Does Cardio Kill Gains? Here's Everything You Need To Know

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Does Cardio Kill Gains
Why Cardio Is Important?
Integrating Cardio
Activities To Practice
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Does Cardio Kill Gains?
Yes. Doing cardio the wrong way can interfere with your weightlifting sessions and lower the anabolic effects of lifting weights, affecting muscle growth. However, if you avoid making these mistakes, doing cardio won't lead to losing muscle mass--which is easy enough to do.

How Does Cardio Affect Muscle Gains?
Fasted Cardio: It can quickly deplete the muscle's glycogen levels. This glycogen breakdown causes the body to burn protein or muscle into amino acids, convert them into glucose, and use them as energy.
HIIT: It causes muscle damage and fatigue, affecting your strength and resistance training performance.
Running: It causes muscle damage and extreme exhaustion that impacts the body’s condition during strength training workouts.
Aerobic Exercises: It can interfere with the signals responsible for adapting the effects of strength training.

Why You Should Still Do Cardio?
While it's accurate that cardio impacts muscle mass, it's still essential for a well-rounded fitness routine. Because cardio can;
- Improve cardiovascular health
- Can help with weight loss
- Improve mental health
- Increase endurance

Integrating Cardio Into Strength Training
- Pace Yourself
- Organize Your Routine
- Eat Enough Calories

Benefits of Combining Cardio and Strength Workouts
Cardiovascular and strength training exercises are a dynamic duo that packs a powerful punch against body fat. By utilizing the rapid movement of cardiovascular exercise in tandem with muscle-building activities, your body can be finely tuned to efficiently shed stubborn fat while developing toned muscles for an optimal physique.

If you're looking to build your muscles, whether to improve your overall health or achieve a bulky physique, you might've gotten the same advice from the bodybuilders and trainers at the gym: "Don't do cardio because it will kill your gains." This notion spread quickly in the community, considering that not many people like cardio.

With this collective idea in mind, you might be prompted to stick with weight and resistance training while minimizing or even wholly disregarding cardio exercises like walking, running, or elliptical.

You might even join the other people in the fitness community that take this idea to extremes, not using the stairs or refusing to take long walks lest they "burn muscle."

But do cardio workouts hamper muscle growth? Or is that just a belief that holds little truth to it? This article aims to shed light on this issue and help you determine whether you should include cardio in your routine.

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How cardio affects muscle gains?

There is some kernel of truth to the saying, “Cardio kills gains.” Cardio exercises, like running or high-intensity interval training (HIIT), can negatively affect your muscle growth since they break down the contractile muscle proteins.

Fasted cardio, in which you wait for your last meal to digest before your cardio routine fully, can quickly deplete the muscle's glycogen levels. This glycogen breakdown causes the body to burn protein or muscle into amino acids, convert them into glucose, and use them as energy.

This conversion makes building up that lost protein difficult, especially when you’re in a fasted state post-workout. We also suggest keeping The Best Quality Propel Watermelon nearby for this.

What’s more, cardio may also “interfere with the molecular pathways responsible for adaptations to strength training,” according to Exercise Physiologist Heather Hart in her interview with Live Science.

Hart says combining cardio and strength or resistance training inhibits muscle buildup since it downregulates the mTOR pathway, which is stimulated during anaerobic exercise.

Meanwhile, some studies found that HIIT can interfere with muscle growth, though not for the same reason as fast cardio. The main reason why this particular workout has an impact on muscular development is that it causes more muscle damage and fatigue, which then affects your performance during strength and resistance training.

Running has also been found to significantly affect your body’s ability to gain muscle the way HIIT does; by causing muscle damage and extreme exhaustion that impacts the body’s condition during strength training workouts.

Aerobic exercises can also affect the muscle growth of women, especially if they do so during their menstrual cycle. Women are likely to build up muscle more effectively during their menstrual cycle due to the low hormone levels in the body.

However, doing cardio exercises like brisk walking, jogging, and running while on your period can interfere with the signals responsible for adapting the effects of strength training.

Depleting energy stores is another suspected reason cardio exercises, combined with muscle-building workouts, may inhibit strength or muscular gains. That’s because a person tries to do too much in a single workout session and fails to get adequate rest between routines.

