Weight training for marathon runners: exercises and benefits
Most marathon runners I know treat weight training like a guilty secret. They squeeze in a few lunges after a long run or skip it entirely because they're afraid of extra soreness. But the data tells a different story. A comprehensive meta-analysis found that runners who added two strength sessions per week improved their running economy by 3.5% on average [1]. That's a free pace increase without a single extra mile. The trick is timing and load management, not avoiding the gym entirely. Dorsi handles that part by adapting your workout based on your daily recovery, so you can squat heavy without sabotaging tomorrow's tempo run. If you've been burned by decision fatigue in the past, the 5 signs article covers exactly why that happens. Below, we walk through the specific rep ranges, exercises, and scheduling strategies that work for marathoners.
Practical Playbook
Build lower-body strength with single-leg work.
Marathon running beats up your glutes, quads, and hamstrings. Heavy squats and deadlifts build raw force, but single-leg exercises, lunges, split squats, step-ups, fix imbalances and protect your knees. Three sets of six to eight reps per leg, twice a week. Trust me, your 20-mile long runs will feel more stable.
How often should you lift during marathon training?
Twice a week during base-building. Drop to once a week when mileage peaks above 50 miles. That single session should hit all major lower-body moves plus a few upper-body pulls. Skip a session when fatigue is high, one lift session lost beats two runs trashed. Listen to your legs, not the plan.
Schedule strength after your hardest runs.
Stack lifting on the same day as a quality run, tempo or intervals, never the day before a long run. You want your nervous system fresh for the hard running, then apply the strength stimulus when your legs are already fatigued. That mimics race conditions and improves running economy without compromising endurance sessions.
Don't ignore anti-rotational core work.
Your core keeps your pelvis stable when fatigue sets in at mile 22. Planks and crunches aren't enough. Add Pallof presses and farmer carries, they train your obliques to resist rotation. Three sets of 30-second holds each side, twice a week. Your form won't collapse in the final miles when every stride feels like a new world.
Common Mistakes
- Mistake
- Marathon runners skip heavy compound lifts because they're scared of getting bulky.
- Why
- That fear is misguided. Heavy squats and deadlifts improve bone density, tendon stiffness, and running economy, the exact things that keep you fast over 26.2 miles. Bulking up requires a calorie surplus and specific hypertrophy work you're not doing.
- Fix
- Include two heavy lower-body sessions per week at 3-5 reps. Focus on depth and control. You'll get stronger, not bigger.
- Mistake
- Runners do too many sets and reps in the gym, turning a strength session into an endurance workout.
- Why
- High volume accumulates systemic fatigue that steals recovery from your running. You end up mediocre at both instead of strong in one.
- Fix
- Cut your total working sets to 6-10 per session. Keep reps at 5-8 for compound lifts. If you're using an adaptive coach like Dorsi, it'll automatically dial back your gym volume after your long runs.
- Mistake
- Runners neglect posterior chain work — they only squat and lunge.
- Why
- Quads get hammered from downhill running, but weak glutes and hamstrings force your lower back and knees to pick up the slack. That's a recipe for IT band syndrome or hamstring pulls.
- Fix
- Add Romanian deadlifts, hip thrusts, and single-leg bridges to your rotation. Strengthen those glutes and hammies at least once a week.
- Mistake
- Runners completely stop strength training during race week or peak training.
- Why
- Completely dropping strength work for 2-3 weeks loses neuromuscular adaptations faster than you think. A tiny maintenance dose preserves strength without extra fatigue.
- Fix
- Do one very light session during race week: 2 sets of 5 reps at 50% of your normal weight. Your body will thank you on race day.
Frequently asked questions
From the Dorsi blog
One Strength Session a Week Is All Your Cycling Season Needs
The most quietly powerful finding in cycling strength research isn't about how to build power in winter. It's about how cheap it is to keep it through summer.
Lifting Won't Hurt Your Watts-per-Kilo. Thirty Years of Cyclist Studies Settle It.
Every climber's quiet fear: lift heavy, get heavy, lose your W/kg. Three decades of cycling RCTs say it doesn't happen — and once you see the mechanism, you'll know why.
Strength Training Won't Raise Your VO2max. That's the Whole Point.
When the 2025 meta-analysis came out, cyclists kept reading it as bad news. Read it again — the part that looks like failure is the entire mechanism.
Just show up. Dorsi handles the rest.
- HRV-driven readiness — today's plan adapts to how recovered you actually are.
- Adapts every session — no decision fatigue, no second-guessing your numbers.
- Apple Watch native — log a set with your wrist, not your phone.