Workout Dilemma: Cardio or Weights First?

Workout Dilemma: Cardio or Weights First?

Cardio or weights

It's a question that has been asked for ages, which should be done first, cardio or weight lifting. There are many theories going around on this topic. Some can be helpful to those serious about their personal fitness, while others are nothing short of misinformation.

The reality is: the answer to that question is very complicated. It's different for every individual. It comes down to what the person's fitness goals are.

Before making an educated decision on whether you should be doing cardio or lifting weights first when you get to the gym, it is important you understand a few things about how the human body works. Read more on how the human body works

Now, let's go over what happens to your body when you decide to do cardio before lifting weights and vice versa. 

Cardio first

Cardio before lifting weights isn't a bad idea if your goal is to be in shape with a decent amount of muscle to turn heads with. By getting to your cardio workout first, your heart rate is elevated early in your workout, as well as you internal temperature and metabolism.

You heart rate will remain elevated when it's time to start pumping iron, so you burn more calories than you would have if you were only lifting weights or decided to lift weights first.

Of course, doing cardio first also means you end up with less energy for your workout. Energy you need to get that final two reps while lifting heavy looking to put on some size.

Weightlifting first

When you go right to the weights, you have all the energy you need to lift as hard as you want. That makes it easier to build huge, bulging muscles. Also, the anaerobic energy system that your body uses to power your weight lifting session isn't as efficient as the aerobic system, so your glycogen stores are depleted at a much faster rate.

That means you start burning fat a lot earlier when it's time for an aerobic exercise.

Now that you have a solid understanding of the energy systems that power the human body and the different efficiencies of both systems, let's go through a few scenarios and figure out what works best for each person.

Scenario 1: Male looking to gain muscle

If you're a male looking to gain muscle mass, you'd be better off starting your workout with weight lifting, then finishing up with some cardio to burn off any fat your body has accumulated. Weight lifting is an anaerobic high-intensity task, so your body burns off a lot more glycogen than it would if you were performing an aerobic task.

That's leaves your body primed to burn fat once you're done lifting weights. A short 30-40 minute aerobic exercise should be enough to burn any fat you have covering those bulging muscles you've been working so hard on.

Scenario 2: Male looking to be fit and build muscle

This scenario is where most fitness-minded males find themselves. You want to have cardio for days because of the many health benefits that come with that, and it's always nice to be the only one of your friends who isn't exhausted after a game of flag football.

You also want to have nice muscles you can show off every now and then, but you're not worried about becoming the next Mr. Universe.

If this sounds like you, you're probably better off doing your cardio first, then moving over to weights. That's because getting your cardio routine out of the way first elevates your heart rate, metabolism, and internal temperature.

Once your heart rate is elevated, it stays elevated when it's time to move over to the weights. Sure, you won't have as much energy to push yourself during your weight lifting sessions, but you will burn a lot more calories and fat while lifting weights. The end result: You end up looking like a lean, mean muscle machine.

Scenario 3: Female looking to burn fat and tone muscles

Many females find themselves in this bracket where your primary workout objective is to lose fat/weight while toning up your muscles. If you find yourself in this bracket, it doesn't matter much whether you decide to start your workout sessions with cardio or weight lifting, since women who are looking to tone their muscles and burn fat generally aren't interested in doing any type of heavy lifting.

If you decide to start off with a low-intensity cardio workout, you get the benefit of having your heartrate and metabolism elevated early in your workout. By the time you're ready to start the weightlifting portion of your gym routine, your body is prime for fat loss. Since there is no desire to gain large muscles with your weightlifting sessions, the fact you won't be able to go as hard as you would have been able to if you didn't start your workout session with a cardio routine won't make any difference.

Scenario 4: Female looking to lose weight and burn fat

If your top priority when you walk inside a gym is to lose weight and burn fat, you're better off starting off with the weightlifting portion of your workout, then moving over to a low-intensity cardiovascular exercise. The reasoning for this is simple. As stated earlier, the anaerobic energy system isn't close to being as efficient as the aerobic energy system that is typically used during cardio sessions, so the glycogen stored in your body is depleted at a significantly higher rate when you're lifting weights, compared to when you're jogging or swimming for instance.

So, when you start off a workout by lifting weights, your glycogen reserves are burnt off a lot faster, forcing your body to start converting fat to energy, then eventually muscle. This is obviously beneficial to someone whose main focus is to lose weight since your body will likely start burning fat off before you even begin cardio work.

Compare that to a person doing only cardio, whose body might spend up to an hour depleting glycogen reserves before beginning the fat burning process.

