This is from Alwyn Cosgrove's site. He's all about interval training. I'm SURE someone could come along with all sorts of info about the fat loss benefits of traditional steady state cardio. The result being that we could only conclude that BOTH probably have their useful place.
(Excerpt from Afterburn)
Energy System Training For Fat Loss – by Alwyn Cosgrove
The difference between cardio training and aerobic training
This is important to understand. Cardio refers to any exercise in which the heart and lungs are involved. This could be jogging, running, sprinting, swimming, circuit training etc. Quite simply – if you are elevating your heart rate and respiration rate, you are doing some form of cardiovascular work.
Aerobic training refers to a state in which the cardiovascular work is performed. Aerobic literally means ‘with oxygen’. It is a relatively low intensity state of exercise that can be maintained almost indefinitely (as long as oxygen is being supplied to the working muscles, in the required amounts – the exercise can be continued. This is aerobic training.
All aerobic training is cardiovascular training. Not all cardiovascular training is aerobic. Hopefully that makes sense.
Steady State Aerobics – why it hasn’t worked
Let’s think of all the reasons steady state aerobic training is supposed to burn fat.
It burns calories. Good. I’ll buy that. How does it burn calories? Because the muscles are hard at work and demand extra oxygen to help them continue working. Hmmm. There are a ton of activities such as weight training, sprinting, sleeping, talking watching TV that ALSO burn calories by requiring work from the muscles. So no extra points for aerobic training.
The fat burning zone. Nope. Sorry – it doesn’t exist. The fat burning zone is a concept that the body burns a greater amount of fat at lower intensity aerobic exercise than it does at higher intensities. This is a misinterpretation. It’s true that the body burns a greater percentage of fat at lower intensities than at higher intensities, but taking this to its logical conclusion – the body will burn a greater amount of fat as a percentage lying on the couch than doing anything else right? And we know how good lying on the couch works for fat loss. It’s the “as a percentage” line. At lower intensities the body may burn 50% of the calories from fat, while at higher intensities it may only burn 35% of calories from fat. BUT at higher intensities you burn way more total calories, and more fat calories overall than you do at lower intensities. Think about a real world example – are sprinters (running 10-20s) fatter than marathon runners (2-2.5 hours of running). No. Actually sprinters carry less body fat than distance runners due to their muscle mass.
Aerobics makes your body an “efficient fat burning machine”. True but this isn’t a desirable response. The ONLY tissue that burns fat in the body is muscle. Yes – aerobic training does demand work from the muscles, but not as much as other activities. Aerobic training doesn’t require the muscle tissue to stay around either. Aerobic training makes muscles more efficient at using fat (don’t get excited – if your car became more efficient at burning gas – you’d be using less of it).
So if muscle is the only tissue that burns fat, and aerobic training makes it smaller and more efficient at burning fat, then essentially you are creating a smaller, more efficient fat burning machine. That’s not effective.
Aerobic training raises your metabolism. I’ll cover this in more detail later but the short answer is no it doesn’t. Metabolism is largely a function of how much muscle you carry. As aerobics does nothing to even maintain muscle, never mind build muscle, it will do nothing to contribute to raising your metabolism at rest. Sure, you’ll burn calories while you’re doing it, but will you burn any more at rest as a result of doing aerobics? No. And as you’ll find out later, you may actually burn less.
The adaptation conundrum
The body literally adapts to anything we attempt to do by responding in the reverse manner. Don’t drink any water? Your body tries to retain water. Does weight training build muscle? No it doesn’t. What actually occurs is a breakdown of muscle tissue and the body ADAPTS by building muscle.
So if you burn a ton of calories doing aerobic training, that same body adapts to aerobic exercise by slowing your metabolism and allowing your body to store more fat. Same body – same system.
The biggest problem with aerobic training is that you get better at it. In weight training, as you get better, you add more weight or more reps and there is literally no finish line. In aerobic training, the work required to run 5 miles will become less and less as you get fitter. So to continue to improve you either go further (do more work for the same amount of calories) or you run it faster. Going further kind of defeats the purpose. Is there much joy in running 40 mins to burn the calories you once burned in 30 mins? And going faster involves the same problem. Eventually, the new speed becomes too easy for you and you have to go more intense to get the same benefits. Now as I mentioned, there is no end point with weight training. However there is an end point with aerobic training. You will reach an intensity eventually that will be the end of the aerobic zone. Quite simply going any harder will send your body into the anaerobic zone. So at some point you’re not doing aerobics any more. So, if you have to stop doing it at some point to get the benefits you seek why not do anaerobic work to begin with?
