Does running build muscle?
The short answer: yes, it can—but it depends on how you train and how you fuel.
Running primarily builds cardiovascular fitness and endurance, but under the right conditions, it can also help you build lean muscle, especially in your legs, glutes, and core.
That said, not all running styles support muscle growth equally, and without proper nutrition and recovery, you could actually lose muscle instead.
In this guide, we’ll break down exactly how muscle growth happens, the role running plays, and six science-backed strategies to help you gain muscle while still logging your miles.
How Muscle Growth Works: The Science Behind Building Strength Through Exercise
Before we delve specifically into whether running can build muscle, it is helpful to understand the process of muscle growth.
Exercising to increase muscle size, known as hypertrophy training, is a two-step process.
Your workouts create the stimulus that ultimately triggers the muscle-building process known as myofibrillar protein synthesis, also referred to as muscle protein synthesis.
When you perform exercise that overloads your muscles, you create microscopic structural damage to the muscle fibers in the form of tiny tears along the length of the muscle fiber.
This microscopic damage to the muscle fibers occurs because the type of load or force you are using, or the force your muscles must generate to contract and produce movement during your workout, exceeds the current functional strength capacity of the tissue.
It may sound counterintuitive that you would want to damage your muscle fibers if you’re trying to become a stronger athlete and build muscle mass.
But the tears are what actually trigger your muscles to adapt to your workouts by becoming stronger and thicker, thereby increasing muscle size and functional ability.
Without inflicting any type of structural damage to your muscle fibers, there is little to no stimulus to begin the muscle-reparative process, which is ultimately required for muscle growth. After your workout is over, muscle protein synthesis begins to occur, provided your body has the necessary resources to carry out this process.
In order to repair the structural damage in your muscle fibers, your body needs amino acids, which come from the proteins that you consume through your diet, as well as energy, which comes in the form of calories that you have taken in.
This is the primary reason why it is crucial to stay on top of your post-run refueling strategy, aiming to consume at least 20-30 grams of protein and approximately 300 calories within the first 30 minutes after completing your workout.1van Loon, L. J. C. (2014). Is There a Need for Protein Ingestion During Exercise? Sports Medicine, 44(S1), 105–111. https://doi.org/10.1007/s40279-014-0156-z
Your body can start breaking down the protein into its constituent amino acids, shuttling these building blocks to the muscles worked by running, and then assembling new reparative proteins to reinforce the areas of structural damage in your muscle fibers.
As these new proteins are manufactured, they are inserted into the weakened areas of your muscles, reinforcing, strengthening, and thickening your muscle fibers. This results in stronger and larger muscles after the recovery process is complete.
Does Running Build Muscle?
Running has the potential to build muscle in the glutes, hamstrings, quads, calves, and hip flexors, which are the primary muscles used during running.
With that said, whether running builds muscle depends on your overall diet, your post-run nutrition strategy, and the type of workouts you are doing.
If you do not have these three factors dialed in to support hypertrophy, running will not increase muscle mass and may actually cause you to lose muscle mass.
Your overall diet, mainly in terms of your caloric intake as well as your intake of protein specifically, will have an enormous effect on whether you are able to build muscle while running.
Running burns calories because your heart and skeletal muscles need energy to contract as you run.
In accordance with the Third Law of Thermodynamics from physics, energy cannot be created or destroyed; it can only be transformed from one form to another.
What this means in terms of your running is that the energy (in the form of calories) you need to run must come from stored fuel, which can be oxidized during exercise to create ATP (cellular energy) for your muscles.
The majority of the energy your muscles will need during exercise comes from burning stored carbohydrates (glycogen) and fat (stored triglycerides in fat cells), with a lesser contribution from protein.
However, the relative percentages of overall energy that each of these three macronutrients provides during your run depend on the intensity of the workout, the duration of the run, and your overall diet and energy balance.
Typically, at lower intensities like slow runs and recovery runs, a higher percentage of the calories your body needs come from burning stored fat.
As the intensity of your workout increases and you run faster, the substrate ratio shifts such that most of the energy comes from stored glycogen instead.
However, although protein typically contributes about 10% of the energy needed when running at moderate to high intensities, this relative percentage increases significantly if you are in a caloric deficit or perform a long, vigorous workout and deplete your ample glycogen stores.
Because protein is only stored in the body in the form of muscle tissue, running initially burns muscle rather than builds muscle, especially if you are in a caloric deficit or following a low-carb diet and doing glycogen-depleted runs.
