Before I get into this topic, let me first say that most of your focus on a diet should be what and how much you eat, lifting weights should be second, and cardio should be last (again, this is generally speaking). After you have a solid diet working with regular weight training in place, then you can start worrying about cardio. One of the only times that you might have a need to perform cardio often is if you are a light-weight female or very light-weight male and lowering the calories any further would not allow you to have proper nutrition.
Alright, on to cardio! First I will talk about steady-state cardio, the slow, jogging kind of cardio. I am going to talk about this type first since this is the type that most people do regularly. Then, in the next post, I will discuss HIIT (High Intensity Interval Training) and other types of cardio similar like hill intervals.
Many people spend so much of their time doing slow cardio on a treadmill (or elliptical… yuck..), and many report less than stellar results. Why is this? Shouldn’t ALL those calories that they are burning while running for an hour make them lose, like, a pound of fat or something?! Well.. no. First off, many people drastically overestimate the amount of calories burned while doing aerobic activity. In relation to the food aspect of the diet, exercise burns very little calories. Also, for some people, doing cardio might actually make them gain weight… due to psychological reasons. There seems to be many people who eat MORE the rest of the day because they “deserve it since they worked out”. This is largely just an excuse. Since people tend to overestimate how much they have burned during a cardio session and underestimate how many calories they eat, this type of thinking that they deserve a dessert or something will actually make them put on some pounds, not lose some.
Now that I have gone over the disadvantages of long, steady-state cardio, I will go over the (few) advantages of it. For one thing, some people tend to feel less hungry after doing cardio. However, you have to be careful about this one as some people report just the opposite. So, next time you perform long aerobic activity, see how hungry you afterwards in order to see if this applies to you.
Also, almost all forms of aerobic activity improve VO2 Max. VO2 Max basically refers to the maximum amount of oxygen that your body can transport to your muscles during activity. One benefit of having a high OV2 Max (besides the obvious health benefits) is that your muscles will receive more oxygen faster during your lifting workout which might make you recover faster between sets, thus allowing you to have a more efficient workout.
Now, the biggest advantage of performing steady-state cardio only occurs if you perform it correctly or for maximal impact. This means that you perform it while slightly fasted (by at least 3-4 hours or in the morning before you eat anything). Also, to make your fat loss even greater, you should be glycogen depleted. This means that you are on a very low carb diet and have had some high rep workouts to deplete your muscle of glycogen. You want to be glycogen depleted during your cardio session so that the body cannot take the glucose from your glycogen storages to use as fuel; it has to rely mainly on fatty acids (good!). In fact, one of the ONLY times I perform steady-state cardio is when I am glycogen depleted, but being glycogen depleted doesn’t always fit into how people want to diet. Some want to eat more carbs. (Lyle McDonald goes into this topic very well in his Ultimate Diet 2.0 book and The Stubborn Fat Solution.)
However, most of the above is really only applicable to very lean individuals. People with a higher percentage of body-fat will get just as good results from just not eating whenever calories they burned while doing cardio.
The other time that steady-state cardio would be VERY beneficial would be after a short HIIT session. Basically, catecholamines (think adrenaline) are released during the HIIT session which only mobilizes fatty acids. The steady-state cardio utilizes this and burns the fatty acids. Again, this is covered very, very well in Lyle McDonald’s book, The Stubborn Fat Solution.
Well there you go: A brief look at some of the major disadvantages and advantages of steady-state cardio.