How Cardio Will Help You Build More Muscle

If you’re someone who’s only worry within fitness is building muscle, then cardio is probably the last thing you’d think would help.

However, it seems to play an important role in improving your body’s ability to build muscle.

How you structure your cardio will look much different for these purposes than it would if you were trying to build high levels of cardiorespiratory fitness.

So, in this article we’ll discuss why cardio actually helps you build muscle and how to set up your cardio for best results.

Why does cardio help muscle building?

Cardio isn’t going to directly help you build more muscle mass.

Also, there probably aren’t going to be any immediate benefits to adding cardio to your resistance training routine.

Rather, adding some cardio to your routine is more like a long-term investment.

To start, here’s what you need to understand: it isn’t the cardio itself that will help you build more muscle. It’s being better at cardio that will.

Improved recovery in between strength training sessions

For instance, this study had their subjects perform 6 weeks aerobic conditioning with one leg, but not the other. Then, they had the subjects perform a 10-week strength training routine and measured how much muscle was built in each leg. They found that the leg that performed the 6 weeks of aerobic conditioning build significantly more muscle across all subjects.

Why would this happen? Well, one of the main adaptations to cardio is an increase in structures called capillaries. You can think of these as the exit ramps that take blood, oxygen, and nutrients from the veins to the muscle.

The more of these you have in a muscle, the better the recovery will be for that muscle. The better a muscle can recover, the more progress it will make over time.

This increase in capillary density also leads in an increase in satellite cell proliferation. These are stem cells within muscle tissue that play pivotal roles in repair and growth of muscle.

The researchers in the mentioned study measured the capillary density of each muscle: the one that performed the 6 weeks of aerobic conditioning and the one that didn’t. The leg that performed the aerobic conditioning had significantly greater capillary density.

Improved recovery in between sets

This study had subjects perform fifteen 40-meter sprints with 25 seconds of active recovery in between sprints. They measured the subjects’ speed in each sprint as well as oxygen uptake rate in between sprints.

They found that those with the greatest oxygen uptake capacity (a fancy way to say how good their cardio is) had significantly smaller decreases in sprint speed throughout the trial. In other words, those with worse cardio had greater decreases in sprint speed throughout the trial.

I know that study looked at sprints and we’re talking about building muscle, but the energy systems used and contraction speeds experienced by the muscle are very similar to lifting weights. So, it makes a good parallel.

How to structure cardio to support muscle building

We’ve covered why it’s important to be developing your cardiovascular system even if all you care about is building more muscle.

Now, let’s talk about how to do it.

It’s worth noting: this section is going to cover how to structure your cardio for the sole purpose of supplementing and supporting the process of building muscle.

These strategies won’t necessarily help you build your cardiovascular system to a high level.

For an article that will help you build large amounts of muscle and endurance simultaneously, click here.

With that said, let’s talk strategy:

In order to do this effectively, our focus needs to be directed toward two goals:

• Not producing excess fatigue

• minimizing muscle damage

From a training standpoint, these are the only two things that can possibly contribute to an interference effect of building muscle.

The more fatigue & muscle damage occur, the less strength training you’ll be able to perform and the poorer your performance will be there. If a negligible amount of them occur, then you can reap all of the aforementioned benefits of cardio without any downside.

In order to accomplish these two tasks, there’s four things you have to get right:

• Right intensity

• Right modality

• Right duration

• Right frequency

Intensity: how hard should you go?

When the purpose of doing cardio is to support your muscle building endeavors, I recommend doing all of the work at a zone 2 intensity (click here for an in-depth breakdown on zone 2 cardio).

This intensity is classically defined as 60-70% of your maximum heart rate. If you don’t have a means to track your heart rate, you can think of this as the ‘conversational’ pace. In other words, this is the intensity where you’re moving fast enough to break a sweat, but can still hold a ~15-20 word sentence without gasping for air.

The reason for this is that this intensity is sufficient enough to elicit significant cardiovascular improvements, but does not dip into the higher intensity energy systems that have the potential to produce some muscle damage.

Modality: what actual exercises should you do?

Again, our goal is to choose modes of exercise that produce very little, if any, muscle damage. There are two characteristics of an exercise that would cause it to produce muscle damage

• Eccentric loading (i.e. the lowering of a weight)

• Impact

Take running for example. There is some impact with every step, and with every step there is some eccentric loading. If you’re a beginner runner or new to cardio in general, this would make a poor option.

Note: you absolutely can build muscle & improve your running. It’s just not the modality I would choose if your only reason for doing cardio is to support your muscle building, and would require some extra programming considerations.

For the same reason, weight or bodyweight circuits would make a poor choice. There may be no impact, but there would be significant eccentric loading; which would interfere with your main strength training.

Now, let’s talk about a better example: cycling.

This form of exercise involves no eccentric loading and no impact. As a result, you’d be able to perform a much higher volume of cycling than running for the same amount of fatigue.

Some other options that make great choices (better, even) if they are available include:

• AirDyne (also commonly called ‘air bike’ or ‘assault bike’

• Ski Erg

• Concept 2 Rower

Duration: how much should you do?

First off, you should understand this: you will measure & progress your volume (duration) of cardio in terms of time per week and not time per session.

If you’re currently not doing any sort of cardio in your routine, I’d recommend starting off with 40 minutes per week.

From here, add 10 minutes each week until you are doing 80 minutes per week.

At this point, you have a choice. Performing 80 minutes per week of low intensity (zone 2) cardio will likely deliver the majority of the benefits you’re looking to achieve.

Or, you can continue to add volume and build your cardiovascular fitness. If you are doing so, you must keep the following points in mind:

• As your workload from cardio goes up, so must your caloric intake. Many people think that cardio killed their gains, when in reality they just didn’t eat enough to support the weight lifting and cardio combined.

• Zone 2 cardio is famous for being “hyper-recoverable.” In other words, your body can recover from it very easily. However, at certain weekly volumes, it can be something that itself requires recovery from. Once you get to the point of doing ~120 minutes per week, you may need to place a greater emphasis on recovery.

Frequency: How many sessions per week do you need?

When we talk about frequency, what we’re really talking about is: in how many sessions per week are we are going to split up our weekly volume (duration)?

Truthfully, you have a lot of leeway here when it comes to how to do this. You can customize your weekly schedule of cardio to however best fits your schedule, as long as it meets the following criteria:

• There are at least two sessions per week.

  • i.e. you aren’t doing all of your weekly volume in one session

• Each singular session is at least 20 minutes in duration.

  • You likely wouldn’t get very much benefit from a 5- or 10-minute session

Conclusion

When you structure your cardio regimen correctly, your capacity to recover from strength training and build more muscle increases. Using the guidelines outlined in this article, you should be able to do so with ease.

As always, if you feel you have questions that are left unanswered, feel free to email them to me directly at info@FitnessSimplified.org.