When Should You Do Cardio?

The Age Old Question

One of the questions that almost every gym rat I know has asked me is whether you should do cardio before or after you do your weight training.

The answer?

It depends on your goals.

If your goals involve getting stronger/more muscular/leaner, you’ll want to do your cardio after your weight training. However, if your goals are more centered around improving at cardio, you are better off doing your cardio first.

The Science Behind It

Your body has two primary methods for storing energy: fat and glycogen. Glycogen is the body’s preferred source of energy because it is very easy to convert and your body can use it very efficiently. Fat is more of a Plan B energy source because you can store a lot more of it than glycogen, but it is harder for your body to break it down and convert it to fuel. As a result, your body usually will run on glycogen for as long as possible, and then switch to burning fat once you run out of glycogen. Burning fat translates to fat loss, hence why you’ll tend to find more success with weight training followed by cardio when you are trying to get lean.

If you’re trying to get stronger or more muscular, the reason why weights first tends to work better is that your body can use glycogen much more efficiently than it can fat, so you’ll be able to get more bang for your buck when you are burning glycogen during your weight training session. If you want to see for yourself, try running a mile or two and then lifting. You’ll notice a significant drop in your weight training performance when you run first because your body is tired and has to settle for less glycogen. For this reason, if you’re focusing on strength and muscle, you’ll want to take full advantage of your glycogen supply when you lift.

On the other hand, if your main focus is your cardiovascular system, doing cardio first will likely make sense for you so that you can use your prime workout time on cardio.

It also isn’t a bad idea to include a day or two of just cardio so that you can work on developing your cardiovascular endurance. Regardless of what I am trying to do with my body, I typically throw at least one dedicated cardio day into my schedule every week. It can be hiking, basketball, jogging, bike rides, the elliptical, or whatever other method of doing cardio that you can think of. This will help loosen up your muscles and get your blood flowing a bit, as well as helping to ensure that you’re getting enough cardio in your life.