Your metabolism or your metabolic rate is what determines how many calories you burn each day – or more importantly for the purposes of this book – how many you need to maintain your current weight. Your metabolism is quite simply how many calories you burn in a typical day. It is affected and controlled by your thyroid, and is largely a factor of your muscle mass. To break it down further – every pound of muscle you put on requires calories per day to maintain. doesn’t take into account the calories burned in training to develop that muscle, or the calories burned in training to keep that muscle – these calories are just the amount needed by that muscle to just sit there.
So in order to really get the athletic look we want to develop, the key is not just how many calories we can burn during exercise, it’s how many calories we can force the body to burn all the time. Raising your metabolism is the real key in long term fat loss and physique change.
In order to lose body fat, you must burn off more calories than you consume. Despite the proliferation of diets- low carbohydrate, low fat, high protein, high carbohydrate etc this simple rule remains. I don’t want to talk about nutrition here as this is more than adequately covered in another chapter in this book, but suffice to say the caloric balance is still important.
I’ve lost count of how many times I’ve heard people say “I barely eat anything – I eat like a bird and I still gain weight”. Oh really. You are eating fewer calories than you need and your body is gaining weight? Impossible. This violates the law of thermodynamics. Usually it’s a case of not really being aware of how much you are actually eating. Because let’s face it – if your body was capable of producing body weight from nothing, then we better get you sent over to NASA or UNICEF immediately – with magical genes like yours, we might just be able to solve the Third World’s hunger problem.
Fat loss is all about caloric expenditure. We must burn more calories than we take in, and the real key to doing this, as mentioned before, is not aerobic training, which will burn calories while you are doing it, its anaerobic training, which burns calories while you are doing it AND increases the calories burned for hours afterwards. In the case of weight training, if we build muscle and keep it, that burns calories forever more. Even when you sleep!
The key with anaerobic training is what is known as EPOC. Anaerobic exercise burns a ton of calories while you are performing it. However, the metabolism remains elevated following this type exercise. This was, at one time, referred to as the oxygen debt, but is now referred to as the excess post-exercise oxygen consumption (EPOC). The recovery of the metabolic rate back to pre-exercise levels can require several minutes for light exercise (aerobic training), several hours for very heavy exercise (anaerobic cardio training), and up to 12 to 24 hours or even longer for prolonged, exhaustive exercise (interval training or circuit weight training).
The EPOC can add up to a substantial energy expenditure when totaled over the entire period of recovery. If the oxygen consumption following exercise remains elevated by an average of only 50 ml/min or 0.05 liter/min, this will amount to approximately 0.25 kcal/min or 15 kcal/hr. If the metabolism remains elevated for five hours, this would amount to an additional expenditure of 75 kcal that would not normally be included in the calculated total energy expenditure for that particular activity. This major source of energy expenditure, which occurs during recovery, but is directly the result of the exercise bout, is frequently ignored in most calculations of the energy cost of various activities. If the individual in this example exercised five days per week, he or she would have expended 375 kcal, or lost the equivalent of approximately 0.1 pounds of fat in one week, or 1.0 pounds in 10 weeks, just from the additional caloric expenditure during the recovery period alone. This is the key to maximizing the return on your exercise investment.
The next obvious idea is – if you trained the next day while your metabolism is still elevated, will we have an even higher return – is the effect accumulative? Is the whole greater than the sum of the parts?
Science has yet to give us an answer, however in the real world, I think so. I have seen amazing results with my clients using this exact protocol.
So is there a better way of performing cardio workouts to prevent these adaptations, and rapidly improve fat loss results? Yes. The key is to perform what is known as interval training.
Interval training simply refers to a series of intense activity separated with short rest periods. Through using interval training you are able to exercise at a higher intensity without getting tired. In other words – because we alternate the periods of high intensity work, with periods of lower intensity work – you are able to do much more work in the same time period than you were before.
The beauty of this is as you improve, the work intervals can get harder and harder, and the recovery intervals can be shortened, or performed at a higher speed. In fact, there is no end in site, and no downside to interval training (other than it is really hard).