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A case for cardio exercises

While there is scientific evidence that cardio affects muscle mass, these facts can be misleading if not explained or understood correctly.

Muscle loss due to depleting glycogen levels occurs if you do cardio for at least 60 minutes or more — that means you don’t have to worry about burning protein if you only do a fasted cardio workout for 30 minutes or less.

On the other hand, protein breakdown caused by muscle damage and fatigue can be prevented by taking enough rest between your workout sessions, mainly if your routine consists of a mix of cardio and strength training.

Additionally, cardio is best after your strength workout if you want to do both training sessions simultaneously. It’s also ideal for keeping your cardio routine short and low-intensity following your weight-lifting session.

Taking ample breaks between sessions and doing low-intensity cardio workouts helps your body fully recover, prevents bodily signals from interfering with each other, and allows adaptation from either routine to sink in the body entirely.

Moreover, doing too much cardio can hinder muscle growth even if you’ve been doing most things right (eating correctly, getting enough sleep, lifting weights, and separating your workout routines).

If you’ve been following your strength training program for most of the week, doing the same amount of running or HIIT might throw off your progress. So, it’s best to dial down the frequency and hours of your cardio sessions per week instead of keeping it proportionate to your strength workouts.

TL;DR: Cardio significantly negatively impacts your muscle gains if you do it too much or too little and don’t have enough rest between your workout sessions.

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Why should you still do cardio?

Endurance training can affect muscle building negatively, but only if it’s not done correctly. Creating and undertaking a well-rounded cardio routine will go a long way in helping you reach your fitness goals, even if it’s focused on muscle growth.

Having robust cardiovascular health and improving your endurance is crucial for strength training. Doing so boosts blood flow throughout the body, which helps delayed onset muscle soreness (DOMS) to go away much faster. A faster recovery from DOMS means you’ll have more time to progress in your strength training routine.

Additionally, doing cardio can work wonders for the skin. The improved blood flow from this workout provides significant health benefits such as boosting oxygen and nutrient delivery and removing waste products like free radicals.

Enhanced blood circulation also promotes collagen production and the renewal of skin cells. However, note that your skin might still break out even as it expels waste products during your workout session. You can prevent this by following a good workout skincare routine.

Moreover, improving your cardiovascular system through aerobic exercises provides other significant health benefits, such as lowering blood pressure and cholesterol and enhancing the body’s ability to burn fat.

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Benefits of combining cardio and strength workouts

Cardio and strength training are two types of exercise that yield disparate results. While one increases cardiovascular health and reduces the risk of many heart-related conditions, the other helps you lose or manage weight and increase your metabolism.

But the differences in their outcomes make these exercises a powerful combination for achieving a healthier body. The most significant effect of mixing cardio and strength workouts is that it speeds up the fat-burning process in the body.

The rapid and continuous movement of the body during cardiovascular exercise, when combined with muscle-building activities of strength training, effectively targets body fat while helping with muscular development. Simply put, these exercises balance each other out and yield results leading to fat loss.

This improved calorie-burning process makes it easier to remove additional fat when you start cutting. Cutting is when you undergo a calorie deficit and do a lot of weight training to lose fat while maintaining or building as much muscle as possible.

Meanwhile, increased muscle mass assists in better and more powerful movements during cardio. That means the improved form to prevent injury, maximize your workout session's benefits, and better target muscle groups.

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Integrating cardio into strength training

If you’re primarily into strength training, it can be difficult to overhaul your routine and incorporate cardio exercises into your sessions. Here are some things you can do to make this process easier:

Pace yourself

It may be tempting to get as much cardio in your routine as possible at the onset to reap its benefits, but, as mentioned before, doing too much has adverse effects on your muscle gains.

So, taking it slow and spacing out your routines is best instead of going all out in your workout sessions. Alternate between cardio and strength training every week instead of doing them back to back on the same day.

If you want to squeeze in some cardio during strength day, consider doing so at least six hours after weight training. It’s the ideal window that allows your body to fully recover and helps it absorb the benefits of each workout.

