Should Runners Train Like Bodybuilders?

Runners are often as nervous about the weight room as they are about taking a day off. Fear of injury, confusion at what to do, and the nerves of pumping iron next to a bunch of meatheads with protein shakers keep them relegated to the “core” area with body weight and bands. They’re also deathly afraid of putting on weight. Maybe bulking up our runners should be the goal?

Running does a lot of good things for our body. It doesn’t do a great job of building strong bones. Probably why most endurance athletes’ closets contain crutches and walking boots. I think growing bigger muscles can keep those accessories out of our wardrobe.

Bone Density and Bone Strength

Athlete’s participating in soccer, football, and other impact sports often exhibit better bone density and bone architecture. Our bones like the high loads, unpredictable movements, and odd angles we navigate as we cut, jump, and sprint. Stronger, denser bones do better at handling the shock of running. Having a weaker skeleton is likely why runners are at high risk for bone stress injuries (BSIs). BSI’s require a long time off of training with a high chance of reoccurrence. Keeping runners away from crutches and walking boots should be a top priority.

Runners with a history of a BSI or “shin splints” have less dense shins1,2. The quality of the bone is worse. Think more styrofoam than steel. Raise your hand if you have had a stress fracture or shin splints? Probably a lot of you which is why most runners should critically analyze their strength routine.

How can we grow strong bones?

Muscles and bones are best buds. Movement happens because our muscles tug our bones into motion. Muscle can absorb 100 more times shock than a bone1, which is essential during the 1000’s of foot strikes of a training run.

Here are a few key ideas:

  • A stronger muscle likely means a stronger bone3
  • A bigger muscle likely means a bigger, stronger bone3.
  • Lean body mass is independently associated with bone mineral density4
  • Smaller calf muscles can be a good predictor of a stress fracture5
  • Mechanically, having wider, bigger bones puts us at a decreased risk of developing a BSI3

Stressing our muscles with strength training helps put our skeleton in a better position to handle running. Athletes in field and court sports often want to build bigger muscles to help with performance and durability. Muscle hypertrophy is an increase in the size of our muscle fibers6. Hypertrophy occurs mainly by loading during resistance training and adequate nutrition. Runners routinely sprint in the opposite direction of gaining mass.

To make this work, we need the right strategy in the gym. It is not realistic to focus on muscle hypertrophy when a runner is in a heavy training block. The most reasonable time to implement these strategies is the offseason. We can significantly increase lifting volume, prioritize appropriate fueling, and hold loosely to easy mileage.

Zooming in on the target

Bone adapts in a site-specific manner, meaning we need to stress the muscles located on problematic bones. If you want your femur stronger, you need to load your…femur. That means you need to perform squat and lunge variations.

Runners tend to have problems in three predictable areas: The hip, thigh, and lower leg. These bones have to handle a lot of stress with running. Prioritizing building the size and strength of the muscles attaching to these bones is critical, especially around our growing years. If you get sidelined with a BSI you’re going to be on the shelf for a while. Let’s avoid that situation. Hopefully, growing bigger muscles in these regions will keep us on track and out of the doctor’s office.

There’s a multitude of ways we can challenge our body in the weight room. If the goal is to build some swole legs, we should promote many loading strategies in our plan. Here are a few fundamental principles we should remember6.

  • Load the bones you want stronger
  • Load them in a variety of ways (repetitions, weight, angles, etc.)
  • Progress those loads over time

Sample Program

Combining strength training and running is both complicated and nuanced while also being simple at day’s end. To get the most out of our time amongst the weights, we take three different strategies. For every movement or body part, we want to do some…

  • Heavy stuff for a few repetitions
  • Lighter stuff for many repetitions
  • An exercise at a slightly different angle

We would progress the weight and volume of each of these variations over time. If we loaded these three regions three times per week, it might look like this. We have one exercise per region that meets those three criteria.

Thanks for taking the time to read! I hope this gives you some practical information for your running journey. If you found this helpful, I’d love to have you join my newsletter. I’ll keep you up to date on the latest running-related science, coffee recommendations, and stories of a solopreneur in the running world.

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Nathan Carlson


  1. Popp K, Hughes J, Smock A et al. Bone Geometry, Strength, and Muscle Size in Runners with a History of Stress Fracture. Medicine and Science in Sports and Exercise. 2009. 2145-2150.
  2. Magnusson H, Westlin N, and Nyqvist F. Abnormally Decreased Regional Bone Density in Athletes in Medial Tibial Stress Syndrome. American Journal of Sports Medicine. Vol 29 Issue 6 2001.
  3. Hart N, Nimphius S, Rantalainen T, et al. Mechanical Basis of Bone Strength: Influence of Bone Material, Bone Structure and Muscle Action. J Musculoskelet Neuronal Interact. 2017 1;17(3): 114-139.
  4. Moon S. Relationship of lean body mass with bone mass and bone mineral density in the general Korean population. Endocrine. 2014 Sep;47(1):234-43.
  5. Benell K, Malcolm S, Thomas S et al. Risk Factors for Stress Fractures in Track and Field Athletes: A Twelve-Month Prospective Study. The American Journal of Sports Medicine. 24(6)1996.
  6. Schoenfield B, Fisher J, Grgic J et al. Resistance Training Recommendations to Maximize Muscle Hypertrophy in an Athletic Population: Position Stand of the IUSCA. International Journal of Strength and Conditioning. 1 (1).
  7. Laddu D, Farr J, Lee V et al. Muscle Density Predicts Changes in Bone Density and Strength: A Prospective Study in Girls. J Musculoskelet Neuronal Interact. 2014 June; 14 (2): 195-204.

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