Strategies to Improve Running Economy — Comprehensive Study Notes
Abstract
Running economy (RE) represents the energy cost of running at a given submaximal velocity and is typically expressed as the submaximal oxygen uptake at that velocity. It results from a complex interplay of physiological and biomechanical factors.
This review considers acute and chronic interventions that may improve RE by enhancing metabolic, cardiorespiratory, biomechanical, or neuromuscular components.
Traditional improvements in RE occur with endurance training; training history and volume may influence RE. Uphill and level-ground high-intensity interval training (HIT) are commonly prescribed and may yield further RE gains.
Short-term resistance and plyometric training can also enhance RE, likely via neuromuscular adaptations.
Altitude acclimatization can improve oxygen delivery and utilization, potentially improving RE.
Other strategies include stretching (which has an optimal flexibility/stiffness balance for RE), and nutritional interventions such as dietary nitrates and caffeine.
The field should further explore mechanisms and practical applicability of RE improvements outside laboratory settings.
Key Points
A range of training and passive interventions may improve RE: endurance training, HIT, resistance training, altitude exposure, stretching, and nutritional strategies.
RE can be improved by modifying metabolic, biomechanical, and/or neuromuscular efficiency.
The most robust RE improvements historically come from endurance training, with additional gains from uphill/flat HIT and resistance-based methods.
Altitude-related adaptations involve central and peripheral changes that can decrease the metabolic cost of running at sea level.
Stretching may influence RE through changes in musculotendinous stiffness, but excessive or poorly implemented stretching can fail to improve economy.
Dietary nitrates (e.g., beetroot juice) have shown potential to reduce the oxygen cost of submaximal exercise, with growing but not yet definitive evidence for RE in distance runners.
Practical takeaway: a periodized combination of endurance and resistance/plyometric training, with consideration of altitude exposure and targeted nutrition, can optimize RE; more work is needed to translate laboratory findings to real-world settings.
1 Introduction
Competitive distance running aims to minimize time to complete a given distance; RE is a key determinant of performance alongside VO2max and fractional utilization of VO2max.
Key determinants of endurance performance include:
High cardiac output and oxygen delivery to working muscles, enabling large aerobic ATP regeneration capacity. ext{VO}_2 ext{max}
Ability to sustain a high percentage of VO2max over time (fractional utilization).
Efficient movement, i.e., RE.
RE is the steady-state oxygen consumption at a fixed submaximal running speed, reflecting energy demand at that speed.
Trained runners generally show superior RE than untrained runners, suggesting training-induced adaptations.
The review covers acute and chronic interventions: various forms of resistance training, HIT, altitude exposure, stretching, and nutritional supplements.
Objective: discuss feasibility, mechanisms, and future research directions for improving RE beyond the lab.
2 Endurance Training in Runners
Endurance training elicits broad adaptations, including mitochondrial enhancements in skeletal muscle, improved buffering capacity, and hematological changes that can influence oxygen delivery/utilization and RE.
2.1 Training History
Long-term training history (years of running) and high cumulative distance are associated with RE improvements in some studies, though longitudinal data are mixed.
Some findings show positive correlations (e.g., Mayhew et al., r ≈ 0.62) between years of training and RE, while others show little or variable changes.
World-class case data suggest RE can improve over several years of training; interaction with training volume and consistency is not fully understood.
Implication: cumulative distance and consistency may contribute to neuromuscular, biomechanical, and metabolic efficiency changes that improve RE.
2.2 Training Volume
The relationship between training volume and RE remains unclear because few studies control for confounding variables like training intensity when adjusting volume.
Cross-sectional data suggest higher training volume is not always associated with better RE, though high-volume training clearly supports adaptations important for distance running success.
Future work should longitudinally examine how subtle changes in volume, intensity, and cumulative volume interact to affect RE.
2.3 High-Intensity Interval Training (HIT)
Flat overground HIT results for RE are mixed; specificity of training velocity relative to habitual running velocity may influence RE gains.
HIT at or around velocity at VO2max (vVO2max, ~93–120% vVO2max) or at the onset of blood lactate accumulation velocity (vOBLA) can improve RE by about ~1–7%, with some studies showing no effect.
Very high intensities (e.g., 132% vVO2max) may not improve RE, possibly due to form deterioration or insufficient training volume to elicit adaptations.
Biomechanical changes from HIT do not consistently relate to RE improvements; physiological adaptations (e.g., improved metabolic efficiency) are more commonly implicated.
2.3.1 Uphill Interval Training
Uphill running (a movement-specific form of HIT) is widely used and associated with better team performance in some cross-country contexts; there is limited direct evidence on its effects on RE.
Mechanisms are likely metabolic, biomechanical, and neuromuscular, given the resistance-like workload of uphill running.
