How Strong Do Runners Actually Need to Be?
By Physiotherapist, Nóirín Gobl Ní Chasaide
Ask ten runners about strength training and you'll get ten different answers. "Lifting will make you slow and bulky." "You just need to run more, not lift." "You need to squat 1.5x bodyweight before you're allowed to race." None of these are quite right — and the confusion is doing runners a disservice, because the actual evidence on strength training and running is fairly clear.
Here's what the research says, and what it means for your training.
Why Runners Benefit From Strength Training
Two separate benefits show up in the literature, and it's worth keeping them distinct:
1. Injury prevention. A widely cited meta-analysis of randomised controlled trials found that strength training reduced sports injuries by roughly a third, and overuse injuries by nearly half (Lauersen, Bertelsen & Andersen, 2014, British Journal of Sports Medicine). Running is a repetitive, high-load activity — every stride puts 2–3x bodyweight through your lower limb — and tissue that can tolerate that load repeatedly is less likely to break down.
2. Performance. Strength training — particularly heavy strength training — has repeatedly been shown to improve running economy (the amount of oxygen you use at a given pace) without negatively affecting VO2 max . Better economy means you can hold a pace for longer at a lower physiological cost — which matters far more over a marathon than over a 5K.
The myth that lifting makes distance runners slower and bulkier doesn't hold up. Strength training for runners isn't bodybuilding-style hypertrophy training — it's aimed at neuromuscular adaptations (better motor unit recruitment, stiffer tendons, more efficient force transfer) that add negligible muscle mass at the loads and volumes typically prescribed.
Heavy vs Light Strength
This is where a lot of the confusion sits. The evidence actually leans toward heavier loads, lower reps being more effective for runners than the high-rep, light-weight circuits many runners default to.
Reviews of strength training interventions in endurance athletes consistently favour protocols working in the ~3–6 rep range at high intensity (roughly 85–90% of one-rep max), rather than muscular-endurance style training . The theory is that heavy loading targets the nervous system, strength and tendon stiffness — improving how efficiently force is stored and returned with each stride — rather than building the kind of muscle bulk that would add unhelpful mass.
That doesn't mean light work has no place. Plyometrics and lower-load, higher-velocity work develop rate of force development (how quickly you can produce force) and reactive strength (how springy you are) which is also relevant to running. Most well-designed programs use a mix. Heavy strength work over endless light-weight, high-rep circuits paired with some body weight or light explosive movements.
Single-Leg vs Double-Leg Exercises
Running is a series of single-leg stances — you're never on two feet at once. This has led some to argue that unilateral exercises (single-leg squats, step-ups, split squats) are inherently more "specific" and therefore superior to bilateral lifts like the back squat or deadlift.
In practice, both have a role:
Bilateral lifts (squat, deadlift, hip thrust) are effective for building maximal force capacity and are easier to load heavily and progress safely.
Unilateral exercises better challenge single-leg stability, hip control, and the frontal-plane stability that matters for injury prevention (particularly at the hip and knee).
Rather than one being "correct," most evidence-informed programs for runners include both — bilateral work for raw strength, unilateral work for the stability and control that mirrors what happens during the gait cycle.
Is There Actually a Magic Strength Benchmark?
Short answer: no — and be sceptical of anyone who gives you a single number and calls it evidence-based.
You'll sometimes hear claims like "you need to squat 1.5x bodyweight" or "you should be able to do 25 single-leg calf raises before you're cleared to run." These numbers usually originate from clinical rules of thumb or small, specific study populations (often post-injury return-to-run criteria) rather than from research establishing a universal strength threshold that predicts performance or injury risk in all runners.
What the research actually supports is more nuanced:
Relative, not absolute, benchmarks matter more. Side-to-side asymmetry (e.g., one calf noticeably weaker than the other) is a more meaningful red flag than failing to hit an arbitrary number.
Strength needs are individual. A 50kg recreational runner and a 90kg former rugby player training for their first marathon do not need the same absolute strength — what matters is whether their strength is sufficient for the load they're asking their body to repeatedly tolerate.
Context matters more than a fixed number. Training history, injury history, running volume, and biomechanics all affect how much strength "is enough" for a given individual.
If someone gives you a fixed number without asking about you first, treat it as a rule of thumb, not a diagnosis.
How to Fit Strength Training Around Running (Without It Becoming Another Training Load)
This is the part that gets missed most often: strength training should reduce your overall injury risk, not add another source of fatigue and overtraining on top of your running.
A few practical principles:
Two sessions a week is enough. Research protocols showing benefits for runners typically use 2 sessions per week, 20–40 minutes each — not daily lifting.
Prioritise a small number of compound movements (squat variation, deadlift/hip hinge variation, single-leg work, calf raises) over long circuit-style sessions with lots of exercises and minimal loading.
Time it sensibly. Where possible, lift on the same day as an easy run or a hard run (rather than the day before a key quality session), so your legs aren't fatigued heading into important training.
Progressive overload, not novelty. Repeating and gradually loading the same few movements over weeks beats constantly changing exercises for variety's sake.
Reduce volume, don't eliminate, in race build-up. In the final weeks before a goal race, strength sessions are often shortened, ore reduced to 1 per week, rather than dropped entirely — maintaining strength without adding fatigue.
The goal is strength training that supports your running, not another training stream competing with it for recovery.
The Bottom Line
Strength training helps runners in two well-supported ways — reducing injury risk and improving running economy — and it does this best through a small number of heavier compound lifts, done consistently, twice a week, with particular attention to the calf and hip. There's no single benchmark number that applies to every runner; what matters more is consistency, appropriate loading for your individual tissue capacity, and making sure strength work supports your running rather than competing with it for recovery.
If you're not sure where your own strength gaps are, a running-specific assessment is a more useful starting point than chasing a number you read online.
References
Lauersen JB, Bertelsen DM, Andersen LB. The effectiveness of exercise interventions to prevent sports injuries: a systematic review and meta-analysis of randomised controlled trials. British Journal of Sports Medicine. 2014;48(11):871-877.
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Blagrove RC, Howatson G, Hayes PR. Effects of Strength Training on the Physiological Determinants of Middle- and Long-Distance Running Performance: A Systematic Review. Sports Medicine. 2018;48(5):1117-1149.
Barnes KR, Kilding AE. Strategies to improve running economy. Sports Medicine. 2015;45(1):37-56.
Dorn TW, Schache AG, Pandy MG. Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance. Journal of Experimental Biology. 2012;215(11):1944-1956.
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Ferber R, Kendall KD, Farr L. Changes in knee biomechanics after a hip-abductor strengthening protocol for runners with patellofemoral pain syndrome. Journal of Athletic Training. 2011;46(2):142-149.
Willy RW, Davis IS. The effect of a hip-strengthening program on mechanics during running and during a single-leg squat. Journal of Orthopaedic & Sports Physical Therapy. 2011;41(9):625-632.