What fuels the human body?

Adenosine triphosphate (ATP) is the fuel that the human body runs off. That's what allows you to contract your muscles when you're doing bicep curls. The thing is, there's only a limited amount of this ATP in your muscles at all times. When it's all gone, your body needs to make more quickly.

Energy creation systems in the human body

There are three main energy systems that power the human body. For our discussion, we only need to cover two of these systems.

  1. Anaerobic system: Also known as the lactic acid system, it works by breaking down glycogen stores into ATP via a complex chemical reaction, leaving lactic acid as a byproduct. That's where the burning sensation you feel while lifting weights comes from. This system is typically activated during high intensity short exercises. Anaerobic conversion: 1 molecule of glycogen= 3 ATP
  2. Aerobic system: Also known as the oxygen system, it works by breaking down glycogen into ATP using oxygen via a complex chemical reaction. That's why you have a harder time breathing during cardio workouts since your body needs more oxygen to create ATP. The aerobic system turns on after 7-10 minutes of light or moderate exercise. It's the reason why jogging – or any other similar low intensity activity – feels easier after the first 10 minutes. Aerobic conversion: 1 molecule of glycogen= 32 ATP (clearly the more efficient of the two systems)

From simply glancing at the conversion ratios above, it's obvious the aerobic system is a lot more efficient than the anaerobic system.

Depending on the particular activity you're performing, it can take your body up to an hour to deplete your glycogen stores. Once the glycogen is out of the way, your body begins to burn fat, then eventually muscle when there is no more fat to burn.

That's the reason why there's no clear-cut answer to the question: "Should I do cardio or weight lifting first when I go to the gym?"

The American College of Sports Medicine recommends 150 minutes of moderate to intense physical activity a week, and a mixture of strength and cardiovascular training but there's not much information out there on which should be done first.


At the end of the day, the most important thing when it comes to figuring out whether you should be doing your cardio or weightlifting first is making sure you're getting the right amount of both in the first place.

Lots of weightlifting without enough cardio, and you will likely find your impressive muscles being covered up by layers of fat. Likewise, lots of cardio without enough weightlifting will leave you looking more like a marathon runner instead of a lean, mean muscle machine.

When starting a new workout routine, before you even get to the part where you're trying to figure out whether cardio or weight lifting should be done first, you need to understand your body.

There are three main body types: endomorph, ectomorph, and mesomorph.


Endomorphs are people who are often pear-shaped, with large amounts of body fat. If you have this body type, you'll likely have a harder time burning off fat and keeping it off, so you need to factor that in when coming up with a workout plan.


Ectomorphs tend to be on the long and lean side. These are people with very fast metabolic systems, whose bodies burn off fat easily and have little problem keeping it off. Ectomorphs tend to have a hard time adding muscle mass to their frame.


Mesomorphs are the people who find themselves in-between the two groups above. Mesomorphs tend to be well-built and muscular with high metabolism and muscles that respond very well to any stimulation. These people tend to have the easiest time achieving the "perfect body."

To maximize your gains, it is important you figure out where you stand in all this. For example if you are an ectomorph trying to build muscle, you certainly want to hit the weights first.


If you have a hard time getting those layers of fat off, you'd also be better of lifting weights first if your primary goal is to lose weight. By starting off with a weightlifting workout, your body's glycogen stores are depleted at a much faster rate. Remember, the anaerobic system uses 1 molecule of glycogen to produce 3 ATPs, while the aerobic system produces 32 ATPs with the same amount of glycogen.

Since glycogen stores must be depleted before your body begins to burn fat. A person who is lifting weights will reach the point where glycogen is depleted before a person who is jogging for example. If losing weight tends to be a struggle for you, it only makes sense that you would want to start burning fat as soon as possible when you get to the gym.

Dedication trumps all

While it is important that you spend as much time as you can learning how to get the most out of your workouts, reading a bunch of articles isn't going to get you your dream body, now is it?

You still need to come up with a workout routine that's perfect for you, come up with a nutritional plan that ensures you're getting all the essential nutrients and vitamins that you need, and, most importantly, you need to go to the gym and work your backside off consistently.

There simply isn’t any substitute for hard work and dedication when it comes to sculpting the body of your dreams. Do whatever you can that makes it easier for you to stick to your schedule. Hire a personal trainer if you feel lost in a gym or just need someone to push you to work harder, and workout when it's most convenient for you so you're less likely to miss a session. If you do end up missing a session, make sure you make up for it when you can.

At the end of the day, your attitude towards working out is more important than whether you decide to do cardio or weightlifting first.