top of page
  • Writer's pictureBrad Cunningham

Why Cardio Is Bad For Fat Loss

If the headline brought you here, I’m sorry to ruin all hope of you not having to do cardio, this post is certainly not a fight against cardiovascular training (a.k.a cardio), in fact I think you need it just as much as strength training, I actually want to share with you a little insight into why it’s not great for fat loss goals or strength based performance goals to do it before your strength workouts.

I will often get clients asking the question, “Can I do cardio before my strength sessions?” Firstly I think it’s great when people want to step up their training, and in short, there is an effective way to train twice in a day or back to back, and a not so effective way, and in this blog I want to share with you what the most effective method is for Fat Loss based goals.

Before we get into the main reasons why, it's important to understand what's happening on a biological level with your muscles when you train.

First here’s a little sciency snippet to add weight to this post:

[Quote " Due to the intense and short-term nature of individual bouts of resistance training, it would seem likely that this activity would be highly dependent upon muscle glycogen for ATP provision. High-intensity exercise of short duration (&Mac178; 30 seconds) is characterized by a rapid breakdown of phosphocreatine for the production and use of ATP, as well as stimulation of glycogenolysis (breakdown of glycogen) and glycolysis (breakdown of glucose), with a lesser contribution of oxidative metabolism.

In a study by Tesch et al. (1986), nine bodybuilders completed five sets each of front squats, back squats, leg presses, and leg extensions to fatigue, comprising 30 minutes of exercise. Biopsies of muscle samples were obtained from the vastus lateralis before and immediately after exercise. Muscle glycogen concentration was 26% lower post-exercise, a rather modest decline considering the demanding exercise protocol completed. This led the authors to conclude that energy sources in addition to muscle glycogen support heavy resistance training. Data from Essen-Gustavsson and Tesch (1990) with nine bodybuilders performing the same exercise regimen (as above) revealed a 28% decrement in muscle glycogen content as well as a 30% decrease in muscle triglyceride content. This suggests that intramuscular lipolysis (breakdown of triglycerides) may also play a role in energy production during repeated high-intensity exercise. Overall, research suggests that intramuscular glycogen is an important fuel supporting weight training exercise, but not the only substrate.” end quote] Taken from

When you train, particularly strength training, your body needs to rapidly use and replenish ATP (Adenosine triphosphate).

The first ten seconds of activity utilizes the ATP readily available in the cytosol of our cells. After that timeframe our body needs to resynthesize ATP from glucose and our stored glycogen.

So while you strength train, your body is utisling stored carbohydrates in the form of glucose, it’s then broken down through glycolysis to assist in resynthesizing of ATP.

So let's for a second imagine how your muscle will function and perform without or with low glycogen levels. Basically your ability to resynthesis ATP, which is the energy your muscle uses to contract, is going to be majorly hindered, therefore effecting your output and overall performance.

And why do we strength train in the first place? It's to increase our strength and lean muscle, to improve our movement, ability to perform day to day to tasks and from a fat loss point of view, remember the more muscle we have the higher our metabolism or fat burning ability is, because muscle tissue requires a lot of energy to maintain.

But if you’re training in a depleted state, it’s going to be hard to train hard enough to cause a training adaptation, and reap the fat loss benefits of strength training.

For those that do a full cardio workout prior to strength training, what you’re doing is creating a depleted state or environment for your muscles to work in. Therefore making your strength training session far less beneficial.

So if you are going to do strength and cardio workouts back to back here’s what you should be doing:

1. Strength train first, utilise your stored glycogen to perform well, lift heavy and create enough stress on your muscles to encourage a training adaptation to occur.

2. Do your cardio after strength training, the goal of cardio is often one of two things, 1) To increase aerobic capacity or 2) to increase fat oxidation. Neither of these 2 things require a huge amount of stored glycogen, it’s more about the rate at which your lungs and heart are working. Therefore it doesn’t matter as much if you are semi depleted from your strength workout prior.

3. Keep the cardio short and sweet 30-45min maximum 60min of High Intensity Interval Training. Interval training is best for Fat loss goals, as it will ensure you don’t begin to breakdown and utilise muscle tissue as energy. If you are going to training for longer than an hour, you may want to supplement with Branch Chain Amino Acid's (BCAA’s) to reduce muscle tissue breakdown. If your cardio goal is endurance based and you need to train for more than an hour, then you should be doing your strength and cardio sessions on seperate days, as you require more energy for both workouts.

I hope you enjoyed today's post, please feel free to share. - Coach Brad

310 views0 comments

Recent Posts

See All


bottom of page