Written by Kyle Ustach | BScEcon
Fact checked by Andrew Lenau, ISSA CPT & Sports Nutritionist
FACT CHECKED
Don't feel bad if you're always looking for excuses to skip the cardio session; you are like most gym-goers. One of the most common reasons that lifters avoid cardio is because of the notion that it kills gains. Considering that you need to consume calories to gain weight and cardio burns calories, it makes sense why so many people believe this. So, does cardio burn muscle tissue?
If cardio kills gains, why does every IFBB professional bodybuilder do cardio? In this article, we will dive into the research and listen to what some of the top IFBB professional bodybuilders think about how cardio training impacts muscle growth.
Table of Contents
- Why Do People Think Cardio Kills Gains?
- Science That Supports Cardio
- How To Combine Cardio and Lifting Properly
- Order Of Exercise
- Jay Cutler On Cardio For Muscle Building
- Other Pros Takes On Cardio
- Other Benefits Of Cardio
- FAQs
Why Do People Think Cardio Kills Gains?
Let's get it out in the open; CARDIO DOES NOT HURT GAINS! The incorrect idea that cardio kills gains has existed for several decades, as countless people have abided by this belief. While the origin of this concept is unknown, we can trace scientific research from 1980 that supported this concept.
In this experiment, they compared muscle growth over ten weeks for a cardio endurance group (E), a strength group (S), and one that performed both cardio and resistance training (S and E). The results predictably showed the most significant increase in the strength group and no strength gains in the endurance group.
The aerobic and resistance training group made gains on pace with the strength group in the first seven weeks before declining in the final weeks. They concluded that combining aerobic and resistance exercises will hinder strength gains, but the results are deceiving.¹
The participants performed cardio for 40 minutes six days a week, combined with five strength training workouts for another 30-40 minutes. That is an absurd amount of time to spend in the gym and certainly considered overtraining, so it makes sense the participants started to lose strength. The extended cardio sessions likely caused their bodies to go into a catabolic state, which causes muscle protein breakdown.
The body needs greater muscle protein synthesis than muscle protein breakdown to build muscle tissue. Muscle protein synthesis is the process where amino acids create muscle tissue. Overtraining, like the participants in this study, is one of the most common ways to cause muscle protein breakdown. Overtraining can also cause other negative consequences, including:
- Risk of injury: When muscle protein breakdown occurs, the body fatigues faster and is at higher risk of injury.
- Nutrient deficiency: Overtraining depletes the body of important nutrients, especially ones that contribute to energy in the workout.
- Hormonal issues: Overtraining can cause an increase in stress hormones, including cortisol.
Science That Supports Cardio
More recent studies have shown that cardio actually helps promote muscle growth rather than a negative effect. A study from 2012 compared resistance training versus resistance training with aerobic exercise in young adult men for five weeks. The results showed greater strength and peak power in the aerobic plus resistance training group.²
A similar study examined untrained men for 21 weeks, dividing them into three groups: strength, endurance, and concurrent training. The combination of weight training and endurance exercise to maximize muscle strength is called concurrent training (CT).
The strength and endurance groups did two weekly workouts, while the combined group performed two of each workout. The results showed an 11% increase in muscle cross-sectional area in the combined group compared to 6% for the strength group and only 2% for the endurance group. This shows that a moderate volume of cardio combined with resistance training is the most effective way to optimize muscle hypertrophy.³
A workout routine where you lift weights three to four times a week with one or two cardio sessions would be ideal. Too much cardio can be counterproductive because the body will start to break down muscle tissue.
How To Combine Cardio and Lifting Properly
While arguments can be made for both sides, it's clear that the real key regarding cardio's effect on muscle growth is volume and intensity. Early studies, like the one we listed from 1980, had participants severely overtraining.
- Volume: As we saw with the experiment from 1980, too much volume will hurt gains. Keeping a moderate volume is key, with weight training as the main priority. To maximize muscle growth, you should only do two to three cardio sessions a week in addition to weight training. Limit your cardio sessions to 20-30 minutes to prevent muscle damage.
- Intensity: The intensity at which you perform cardio is also important for maintaining or gaining muscle. Steady-state cardio is one of the worst methods for muscle growth. Steady-state cardio is a technique where you maintain the same intensity for an extended period (30-60 minutes), such as with jogging or walking. If your body is in a caloric deficit, the body will break down amino acids from muscle tissue for energy. This can lead to catabolism and cause you to lose muscle. A better approach for muscle growth is moderate-intensity or high-intensity interval training (HIIT). Too much high-intensity cardio can negatively impact gaining muscle if performed too long. HIIT is time-efficient and effective, making it perfect for strength training. Another method that promotes gains is moderate intensity with resistance, such as circuit training. Low-intensity steady state (LISS) is another strategy that supports muscle growth. To learn more, check out our article What Is LISS Cardio and Should You Be Doing It?
To summarize:
- HIIT, LISS, or low-intensity training and low volume for muscle growth.
- Steady-state cardio or high-intensity for extended periods with higher volume for fat loss.
As always, you should listen to your body and adjust accordingly, but one or two weekly cardio sessions with lifting weights appear to be the sweet spot for most people.
