Timing Your Cardio: How to Optimize Your Gym Routine for the Best Results

CNET

22-07-2025

If you work out, you will have at some point wondered about whether you should start with weights or cardio. Whether you're already deep into your fitness journey or just getting started, you've probably had this question. You've probably also wondered if the order even matters. There's no scientific agreement on whether cardio before or after weights is better. As such, it all comes down to your goal: improving your overall health, gaining muscle or losing weight. To get an understanding of how to time your cardio sessions to help you lose weight or build strength, we talked to a personal trainer. Here's what we found out.
What are your fitness goals?
When it comes to deciding whether to do cardio or weights first during your workouts, it's a good idea to start with your goals. Do you want to lose weight or gain muscle tone? Maybe you want to improve your endurance or build bigger muscles.
One common misconception is that cardio is the most important exercise for losing weight, but both cardio and strength training are important for this.
Benefits of doing cardio before weights
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Cardio is well-documented to be effective at burning calories. If you lift weights for 30 minutes versus doing any other cardio activity for the same amount of time, cardio will burn more calories. With that in mind, you may want to start your workouts with cardio at a steady intensity to get into the heart rate zone you need for burning fat. You can then transition into weight lifting, which will create an "afterburn," that helps burn calories after you're done exercising.
You don't even necessarily need to work your body hard to reap the benefits of a cardio workout. "Cardiovascular exercise at a lower intensity (in the fat burning zone/aerobic training zone) will help you to lose weight. [But] it needs to be sustained for longer periods of time," said Mollie Millington, a personal trainer based in London.
Lifting weights first, especially if you are lifting heavy using your entire body, will tire you out before you make it to the cardio portion of your workout. That means you might cut your workout short and not reap the calorie-burning benefit of cardio -- especially if you want to burn as many calories as you can in a set amount of time. Try both starting with cardio and starting with weight lifting to get a sense of what works best for you. If you are performing exercises with light weights, that can help get your heart rate up and get your body ready for running, biking or another cardio activity.
Lastly, if you like to run, bike or swim and want to improve your speed or overall endurance, then choosing cardio first is smart because you're going into those workouts fresh. This way you are starting with the most important exercise for your long-term goals and will make progress more quickly.
Benefits of doing weights before cardio
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If your main goal is to improve your strength, be able to lift heavy things or build more muscle, then lifting weights first is best. Don't tire out your body by doing cardio first. The less tired you are, the more repetitions you'll be able to do with correct form -- and good form is crucial for performing strength training exercises safely and effectively.
Doing weights first may also be helpful for fat loss when combined with cardio, according to Millington. "In theory, doing weights first would put your body into aerobic mode [so] by the time you to get to running, you will already be in aerobic/fat burning state. So you may maintain [that aerobic state] longer while running and thus use fat as an energy source," Millington said. This is best when you are lifting lighter weights that don't fatigue your entire body.
Can you do cardio and weightlifting on the same day?
Finally, although science is pretty inconclusive about whether doing cardio or weights first is best, one very clear thing is that doing both is beneficial. Studies show that doing a combination of the two is best for overall health, increasing muscle and reducing body fat.
If you want to do both cardio and weight training at 100% effort, then you can try doing them on separate days, allowing your body to recover in between. If you prefer to do both at once, see what feels and works best for you.
"I am a firm believer in doing what you love. Exercise can be fun," Millington said. "If you are in the groove during your warm up on the treadmill and having fun, don't stop to do weights. Keep going until you are ready to change to weights. Or if you prefer weights to running, start off with a shorter run and then 'treat' yourself to weights," Millington said.