Which Should You Do First, Cardio or Weights? Here's What Fitness Trainers Say

My workouts have basically been the same since I started going to the gym in high school: I do cardio for about 30 minutes, then I hit the weight room for 30 minutes. In college, that was bumped up to an hour of cardio followed by an hour of lifting (which was not very healthy, and I do not recommend it!), but my timing was always the same: cardio first, strength training after.

Ever since I started going to Orangetheory Fitness a couple of years ago, I've kept the format the same: I always do the treadmill portion first, which is about 30 minutes, then I'll do the weights (another 30 minutes). My thinking goes that I'll get the most taxing (and sometimes boring) portion of the workout, cardio, out of the way so I can focus on lifting. Plus, the cardio gets my heart rate up to crush the weight room. Turns out I've been working out all wrong for the past 15-plus years.

I tapped a few certified personal trainers to see which was a better option: cardio first or strength training first? And while many trainers recommend not even doing both during the same workout — you should dedicate some days of the week to just cardio workouts and others to strictly strength training — some people prefer to incorporate both in the same training session or go to mixed-format studios like Orangetheory and Barry's Bootcamp.

For the most part, they agreed you should strength train first, then do cardio — but there's a catch. Here's why.

Why You Should Strength Train First

"For overall muscle growth, I recommend weights first so you can utilize your maximum stores of muscle glycogen, which is stored energy, for your strength session," ACSM-certified personal trainer Jim White, RDN, owner of Jim White Fitness and Nutrition Studios, told POPSUGAR. "Oftentimes, if you burn yourself out with cardio before weights, you can use up a lot of your energy, causing a lower exertion during your weight-training session."

NASM-certified personal trainer Nick Bolton agrees. He explained that when you step in the gym, you have a limited supply of energy, and you want to prioritize your energy expenditure. "Strength training requires the most energy to perform," he said. "In order to make the most of your workout, you need to be able to get quality sets in, which requires engaging more muscle fibers by performing more sets and reps under an appropriate amount of weight." He added that when you lift first, you also have more energy for the proper technique, which is crucial to seeing results and preventing injury.

However, before you hit the weights, Jim recommends warming up for five to 10 minutes. Here's a dynamic warmup to get you started.

In General, It Depends on Your Goals

Although the conventional wisdom goes that lifting first will help you with strength gains, it ultimately depends on your goals. If you are looking to gain muscle and get stronger, then lifting first is key. NASM-certified personal trainer Cary Williams, CEO of Boxing and Barbells, agrees with this sentiment. However, that order is not best for everyone.

"If you are working on improving your run time and need to knock out three miles along with your weight training, you may want to hit the treadmill first when you have more energy, and then do weights after," she told POPSUGAR, adding that you will push harder with the first thing you do.

Ryan Fairman, ACSM-certified personal trainer, echoed that statement. He said weightlifting first is best for people who are looking to improve strength or gain muscle, but cardio first is ideal for someone gearing up for a race or who wants to improve their heart health. "Energy is lost during both types of exercise . . . you will feel less fatigued at the beginning vs. the end," he told POPSUGAR. "Having a goal will make the distinction of which one you choose."

Not to mention, if you spend too much time scrolling to find the perfect playlist and run out of time during your workout, whatever is second will be cut short (guilty!). For years, I would sacrifice my weight training because cardio took too long, which didn't lead to any progress.

So while hitting the weight room first will help improve your muscle mass, if that's your objective, it may not be the best option for you if you're focused on improving your mile time. Decide on your ultimate goal and go from there.

Not sure how to approach your workouts now that you have this information? Here is a four-week workout plan for you to follow; it has strength-training and running workouts scheduled for separate days.