Most marathon runners have a complicated relationship with the gym. They know they should go. They've read the articles and seen the Instagram posts of elites doing single-leg squats and box jumps. And yet, given a choice between an extra easy run and a strength session, the run almost always wins.

Usually because nobody has said precisely what to do. So here it is.

The minimum effective programme

Strength training for marathon runners comes down to about six movements. If you're running 3-6 days a week and want to get faster without living in the gym, this is your set.

1. Calf raises.

2. Ankle dorsiflexion work (banded pulls, or toe raises against a wall).

3. Knee extension, so leg press or step-ups (step-ups with a backpack work fine at home).

4. Knee flexion, so hamstring curls or Romanian deadlifts.

5. Hip abduction (lateral band walks or clamshells).

6. Hip adduction (Copenhagen adductors).

Two to three sets of eight to twelve reps each, stopping two or three reps short of failure. Two sessions a week when your running volume is moderate, dropping to one as race-specific work ramps up, and none in the final fortnight.

That's the programme. It takes about half an hour, it needs almost no equipment, and the evidence says it will make you roughly 2-4% more economical. For a three-hour marathoner, that's two to four minutes.

Here's why those movements, why that dose, and how to fit it around your running.

Why does strength training make you faster?

Most runners are told strength work is about injury prevention. Strengthen your glutes, stabilise your hips, protect your knees.

There's something in that, but the evidence is thinner than the headlines suggest. Retrospective studies consistently find hip weakness in runners who are already injured. But prospective studies, which follow runners forward to see who gets hurt, have struggled to show that unsupervised strength training reliably prevents injury. A 2025 scoping review in Translational Sports Medicine noted that running injury rates haven't fallen in decades, despite strength training becoming far more common.

So yes, strength may help reduce some injuries for some runners. But the reliable benefit is performance: making each stride cheaper.

That's running economy, the oxygen cost of running at a given pace. Two runners with identical VO2max can perform very differently over 42.2km if one uses less oxygen at race pace. Efficiency of the machine rather than size of the engine.

A 2024 systematic review and meta-analysis in Sports Medicine examined strength training's effect on running economy in middle- and long-distance runners. Loads at or above 80% of one-repetition maximum improved economy by 2-4%. Not from running more. Not from running harder.

The mechanism is neuromuscular rather than muscular. Heavy strength work improves rate of force development and the stiffness of the muscle-tendon unit. In plain terms: your legs behave more like springs and less like shock absorbers, so every step costs you less. You're not building bigger muscles, you're building muscles that fire more efficiently.

The durability effect

There's a second benefit, only recently measured, that probably matters more than the economy gain.

A 2025 randomised controlled trial in Medicine and Science in Sports and Exercise looked at running economy durability: holding efficiency as fatigue accumulates. After ten weeks of concurrent strength and endurance training, the strength group maintained better economy after 90 minutes, the point where most marathon pace charts start to fall apart. They also improved time to exhaustion at high intensity by 35%. The run-only control group declined 8%.

That doesn't mean your marathon gets 35% faster. It means you fade less when it matters.

This is the finding that should change how you think about the gym. Marathon performance isn't decided by how efficient you are at 5km. It's decided by how efficient you are at 35km, when your muscles are damaged, your glycogen is low, and your form is going. That gap you see in the closing stages, between the runners holding their shape and the ones coming apart, is partly structural resilience built in the gym months earlier.

Why those six movements?

The movements that matter for runners are simpler and more targeted than most gym programmes suggest.

Calf raises are non-negotiable. The calf and Achilles complex absorbs two to three times body weight every stride, and it's the most common site of running injury. If you do nothing else, do these.

The other five each have a distinct job. Dorsiflexion protects the shin and controls how your foot meets the ground. Knee extension drives you forward. Knee flexion decelerates the leg in late swing, which is where hamstrings tear. Abduction stops your pelvis dropping as you fatigue. Adduction stops your knee collapsing inward. Six movements, six separate problems solved.

None of it is glamorous. All of it works in a gym or at home with a resistance band, a step, and a loaded backpack.

A note on plyometrics. Box jumps, bounding, and depth jumps train the stretch-shortening cycle, and the research supports their benefit for economy. But they carry higher injury risk and shouldn't be added by default. They're a considered addition for experienced runners, and only once your basic strength work is rock solid.

What you don't need: a forty-five-minute circuit, unstable-surface work, or anything that treats strength as a goal in itself.

How heavy, and how do you know?

The research showing the biggest economy gains used loads at or above 80% of one-rep max. That's genuinely heavy, and it needs testing and confidence under load most runners don't have.