2.4 Summary
More research is needed to define the relative efficacy of HIT for improving RE in long-distance runners and to understand how uphill vs flat HIT, frequency, duration, volume, and periodization influence RE.
3 Resistance Training
Resistance training is used to augment neuromuscular characteristics that may contribute to RE and running performance.
Definitions used in the review: heavy resistance training = loads ≤ 6 RM; strength-endurance resistance training = loads > 6 RM.
3.1 Heavy and Strength-Endurance Resistance Training
Mechanisms proposed for RE improvements with resistance training:
Improved lower-limb coordination and co-activation increase leg stiffness, promoting faster transitions from braking to propulsion via elastic recoil.
Hypertrophy in fast-twitch fibers (IIA/IIB) may increase force production efficiency, though neural adaptations may allow improvements without hypertrophy.
Neural adaptations (increased motor unit recruitment/synchronization) can enhance efficiency and delay fatigue, reducing oxygen cost at a given speed.
Reduced muscular fatigue leads to smaller increases in oxygen uptake for the same speed.
A caveat: increased body mass from hypertrophy can be counterproductive for distance running; however, neural adaptations can improve performance without large mass changes.
Some evidence suggests resistance training improves RE via improved biomechanical efficiency and possibly modest fiber-type shifts, though data on fiber-type conversion are mixed.
3.1.1 Mechanisms of Improvement Following Heavy or Strength-Endurance Resistance Training
Neural adaptations reduce the energetic cost of contraction and improve stride mechanics.
Heavy resistance training may preferentially hypertrophy fast-twitch fibers, but neural factors often account for early gains in running economy.
Increases in muscle strength can delay fatigue, leading to lower oxygen consumption at a given speed.
Some studies report concurrent improvements in RE and endurance performance when resistance training is added to endurance training, with no detrimental effect on VO2max.
3.1.2 Heavy Versus Strength-Endurance Resistance Training
Sedano et al.: heavy resistance training yielded greater RE improvements (≈5%) and better 3-km times than strength-endurance (≈1.6%) when added to endurance training.
Berryman et al.: strength-endurance training improved RE by ≈4% and improved 3-km performance significantly without VO2max change.
Taipale et al.: heavy resistance training led to notable RE improvements (mean ≈8%) and vVO2max gains (≈10%), with neuromuscular improvements; however, substantial endurance volume increases may confound results.
In females, 10 weeks of strength-endurance training plus endurance training improved RE by ≈4% without VO2max changes.
Overall: concurrent resistance and endurance training can improve RE without sacrificing VO2max or endurance performance, but effects are likely subject- and protocol-specific.
3.2 Plyometrics and Explosive Resistance Training
Concept: movement specificity and stretch-shortening cycle (SSC) exploitation to increase muscular power and stiffness.
Mechanisms: increased leg stiffness, store-retain elastic energy, reduced ground contact time, and enhanced neuromuscular function.
Paavolainen et al.: explosive-resistance training improved 5-km time by ~3.1% and RE by ~8.1% without VO2max change; also improved sprint, jump, and stance times.
Spurrs et al.: plyometrics improved RE and various performance indices (but some studies show limited or no change in certain biomechanical proxies).
Other studies show that plyometrics can improve RE in recreational, moderately trained, and highly trained runners; improvements may be variable across testing speeds.
Possible explanations: increased lower-limb stiffness and elastic energy return, stronger power output, improved running mechanics; however, not all studies observe mechanistic changes directly (e.g., EMG or stiffness measures).
Some studies suggest warm-up strides with a weighted vest can acutely improve RE via increased leg stiffness.
3.3 Resistance Training Versus Plyometric or Explosive Resistance Training
Across several studies, traditional heavy resistance training tends to yield greater RE improvements than plyometric-only interventions when volume is matched.
Some findings suggest plyometrics provide additional or complementary benefits to running economy, especially when combined with endurance work, but the strongest effects are often from heavy resistance training.
Movement-specific resistance approaches (e.g., hill running, sand running) may offer targeted benefits for RE and performance, though more research is needed.
3.4 Summary
Individual responses to resistance training vary; traditional resistance training often provides greater RE benefits than plyometrics, though plyometric or explosive styles can contribute via neuromuscular adaptations.
Mechanisms likely include neuromuscular improvements, changes in running mechanics, and possibly selective fiber-type adaptations; direct EMG or muscle-tire recruitment evidence is limited.
Movement-specific resistance training approaches may offer promise for RE improvements; further research is warranted.
4 Altitude Exposure
Altitude exposure strategies aim to improve RE through central and peripheral adaptations that improve oxygen delivery/utilization and metabolic efficiency.
Meta-analytic evidence suggests modest performance gains (approximately 1–4%) across protocols with natural and artificial altitude exposure in trained athletes.
