• Darshini Krishna

Should I Do Cardio If I'm Trying To Build Muscle?

Updated: Aug 15



This is a question I often get asked especially from clients that are trying to put on muscle.

In this article, we are going to explore the main purposes of cardio training, and if there are any negative effects that cardio has on the muscle building process.

We will look at how to best implement a cardio regime alongside our resistance training for the best physical adaptations, in terms of hypertrophy and strength.

But first of all, we need to be on the same page as to what resistance training and cardio is. So let’s define it.

Defining Resistance Training and Cardio

Resistance training is any exercise that uses resistance to cause muscular contraction with the expectation of increases in strength and size of muscle tissue.

Cardio is aerobic exercise that is performed continuously and for relatively extended periods of time, usually 20-60 minutes or longer.

Typically, people differentiate between resistance training and cardio by looking at the training modality being used. For example, anything that utilizes free weights, machines or resistance bands, they would consider resistance training. While cardio includes the likes of running, cycling, rowing, swimming.

It is possible to elicit a cardio-effect from weight training, but in this article we are going to focus on the more traditional forms of cardio.

Why Perform Cardio?

You may notice that the first thing people turn to when they want to lose fat is to start doing more cardio, most usually running. While cardio may help you burn more calories, it does not mean it will help you lose more fat. Other than the obvious caloric expenditure effects that cardio has (elaborated in point 2 below), cardio serves other purposes as well.

1- Cardio & Metabolic Health Benefits

First of all, cardio or metabolic work trains your cardiovascular system- your heart, lungs and blood vessels. The gold standard for measuring cardiovascular fitness is VO2max.

VO2max represents the maximum amount of oxygen your body can effectively use during exercise. The higher your VO2max, the more aerobically fit you are.

2- Caloric Expenditure

Next, doing cardio can help increase your caloric expenditure. If we are looking at your total daily energy expenditure, calories burnt from dedicated cardio sessions would come under exercise activity.

While cardio is commonly used by gen pop who are seeking fat loss, cardio needs to be implemented strategically for those chasing specific physique changes.

More specifically, it should be added as a toggle on top of a strength training program in fat loss phases to speed up the rate of fat loss, alongside a smart nutrition protocol. My take is that it need not be added during building phases, especially if your cardio system is not currently a limiting factor in your training. Overall, calories expended from exercise make up a mere 10% of your daily output, so trying to create a deficit purely through cardio is insufficient. Or worse trying to outwork your diet through adding more cardio sessions is extremely inefficient.

3- Appetite Regulation Effect

Performing cardio also has also been shown to have an appetite regulation effect in terms of influence on appetite-related hormones, reducing food cravings, and increasing cognitive restraint. All of these points are particularly helpful when you are in a fat loss phase. Again, not the main reason why you would implement cardio then, but definitely positive side-effects.

4- Quality of Life & Well-being

Improved cardiovascular fitness also generally improves your quality of life and wellbeing- both the years of life, and life in your years.

Cardiorespiratory fitness is a strong predictor of all-cause mortality. Having better cardio fitness will also help you feel less strained while performing activities of daily living which is something we could all benefit from.

Performing cardio regularly can also help boost overall energy and reduce stress levels.

Will Cardio Help Me Build Muscle?

Yes and no. If you are untrained, even cycling has been shown to lead to some muscle growth.

However, if you are no longer a complete novice, your cardio sessions are not going to lead to any significant muscle growth.

You should place a heavy emphasis on strength training as the main means to drive muscle growth. "But Cardio Improves My Work Capacity"



This is true, having better aerobic fitness means you won’t be gassed as fast in your resistance training sessions.

This could influence how well you can recover between sets, and thus how much total volume you can tolerate in a training session.

So yes, cardio could have positive spillover effects for muscle building

But this is going to depend on various factors. First one being, the current state of your cardiovascular fitness. We all know that there will be adaptations when you train something. Do more cardio = create adaptations = you get better at it. But aerobic fitness does not directly translate to hypertrophy or strength gains, especially if your aerobic capacity is currently not the limiting factor in your training sessions.

Increasing your VO2max alone, does little in the way of building muscle, and it surely is not going to get you jacked.

The rep ranges you are training in also matter.

If you are performing heavy lifts for low reps and resting 3 to 5+ minutes between sets, your cardio fitness matters less.

The longer rest periods you are taking is more than sufficient for you to recover before your next set.

Typically speaking, your cardio fitness is more applicable when you are training at higher rep ranges. And since now know that hypertrophy occurs at all rep ranges as long as we are taking our sets close enough to failure, our training program should constitute of a combination of sets across low reps (3-6reps), medium reps (7-12 reps) and high rep (13-20+ rep) ranges.

If your goal is to put on as much muscle mass possible, or in girly terms become toned, realize that the main driver of hypertrophy (building muscle) is still mechanical tension. In other words, the sheer amount of tension you are applying to your muscles, and this can only be done through strength training.

So while there is some merit in a higher VO2max, improving your cardio system is not going to dramatically alter your hypertrophy outcomes.

What If I Want The Best Of Both Worlds?

So you have made it this far down the article, but you are still convinced you want to include some cardio in your training routine, but you are scared cardio will kill your gains. Well, cardio may not automatically kill your gains, but it can definitely limit it. This is basically what researchers call the Interference effect.

Where it has been found that people generally gain less muscle mass and strength when doing both resistance and aerobic training compared to if you are only performing resistance training.

However, things are rarely as black or white- do only cardio, do only strength training.

Most people want to and probably should do both for all the reasons previously stated. I personally believe there is a time and place for both, and what we need to focus on is understanding what causes greater interference, and how we can do our best to strategically avoid it.

How To Implement Concurrent Training?

The first recommendation would be to opt for a modality of aerobic training that has lower levels of interference, such as cycling, rower, incline treadmill walking, stair stepping or the elliptical over running which has a larger interference effect.

Next, to err on the most conservative side, if your schedule permits, complete your cardio and resistance training sessions on different days altogether. I.e. Strength train on Monday, Cardio on Tuesday, Strength train on Wednesday. If you need to do them on the same day, then do your strength training session first in the day, and cardio in the next session. You should also try to separate your resistance and endurance training by at least 6 hours if possible. But realize that at the end of the day, most of us simply need to train when our schedule allows us to.

So what ends up being practical may not be optimal. And that is okay.

Optimal and practical aren’t the same. And practicality always takes precedence.

However, if you do have more flexibility in your schedule, it’s worth switching up your training sessions to limit the interference effect. A question also worth considering here is which is your priority at the moment? For most people chasing aesthetic goals, strength training should always be a mainstay in your program. But depending on your current fitness level and needs, and whether you are currently in a gaining or fat loss phase, you can adjust the frequency, length and even modality of your cardio sessions accordingly. Whatever it is, remember your goals aren't static and you can be fluid with how you structure your training to find the best fit for you at this moment in time. Hopefully this article helps you gain some clarity and shed some light on this very popular topic! If you're looking to improve your body composition and want a detailed guide explaining how you can get started and specifically how much cardio you should be doing, definitely download my free guide on this! For 1-1 coaching and guidance to achieve your physique goals, apply for coaching here.

Alright that is from me, time to crush!!!

- Darsh

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