Order of Exercise
Aside from managing the volume and intensity of your cardio sessions, you must also consider the order in which you perform them. The general school of thought amongst gyms is that you should always do your cardio after lifting to ensure you have optimal energy to maximize your lifts. One study tested this by examining the effect of 30 minutes of moderate intensity (55% of maximum oxygen consumption) cycling on muscle hypertrophy.
One group of participants performed the cycling immediately after lifting weights, while the other group performed the cycling on a separate day of the strength training. After eight weeks, both groups had increases in muscle cross-sectional area, but the group that performed cardio on a separate day had roughly 50% more muscle growth than those that did cardio immediately after lifting.⁴
Other studies have shown similar results, indicating that cardio and weight training should be separated by at least a few hours to give the body time to recover. A separate study examined how the duration of recovery time between endurance exercise and lifting weights affects muscle building in a concurrent training program. They divided participants into a control group, a weight training group, and concurrent training groups with either zero, six, or twenty-four hours between cardio exercise. The results showed the most significant gains in strength of the bench press and half squat for the group with 24 hours of recovery time, followed by six hours of recovery. They concluded that people should ideally allow 24 hours, with a minimum of six hours, of recovery between lifting workouts and cardio to maximize gains.⁵
These studies show that cardio should be separated from weight training, with ideally six hours between. If you need to do both at the same time, do the weight training first.
Timing Summary:
- If your goal is muscle building, the best time for a cardio session is ideally six hours before or after lifting weights or first thing in the morning with low intensity. If you're doing both in the same workout, lift weights first so your muscles are fresh. High-intensity interval training (HIIT) can also be used for building muscle.
- If your goal is losing fat, you should perform cardio first in your workout. Fasted cardio in the morning is a great technique as well.
To learn more about the best way to lose body fat, check out our article What Is The Best Cardio To Burn Fat?
Jay Cutler On Cardio For Muscle Building
Arnold Schwarzenegger, Ronnie Coleman, and Jay Cutler are often considered the kings of bodybuilding, among a few other legends. Cutler, a four-time Mr. Olympia champion with six runner-ups, sculpted one of the best physiques of all time by combining cardio and resistance training. Cutler explains how he uses cardio training in the attached video.
"I do a lot of cardio, I do my fasted cardio in the morning. I have everything at my house, whether it's bike, treadmill, step mill, or elliptical, I do it all. Remember, cardio is necessary when you're trying to lean down, and increase metabolism. I prefer to do it either first thing in the morning or after the weight training session. Pay attention to that because you don't want to burn up glycogen prior to working out with weights. So, really focus on adding your cardio as necessary, but remember the training is the most important thing."
Cutler's point of view lines up with conventional research, suggesting that weight training should be the focus, with a few light cardio workouts mixed in.
To learn more about Jay Cutler and hear his tips, check out our articles Exclusive 2023 Q&A With Bodybuilding Legend Jay Cutler and What Is The Jay Cutler Bodybuilder Workout Routine?
Other Pros Takes On Cardio
If you have any doubt about the conflicting research, several top professional bodybuilders have addressed the debate, "Does cardio burn muscle?"
Rich Piana: Legendary bodybuilder and fan-favorite Rich Piana (RIP) had a massive, lean physique that reached 315 lbs at 6'1". In a YouTube video posted on his official account, Rich acknowledges that the "old school" opinion that cardio kills gains is entirely wrong.
"They used to say 'a lazy bodybuilder is a good bodybuilder.' I have to say that times have changed, and honestly, cardio helps you grow. Yes, cardio helps you grow. If you're feeding your body enough to make up for those calories you're burning, what happens is cardio turns your body into a machine. The faster the machine is, the more muscle you can put on, the faster the food goes through your body, and the faster your body processes the protein. Having a fast metabolism and eating a ton of calories is the best way to put on the most muscle mass."⁶
Chris Bumstead: Chris Bumstead is arguably the top active bodybuilder on the planet, winning the last five Mr. Olympia Classic Physique titles. Bumstead, known as CBum, is very open about his fitness regimen, including the importance of cardio. In a YouTube video he posted, he goes through his full day of eating leading up to the Olympia. "I do like a 20 or 30-minute light walk at night mainly for digestion."⁷ In a separate podcast interview with Chris Williamson, CBum revealed his routine is fluid in the off-season, but he has a strict schedule during contest season that involves cardio. During contest prep, Chris will start his day with Wim Hof breathing exercises, followed by 20 minutes of light cardio, then a sauna and ice bath.⁸
Phil Heath: Phil Heath, a 7-time Mr. Olympia winner, is a bodybuilding legend who has openly discussed the importance of cardio. Heath posted a video on his Instagram account (@PhilHeath) where he debunked the idea that combining cardio exercises with weight lifting will burn muscle. "Of course, cardio stands for cardiovascular health. Alright? So, what don't you wanna exercise your heart? I see a lot of guys specially on social media, talk about how, 'oh I wanna don't cardio because it's gonna ruin my gains.' Well, guess what, you're gonna need your heart to build a pump, as you pump those weights." Heath does cardio training three to four times a week in addition to his strength training. His favorite cardio exercises include the incline treadmill, stationary bike, or running on the treadmill.⁹
Other Benefits Of Cardio
A common misconception in the fitness world is that you should only do cardio when trying to lose weight. This aligns with the concept that cardio kills gains because people think it is only used to lose fat. There are several other benefits of performing cardio in addition to weight training. These health benefits include:
- Cardiovascular health: Regardless of your weight or goals, exercising the heart and cardiovascular system is crucial to overall health. Cardio exercise strengthens the heart, lungs, and overall cardiovascular heart. Cardio also improves blood vessel health by growing more blood vessels, which allows muscle cells to use oxygen more efficiently and generate more energy.