Altitude adaptations are often attributed to hematological changes (increased total hemoglobin mass) and peripheral adaptations, but nonhematological mechanisms also contribute to RE improvements.
4.1 Altitude Versus Sea-level Natives
Descriptive data show Kenyan runners training at altitude exhibit better economy (lower VO2 at submaximal speeds) and less lactate accumulation than sea-level natives, potentially due to body composition and distribution differences; allometric scaling (e.g., ml·kg^-0.67·min^-1) may improve cross-group comparisons.
Sea-level natives generally show smaller or no RE improvements after similar altitude exposure when compared with altitude natives.
Some studies (e.g., 46 weeks at 2,210 m) indicate that altitude natives experience greater changes in RE than sea-level natives, possibly due to genetic, development, or long-term acclimatization differences.
4.2 Adaptations to Different Hypoxic Environments
Blood parameters: increases in hemoglobin mass with prolonged hypoxic exposure can contribute to improved oxygen transport, but not all hypoxic protocols yield substantial Hb mass changes; some RE improvements occur with modest or no Hb-mass changes.
Cardiorespiratory adaptations: reductions in minute ventilation (VE) and heart rate (HR) during submaximal exercise, shifts toward more carbohydrate use, and improved muscle efficiency may reduce oxygen cost and improve RE.
Metabolic efficiency: some studies show improved RE without major changes in VE, RER, or Hb mass, suggesting other nonhematological mechanisms at work.
Moderate-duration intermittent hypoxia (e.g., 2–3 weeks of hypoxic exposures) can improve RE by small margins (e.g., ~2.6–7.7%), sometimes with accompanying HR reductions and improved submaximal performance.
Fluid/oxygen transport and excitation-contraction coupling changes are proposed as contributing mechanisms.
4.2.1 Blood Parameters
Increases in Hb mass and concentration can boost oxygen-carrying capacity, potentially contributing to RE improvements via reduced oxygen cost at higher heart rates.
Approximately 400 hours of hypoxia may be required to increase total Hb mass; shorter protocols may still improve RE via other mechanisms.
4.2.2 Cardiorespiratory Adaptations
Reductions in VE and HR at submaximal workloads are commonly observed after altitude exposure, contributing to lower oxygen costs.
Adaptations may include more efficient excitation-contraction processes and improved substrate utilization.
4.2.3 Metabolic Efficiency
Some studies indicate that improvements in RE after hypoxia do not depend on reduced ventilation or large shifts in substrate utilization, pointing to other efficiency gains.
4.2.4 Muscle Fiber Type
Type I fibers are more efficient; acclimatization might shift fiber-type characteristics toward more economical profiles, though direct evidence in runners remains limited.
4.3 Other Environmental Strategies
Other environmental strategies (e.g., heat exposure, cold exposure, surface variations like sand) have been proposed but require more research to determine effects on RE.
4.4 Summary
Altitude exposure can improve RE without detrimental effects; the magnitude is modest and timing/phase relative to competition matters. Hematological and nonhematological adaptations likely contribute to improvements in RE.
5 Flexibility and Stretching
The literature on flexibility/stretching and RE is equivocal.
Some studies report an inverse relationship: less flexibility correlates with better RE, possibly due to greater stiffness and elastic energy storage in muscles/tendons. Key findings include:
Gleim et al.: tighter, less flexible individuals showed better RE across speeds.
Lower limb/trunk stiffness and reduced excessive joint range of motion may stabilize the pelvis on ground contact, reducing costly stabilizing activity.
Other studies show conflicting results or even improvements in RE with increased flexibility, suggesting context matters (e.g., population studied, testing protocol, treadmill familiarization).
Meta-level takeaway: a certain degree of musculotendinous stiffness appears beneficial for RE, but stretching remains valuable for injury prevention and stride optimization; optimize balance between flexibility and stiffness.
5.2 Stretching
Methodological issues often confound findings: lack of treadmill familiarization, non-runners, mixed sexes, etc., limit conclusions.
Acute stretching may transiently improve RE in some contexts, but chronic stretching prior to running does not reliably enhance economy.
Systematic reviews suggest acute stretching can temporarily enhance RE, but habitual pre-run stretching does not consistently improve economy.
5.3 Summary
Increasing stiffness in lower-body musculotendinous structures appears to improve RE, but stretching should not be avoided: it aids injury prevention and stride mechanics when applied appropriately.
6 Nutritional Interventions
Nutrition strategies that modulate oxygen cost and metabolic efficiency are of growing interest for RE
essay.Dietary nitrate (NO3−) supplementation is the most studied ergogenic dietary intervention with potential to lower the O2 cost of submaximal exercise and improve running performance.
