Running Economy
Also known as: RE, Movement economy, Oxygen cost of running, Energy cost of running
The amount of oxygen (or energy) you consume to run at a given submaximal pace, typically expressed in mL of O2 per kg of body weight per kilometre (mL/kg/km). Running economy is the efficiency of the engine — two runners with identical VO2max can race minutes apart over a marathon because one converts oxygen into forward motion more cheaply than the other. Alongside VO2max and lactate-threshold fraction, it's the third leg of the endurance-performance tripod.
Formula
RE = VO2 (mL/kg/min) at a fixed submaximal pace / running speed (m/min)
Result expressed as mL/kg/km. Lower = more economical.
Field proxies (no metabolic cart): heart-rate at fixed pace over time, or pace at fixed perceived effort. Both improve as economy improves, even when VO2max is unchanged.Example
Two runners, both VO2max 65 mL/kg/min, both racing a marathon. Runner A: RE 210 mL/kg/km. Runner B: RE 185 mL/kg/km — about 12% more economical. At marathon pace (~80% VO2max), Runner B sustains a faster speed at the same oxygen cost and finishes 6-10 minutes ahead. Same engine, cheaper fuel burn.
How Afitpilot Uses This
We don't yet ingest pace, GPS, or per-stride biomechanics from devices, so running economy isn't computed directly. The training stimuli known to improve it are already part of our endurance prescriptions: high-volume Zone 2 builds the aerobic substrate, short hill repeats and strides develop neuromuscular stiffness, and heavy strength work (3-5 reps at RPE 8-9) on compound lifts improves the elastic return that drops oxygen cost per stride. Future surface: ingest pace + HR from wearables so economy trends can be tracked alongside e1RM (strength) and VO2max (capacity), closing the picture of why two athletes with the same VO2max race differently.
Running economy across athlete profiles
| Who / Context | Value | Note |
|---|---|---|
| Elite male marathoner (Kipchoge tier) | ~175-190 mL/kg/km | Some of the lowest values ever recorded — minutes of marathon time |
| Elite female marathoner | ~180-200 mL/kg/km | Comparable to male elites; the gap is in VO2max and LT2, not economy |
| Sub-elite club runner | ~200-220 mL/kg/km | Room to improve — strength work + plyometrics typically yields 3-7% |
| Recreational runner | ~220-260 mL/kg/km | Biggest gains come from consistent volume and basic strength work |
| Trainability — heavy strength | +3-8% RE in 8-12 weeks | Heavy compound lifts (3-5 reps RPE 8+) consistently improve economy |
| Trainability — plyometrics | +2-6% RE in 6-12 weeks | Tendon stiffness + elastic return drop oxygen cost per stride |
| Trainability — high-volume easy running | +5-10% RE over a season | Mitochondrial and capillary adaptations make each stride cheaper |
Known Limitations
- •Running economy is highly individual and partially genetic — limb length, Achilles stiffness, foot strike, and torso geometry all contribute. Two athletes with identical training will not converge on the same RE.
- •Measurement requires a metabolic cart or accurate field protocol. Wearable estimates of 'running economy' (Stryd, Garmin) are proxies based on power or HR, not actual oxygen consumption — useful for tracking trends in one athlete, not for cross-athlete comparison.
- •Improvements come slowly — 2-5% over a year of focused training is a strong result. Beginners gain faster (5-15% in the first 6-12 months) as movement patterns and tissue stiffness adapt.
- •RE is pace-dependent. A runner economical at 5:00/km marathon pace may be wasteful at 3:30/km 5K pace, because stride mechanics and substrate use shift. Always specify the pace when comparing values.
Science Context
Daniels & Gilbert formalised running economy in the 1970s and demonstrated that elite endurance performance correlates more strongly with RE × LT2 fraction × VO2max than with VO2max alone (Joyner & Coyle, 2008 — the canonical performance model). Saunders et al. (2004) catalogued the training interventions that improve RE in trained runners: heavy strength training (highest-confidence effect), plyometrics, high-volume aerobic work, and altitude exposure. Recent work on shoe technology (Hoogkamer 2018, Vibram/Nike Vaporfly studies) showed that carbon-plated foam can reduce the metabolic cost of running by 4%, the largest single-intervention RE improvement ever published — confirming that economy is a function of both the athlete and the system around them. The mechanism is multi-factorial: tendon stiffness, ground-contact time, vertical oscillation, fibre-type composition, and substrate utilisation all contribute.