Should You Do Cardio Before or After Weights?

This question gets asked a lot. Someone will tell you it is better to do cardio before lifting weights, while someone else will have a different opinion. You shouldn’t listen to either one of those. Then, who should I listen to? – you might think. Simple, listen to yourself. This decision depends a lot on your fitness level, personal goals and other factors. So only you can know which option is the best for you when it comes to doing Cardio Before or After Weights.

The Source of Energy

Before making this decision, you should get to know your body, and how it uses energy. The main source of energy in your body is ATP – adenosine triphosphate. There are many ways to produce ATP and your body uses them all.

Possibly the best system your body uses to get energy is the aerobic system. This system primarily uses glucose, glycogen, and fat as sources of energy. Oxygen is also needed. Aerobic system produces a lot of energy. It is perfect for supplying your body with energy for those long exercises like running, biking, swimming etc.

The next system that yields a good amount of energy is the anaerobic – glycolytic system. It breaks down glucose stored in the liver and muscles as glycogen, and creates ATP. This system starts working when you do high intensity workout, because your body can’t supply enough oxygen to maintain the aerobic system.

Lactic acid is another source of energy. During the anaerobic energy production a lot of lactic acid is created. Fortunately, nothing goes to waste. The lactic acid is transferred to liver, where it is converted to glucose and sent back to muscles.

The last important system for muscle energy is ATP-PCr system. PCr is phosphocreatine. It is attached to ATP. When the muscles need to contract, PCr separates form ATP, and releases the needed energy. This system supplies the energy for very short exercises like jumping or sprinting.

How Does it All Fit Together

When you start your exercise the body uses glycose from blood, and glycogen stored in the liver and muscles. Aerobic system is the main player here. As your workout goes, your body wants more oxygen. This is why you start breading faster and deeper, while heart rate increases. As there is less glucose available, the body goes to fat for energy. Even though fat produces a lot of energy, your lungs can’t supply enough oxygen anymore and muscles switch to anaerobic system. While in anaerobic state lactic acid is created, and used to supply muscles with more energy. With increase of intensity in your workout, your body is unable to create enough energy, lactic acid builds up and causes cramps. This is where your muscles reach their limit, and you can not workout anymore.

Remember the order: aerobic glucose and glycogen – aerobic fat – anaerobic – lactic acid.

What about cardio?

Cardio is any type of exercise that causes your heart rate to go from 50% to 70% of your maximum heart rate such as running on a treadmill. You can calculate your maximum hart rate easily – 220 minus your age. So if you are 30 years old, your maximum hear rate will be 190. Your cardio exercises should get your heart rate going from 110 – 133. Cardio uses mostly aerobic system to get energy. Usual cardio exercises are running and biking, as they are simple, and effective.

Cardio Before Weights

As cardio uses a lot of energy, it can deplete the aerobic system, forcing your body to use anaerobic sources of energy for later exercises. This means that you might experience energy drop while lifting weights, and not be able to do your best.

There are some benefits to this order. A light cardio session before weights can warm up your body, get blood flowing and prepare it for what’s to come. But, if you do long cardio sessions the aforementioned depletion of energy may occur. This is probably not what you want, as it will make it harder for you to build and maintain muscles.

Cardio After Weights

Unlike cardio, weightlifting doesn’t need so much energy. So there will be some energy left for you to use on cardio right after. However, if you do some intense training, it will be hard for you to do cardio, so you might want to skip it.

Your fitness goals choose for you

This is a part where you have to ask yourself what do you want out of your workout. Is it losing weight, bulking up, maintaining what you have or something else? Never go to the gym without knowing this. Not having a plan is planning to fail.

If you want to work on your endurance (like for marathon, triathlon etc.) you should do cardio first. You will have enough energy for it, and it will increase the time you can run, swim etc.

Do you want to lose weight? Than go with lifting weights first. As mentioned weights use less energy, so you will be able to do cardio as well. Also, good weight lifting workout burns the most energy 2 hours later, while you’re resting. Cardio on the other hand burns the energy immediately, so you will get the best out of both.

If you are thinking about improving your strength, do weights first. Most of the energy will be used for muscle contraction and will give you the results you want.

When you are working on your upper body, it is completely irrelevant which you do first. As cardio doesn’t hit upper body muscles a lot, you will have energy for both no matter the order.

If you do lower body exercises, you might want to do weight first. High intensity workout will use a lot of energy, so you can skip cardio if needed.

When maintaining fitness level, you can do whichever you want first. The best practice here is to put the one you enjoy less on the first place. That way you will get it done, and not skip it.

Alternatively, you can just separate cardio and weightlifting. This will give you good results, but will require more time in the gym.

For the end – always remember to listen to your body! If you are not getting the results you want, switch it up. Test different routines, and find the one that fits you the best


Should You Do Cardio Before or After Weights?
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