Does Running Really Kill Your Gains?

One of the longest-standing myths in the fitness world is that running a few miles will lead to a body that is lean and devoid of muscle mass. You’ve probably seen the common meme that has a picture of marathoners who look like they’re a few steps from dropping.

This is used to say, “See, this is what running will do!?” But is that reality? Will running kill all your gains? This article will break down these claims while also giving you advice on keeping your muscles.

Is Running Good For Bodybuilding? 5 Points To Consider

A few caveats should be made when speaking about this topic, as it’s highly nuanced. 

There is truth that running can blunt your growth and strength, but it’s important not to blindly suggest this applies to every situation. (Sporer & Wenger, 2003). Keep these points in mind;

1. There is a difference between an actual bodybuilder, a hybrid/cross-training athlete, general fitness, etc. We can go on and on, but different trainees have different needs. An actual bodybuilder who has a significant amount of mass is at much greater risk of dropping mass compared to an average lifter.

2. If building mass is your ultimate goal, running is probably not the best option. Setting nuance aside, running consumes a significant amount of calories while also causing muscle damage during longer durations. Other sports, such as cycling, seem to support muscle mass (Murach and Bagley, 2016), 

3. There are many variables that dictate whether “running is bad for muscle growth”. This can include: duration, nutrition, total volume, and order of training (Fyfe et. al, 2014). 

4. If you don’t want to run, don’t. But you do need some aspect of cardio. This article is not necessarily about convincing you to run. It’s simply pointing out some misunderstandings, so if you simply hate it, include something else.

5. Running is the most natural, athletic, and functional movement we can do. Suggesting running is going to eat all your muscles ignores the natural athleticism that humans possess.

Lifters Vs. Runners: The Marathon Strawman

Perhaps the largest tactic used to “prove” running will make you skinny is pointing to marathon runners, often compared to a sprinter or a bodybuilder. 

This is insincere.

Thinking that running will make you skinny because a marathon runner is skinny is similar to girls pointing to female bodybuilders and saying, “I don’t want to lift weights because I don’t want to look bulky”.

Lifters know how silly that sounds because there is a lot that goes into building muscle that many people don’t realize. Well, the same thing is true for running.

The training regime of bodybuilders is nothing like a marathoner, so comparing them is misleading.

Runner Vs. Bodybuilder

Here is a quick comparison that shows how drastic the differences are.

Needs and Training of a Marathon Runner 

1. Advanced runners perform high weekly mileage (100km+)

2. Their runs regularly last longer than 60min with many lasting 90-120min

3. Many runners perform minimal strength training. When they do, muscle hypertrophy is not a main goal (Here’s a proper running strength workout)

4. Runners don’t want to have excessive muscle mass. Building large amounts of mass simply isn’t conducive to their sport. 

5. Runners consume extreme caloric expenditure through running, in relation to their BMR

Think of it like this: I can find a skinny gamer who doesn’t lift weights. Does that mean gaming makes you skinny? Of course not. Not lifting makes you slim. Running doesn’t erase muscle — neglecting strength training does.

Myths vs Reality: Will Running Kill Your Gains?

Myth 1: Cardio cancels out strength gains

Reality: The “interference effect” is real but dose-dependent.

Research does show that endurance training can blunt hypertrophy, but primarily when performed in higher volumes (Wilson et al., 2012).  Interestingly, detriments were most significant in power athletes while less pronounced in strength and muscle growth.

This specific research recommends that when building mass, stick to 3 or fewer sessions of 20-30 minutes.

Other research found that running 3 km (∼18 minutes) did not diminish performance, whereas running 5 km (∼30 minutes) and 7km (∼42 minutes) did. Mind you, this was specifically a strength performance, but it demonstrates the nuance (Panissa, et. al, 2022)

Myth 2: All endurance training is catabolic

Reality: There’s a big difference between running 3, 5k, 10k, and 42k. And nutrition matters.

When speaking about running, the general population will hear things like “cortisol” and “muscle breakdown” and immediately assume it means you’re losing mass. However, did you know that resistance training can also increase cortisol and even rates of muscle protein breakdown?

Now obviously, lifting weights can increase muscle mass, so what’s happening? Pointing to a single mechanism doesn’t prove the outcome, as there are dozens of processes going on. 

Just because cortisol is catabolic, it doesn’t mean muscle catabolism will occur every time you run.

It’s crucial to consider all the training variables in order not to interfere with hypertrophy (Fyfe et al., 2014):

• Nutrition
• Resistance training
• Running volume and duration
• Recovery

In addition, a recent meta from Schumann et. al (2022) concluded:

“The main finding was that concurrent aerobic and strength training did not interfere with the development of maximal strength and muscle hypertrophy compared with strength training alone.”

Myth #3: Running Eats Your Muscles

Reality: Muscle breakdown is dependent on nutrition and running duration.

Running with high volume and improper nutrition can definitely have a negative effect on your muscles.  Long-distance runners usually put a lot of stress on their bodies, including:

• Increased muscle damage due to high miles
• High levels of cortisol for a prolonged duration
• Running with lower levels of muscle glycogen after 60 mins of constant exercise

However, this tissue is not inherent to running; it’s inherent to their running.

