Should You Do Cardio After Lifting?

Sometimes I get asked, “Should I do cardio after lifting weights?”  Well, it really depends on your goals, is what I normally say.  There are many people that when I ask them why they run after they lift, they say it’s because they want to build muscle by lifting and then lose fat afterward by running.  First of all, as I’ve stated before, trying to build muscle and lose fat at the same time is a VERY LONG AND DIFFICULT PROCESS.  There are many, many, MANY reasons for this, but the main one is that in order to build muscle mass, you need to eat over your maintenance level in calories (maintenance level is the amount of calories that you burn averagely in one day by metabolism and exercise).  In order to lose fat, you need to eat under your maintenance level.  So, as you can hopefully see, trying to do both at the same time is very hard.  It’s much easier just to pick one goal, either gain muscle or lose fat, and stick with that for a while.

So back to doing cardio after lifting… The only time that you should do cardio after you lift is if you are trying to lose fat, and sometimes it would be better to do it another time still.  First, let me explain how doing cardio after lifting became popular.

When do any type of exercise, your body basically relies on 3 sources of energy:  protein, carbs, and fat.  Each of those 3 macronutrients can be converted and used as fuel.  Ideally, when trying to build muscle, we would want all the energy to come from carbs, as it is used to make ATP, the most explosive form of energy.  Moreover, when doing cardio or trying to lose fat, we would want all the energy to come from fat cells so that we will look leaner.  So, people thought that they could get the best of both worlds by doing both!  That is, if they lifted first, their glycogen storages would be full (the energy from glycogen storages is converted into ATP and it comes from carbs) and they would be able to lift with high intensity and deplete their glycogen storages in their muscles so that when they ran afterwards, most of the energy would come from fat cells instead of glucose in the glycogen storages.

Well, this all looks fine and dandy, but there are just a couple problems with it…  First, the Most Important meal of the day is always after you lift, and as I discussed in The Surprising Truth about Pre- and Post-Workout Meals, you should have protein and carbs anywhere from immediately PWO (post work-out) up to 45 minutes later.  If you choose to run after your workout, you will be jeopardizing your body of this valuable nutrient absorbing time.  Moreover, because of this failure to consume protein, your body will NOT be taking all of the energy it needs from fat, it will take a good portion from muscle!

You see, as I explained in The Surprising Truth about Pre- and Post-Workout Meals, the reason why you need to consume carbs is because they are anti-catabolic.  That is, they stop your body from taking the energy that it needs from muscle and instead takes it from the carbs.  If you run straight after your workout, your body will definitely be requiring energy but there will be nothing stopping it from taking that energy from the protein in your muscles!  It is this very reason that I do not run after I lift; I want to keep all the muscle that I can!  There is another time to run that does basically everything that running after a workout does but without some of the negative side-effects, and it is probably what you are thinking:  Running first thing in the morning.

Now, I don’t normally jog in the morning, I do HIIT style running which will be in a future article, but for the purposes of this article, I going to specifically address jogging (or steady state cardio) and why I do not do it too.  The biggest reason why running after a workout became popular is because it depleted glycogen storages and would therefore use fat as fuel instead of glucose.  Now without restating the problems with this, running in the morning does virtually the same thing!  How?  Well when you sleep, your body is still using a little bit of energy and by the time you wake up, you haven’t eating for many hours and are partly carb depleted already.  Also, your body isn’t STARVING for protein like it is PWO, so the jog won’t take as much of its energy from protein in your muscles.  However, if you eat before the jog, then the whole purpose of doing it in the morning is gone as you will no longer be carb depleted at all.

The reason why I don’t normally do steady state cardio at all is because it is a catabolic activity that decreases your muscle mass whenever you partake in it, even if it is just a small amount.  I normally will do a variation of HIIT, the details of which will be in a future article.  That being said, there are a lot of bodybuilders who do perform slow, steady state cardio and get great results with it, so if you do try it out and are getting the results that you want, then go ahead and keep doing it first thing in the morning.

PS:  Even though I haven’t directly stated why you should only do cardio after lifting if you are on a diet (and probably not even then), it should be pretty clear by now why you don’t want to do cardio after lifting while trying to build muscle.  However, the main reasons are

  1. When bulking, you need to eat a TON, wasting energy jogging is not in line with your goals.
  2. You are ROBBING your body of an important time to take in nutrients PWO.
  3. You will not be losing fat because at the end of the day, the total intake of calories is more that you burned through metabolism and exercise.  In other words, you are eating over your maintenance level (at least hopefully).

So, unless you have some strange reason why you should keep doing it, I can’t see any reason why to do cardio after lifting.  If you are worried about your cardiovascular health, then do it first thing in the morning instead.  You need the protein and carbs PWO.