A more practical approach is reps in reserve. Aim for two to three sets of eight to twelve reps, stopping when you could still manage two or three more with good form.

A simple cue if you're unsure: if your last rep looks as crisp as the first and you feel you could easily do five more, it's too light; if your form is breaking down, it's too heavy or too many reps.

That gives up a little of the peak adaptation seen in the studies, deliberately. It's enough to drive meaningful change without the muscle damage that leaves you stiff for your next quality run. Consistency beats optimisation.

How do you fit it around your running?

This is where most runners go wrong. They either repeat the same routine year-round regardless of phase, or drop it the moment mileage climbs.

The principle is the one we set out in our piece on training load management: one lever at a time. You don't raise running volume and introduce heavy lifting in the same week. You sequence them so each new stressor is absorbed before the next arrives.

Base phase, 12+ weeks out. Your best window. Two to three sessions a week, progressing over six to eight weeks. Volume is moderate and intensity is low, so you have the bandwidth to push the strength work harder.

Build phase, 8-12 weeks out. Strength shifts from building to maintaining. Drop to one or two sessions, fewer sets, fewer exercises. Preserve what you built rather than adding to it.

Taper, 2-3 weeks out. One short session or none at all. Months of adaptation won't vanish in a fortnight, and what you're protecting is freshness. This is the same principle we set out in the science of tapering: the final weeks are about arriving fresh, not about adding fitness. Your HRV should be climbing through the taper, as we covered in our piece on HRV-guided training, and extra gym sessions work against that.

Post-race. At least a week away from structured strength, ideally two. Keep walking and moving normally, this is time off the gym rather than time off your feet. Then rebuild over two to three weeks rather than resuming where you left off.

One rule runs through all of it: never put strength on the same day as a hard run. Not separated by a few hours. A genuinely different day. No "I'll just lift after track" compromises, because that's exactly how you turn good strength work into junk fatigue.

The test is simple. Can you arrive at your next quality session without soreness from the gym? If not, change the load, volume, or timing.

Will lifting make my legs too tired to run?

This is the interference effect, and the worry has a real basis. The molecular pathways for endurance adaptation (AMPK) and muscle growth (mTOR) can compete when activated together. Hickson identified this in 1980.

Translated: the same signals that tell your body to build big muscles aren't the ones that make you better at long-distance running.

For runners it's largely a non-issue. It's a genuine problem for athletes chasing maximum muscle size alongside endurance, but if your goal is neuromuscular efficiency, it's minimal. The meta-analyses consistently show concurrent training improves running economy, VO2max, and time-trial performance without blunting endurance gains.

The practical version: if your key running sessions are going well and you're not turning every gym day into a bodybuilding workout, you can stop worrying about interference.

Where this gets genuinely difficult

The principles are simple. Week-to-week execution is not.

Strength work adds a second fatigue system on top of your running. Monday's session affects Tuesday's legs, which affects Wednesday's intervals, which affects Thursday's recovery. Those ripples only become obvious when something hurts or your running dips for reasons you can't pin down.

Keep this week's maintenance session, or skip it because the long run took more than expected? Is the heaviness in your legs from the squats or the tempo run? How much can you handle with your HRV trending down?

These are the multi-signal decisions we described in our piece on how AI adjusts your training in real time. Most static plans treat strength as a separate track, a PDF on the fridge beside the running schedule. But the two systems interact constantly, and that's the difference between strength work that makes you faster and strength work that just makes you tired.

Key Takeaways

• Six movements cover it: calf raises, ankle dorsiflexion, knee extension, knee flexion, hip abduction, hip adduction. Calf raises are the non-negotiable one.

• Two to three sets of eight to twelve reps, stopping two or three short of failure. Reps in reserve beats percentage-based loading for most runners.

• Expect a 2-4% improvement in running economy, worth two to four minutes for a three-hour marathoner.

• The bigger benefit is durability. Strength-trained runners hold their economy far better after 90 minutes, exactly where marathons are decided.

• Periodise it: two to three sessions in base, one to two in build, one very short session or none in the taper, then two weeks off structured strength after the race before rebuilding.

• Never schedule strength on the same day as a hard run (hard being tempo, intervals, or a long run with efforts). If you arrive at a quality session sore from the gym, reduce the load or move the day.

• The interference effect is real but mostly irrelevant to runners, since you're chasing neuromuscular efficiency rather than muscle size.

Strength training for marathon runners isn't dramatic on any single day. It compounds quietly over months and shows up in the final third of a race, when everyone around you is slowing down and you aren't.

This is where adaptive coaching matters: it watches the ripples from both systems and adjusts in real time instead of leaving you to guess.

Zepho is adaptive coaching for serious runners. It's live and available now on the App Store.