by Kris Pitcher
To do your cardio exercise before or after you lift?
When we're lifting weights, traditionally, we are anaerobic, which means "without oxygen". In this energy system we are utilizing primarily amino acids for fuel. Why the recommendation to do cardio after we've lifted?
The notion that we have "burned through our carb stores" during our lifting assumes that we are on a low carb diet. The idea is that then we'll burn more fat when we're doing our cardio. Well, most people are not on a low carb diet. They have plenty of carbs in their diet, and plenty of carbs stored in their muscles and liver as glycogen.
Most people store enough glycogen for an 75% heart rate max for 4 hours of continual work (J APPL Phys. 1993 August, 75(2)1019-23. This is why marathon runners need to ingest while they perform. You get the idea...we store a lot.
Same goes for doing our cardio on an empty stomach first thing in the morning. If we are on a low carb, or ketogenic, diet and we've used our stores...this makes sense. If we aren't it doesn't. How many grams of carbs are you eating? This is a good question for you to start with.
So, the recommendation to do your cardio after you lift works for a very few elite or specialized athletes. It doesn't work for people with hundreds of grams of carbs in their diet. Or for people with plenty of stores. When should you do your cardio?
When ever it fits into your schedule. You control which energy system (fat or glucose) you use by how hard you work. How? By monitoring and manipulating your heart rate. When we are working at the low end of our heart rate zone we are burning a larger percentage of fat for fuel. The higher the intensity, the more over all calories but the smaller the percentage of fat. High intensity, more glucose for fuel.
For the competitor at a low body fat percentage trying to get leaner, working at a lower heart rate is better in this case. However, it takes longer. You have to have the time. This is why you see bodybuilders do more time, at low intensity. To burn the fat and spare the muscle.
But for the average person who's goal is to lose weight over all. Their goal is to burn more calories, regardless of whether they come from fat or glucose (carbs). Work at a higher intensity, burn more calories over all.
The golden nugget? If you have the energy to do your cardio after you've lifted, great. Go for it. Know the science and why. Know if you're on a low carb diet, or not. If it works for you to do it at another point in your day... That's fine too. Because for most of us, the science doesn't apply.
Don't get caught up in the minutia unless it applies to you. If you are caught up in it, learn why and ask the questions. Analyze your dietary intake so you know if it means anything to you. Bottom line, do your cardio and monitor your heart rate to know what energy system you are working in. Cardio before or after, you decide.