Can Running Build Muscle? Why Variety Is the Key
You started running for your heart, your head, or simply to get outside. Now you may be wondering whether those miles are doing anything for your muscles, or whether running only maintains what you already have. The honest answer is yes, running can build muscle, but there is a principle behind it that matters more than any single session.
What Runner's World found
In a piece for Runner's World, "New to Running? Your Miles May Build More Muscle Than You Think", Ashley Mateo reports that running can increase muscle, especially for beginners. However, steady, familiar running is more likely to maintain muscle than to add much extra.
The article points to a 2015 research review in Exercise and Sport Sciences Reviews, which found that aerobic exercise can increase skeletal and whole-muscle size, particularly in sedentary people. It also describes a 2017 study in the International Journal of Exercise Science. Twelve recreationally active university students did about 25 high-intensity running sessions over 10 weeks and showed increased growth in the vastus lateralis, a thigh muscle. Each session was four 4-minute runs at 90 to 95 per cent of maximum heart rate, with 3 minutes of active recovery between runs.
Exercise physiologist and USATF-certified running coach Joe McConkey explains part of the reason. Running loads the lower body eccentrically, meaning your muscles work as they lengthen, and the article says landing absorbs two to four times your body weight. Mateo also notes that steady-state running may make muscles look more defined as body composition changes, even when it does not add muscle mass.
Why it matters for a busy reader
If you are new to running, this is encouraging. The article says beginners are more likely than experienced runners to notice changes in muscle and strength when they run more often or for longer. Your legs are being asked to do something new, and they respond.
The catch is that familiarity works against you. Run the same loop at the same pace every time and your body has less reason to keep adapting. That is why the core principle of good training is variety. Instead of adding more of the same miles, change what the miles ask of you.
The article backs this up in one specific way. McConkey says progressive, short, high-power exercise can recruit fast-twitch muscle fibres, and running coach Janet Hamilton, C.S.C.S., notes that running uphill requires more muscle power than running on level ground. Hills, in other words, are a time-efficient way to make an ordinary run more demanding.
How to try it
Think of your week as a mix rather than a routine. Within your running, you might combine:
Longer, easy jogs to build your routine and enjoy being outdoors.
Short, faster efforts woven into a run, followed by plenty of easy jogging to recover.
Hills, both up and down, rather than only the flat.
Different terrain, such as road one day and a park path or trail the next, so your legs rarely do exactly the same job twice.
The research study above used very hard intervals, which is a demanding session and not a place for a beginner to start. The gentler place to begin is the beginner hill workout in the Runner's World article:
Warm up with at least 1 mile at an easy effort, or one-third of your planned distance.
Choose a gradual hill that takes 30 to 60 seconds to run up at an easy effort.
Run up and back down at the effort you would use on level ground.
Repeat the sequence 1 to 4 times, depending on your fitness level.
If you are just starting out, do it once or twice and stop while you feel you could do more. Add a repeat in later weeks if it feels comfortable.
Running is only part of the picture. The article's weekly recommendation is at least three cardio workouts, two strength workouts and one flexibility workout. If strength work is missing from your week, that is the simplest gap to fill.
One honest caveat
Running is not a substitute for strength training if building muscle is your goal. The article says aerobic exercise may be better at maintaining muscle than building it, particularly without added intensity, and that repeating the same steady routine is less likely to produce further growth. Beginners may see more change than established runners. The 2017 study involved just 12 people, so treat the findings as encouraging rather than conclusive.
Hills and faster efforts put more load on your legs. If you have a health condition, a past injury, or you are returning after a long break, check with your GP before adding hills or faster efforts.
Your next step
This week, swap one of your usual runs for the beginner hill session above: an easy warm-up, one or two gentle climbs, and an easy finish. Then notice how your legs feel the next day. That small change is the start of a more varied routine.
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