There are three physiological factors that show up again and again in the research as the biggest predictors of running performance: VO2 max, lactate threshold, and running economy. Strength training, it turns out, barely touches the first two. So why does virtually every study on strength training and runners show a real performance benefit? Exercise physiologist Dr Bill Evans unpacks how these three factors actually adapt, and why the order you train them in matters, which is worth reading alongside this.
The answer is running economy - and understanding how strength training improves it changes how you should think about programming, whether you're chasing a 5K PB or getting ready for your first 100km ultra.
What running economy actually is
Running economy is a measure of how efficiently your body uses oxygen to run at a given pace - essentially, how much fuel it costs you to hold a certain speed. It's been shown to be a stronger predictor of performance than VO2 max alone. Some elite marathon runners have lower VO2 max values than their competitors, yet still out-perform them, because their running economy is better. They're simply more efficient.
Across multiple studies, strength training has been shown to improve running economy by 2–8%. For context: Nike's Vaporfly shoes made headlines for offering roughly a 4% running economy improvement. Doubling that through a couple of gym sessions a week is a pretty good return, and considerably cheaper than a $400 pair of shoes.
Why it works: three mechanisms
Strength training doesn't build running economy through bigger muscles. It works through the nervous system and connective tissue.
Neuromuscular adaptations
Strength training increases neural drive to the muscles, improves motor unit firing frequency and synchronisation, reduces neural inhibition (the body's natural reflex to dampen force output), and improves intramuscular coordination. None of this requires more muscle mass - it's about your nervous system getting better at using the muscle you've already got.
Rate of force development
This is how quickly a muscle can produce force. A faster rate of force development means less time spent on the ground and a quicker transition from the braking phase of your stride to propulsion. It also creates something close to an isometric muscle contraction on contact - the muscle fibres barely lengthen or shorten, which costs less energy than a full contraction cycle. Less energy per stride, at the same pace, is exactly what running economy is measuring.
Tendon stiffness
Think of a spring: a stiffer spring doesn't compress or stretch as far, but it rebounds faster. Optimal tendon stiffness (particularly through the Achilles) reduces how much your muscle fibres have to lengthen and shorten with every stride, which lowers the energy cost of running at a given speed.
The injury-performance cycle
There's a well-documented cycle in distance running: injury, followed by rehab (usually reduced running plus strength work), followed by a return to normal training, followed by a push toward a performance goal - which often ends in another injury. Around 50–60% of novice runners are injured within their first year of running, and most runners get injured more than once over time. Beau Tyrrell's own tibial stress fracture is a good real-world example of exactly how this cycle plays out, and how to break it.
One study of 300,000 recreational runners found that training disruptions of more than a week before a race cost runners 5–8% off their finish time - in marathon terms, that's roughly 20 minutes. The practical implication: time spent injured isn't just lost training, it's a direct cost to performance. More time spent uninjured means more time training, which means better performance.
Strength training doesn't prevent every running injury - nothing does - but building tolerance and capacity in bones, tendons, ligaments and muscles means your body can handle more of the load you're asking it to absorb.
Progressing beyond bodyweight
A common mistake: staying in low-intensity rehab-style exercises for too long. There's a natural progression as symptoms settle and capacity builds:
- Early stage - higher reps (10–15), lower intensity (RPE 5–6/10), 2–3 sets. Think bodyweight glute bridges, step-ups, calf raises.
- Intermediate stage - moderate reps (8–10), moderate intensity (RPE 6–7/10), 3 sets, adding load.
- Building toward performance - lower reps (6–8), 3–4 sets, working toward lifting more than 80% of your one-rep max.
If you've been doing the same exercise for months and can comfortably knock out 12–15 reps, it's probably too light. Runners need to actually get strong - bodyweight training alone isn't enough once you've built a base.
Why the program should change across the running spectrum
Sprinters, middle-distance runners, marathoners and ultra runners share plenty of overlap in their strength training - most benefit from some form of squat pattern, a single-leg movement, a plyometric or power-based exercise, and a calf raise variation. But the emphasis shifts significantly depending on where you sit on the spectrum, because the biomechanics of propulsion change.
Sprinters: hip-dominant
Propulsion in sprinting comes primarily from the hip - hamstrings, glutes and adductors do most of the work. This is part of why hamstring injuries are so disproportionately common in sprinters (one study found upper leg injuries accounted for 32.9% of injuries in track sprinters, roughly three times the rate seen in recreational or marathon runners).
Programming for sprinters tends to be low volume, high load, high velocity - think 2–4 rep ranges, hip thrusts, RDLs, power cleans, eccentric hamstring work (like Nordic curls), and genuine plyometric/reactive strength work like drop jumps.
Distance runners: calf and Achilles-dominant
For joggers and distance runners, propulsion shifts down the leg - the calf and Achilles do more of the work than the hip. Injury patterns shift too: knee injuries (patellofemoral pain, ITB syndrome) are far more common in novice and recreational runners than in sprinters, and calf and Achilles work becomes a bigger programming priority.
Training here tends to sit at moderate intensity and moderate volume - still lifting heavy (well above 80% of 1RM when appropriate), but balanced against the conditioning and volume demands of longer races.
Ultra and trail runners: eccentric and environmental demands
Ultra running adds variables the other groups don't have to deal with as much: significant elevation change (meaning heavy eccentric quad loading on descents), variable and technical terrain (raising ankle sprain risk), an older average demographic (most competitive ultra runners are over 35), and extended exposure to fatigue, temperature swings and sleep deprivation on longer or multi-day events.
Programming for this group often includes reverse Nordics for eccentric quad strength, step-ups (given how stair- and hill-heavy many ultra courses are), single-leg balance and stability work, and sometimes weighted-vest training to simulate carrying mandatory race gear.
The bottom line
If you want to run better, strength training is one of the more reliably effective tools available - not because it will change your VO2 max, but because it improves running economy through your nervous system, your rate of force development, and your tendon stiffness. And once you're strength training, how you program it should reflect where you actually sit on the running spectrum - your injury history, your training age, your current load, and your goals, not a generic one-size-fits-all plan.