Decoding Running Economy: What It Is and How Strength Training Improves It

Running economy is one of those terms that gets used frequently in endurance circles, often without a precise understanding of what it actually measures or why it matters. Most runners know it's something to do with efficiency, and that improving it is desirable, but the mechanism behind it – and how to actually train for it – tends to be less clear.

This is worth unpacking carefully, because running economy is arguably the most trainable determinant of trail running performance, and strength training is one of the most direct levers for improving it.

What Running Economy Actually Measures

Running economy is defined as the oxygen cost of running at a given submaximal velocity. A runner with good economy uses less oxygen to maintain a given pace than a runner with poor economy. Practically speaking, this means a more economical runner can run faster at the same aerobic effort, or sustain the same pace at a lower physiological cost – which matters enormously over the course of a long trail race.

It is worth distinguishing running economy from VO2max, because the two are often conflated. VO2max describes the ceiling of a runner's aerobic capacity – the maximum rate at which they can consume oxygen. Running economy describes how efficiently they use that capacity at submaximal intensities. Two runners with identical VO2max values can have meaningfully different performances if their running economies differ, and research has shown that running economy is often the stronger predictor of performance among trained runners of similar fitness.

The Mechanical Basis of Running Economy

Understanding how strength training improves running economy requires understanding what drives poor economy in the first place.

Every running stride involves two phases: a loading phase, where the foot contacts the ground and the leg absorbs impact force, and a propulsion phase, where that stored energy is redirected into forward movement. The efficiency of this cycle – how much energy is absorbed, stored, and returned – is the mechanical foundation of running economy.

Several factors determine how efficient this cycle is, including the stiffness and elasticity of the muscle-tendon unit, the capacity of the neuromuscular system to produce force rapidly, and the degree to which the runner can maintain optimal joint positioning under fatigue. All three of these factors are directly trainable through strength work.

How Strength Training Improves Running Economy

Musculotendinous stiffness. The tendons and muscles of the lower leg – particularly the Achilles tendon and the calf complex – function as elastic springs during running. A stiffer, more elastic spring stores and returns energy more efficiently than a compliant one, which means less metabolic energy is required to maintain pace. Heavy strength training increases musculotendinous stiffness by stimulating tendon collagen synthesis and improving the force-transmission properties of the muscle-tendon unit, which directly reduces the energy cost of each stride.

Neuromuscular efficiency. Running economy is not purely a mechanical phenomenon – it also reflects how efficiently the nervous system recruits and coordinates muscle fibres during the running stride. A runner with poor neuromuscular efficiency activates more motor units than necessary to produce a given amount of force, which increases the oxygen cost of running. Heavy resistance training improves inter- and intramuscular coordination, allowing the neuromuscular system to produce the same force output with less total activation. Over time, this reduction in unnecessary activation translates directly into improved economy.

Rate of force development. Ground contact time – the duration of each footstrike – is a key determinant of running economy. Shorter ground contact times are associated with greater economy, and the ability to shorten ground contact time depends on how quickly a runner can produce force at foot strike. This quality, known as rate of force development, is trained most effectively through heavy compound lifts in the 3–6 rep range and, at later training phases, through plyometric and reactive work. Studies measuring ground contact time before and after strength training interventionsconsistently report reductions of 4–8%, which corresponds to measurable improvements in economy at submaximal paces.

Postural endurance. This factor is less frequently discussed but is particularly relevant for trail and ultrarunners. As running duration increases, form deteriorates – the hips drop, the trunk flexes forward, and the stride mechanics become progressively less efficient. Strength training that targets the posterior chain and the deep core stabilisers builds the capacity to maintain optimal running posture deeper into a race, preserving economy when it is most likely to degrade.

The Evidence

The research on strength training and running economy is now well-established. A 2016 meta-analysis published in the Journal of Strength and Conditioning Research examined the effect of concurrent strength and endurance training on running economy across multiple studies and found consistent improvements in the range of 2–8% following heavy resistance training programmes of 6–14 weeks. For context, a 4% improvement in running economy at race pace is a meaningful competitive advantage – the kind of margin that separates podium positions at the trail level.

Importantly, these improvements occurred without significant changes in VO2max, confirming that the mechanism is neuromuscular and mechanical rather than aerobic. This is why strength training is most usefully understood as a complement to aerobic training, not a substitute for it – it improves the efficiency with which the aerobic engine is used, rather than the size of the engine itself.

Practical Implications

The strength training variables most associated with running economy improvements are heavy load (above 70% of 1RM), compound lower-body movements, and adequate volume – typically 3–4 sets per exercise across 2 sessions per week. The exercises with the strongest evidence base for economy improvement are the back squat, the Romanian deadlift, and single-leg variations of both, along with heavy calf work targeting the Achilles complex.

Plyometric training also improves running economy through its effect on musculotendinous stiffness and rate of force development, and it is most effective when introduced after a maximal strength base has been established – a sequencing point worth bearing in mind when structuring a training cycle.

Conclusion

Running economy is the efficiency metric that underpins trail running performance, and it is more trainable than most runners realise. The mechanisms through which strength training improves it – increased musculotendinous stiffness, better neuromuscular coordination, greater rate of force development, and improved postural endurance – are well-documented and well-understood. The practical implication is straightforward: a strength programme built around progressive heavy loading of the lower body is one of the highest-return investments a trail runner can make, and its benefits show up not in VO2max scores but in the efficiency of every stride across the full duration of a race.

For a deeper look at how to structure heavy strength work within a trail running training cycle, read our post on Why Ultrarunners Should Lift Heavy.