Other nutritional approaches (caffeine, creatine with glycerol, echinacea) show varied and modest effects on RE; more research is needed.
6.1 Dietary Nitrates
Source: leafy greens and beets (rich in nitrate, NO3−).
Mechanisms: dietary nitrate increases plasma nitrite and nitric oxide availability, potentially improving contractile efficiency and mitochondrial efficiency, thereby reducing O2 cost for a given work rate or improving oxidative phosphorylation efficiency.
Physiological pathways include improved calcium handling and actin-myosin interaction, and enhanced mitochondrial efficiency.
Evidence: some studies show a reduction in steady-state VO2 by ~5% with nitrate supplementation in cycling tasks; a single study reported RE improvements in running with beetroot juice, but data are not yet robust across all running contexts.
Practical note: nitrate effects may be time-dependent (3–6 days of supplementation in some studies) and may vary with training status and target intensity.
6.2 Other Nutritional Interventions
Echinacea: limited and trivial improvements in RE (~1.7%) with a high typical error of measurement, suggesting chance effects.
Caffeine: ingestion at ~7 mg·kg−1 prior to submaximal running may offer modest ergogenic effects via improved respiratory efficiency and psychological lift.
Creatine + glycerol: can reduce thermal and cardiovascular strain in the heat without negatively impacting RE.
6.3 Summary
Dietary nitrate shows promise as a natural means to improve RE, but more research is needed to determine its scope across well-trained distance runners and different events.
Other nutritional interventions may offer modest or context-dependent benefits; more robust trials are required.
7 Conclusions and Future Directions
A range of training and passive interventions can improve RE by modifying metabolic, biomechanical, and neuromuscular efficiency.
The most reliable improvements historically arise from endurance training; however, HIT, uphill and level-ground, resistance training, and plyometric training can provide additional gains via neuromuscular mechanisms.
Altitude exposure yields moderate improvements in RE, likely via central and peripheral adaptations that improve oxygen delivery/utilization and metabolic efficiency.
Stretching and flexibility play a nuanced role: there appears to be an optimal balance between stiffness and flexibility that supports RE; stretching remains valuable for injury prevention and athletic maintenance.
Dietary nitrate supplementation holds promise for reducing the oxygen cost of submaximal exercise and may improve RE, but further research with well-controlled trials is needed to establish efficacy across athletes and events.
For practical application, coaches and researchers should pursue integrated training plans that incorporate endurance work with targeted resistance/plyometric components, consider altitude exposure strategically, and explore nutrition-based strategies, while continuing to investigate individual variability in response to these interventions.
Acknowledgments
The authors report no external funding or conflicts of interest relevant to this review.
References (selected key sources)
Foundational works on RE and running economy include Foster & Lucia (2007); Costill et al. (1973); di Prampero et al. (1986).
Classic studies on resistance and plyometric training effects include Paavolainen et al. (1999); Spurrs et al. (2003); Taipale et al. (2009, 2013); Storen et al. (2008); Sedano et al. (2013).
HIT and interval training research includes Franch et al. (1998), Billat et al. (1999), Denadai et al. (2006), Enoksen et al. (2011).
Altitude and hypoxia literature includes Levine & Stray-Gundersen (1997); Saunders et al. (2004, 2009); Katayama et al. (2003, 2004); Truijens et al. (2008); Bonetti & Hopkins (2009).
Dietary nitrate and nitrite research includes Bailey et al. (2009, 2010); Larsen et al. (2011); Jones et al. (2012, 2013).
Definitions and key terms (glossary)
RE(v): Running economy at velocity v; the submaximal VO2 at a given running speed. ext{RE}(v) = ext{VO}_2( ext{submax}, v)
VO2max: Maximal oxygen uptake, a measure of aerobic capacity.
vVO2max: Velocity at VO2max.
vLT: Velocity at lactate threshold.
OBLA: Onset of blood lactate accumulation; often used to define a running pace.
MAS: maximal aerobic speed.
Hb mass: Hemoglobin mass; a determinant of oxygen-carrying capacity.
LHTL/LHTH/LLTH/LLTL: Live High Train Low/High; Live Low Train High/Low – altitude exposure protocols.
1 RM: One-repetition maximum (maximal strength testing).
SSC: Stretch-shortening cycle; a mechanism by which muscles store and return elastic energy.
NO3−/NO2−: Nitrate/nitrite, dietary precursors to nitric oxide.
RER: Respiratory exchange ratio; an index of substrate utilization.
VE/HR: Ventilation and heart rate, indicators of cardiorespiratory cost during submaximal work.
NOTE: All numerical values and study results above are taken from the provided transcript of the review article and tables. Where multiple values are given per intervention, summaries reflect the typical direction and magnitude reported (e.g., RE improvements in the range of approximately 1–8% depending on the protocol).