How To Build Muscle AND PB Your Next Marathon

Can You Train for a Marathon and Still Build Muscle?

For a lot of athletes, committing to marathon training comes with an unspoken concern. Not the distance. Not the early mornings. But the fear of what happens to their strength.

They enjoy lifting. They’ve spent years building muscle. And the idea of trading all of that for months of slow mileage and a finish-line photo doesn’t sit right. It’s one of the most common reasons athletes delay signing up for a marathon at all.

So the question comes up constantly: can you actually train for a marathon and still build muscle?

The answer is yes - but only if you understand the context.

The problem is that most people approach this question in black-and-white terms. They’ve heard about the “interference effect” and assume endurance training and hypertrophy cancel each other out. Running improves efficiency and fatigue resistance, while lifting builds muscle and force production. Because the signals are different, the assumption is that you must choose one.

In reality, interference isn’t an on-off switch. It exists on a sliding scale.

How much interference you experience depends on several factors: how much you’re running, how hard you’re lifting, how well your sessions are structured, how effectively you recover, and how trained you already are. When those variables are managed properly, there is far more overlap between endurance and muscle gain than most people realise.

One of the biggest determinants is training experience. If you’re a beginner or intermediate lifter, your body doesn’t need a huge stimulus to grow muscle. You can lift a few times per week, train for a marathon, and still come out the other side stronger and more muscular. Progress doesn’t need perfection at this stage - consistency and intent go a long way.

Advanced lifters, however, are playing a different game. When you’re already strong and well-muscled, gaining more requires higher volumes, tighter execution, and a much smaller margin for error. As marathon mileage increases, recovery becomes the bottleneck. Muscle gain doesn’t become impossible, but it does slow, and expectations need to adjust.

This leads to the most important variable of all: volume.

Running itself isn’t the issue. The dose is. There’s a huge difference between running four to six hours per week versus eight to ten or more. At moderate volumes, muscle gain is very achievable alongside marathon preparation. At higher volumes, maintenance or small gains may be the realistic win, especially for athletes juggling work, family, and other stressors.

This is where lifting needs to be efficient rather than excessive. Instead of chasing maximal volume in the gym, the focus should be on quality. Fewer exercises per session, fewer total working sets, and higher intent on every lift. You don’t need to train to failure to grow muscle, but you do need a stimulus you can recover from consistently.

For most athletes, this means two to three lifting sessions per week, with a limited number of hard sets per movement and clear progression intent. As running volume rises, gym volume comes down — but effort stays high. Half-hearted lifting sends a weak signal. Intent keeps the adaptation alive.

Fueling is the final piece that often gets overlooked. Marathon training is inherently catabolic, especially when long runs aren’t fueled properly. Low carbohydrate availability increases muscle damage and compromises recovery, which carries over into poor gym performance later in the week. Fueling long runs isn’t just about race-day practice — it’s about preserving muscle, supporting recovery, and making concurrent training sustainable.

So what does this all mean in practice?

You can build muscle during marathon training if your running volume is moderate, you’re not already near your hypertrophy ceiling, your lifting is structured intelligently, and your recovery and nutrition are dialled in. As mileage increases, muscle gain slows - it doesn’t disappear. Maintenance can still be a successful outcome depending on context.

The athletes who manage this best don’t try to maximise everything at once. They periodise their priorities across the year. There are phases where muscle gain takes the lead and running volume is controlled, and phases where marathon performance becomes the focus and lifting shifts to maintenance.

Training for a marathon doesn’t mean abandoning strength. It means being strategic with it.

And when that balance is done well, endurance and muscle don’t compete - they complement.

Download our FREE Hypertrophy guide here https://www.omnia-performance.com/downloads/hypertrophy-test

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