Should You Do Cardio Before or After Weights?

Cardiovascular (aerobic) exercise, aka "cardio," is an essential component of any workout routine, regardless if your goal is to build muscle mass or burn fat. Many bodybuilders and gym-goers understandably dread doing a cardio workout before weight training, but the other option — doing cardio after lifting weights — is easy to neglect if you're feeling exhausted and just want to call it a day.

So, what's the best order of operations: Cardio or weights first? Well, it depends, but for the most part, it seems that cardio workouts are best saved until after weight training if your goal is to lose weight and gain muscle.

But there are other factors to consider when doing cardio and weight training in the same workout session. For some people, it may be optimal to do a light cardio warm-up before resistance training.

Read on, and we'll analyze both sides of the cardio-or-weights-first dilemma.

Cardio and Weight Training: Adversaries or Allies?

It's traditionally assumed that cardio and strength training are at odds with one another; if you focus on cardiovascular exercise instead of weight lifting, you'll have a harder time building muscle. Conversely, lifting weights and not doing any cardio exercise can make it challenging to lose body fat consistently.

The reality is combining cardio and strength training in the same workout session, also known as concurrent training, may have synergistic effects when done appropriately [1, 2, 3]. However, intense cardio sessions should ideally be separated from weight training by several hours or more to minimize acute interference of muscle-building and fat-burning pathways [4].

Naturally, for those looking to combine low-intensity, steady-state cardio and weight lifting when they hit the gym, the question is, "Should you do cardio or weights first?" The answer to this is relative and a bit nuanced. Let's take a look at what research has to say on the matter.

Cardio or Weights First for Improving Body Composition

A meta-analysis of 15 studies found no differences in muscle fiber hypertrophy between groups that performed cardio before or after strength training in the same workout session [5]. However, another meta-analysis demonstrates significant detriments in strength-training performance when cardio is performed beforehand [6].

Moreover, strength gains tend to be greater in individuals who lift weights first and do cardio after than in those who do the inverse [7]. Further research suggests that performing cardio after strength training results in a more favorable muscle-building milieu than doing cardio prior [8]. Yet, these findings are discordant with more recent observations that the order of endurance and resistance training has no significant effect on anabolic signaling [9].

Interestingly, several studies have found that both testosterone and cortisol levels were greater in subjects that performed moderate-intensity cardio before intense strength training [10, 11]; this might imply that it's best to do cardio before strength workouts for optimal weight loss. But again, doing cardio before lifting weights will come at the expense of strength and stamina.

The long-standing debate about whether you should do cardiovascular training before or after lifting weights is more so a matter of personal preference and performance goals. Despite some equivocal findings in the literature, it's hard to argue against saving cardio until after resistance training because low-intensity, steady-state cardio is less strenuous than lifting (heavy) weight.

Why Lifting Weights Before Cardio Is (Probably) Ideal

The salient takeaway is that it's likely better to do cardio after pumping some iron for body composition purposes. Doing so will also allow you to put more energy into your strength workout, which should take precedence over cardio if you want to pack on muscle mass and cut body fat.

Intuitively, using up all your energy to do cardio will hamper your strength. And even if your main desire is to lose weight, weight training should get the bulk of your attention in the gym. You can learn more about why that is in this article: Weight Lifting for Weight Loss.