STRENGTH TRAINING + MARATHON.

"I don't want to build muscle — I run marathons." Magnus Bohlmann, Head Coach and Founder of runningsociety.de, hears this regularly. It's based on a deep-rooted misconception: that strength and endurance are opposites, that muscles make running harder, that a marathon runner should train as "light" and "lean" as possible. Magnus Bohlmann clears this up — and explains why strength isn't the runner's enemy, but their best protection.

The myth of the runner without muscles

The image of the "real" runner is thin, light, not an ounce of muscle to spare. This ideal isn't just unrealistic for most recreational runners, it's also bad for your health. A marathon runner without a solid strength base is like a house without a foundation: it stands, until the first real load hits it.

What actually happens when you run? With every step, your body weight lands on your foot at 2 to 3 times your bodyweight. Over a marathon, that's roughly 25,000–30,000 ground contacts. Every single one of these landings has to be absorbed and controlled by muscle. The weaker those muscles are, the more the load gets dumped onto passive structures: tendons, ligaments, joints, bones.

In most cases, injuries aren't bad luck. They're the logical consequence of an insufficient strength base.

Muscles as a protective structure

This is the core idea Magnus keeps coming back to with his athletes: muscles are the active protective structures of the musculoskeletal system. Passive structures like tendons and joints regenerate slowly — and they don't have reserves that training can directly top up. Muscles, on the other hand, adapt fast: they get stronger, they get more efficient.

A stronger Gluteus maximus takes load off the knee. Stronger calf muscles protect the Achilles tendon. A stronger core keeps your posture upright at kilometer 35 and stops poor biomechanics from turning into overuse injuries.

Sports science research consistently shows: runners who strength train regularly have significantly lower injury rates than those who don't — especially when it comes to knee syndromes, shin splints, and Achilles tendon issues.

Does strength actually make you faster?

Yes — and this is the part that surprises most people.

Strength improves running economy: the energy cost per step. Stronger leg extensors can return more energy from every ground contact — similar to how a stiffer spring returns more energy than a soft one. In practice, that means you run faster at the same effort, or the same speed with less effort.

Meta-analyses show that strength training can improve running economy in endurance runners by 2–8%. Over a marathon, that translates to several minutes — without a single extra kilometer of running.

How much strength, which exercises?

The misunderstanding about strength training for runners is usually methodological: if you think it means training like a bodybuilder, you'll reject it — rightly so. That's not what this is about.

Goal: Functional strength, not hypertrophy for its own sake. Exercises that directly support running — single-leg loading, posterior chain, core stability.

Recommendation: - 2 sessions per week, 40–50 minutes each - Focus: Bulgarian Split Squat, Romanian Deadlift, Step-Down, Copenhagen Plank, Hip Thrust - Intensity: 3–4 sets, 6–10 reps, heavy enough that the last reps are hard - No strength sessions directly before or after long runs — at least 24 hours apart

This amount is enough to produce significant strength gains without compromising your running sessions.

When to integrate — and when to cut back?

Strength training is worthwhile year-round, but the dosage shifts with the training phase:

This periodization ensures strength is built and maintained without disrupting the taper.

Conclusion: no marathon without strength

The question is no longer whether strength training makes sense for marathon runners — science has answered that. The question is how. And that's exactly the question that needs to be answered individually in coaching.

If you want a marathon plan that builds in strength from day one, not as an add-on but as the foundation, that's the approach we follow at runningsociety. Together with top coach Benz Franke, we develop plans built for ambitious runners, with everything that comes with it.

June 4, 2026