A typical gym-goer can easily mitigate muscle loss through running by;

• Following simple nutrition guidelines
• Managing total running volume.
• Keeping single running sessions to 20-45 mins.

Myth 4: Runners are skinny because they run

Reality: Runners are skinny because they want to be skinny. They also don’t perform progressive weight training. At least the ones used to make the argument.

People will look at professional runners and make a judgment on its effect on the body.

But consider this: This would be like pointing to an eGamer and saying, “See, playing games makes you skinny.”

Obviously, this isn’t an exact comparison. However, you can’t say “running makes runners” skinny when the reality is they’re not trying to put on muscle! 

Most advanced runners don’t make weight training a main component of their training apart from a prehab angle for various reasons:

• They’re focused on running.
• Having excess muscle makes them slow. 
• It’s simply not a goal (not everyone wants large amounts of mass)

Running isn’t supposed to build muscle, so unless that person has a component of hypertrophy training, there’s no reason they would have muscle.

Is Running Going To Kill Your Progress In The Gym?

The truth is in the middle; running can hurt muscle hypertrophy if volume isn’t managed, yet it can possibly enhance your training and even increase muscle development when done properly. (Tan et. al, 2023).

If you want to include running in your program and keep your progress, follow these simple guidelines.

How To Include Running in a Bodybuilding Program

However, even in these conditions, we still recommend a component of running.

1. Keep mileage moderate. There’s no hard number, but for those who are running for fitness but want to maintain mass, 45 minutes should likely be your max run time. 

However, keeping your total running time to three sessions of 20-40 minutes is likely good advice for general lifters.

2. Lift heavy. Obviously, you need to be lifting! Be sure to include compound movements and still apply progressive overload.

3. Separate sessions. If possible, separate your running and lifting sessions by at least 6 hours, ideally 8 or more. Further, try to lift in the morning if possible (Sporer et. al, 2003).

4. Fuel Properly. Nutrition is still going to play a role in your training. Be sure to eat sufficient calories and macros. 

• Calories: Be sure to calculate any added energy expenditure
• Protein: 1.8-2.2 g/kg/bw
• Fat: 30%
• Carbs: Fill in the rest

Further, avoid doing longer runs while fasted. Be sure to consume nutrition before any longer runs.

5. Recover. Sleep, hydration, and deload weeks matter for both cardio and lifting. Be sure to plan your week to ensure you can optimize your training.

References 

1. Fyfe, J. J., Bishop, D. J., & Stepto, N. K. (2014). Interference between concurrent resistance and endurance exercise: Molecular bases and the role of individual training variables. Sports Medicine, 44(6), 743–762. https://doi.org/10.1007/s40279-014-0162-1
2. Fyfe, J. J., Bartlett, J. D., Hanson, E. D., Stepto, N. K., & Bishop, D. J. (2016). Endurance training intensity does not mediate interference to maximal lower-body strength gain during short-term concurrent training. Frontiers in Physiology, 7, 487. https://doi.org/10.3389/fphys.2016.00487
3. Murach, K. A., & Bagley, J. R. (2016). Skeletal muscle hypertrophy with concurrent exercise training: Contrary evidence for an interference effect. Sports Medicine, 46(8), 1029–1039. https://doi.org/10.1007/s40279-016-0496-y 
4. Panissa, V. L. G., Greco, C. C., Ribeiro, N., Julio, U. F., Tricoli, V., & Franchini, E. (2022). Concurrent training and the acute interference effect on strength: Reviewing the relevant variables. Strength & Conditioning Journal, 44(3), 46–57. https://doi.org/10.1519/SSC.0000000000000668
5. Sporer, B. C., & Wenger, H. A. (2003). Effects of aerobic exercise on strength performance following various periods of recovery. Journal of Strength and Conditioning Research, 17(4), 638–644. https://doi.org/10.1519/00124278-200311000-00005 
6. Schumann, M., Feuerbacher, J. F., Sünkeler, M., Freitag, N., Rønnestad, B. R., Doma, K., & Lundberg, T. (2022). Compatibility of concurrent aerobic and strength training for skeletal muscle size and function: An updated systematic review and meta-analysis. Sports Medicine, 52(3), 601–612. https://doi.org/10.1007/s40279-021-01587-7
7. Tan, J., Krasilshchikov, O., Kuan, G., Hashim, H. A., Aldhahi, M. I., Al-Mhanna, S. B., & Badicu, G. (2023). The Effects of Combining Aerobic and Heavy Resistance Training on Body Composition, Muscle Hypertrophy, and Exercise Satisfaction in Physically Active Adults. Healthcare (Basel, Switzerland), 11(17), 2443. https://doi.org/10.3390/healthcare11172443 
8. Tomlin, D. L., & Wenger, H. A. (2001). The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Medicine, 31(1), 1–11. https://doi.org/10.2165/00007256-200131010-00001 
9. Willis, L. H., Slentz, C. A., Bateman, L. A., Shields, A. T., Piner, L. W., Bales, C. W., Houmard, J. A., & Kraus, W. E. (2012). Effects of aerobic and/or resistance training on body mass and fat mass in overweight or obese adults. Journal of Applied Physiology, 113(12), 1831–1837. https://doi.org/10.1152/japplphysiol.01370.2011