Does Cardio Kill Gains? Or Help Gains?

We’ve all heard the bro science, “dude, cardio kills your gains, what are you doing?”! Some of us (see: me) are stuck there doing cardio for hours on end when we binge on our diets too hard. We all wonder, Does Cardio Kill Gains?

I’ve always had a theory that even if you go way over your TDEE, if you add some cardio it may actually make your gains better.

Today, we will look at scientific research and evidence with sources cited to explain this and try and see what the truth is! (This is important to me and a learning experience for me too!)

Rich Piana always said doing an hour of cardio a day would cause you to grow like crazy, so let’s see if the giant was speaking the truth.

Does Cardio Kill Gains? An ab machine for growing muscle in the gym or inbetween cardio.
Ab machine for growing muscle in the gym or in between cardio. Does Cardio Kill Gains?

Does Cardio Kill Gains? – Introduction

For starters, all of my sources will be cited in the sentences and at the bottom of this post. For starters, it is no secret that for someone to build muscle they NEED to be in a caloric surplus. This means they need to actively be gaining weight to gain a “significant” amount of muscle (more than .1 lb a year basically).

While some studies have said lean muscle mass can be produced during a time of caloric reduction, this science is still new and the subjects in the study didn’t gain much muscle mass at all compared to a caloric surplus. For this article, we will assume that if you want to gain the most amount of muscle you will be bulking (which 99% of bodybuilders will be doing to gain muscle usually).

Does Cardio Affect Muscle Growth if I End Up In a Caloric Deficit? – Does Cardio Kill Gains?

This article published by LDNMuscle provides a simple answer to the above question.

They basically say if you do so much cardio you end up losing weight at the end of the day, you will not be gaining muscle.   This is a simple answer, but I will be covering other examples later in this blog post.

In short, if you run so much you burn 1,000 calories and only ingest 2,000 calories a day, your total calorie allowance will be 1,000 calories out of your 2,000 calories required.   Therefore you will lose .33 lbs and not gain any weight, therefore not gaining muscle mass.

The article also states if you do cardio so tough that you are unable to lift weights normally. Then this will affect your muscle growth too.  So, if you end up doing so much exercise your total calories in is less than calories out, eat more!

Arnols Schwarzenegger riding his bike and looking huge, answering our question “Does Cardio Kill Gains”?

Doing Too Much Cardio May Actually Hinder Your Gains!

An article published on by PhD Ciaran Fairman cited many scientific studies saying way too much cardio (5-6 days of 1+ hour of cardio) can slightly hinder muscle growth. However, he also cited that 2-3 days of average cardio had shown to increase muscle gains.  

Additionally, he cites that running places lots of strain on the body. Fairman also says that cycling in the weight room is a great alternative that keeps your joints healthy!

Overall, the verdict in his article is saying if you’re doing absolutely massive amounts of cardio daily it will slightly hinder your muscle growth.

But it is highly unlikely you are actually doing that large amount of cardio. That is, unless you are preparing for a marathon.  

Additionally that article that PhD Fairman cites was published in 1980. Since then,many newer scientific articles published in 2013 state that cardio actually supports gains.

To recap once more, if you’re not training for a triathlon, you’re fine.

The Benefits of Cardio to Your Lifting Sessions – Does Cardio Kill Gains?

Now that we know if we aren’t doing a massive amount of cardio our gains will be fine. We should actually consider how cardio actually helps our lifting sessions!  

For starters, this article by excellently explains how doing cardio increases your body’s ability to get oxygen to your muscles and causes cardiac hypertrophy.

Cardiac Hyperthrophy is when your heart muscle grows to become more efficient.  

Cardiac Hyperthrophy that happens after lots of cardio, allowing your heart to pump more blood. This is useful when wondering if Cardio Kills Gains.

This can therefore lead to you being able to lift weights easier and more efficiently, therefore helping you in the long term.

I would assume if you have really strong heart health it may make you it’s better for you long term.

Those “gains” you lost with your massive exercise will not happen because you’re lifting much more efficiently and stronger than before triggering more muscle hypertrophy.

More On Cardiac Hypertrophy and When You Should Do Cardio – Does Cardio Kill Gains?

This article published by Coach Tanner Baze of cites how cardiac hyperthrophy and helping grow their body’s ATP energy systems will help you push through plateaus in the weight room.

He even cited a famous marathon runner Alex Viada who boasts a whopping 700 lb squat.   Baze also mentions how if your heart can pump more efficiently, it will boost your recovery.

However, he did mention that doing cardio the same day you weight-lift may be bad. This is due to the effect of the muscle tissue damage it will cause on those days you’re already lifting. He mentioned trying to do it far away from your lifting sessions or on your rest days.

Russ Howe, PTI shows us that cardio will not kill your gains, it’s just a meme. “Does Cardio Kill Your Gains”? NO!

Baze also says it is reality that cardio can “kill” gains, but only a small amount of it. Baze finishes his article by restating how sometimes it ends up helping you in the long-term.


Overall we learned today that cardio CAN kill gains, but most of the time it won’t. It may actually help you!

If you’re running for hours everyday you will likely see some failure in your muscle hypertrophy.

But, a good mix of cardio 2-3 times a week for 30 minutes can easily help you push through plateaus, make your heart stronger, and boost your recovery.


LDNMuscle:, Ciaran Fairman:

5 thoughts on “Does Cardio Kill Gains? Or Help Gains?”

    • Hmm, interesting. It all depends on your diet really. To be fair, if you do not eat enough and you do a lot of cardio you will lose weight and some muscles. Sometimes that’s not always a bad thing.


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