Mallory Griffis

Mallory Griffis

Which Comes First... Cardio or Weights?

Cardio and resistance training are often put together in programs and can improve your athletic performance. Both of these can be extremely important when it comes to altering body composition and overall health. However, when someone is working with a plan that strategizes both, there always seems to be confusion about which should come first. And no, this isn’t referring to a 5-10 minute pre-lift warm up you may do before lifting. Those warm-ups are extremely important but this is an article to discuss cardio training sessions.  Here are a few things to look at to determine the timing:

Fatiguing Your Body: Mentally and Physically

Those who have been in the fitness world a little longer will understand that doing cardio before a lift can be exhausting. Thus, providing less energy during their workout. The misconception about when to do cardio generally comes from novice gym-goers. For those who aren’t comfortable or familiar with gyms, the safe zone is usually a treadmill or elliptical. Cardio equipment at a gym is seen as a safe place to shy away to for those less experienced. It’s okay to start where you are comfortable, but that’s where ideas of doing cardio before lifting usually come from.

An issue that is often associated with doing cardio first is fatigue. Excessive amounts of cardio can quickly tire your muscles and limit the amount of force exerted during lifting. Even if you don’t feel tired or sore from your cardio session, your muscles are still impaired. This will impact the force needed to move weights around and affects the energy systems used.

After a workout, your body continues to burn calories up to 48 hours. This is known as excess post-exercise oxygen consumption. EPOC occurs because your body is repairing the muscles that you broke down during exercise. It occurs at a much higher rate after intense weight-training that puts a lot of strain on your muscles as opposed to low-intensity, steady-state cardiovascular training; that’s why it’s important to put as much energy into your lifting sessions as possible. If you do steady-state cardio before you lift, you won’t have the energy to work as hard as you can. A less productive weight-training session can impact EPOC.

Use of Your Energy Systems

The body has three types of energy systems. These are ATP-PC, Glycolytic, and Oxidative. Each energy system will play a role in different activities depending on the intensity:

  1. The adenosine triphosphate–creatine phosphate (ATP-CP) system, or phosphagen system. This supports very brief, high-intensity activities. These are fast, explosive, and strong movements. (Approximately 12 seconds of high-intensity energy per round).
  2. The glycolytic system. This system provides energy for activities of slightly longer duration and lower intensity. Generally, this energy source is used when you’re doing moderate training. (Approximately 30 seconds to 2 minutes of energy per round).
  3. The oxidative system. This supports long-duration, lower-intensity activity. These include long steady state activities. ( Approximately 2 minutes and more minutes of energy).

So what does that mean for you and your training? Understanding your energy sources can help you determine what type of cardio you do on your lifting days.  For example, if you’re performing high-intensity sprint work, you’ll tax energy systems that heavier lifts require. This is why lifting should take priority over cardio training when performed on the same day. You may find it helpful to plan your type of cardio around what type of lifting you do.  

For example: if your workout has a lot of heavy power movements, you’ll need to save the ATP-PC energy for your lift, so slower cardio that uses the oxidative system as an energy source would be best. This also works the other way around: if your training for the day is a lower intensity lift with high reps, try pairing it with explosive cardio for maximal energy output in both areas.

Understanding Your Fuel Sources

There are three types of energy your body uses during and after your workouts: protein, carbs (glycogen), and fats. Which one your body uses depends on what energy system you’re using. This also ties along with your body’s two main fuel systems: Anaerobic and aerobic systems.

  • Anaerobic system: Breaks down glycogen using a complicated chemical reaction that leaves lactic acid as a by-product. This is responsible for the intense burn you get after running intense sprints or doing a set of explosive lifting.
  • Aerobic system: Uses an even more complex chemical reaction to break down glycogen into ATP using oxygen. This is why you breathe harder during cardio than strength training. Your body needs more and more oxygen to sustain your workout. Your body can’t burn fat without oxygen.

During anaerobic exercise (weightlifting) your body will run off the ATP-CP system, using your glycogen storage for muscle contraction. Once your body burns through this storage, it will transition to burn fat instead as a secondary fuel. Since the aerobic system is more efficient in generating ATP, weight training first allows you to burn through glycogen faster. Thus, getting to the fat burning portion of the workout faster than if you had done cardio first.

Although there are many more benefits to doing your cardio after a lifting session as opposed to before, there is no one-size fits all approach to a training plan that works for you. Doing what you’re comfortable with should always be a priority and whatever you have to do to get it done, is the most important. However, if you’re looking to take your routine to the next level, having this knowledge and scheduling your cardio accordingly will help you turn it up a notch.

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