Moreover, studies suggest that muscle protein breakdown escalates rapidly after exercise is over.
With that said, if you’re in a well-fed state, eating a well-rounded diet, not in a significant energy deficit, and running less than 90 minutes or so, the amount of protein—and thus muscle tissue—burned on a run is minimal.
For example, if you are meeting your daily energy needs and running for 45 minutes and burning 600 calories, you might burn about 60-65 calories from protein.
On the other hand, if you are dieting and in a caloric deficit, do a faster run or do a vigorous, long run; you might burn quite a bit of protein.
As long as you refuel immediately after your run with protein, carbohydrates, and sufficient calories, you shouldn’t experience a significant loss in muscle mass from any given workout. However, if you habitually undereat and refuel poorly, muscle loss from running is certainly possible.
How to Build Muscle Running
As mentioned, the muscle protein synthesis process requires protein and energy in the form of calories.
#1: Eat Enough Protein
According to The International Society of Sports Nutrition (ISSN)2Knuiman, P., Hopman, M. T. E., Verbruggen, C., & Mensink, M. (2018). Protein and the Adaptive Response With Endurance Training: Wishful Thinking or a Competitive Edge? Frontiers in Physiology, 9. https://doi.org/10.3389/fphys.2018.00598 position on protein needs for athletes, athletes looking to build muscle should consume at least 1.4–2.0 grams of protein per kilogram of body weight per day, and protein needs to be spread out throughout the day, in doses of 20-40 grams of 0.25 g/kg of body weight per meal and snack.3Schoenfeld, B. J., & Aragon, A. A. (2018). How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. Journal of the International Society of Sports Nutrition, 15(1). https://doi.org/10.1186/s12970-018-0215-1
#2: Eat Enough Calories
In terms of the caloric needs to support muscle building from running, most health and fitness experts say that you need to be in a slight caloric surplus (consuming 10-20% more calories per day than you’re burning) to support significant hypertrophy or muscle growth effectively.4Iraki, J., Fitschen, P., Espinar, S., & Helms, E. (2019). Nutrition Recommendations for Bodybuilders in the Off-Season: A Narrative Review. Sports, 7(7), 154. https://doi.org/10.3390/sports7070154
#3: Focus on Your Post-Workout Nutrition Strategy
Refueling with a nutritious post-run snack or meal as soon as possible after your workout will help your body initiate muscle protein synthesis, allowing you to build muscle from running.
Most sports dietitians and research on protein fueling for athletes suggest that the ideal post-workout nutrition involves ingesting a 3:1 or 4:1 ratio of carbohydrates to protein, with at least 20-30 grams of protein consumed in this post-run snack within 30 minutes after exercise. 5Moore, D. R., Robinson, M. J., Fry, J. L., Tang, J. E., Glover, E. I., Wilkinson, S. B., Prior, T., Tarnopolsky, M. A., & Phillips, S. M. (2009). Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. The American Journal of Clinical Nutrition, 89(1), 161–168. https://doi.org/10.3945/ajcn.2008.26401
The protein yields the amino acids necessary to manufacture new proteins to repair, rebuild, and strengthen muscle fibers; carbohydrates help replenish depleted muscle and liver glycogen stores, and adequate calories are required to support the muscle protein synthesis process.6Knuiman, P., Hopman, M. T. E., Verbruggen, C., & Mensink, M. (2018). Protein and the Adaptive Response With Endurance Training: Wishful Thinking or a Competitive Edge? Frontiers in Physiology, 9. https://doi.org/10.3389/fphys.2018.00598
If you strive for a minimum of 20 grams of protein with a 3:1 ratio of carbohydrates to protein, these guidelines suggest that you should consume 60 grams of carbohydrates, which would provide a total of 320 calories (protein and carbohydrates each provide 4 kcal/gram).
Since these guidelines constitute the minimum, if you are looking to maximize your ability to build muscle from running, you should increase the protein, carbs, and calories in your post-run snack.
#4: Add Hill Workouts
Hill workouts can build leg muscle in the glutes, hamstrings, and calves.
#5: Do Not Run In a Fasted State
Fasted running will increase the percentage of energy supplied by protein.
#6: Add Strength Training to Your Workout Routine
Hypertrophy can be supported by strength training workouts that involve lifting loads of 65-85% of your 1RM for three sets of 8-12 repetitions.
It’s certainly possible to build muscle by running, but focus on your nutrition to maximize your gains.
To optimize your nutrition for building muscle while still running, try our 7-day meal plan for muscle gain:
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