Take two runners. Same age, same sex, same weekly mileage, same weight. Both tested at a VO2 max of 62 ml/kg/min. On paper, identical aerobic engines.
Put them both in a marathon. One finishes in 2:42. The other finishes in 3:05. Same aerobic capacity, 23 minute gap.
The variable that explains most of the difference isn’t fitness. It’s running economy. How much oxygen each runner uses to sustain a given pace. And it’s one of the most important performance determinants in endurance sport that almost no wearable tracks.
What Running Economy Actually Means
Running economy is the steady state oxygen cost of running at a given submaximal pace. A runner who uses less oxygen to run at 4:00 per kilometre is more economical than one who uses more. Less oxygen demand at the same pace means the pace is sustainable for longer. That translates directly to race performance.
In elite marathon runners, running economy varies substantially between athletes with similar VO2 max values. Two runners with 70 ml/kg/min VO2 max can differ by 15 percent or more in oxygen cost at marathon pace. That difference completely explains why some 70 ml/kg/min runners can run a 2:10 marathon and others can’t crack 2:20.
For age group athletes, the gap is even more pronounced. Running economy at recreational levels is often 20 to 30 percent worse than in elite runners. Closing even a fraction of that gap produces meaningful race time improvements without any change in aerobic fitness.
What Determines Running Economy
Several factors feed into how much oxygen you need at a given pace.
Biomechanical efficiency. Stride length, cadence, vertical oscillation, ground contact time, arm swing pattern, posture. Efficient biomechanics mean less energy wasted on unnecessary movement and more energy directed into forward propulsion.
Muscular qualities. The stiffness of your tendons, particularly the Achilles, affects how much free elastic energy you can use per stride. Stiffer, more responsive tendons return more energy from each ground contact, reducing the work your muscles have to produce.
Fibre type distribution. Higher proportion of slow twitch fibres generally correlates with better economy at submaximal paces. This is largely genetic but also shifts with years of endurance training.
Body composition. Lower body fat percentage reduces the load that has to be moved with each stride. Leaner runners are generally more economical at the same pace.
Neuromuscular coordination. The skill of running at speed. Experienced runners execute the running motion more efficiently through years of neural refinement.
Equipment. Modern super shoes with carbon plates and high energy return foams improve running economy by 2 to 4 percent for most runners. This is a large effect. It’s one of the reasons marathon times have dropped so dramatically over the last 5 years.
What Your Wearable Tracks vs What Matters
Your Garmin or Coros running watch probably shows you several biomechanical metrics. Cadence, vertical oscillation, ground contact time, stride length. These are inputs that could contribute to a running economy model.
What your watch does not do is connect these metrics to an actual oxygen cost estimate. It shows you the numbers but doesn’t tell you what they mean for your efficiency at race pace.
Your cadence might be 172 steps per minute. Is that optimal for you? Depends on your height, your leg length, your current pace, your fitness, and your specific biomechanics. A 1.85m runner and a 1.68m runner have very different optimal cadences. The watch shows you the number. It doesn’t tell you what to do with it.
Your vertical oscillation might be 8.2cm. Good or bad? Without reference to your height, pace, and stride length, it’s an uninterpreted datapoint. In general, lower vertical oscillation at a given pace is more economical. But there are tradeoffs. Reducing vertical oscillation too aggressively costs running fluidity and often increases ground contact time, which can actually worsen economy.
Your ground contact time might be 240ms. Is it too long? For elite runners at race pace, ground contact times of 180 to 210ms are typical. Recreational runners often sit in the 240 to 280ms range. Reducing ground contact time is a real performance lever. Your watch records the number but doesn’t flag it or suggest interventions.
The data is there. The interpretation layer that would turn the data into training decisions is not.
How to Actually Improve Running Economy
You can train running economy. It takes dedicated work, not just base miles.
Stride drills and cadence work. Short high-quality efforts focused on specific elements of running form. Fast feet drills, high knees, bounding work. Done before quality sessions or as standalone 10 minute sessions. Improves neuromuscular coordination and stride efficiency.
Hill sprints and short high-intensity intervals. Short, near-maximal efforts improve several economy determinants simultaneously. Tendon stiffness adapts. Neuromuscular recruitment becomes more efficient. Stride power improves. 8 to 10 second efforts at 95 to 100 percent, full recovery between. One session a week during base building is enough to produce measurable economy improvement over 8 to 12 weeks.
Strength training focused on lower body power. Heavy squats, deadlifts, and single leg work. Plyometric work including bounding and depth jumps. These improve tendon stiffness and force production. Economy improvements from strength training are real and well documented, typically in the 2 to 5 percent range over 8 to 12 weeks of consistent work.
Technical running instruction. A few sessions with a biomechanics-focused coach or a gait analysis can identify specific inefficiencies in your form that you can work on. Low-hanging fruit for many recreational runners. The instruction cost is small relative to the time investment most runners put into mileage.
Racing and race pace work. Economy at race pace improves with race pace work. The body learns to execute the movement pattern more efficiently when it has repeated exposure to that specific stimulus. Tempo runs and race pace intervals build economy at the specific pace you care about.
Body composition management within reason. Lower body mass at stable strength improves economy. This is true but needs caution. Aggressive weight cutting for runners often costs more in maintained fitness than it gains in economy. The sweet spot is individual but usually involves modest, slow, training-sustained changes, not sharp cuts.
Testing Your Own Economy
You can rough-measure running economy without a lab. It’s not perfect but it’s informative.
Set a reference pace that’s comfortably submaximal but meaningful. For most runners, something like 10 seconds per kilometre slower than threshold pace. Run that pace for 20 minutes on a flat route or treadmill. Record your average heart rate.
Repeat the test every 6 to 8 weeks at the same pace on the same route at the same time of day. If your heart rate at that reference pace drops by 4 to 8 beats over a training block, you’ve improved either aerobic fitness or running economy or both. If heart rate stays the same but your perceived effort drops, that’s an economy improvement.
For a more precise test, a local sports science lab can do a VO2 submaximal test with gas exchange for around $200. You get an actual ml/kg/km measurement. Do it twice a year if you’re serious about race performance.
The Integration Gap
The wearable industry has the data. Cadence, vertical oscillation, stride length, ground contact time, heart rate, pace. Combined with training history, this data could produce a running economy estimate that updates over time and flags the specific biomechanical issues each runner should work on.
No consumer wearable currently does this. The data sits in the platform as individual metrics on a dashboard. The synthesis that would turn it into actionable training guidance is the gap.
For now, the work is up to you. Track your biomechanical metrics. Do regular submaximal reference tests. Address the form elements that matter. Run enough easy volume to build the aerobic base, but don’t neglect the economy work that distinguishes finishing from performing.
Two runners with the same fitness finish 20 minutes apart. The one who paid attention to economy is the one who wins.
Green score. Destroyed legs. There are 6 blind spots in your wearable data. We wrote a free guide covering every one of them.
Green score. Destroyed legs. There are 6 blind spots in your wearable data. We wrote a free guide covering every one of them.
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