So In last week’s post we learned all about how your body converts and uses energy. If you haven’t given it a read, you can find it here: Take it from a Chemist: Cardio Before or After a Workout? (Part 1 – The Science!)
In this week’s installment let’s actually take a look at how this energy usage is advantageous or detrimental to your workout plan.
As a refresher from last week, two things to remember:
Cardio Before a Workout – Energy System Used: Aerobic
Cardio After a Workout – Energy System Used: Anaerobic (Glycogen-Lactic Acid)
Cardio before a workout is great because it gives you the opportunity to burn more calories overall by beginning your workout with an elevated heart rate. This in turn increases your internal temperature and elevates the metabolic demands placed on your body. The downside is that you’ll most likely be more tired after doing the aforementioned cardio and won’t have as much energy to use on weight training.
Since the aerobic system is much more efficient when it comes to making ATP (i.e. energy), weight training first is great because it allows you to get to the fat burning portion of the workout faster than if you had done cardio first. By weight training first, you will deplete the majority of your glycogen and then after all the glycogen is depleted, the subsequent cardio will result in a much higher percentage of fat being burned.
(If you want to know more – Check this out: The University of Tokyo published a study in the journal of Medicine and Science in Sports and Exercise that found that doing cardio after weight training burned more fat during the first 15 minutes of the cardio session than doing cardio before lifting.)
So Which is Better?
By doing cardio first we are using the aerobic system to burn energy and eventually burn fat. In the aerobic system we need to burn up 32 energy “pieces” (ATPs) before we ever get to burn fat for energy. You’ll eventually get there, BUT it will take a little longer.
By doing resistance training first we are using the glycogen-lactic acid system to burn energy and eventually burn fat. NOW you only need to burn up 3 energy “pieces” (ATPs) before we get to that fat energy. Sounds more efficient huh??
Annnnnddd Just for funsies.. Here’s another bit of information for you:
After a workout, your body continues to burn additional calories up to 48 hours. This is known as excess post-exercise oxygen consumption (or in other words – EPOC). EPOC occurs because your body needs energy to repair your muscles after you’ve challenged them. It occurs at a much higher rate after intense weight-training THAN after low-intensity, steady-state cardiovascular training. This is why it’s important to give it your all during weight training AND if you do steady-state cardio before you lift, you won’t necessarily have the energy to do that. A less productive weight-training session can create a less productive EPOC burn. Which means less calories burned overall. (Want to know more about EPOC? Check Out: Fitness Myths #6 – Need Cardio For Fat Loss)