poorer method of development on both counts. As is often the case in training, when you try to do two (or more) things at once, you tend not to do either thing as well as possible.
Now, this isn’t to say that circuit training is useless. I use it almost all the time in my own training. There are effective ways to circuit train, just not in that fashion.
For example, circuit training could be used as a fun way to circulate athletes between “technique stations” or various types of drills. In this case, each activity is performed with adequate rest and the emphasis is on the skills developed from the variety of exercises. Other types of circuit training could be something like an obstacle course, where again the focus is not on development of maximal strength or muscle mass, but rather mastery of difficult, repeated activities. Another great example of a circuit-type workout style aimed at general fitness and work capacity — sometimes called “metabolic conditioning” — is CrossFit.
I do my circuit training by assembling a variety of demanding, full-body exercises such as jumps, Olympic lifts, burpees, etc. and then doing each one for a specified length of time (usually 30-60 seconds), moving between each exercise without rest, and then resting between “rounds”. This style of training is tougher, and better, than both traditional low-intensity cardio and traditional lower-intensity circuits.
myth #6: cardio is antithetical to strength training
Well, this one isn’t completely a myth. But it’s all a question of proportion. I get lots of email from people who are terrified to walk to their local 7-11 for fear of burning through precious muscle. OK, maybe not lots of email about that one. Anyway, people who are trying to gain mass and strength often worry that too much cardio will impede this. Too much cardio, especially endurance-type cardio, will indeed do so, because of the physiological processes involved.
Endurance cardio tends to be catabolic (“breaking-down”) while weight training is thought of as anabolic (“building-up”). The hormonal enviroment which is produced with long sessions of low intensity cardio is not the same as the one which is needed for gaining mass and strength. The body can balance these pretty well, as long as both activities are kept in the desired proportion. Indeed, well-directed strength training can also benefit people who make endurance training their main focus.
So how much is too much? A moderate amount of cardio, say three or four 20-minute sessions per week, should pose no problem. You may wish to experiment with different amounts and intensities of cardio to see what works for you. For example, substituting 15-minute sessions of sprints for a typical cardio session may actually improve your performance overall, while too much of this might hinder the development of squatting strength. Regular walking may serve you well as “active recovery”, but power walking an hour a day may cut into your gains. The opposite is true for an endurance athlete: if endurance training is your main goal, then keep strength training moderate and tailored to your needs. Three general rules, then: everything in moderation, work according to your goals, and don’t be afraid to experiment.
what kind of cardio is best for you?
Well, the answer to that depends on your own needs and interests.
- What activities do you like to do? Irrespective of any other consideration, sometimes the best exercise is whatever you’ll do regularly. Do you like to dance, whack a punching bag, jump rope or ride bikes with the kids, throw a frisbee around, chase a soccer ball, hike through nature, walk through a shopping mall looking at the fabu new shoes? As best as possible, do something you enjoy.
- What do you want out of your cardio? Do you want it to give you cardiovascular endurance? Do you want to improve your speed? Do you want to improve your general fitness? Do you want some lighter, “active recovery” cardio for rehab and restoration? Do you enjoy the social atmosphere of a walking partner or cardio class? Do you want fat loss?
- How much time are you willing to devote to it? If cardio endurance isn’t your main goal, then you don’t need to do huge amounts of it. 3-4 sessions a week of 20 minutes per session is fine. If you’re short on time but still want to train cardio, experiment with using brief episodes higher intensity cardio, such as sprints, hill/stair runs, or jumping rope. 10 minutes of sprints will make a big difference if done regularly.
- What’s your starting level of fitness? Tailor the intensity to your abilities. Don’t start running if you can’t briskly walk well. Build a base of cardio fitness and work from there. A good way to develop your ability is to gradually introduce “intervals” of higher intensity alternated with “intervals” of lower intensity. I put “intervals” in quotes because it could be something as simple as walking up a hill, walking briskly, jogging, whatever you can do for 30 seconds or a couple minutes at a faster pace. It doesn’t need to be the standard sprint-walk of regular interval training.
The bottom line is this: cardio and aerobic activity have a place in a well-rounded fitness program. But what their place is, and what that looks like, is up to you. You don’t need to follow anyone else’s exercise prescription, and you don’t need to worry that you’re doing the cardio “wrong”. If you are working within your abilities, are building a good base of general fitness, and are tailoring your activities to your goals and interests, then don’t, uh, sweat the small stuff.