It's always made sense to me to do my workouts in the classic cardio-then-strength order. Cardio warms you up to do resistance training, right? Well, yes; some light cardio will increase your heart rate and warm up your muscles. 

Many people split their cardio and strength workouts into different days of the week. But if you're doing them both in the same session, it turns out that the order in which you complete them can really impact your results. If you are trying to lose weight, then it's even more crucial.

Strength Train First, Then Do Cardio

If your goal is weight loss, hitting the weights first is your best choice. "Whichever type of workout we choose to do first is where our focus will be," explained Ally McKinney, ACSM, a certified personal trainer at Gold's Gym. When it comes to losing weight and especially fat, weightlifting is typically seen as more effective than cardio, so it makes sense to do it first when you have the most energy. Additionally, when you strength train first, your body will be using up most, if not all, of your glycogen stores — a form of glucose that your body source of carbohydrates, which is your body's first choice of energy. Once the glycogen is used up, Ally explained, your body will switch to its second choice: fat stores. By the time you set down the weights and head to the treadmill or elliptical, you should be starting to burn fat instead of glycogen, which can lead to greater weight loss.

One last reason to get your strength training done first has to do with your post-exercise energy expenditure, aka how many calories you burn after a workout. "After an intense weight session, your body continues to use energy to repair muscle and burn fat cells," said Ashley Kelly, NASM, a personal trainer. Known as EPOC (excess post-exercise oxygen consumption), that's extra calorie burn that you don't get after a steady-state cardio session.

If you finish your weight session and then switch over to cardio, Ashley told Maximum Slim, you'll burn more calories during the first part of your cardio workout — as your body continues to repair and recover from the strength training — than if you'd simply started with the cardio. It may not be a huge increase in calories burned, but it's "a little extra cushion," Ally said.

The order of your workout comes down to your end goal, Ally told Maximum Slim. If you're more interested in increasing your endurance, doing cardio first is the way to go. If weight loss is what you're after, strength training should be first up. "Remember that you're going to be able to give 100 percent to whatever comes first and, depending on intensity, the second part of your workout gets whatever is left in the tank," she said.