- Boost metabolism: Performing cardio helps boost your metabolic rate, which is important for body composition. A faster metabolism improves energy levels, helps maintain muscle mass, and burns more calories at rest to keep the body lean.
- Improve recovery: Cardio helps to keep the heart pumping, which means an improved blood flow. Improved blood flow helps to remove waste, like lactic acid and metabolic byproducts that cause soreness. The improved blood flow also helps nutrient delivery to the muscles.
- Increase aerobic capacity: Aerobic training improves the body's ability to use oxygen during exercise. This can help in the gym because your body can perform better for high-intensity workouts.
- Mobility/Joint health: Doing low-impact cardio, like walking, cycling, or swimming, can improve mobility and joint health.
- Mental health: Cardio and exercise, in general, help release endorphins that lower stress and improve your mood. Exercise is one of the best ways to relieve stress.
FAQs
Below are some of the most commonly asked questions related to cardio and strength training.
Does cardio burn muscle?
Yes and no. If you perform cardio either after your workout or at least six hours after lifting weights, in combination with eating enough calories, you can build muscle. You will lose muscle if you perform too much cardio in a caloric deficit.
Should I do cardio if I'm already skinny?
Yes, cardio has several other benefits besides just weight loss, including heart health, increasing muscle, and boosting metabolism.
How much cardio should I do to avoid muscle loss?
You should limit cardio to two to three times a week when trying to build or maintain muscle mass. If you are trying to lose weight, you can do cardio every day.
Does Cardio Kill Gains? Only If You Let It
Based on all of the research and input from the best bodybuilders in the world, it's clear that cardio does not kill muscle gains when they are done correctly. While "old school" logic and research suggest cardio will burn muscle, modern studies suggest that aerobic training helps gain muscle. Cardio workouts should be performed on a separate day or at least six hours apart from resistance exercise. If you need to hit both at once, perform the weights workout first while your muscles are fresh.
If you doubt the research, take the word of the most respected bodybuilders in the world, who all support cardio and strength training to maximize muscle growth. Top pros and multi-Olympia winners like Jay Cutler, Phil Heath, and Chris Bumstead all do aerobic training without muscle breakdown. Even the legendary mass monster Rich Piana stated the old-school logic was wrong and cardio was important for gains. If you want to maximize muscle gains, take it from the best in the business and do your cardio two to three times a week!
References
- Hickson, Robert C. "Interference of Strength Development by Simultaneously Training for Strength and Endurance." European Journal of Applied Physiology and Occupational Physiology, vol. 45, no. 2-3, Dec. 1980, pp. 255–263, https://doi.org/10.1007/bf00421333.
- Lundberg, Tommy R., et al. "Aerobic Exercise Does Not Compromise Muscle Hypertrophy Response to Short-Term Resistance Training." Journal of Applied Physiology, vol. 114, no. 1, 1 Jan. 2013, pp. 81–89, https://doi.org/10.1152/japplphysiol.01013.2012.
- Mikkola, J., et al. “Neuromuscular and Cardiovascular Adaptations during Concurrent Strength and Endurance Training in Untrained Men.” International Journal of Sports Medicine, vol. 33, no. 09, 15 June 2012, pp. 702–710, https://doi.org/10.1055/s-0031-1295475.
- Tomiya, Shigeto, et al. "Moderate Intensity Cycling Exercise after Upper Extremity Resistance Training Interferes Response to Muscle Hypertrophy but Not Strength Gains." Journal of Sports Science & Medicine, vol. 16, no. 3, 8 Aug. 2017, pp. 391–395, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5592291/.
- Robineau, Julien, et al. "Specific Training Effects of Concurrent Aerobic and Strength Exercises Depend on Recovery Duration." Journal of Strength and Conditioning Research, vol. 30, no. 3, Mar. 2016, pp. 672–683, https://doi.org/10.1519/jsc.0000000000000798.
- Rich Piana, Youtube. https://www.youtube.com/watch?v=Y0LVNrWxLiM
- Chris Bumstead, YouTube. https://www.youtube.com/watch?v=329QPlGL4zM&t=7s
- Chris Bumstead with Chris Williamson, YouTube. https://www.youtube.com/watch?v=oPGeI2D1yn8&t=1s
- Phil Heath, Instagram. https://www.instagram.com/philheath/reel/_5MiU8pYhK/
Kyle Ustach
Author