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Organize your routine

As mentioned, doing your strength training before cardio is the best way to combine these exercises if you’re aiming for muscle growth. By prioritizing resistance training, you’ll have more energy to complete your reps and minimize interference to subsequent adaptations.

You should also keep your cardio sessions short (below 90 minutes) for each session. Where 60 minutes is the mark that glycogen levels start to deplete, an hour and a half of cardio increase this process of breaking down protein — thus reducing muscle gains.

Eat enough calories

Getting the proper nutrients and calories is always necessary, even if you’re building muscle and endurance. Increasing your calorie intake will fuel you with enough energy to complete both workout sessions and recoup lost proteins.

Before starting a strength training session, eat carbohydrates with a low glycemic index, such as nuts, beans, fruits, and sweet potatoes before your session. These food items take longer to digest and will sustain you while lifting weights.

After your resistance workout, eat high-protein foods such as milk, fish, or chicken to stimulate muscle development and aid recovery. Consuming carbohydrates also helps recharge glycogen levels that were lost during strength training.

Carbohydrates and proteins are macronutrients that you should also consume before a cardio session. Consider eating fat one to two hours before your workout for added energy, especially for low-intensity or longer cardio routines. Our Best Ten Reviewed Nutrition Journal Products should help you manage your nutrition.

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Cardio activities to include in strength training

There are many fun cardio exercises that you can incorporate into your resistance training to help improve your endurance and build up your strength. Here are some activities that will get your heart pumping without interfering with the effects of your strength training.


This form of exercise simultaneously burns body fat and builds muscles. The variety of movements involved in burpees allows it to target major muscle groups in your body, such as your triceps, abs, chest, glutes, quads, chest, hamstrings, calves, and shoulders.

Jogging or running

This cardio exercise is a great way to reach muscle groups in the legs that resistance routines might overlook. Adding a well-paced run between your weightlifting sessions can help prevent muscle deterioration and increase muscle development.

Moreover, the increased strain on your legs during a run or jog — after a full recovery from your strength training — will make them appear more defined.

Jump rope

Jumping rope can be an excellent alternative to running or jogging. It’s a full-body workout that helps build coordination, improves weight loss, and targets different muscle groups.

The repeated jumping motion works out the muscles in your lower extremities, while the continuous movement of the rope exercises parts of the upper body such as shoulders, arms, pecs, biceps, and even the abs.

Jumping Jacks for leg workouts

Jumping jacks

Like jump rope, doing jumping jacks also builds leg strength. It exercises all the key lower body muscles and improves the condition of your glutes, hamstrings, quadriceps, hips, calves, and shins.

Strengthening your legs through jumping jacks can improve your ability to squat, deadlift, and jump vertically.

Box jumps

This is a type of exercise that aims to increase leg strength by moving all of your body weight. Jumping from the ground to an elevated surface efficiently works out the glutes, hamstrings, quads, abductors, adductors, and calves.

Box jumps also improve your stability and mobility, helping you become more coordinated with your movements and improve your balance.


A long-standing notion in the fitness and weight-lifting community is that cardio should not be part of a body-building routine since it burns away muscle tissues.

It’s an understandable concern, considering aerobic training does affect muscle growth. However, it can also harm those who wish to stay on top of their cardiovascular health while also reaching for gains.

Finally, cardio and strength training are essential to your fitness routine. Instead of sacrificing one for the other, it’s best to create a balanced composition program that complements both exercises.

Answers And Questions

How Much Cardio Should I Do?

The amount of cardio you should do depends on your goals. If you're looking to lose weight, you'll need to do more cardio than if you're looking to build muscle.
typically, people trying to lose weight will do anywhere from 30-60 minutes of cardio per day, 3-5 days a week.

What are the Benefits of Cardio?

Cardiovascular exercise has been shown to improve heart health by decreasing the risk of coronary artery disease, high blood pressure, stroke, and other chronic conditions. Cardio also helps to increase overall lifespan by promoting better health and preventing disease.

Guest Author


Myrtle Bautista

Myrtle is a journalism major, a social media marketer and is now exploring freelance writing. She's fond of anything related to health and wellness, and when she's not writing, you'll find her doing long-distance cycling, ultramarathons, hiking, or in a local cafe enjoying a good cold brew.

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