The Great Debate: Should You Do Cardio or Weights First?

Precisely how to schedule your sweat sesh for your goals.

Fast Facts

  • Mixing strength training and cardio in the same workout session can make your workouts more efficient, but might reduce your performance.
  • For endurance, do cardio before weights.
  • To build muscle, do weights first.
  • For general fitness, timing matters less; but we suggest doing weights first—the stakes are higher at heavier loads, and lifting when low on energy can increase your risk of injury.

Ask any personal trainer exactly what you need to do to be fit, and they’ll ramble off a list of training targets. At the bare minimum: two days of strength training a week, 150 minutes of low and slow zone 2 training, and a session or two of HIIT cardio. It’s a lot. But whether you’re working out to live longer, get stronger, build endurance, or feel good, research shows the juice is worth the squeeze.

The problem: there’s only so much time in the day. Unless you’re an athlete or riding the gains train (mad respect), odds are good you’re cramming workouts into a single, efficient session just to get it in. Whether you do cardio before or after weights or combine them into a merciless metabolic workout, the most important thing is you get it done.

But will doing cardio and weights in the same workout stunt your muscle gains? And what’s the best way to sequence cardio and strength for faster progress? Here’s everything you need to know.

Should You Do Cardio and Weights on the Same Day?

The debate is still alive and well. Thanks to the Chronic Interference Hypothesis—which claims that strength training is anabolic (or builds muscle) and aerobic exercise is catabolic (or breaks it down)—many people believe doing cardio and lifting weights on the same day can hinder muscle gains.

However, according to renowned exercise science researcher, Brad Schoenfeld, Ph.D., CSCS, CSPS, FNSCA, this view is oversimplified.

On an episode of FoundMyFitness, he explains to doctor Rhonda Patrick that at some point cardio will interfere with gains, but it likely has more to do with overtraining than the intracellular effect. “Within decent volumes of training there does not seem to be a blunting of the anabolic effect, and that’s even when [cardio and strength are] performed on the same day,” says Schoenfeld. He points to a recent review which found that regardless of exercise order, at normal training volumes, there’s little to no difference in muscle mass (1).

But, it also depends on your training load. If you’re walking 10,000 to 12,000 steps a day, or doing high-intensity interval training three times a week, you’re in the clear. However, turn up the volume on cardio (i.e. six, slow, long-distance runs a week), and you might begin to see a negative effect on muscle development.

In the interest of workout quality, Schoenfeld recommends alternating your cardio and strength training days if possible. If not, he suggests a morning and afternoon split, so you’re able to give each session the energy it deserves. If you *must* pack them into one session, no problem—opt for strength first, unless endurance training is your goal.


Is It Better to Do Cardio Before or After Weights?

It depends. Because your energy is limited, the workout that will make the most impact on your primary fitness goal should come first. Why? With more energy in the tank, you’ll put up your best performance—whether that means better form, more reps, a faster pace, or more distance covered.

Here’s how to break it down:

  1. If you want to build endurance, do cardio before weights.
  2. If you want to lose weight, do cardio after weights.
  3. If you want to get stronger, do cardio after weights.
  4. If you want to build general fitness, do cardio after weights.

Why the emphasis on strength training? Doing cardio first can compromise your energy levels and performance during a strength workout. Lifting heavy loads requires your body to perform at a high level; tamper with performance and you increase your risk of injury. By lifting first, you ensure you have all of the mental and physical energy to execute each rep safely and effectively.

When to Do Cardio Before Weights

To warm up

It’s essential to increase blood flow and range of motion in your muscles before you work out—whether that workout is strength training or cardio. Ideally, your warmup should include light cardio, and dynamic stretches and exercises that mimic the range of motion you plan to use during your workout.

Whether you hop on a cardio machine, jump rope, or stick to bodyweight exercises like mountain climbers and jumping jacks—aim to slowly increase your heart rate over the course of five to ten minutes. Just keep it low-intensity. Going ham on cardio during your warm-up can zap your energy (and performance) before the rest of your workout (2).

To increase endurance

If you’re training for a big endurance event, such as a triathlon or marathon, you’ll want to put cardio front and center. If you’re doubling up on sessions, do cardio first to improve cardiovascular endurance; then, polish off your workout with some lightweight, high-rep strength exercises to increase muscular endurance.

If you have a satellite strength-related goal—such as increasing your deadlift PR or nailing your Turkish get-up form—save it for a low-intensity cardio day. Lifting heavy before a cardio workout can reduce your economy and performance during your cardio sesh (3). And stacking heavy strength work after high-intensity cardio increases your chances of loading already fatigued muscles, which can reduce your movement quality and increase your risk of injury. If you have to double up, try to separate intense cardio and strength training by at least six hours (4).

When to Do Weights Before Cardio

To build muscle

Do cardio after weights if you’re looking to build strength. Why? Lifting is hard. In order to build muscle, you should be lifting somewhere between 65 to 85 percent or more of your one rep max. You’ll need all the physical and mental energy you can muster to move those heavy loads with proper form.

The science agrees. When researchers compared strength training alone, with running or cycling followed by strength training—they found that doing cardio before a weight lifting session reduced the amount of reps participants were able to eke out during their strength workout (5). It also reduced peak performance and velocity.

To lose weight

When it comes to weight loss, cardio gets all the attention. It burns more calories than strength training, and if you had to pick between the two it’s more effective at reducing total body mass than strength training (6). Plot twist: Do weights first.

Cardio is great for burning calories and losing weight, but if you’re in a caloric deficit it can also eat up lean muscle mass (7). The more muscle mass you have, the higher your resting metabolic rate (or the amount of calories your body burns throughout the day at rest). In other words: Muscle keeps your metabolism humming, so you want to keep it around.


The Bottom Line

Cardio won’t eat up your gains (unless you’re overtraining), so it’s okay to pack both cardio and strength training into one efficient session. Whether you do cardio or weights first also won’t impact your results on a cellular level; but, it may affect your energy levels—and thus, performance. Prioritize the workout that makes the greatest impact towards your fitness goals first.