There’s a reason most elites don’t look like they spend a lot of time in the weight room. Running isn’t exactly known for building bulk. But strength isn’t just about how much weight you can lift; it also encompasses power (or how fast you can use the force you’ve built up) and the ability of a muscle fibre to do what it’s designed to do.
So does running build muscle? The short answer is yes, it is possible to build muscle while running.
“With running, the majority of the muscle work or contraction is eccentric, which is the hardest load on the body,” explains Joe McConkey, a Boston-based exercise physiologist and USATF-certified running coach. Eccentric contractions occur when a muscle lengthens—not shortens—under load or tension. For example, during the lowering phase of a squat, the quadriceps (front of thigh) muscles eccentrically contract.
When running, “the act of landing, where you’re absorbing two to four times your body weight, is done eccentrically. That’s the major stimulus for muscle growth during running, particularly for beginners,” McConkey says.
The research backs this up. Aerobic exercise was shown to be enough to produce some skeletal muscle growth in a study published in the journal Exercise and Sport Sciences Reviews.
The catch: If you’ve been running a really long time, you’ve probably already built strength in the slow-twitch muscle fibres that primarily power your long-distance running, says Janet Hamilton, C.S.C.S., owner of Running Strong. Runners who consistently do steady-state runs won’t build more muscle mass, but their muscles can start to look more defined as your body composition changes while increasing your mileage, adds McConkey.
New runners are more likely to see the most noticeable changes in muscle mass and strength just by virtue of running more often or for longer for the first time (or the first time in a long time). But just because you’ve got a history of logging kilometres doesn’t mean you can’t make any gains. Any runner can develop more strength—in terms of power and muscle ability—by tapping into their fast-twitch muscle fibres, which have less endurance than slow-twitch fibres but exert more force. “These don’t really get called upon until either a) there’s an activity that requires more strength than slow-twitch fibres can muster or b) the slow-twitch fibres are fatigued and you keep going,” says Hamilton.
To recruit more of those fast-twitch fibers, you need to do something that’s going to require greater power output. Think about the massive leg muscles of a sprinter: “Any high-powered, short bout of exercise—so long as it is progressive in nature (i.e. harder, faster, higher than what you have already adapted to)—will increase the size of fast-twitch fibers, and thus increase muscle mass,” says McConkey.
An easy way to do that is through hill workouts. “Running up a hill requires more muscle power than running on level ground,” says Hamilton. You may not be lifting a weight, but you’re carrying your own weight up an incline against the force of gravity—its own kind of resistance training.
Speed workouts will also engage fast-twitch muscle fibres. “If you’ve been doing nothing but easy effort, marathon-pace runs, incorporating short to moderate intervals at a faster, 5K pace is going to require you to exert more force every time your foot hits the ground,” says Hamilton. “And that’s how you speed up—you generate a greater push-off.”
While running can build muscle, it’s still important to include strength training in your training regimen. Not only does strength training increase your endurance running performance, running economy (or how efficiently your body uses energy), and maximal sprint speed, according to a study published in the British Journal of Sports Medicine, it also helps prevent injuries by strengthening your muscles and connective tissues—all of which will keep you running stronger, longer.
To build more muscle on your runs, check out these workouts below. The mileage, effort, and total distance will depend on where your running fitness is at, but each workout can be scaled up or down to meet you where you are in your training.
Beginner Hill Workout
- Warm up for at least a kilometre at easy effort (or 1/3 of the day’s total planned distance)
- Find a gradual hill that takes about 30 to 60 seconds to run up at an easy effort.
- Run up the hill at the same effort as you would on level ground (you will slow down a bit).
- Run down the hill at the same effort as you would on level ground (you will speed up a bit).
- Repeat 1-4 times (depending on fitness level).
- Cool down for at least a kilometre at an easy effort.
Intermediate Speed Workout
- Warm up for at least a kilometre at an easy effort.
- Run 400 metres at 5K pace (a hard effort but not a sprint)
- Run 200 metres at a recovery pace.
- Repeat 2 to 4 times if you run less than 32.1 km per week. Repeat 6 times if you run at 32+ kilometres a week, or 8 times if you run 48+ kilometres per week.
- Cool down for at least a kilometre at an easy effort.
