Running Efficiency: Calculation Methods, Factors, and Improvement Strategies

How do you calculate running efficiency?

Running efficiency, often referred to as running economy, is primarily calculated by measuring the oxygen consumed (VO2) at a given submaximal running speed, reflecting the energy cost required to maintain that pace.

What is Running Efficiency?

Running efficiency, or running economy, quantifies how much energy an individual expends to maintain a particular running velocity. In simpler terms, it's a measure of how "efficiently" your body uses oxygen to power your movement. A more efficient runner uses less energy (and thus less oxygen) to run at a specific speed compared to a less efficient runner. This metric is distinct from VO2 max, which measures the maximum amount of oxygen an individual can utilize during intense exercise; running efficiency focuses on submaximal efforts. For endurance athletes, superior running efficiency can be as crucial as a high VO2 max, as it dictates how long and how fast they can sustain a given pace without premature fatigue.

The Science Behind Running Efficiency

At its core, running efficiency is about metabolic cost. When you run, your muscles require energy, primarily derived from the breakdown of carbohydrates and fats, a process that requires oxygen. The more oxygen you consume at a given speed, the higher your energy expenditure for that speed, indicating lower efficiency.

This concept is rooted in the principles of bioenergetics and exercise physiology:

• Oxygen Consumption (VO2): Directly reflects the rate of aerobic energy production. A lower VO2 at a given submaximal pace signifies better running economy.
• Carbon Dioxide Production (VCO2): Along with VO2, VCO2 helps determine the Respiratory Exchange Ratio (RER), which indicates the proportion of carbohydrates and fats being metabolized.
• Energy Expenditure: Calculated from VO2 and RER, providing a precise measure of caloric cost.

Laboratory Methods for Measuring Running Efficiency

The gold standard for calculating running efficiency involves sophisticated laboratory equipment and protocols, typically performed on a treadmill.

Indirect Calorimetry

This method directly measures the volume of oxygen consumed and carbon dioxide produced by an individual during exercise.

• Protocol:
  1. The runner wears a mask or mouthpiece connected to a metabolic cart, which analyzes inhaled and exhaled gases.
  2. They run on a treadmill at several predetermined submaximal speeds (e.g., 8 km/h, 10 km/h, 12 km/h).
  3. Each speed is maintained for several minutes (typically 4-6 minutes) to allow oxygen consumption to reach a steady state.
  4. Data on oxygen consumption (VO2) and carbon dioxide production (VCO2) are collected during the steady-state period.
• Calculation:
  • The primary output is VO2 in milliliters per kilogram per minute (mL/kg/min) at each specific speed.
  • A lower mL/kg/min value at a given pace indicates better running efficiency. For example, if Runner A consumes 40 mL/kg/min at 12 km/h, and Runner B consumes 45 mL/kg/min at the same speed, Runner A is more efficient.
  • Sometimes, efficiency is expressed as the energy cost per unit distance (e.g., kcal/km), which is derived from VO2 and RER.

Key Metrics from Lab Testing:

• Oxygen Cost (VO2): The most direct measure. It quantifies how much oxygen your body uses per minute per kilogram of body weight to run at a specific submaximal speed.
• Respiratory Exchange Ratio (RER): The ratio of VCO2 produced to VO2 consumed. While not a direct measure of efficiency, it indicates substrate utilization (carbs vs. fats) and can influence the calculation of caloric expenditure.

Practical Field-Based Approaches to Estimate Running Efficiency

While laboratory testing provides the most accurate data, several practical, field-based methods can offer valuable insights into your running efficiency without specialized equipment. These methods are estimates and rely on correlating external factors with assumed internal energy expenditure.

Pace vs. Heart Rate Relationship

This is a common and accessible method for tracking changes in efficiency over time.

• Concept: For a given running pace, a lower average heart rate suggests that your cardiovascular system is working less intensely, implying lower energy expenditure and thus better efficiency.
• Method:
  1. Perform a consistent running workout (e.g., 30 minutes at a steady, moderate pace) at regular intervals (e.g., once a month).
  2. Use a GPS watch and heart rate monitor to record your average pace and average heart rate for that workout.
  3. Calculation: Compare your average heart rate for the same pace over time. If your heart rate decreases while maintaining the same pace, or if your pace increases at the same heart rate, your efficiency is improving.
• Limitations: Heart rate can be influenced by many factors (stress, fatigue, hydration, caffeine, heat), so consistency in testing conditions is crucial.

Pace vs. Perceived Exertion (RPE)

The Rate of Perceived Exertion (RPE) scale (typically 6-20 or 1-10) is a subjective but useful tool.

• Concept: If you can run a specific pace with a lower RPE, it suggests that pace feels easier, indicating improved efficiency.
• Method:
  1. Regularly assess your RPE during consistent runs at a given pace.
  2. Calculation: If you consistently achieve a faster pace at the same RPE, or the same pace feels easier (lower RPE), your efficiency is likely improving.
• Limitations: Highly subjective and can be influenced by mood, sleep, and other non-physiological factors.

Running Economy Field Tests

While not as precise as lab tests, some field tests attempt to mimic the concept.

• Submaximal Timed Runs: Run a set distance (e.g., 5k or 10k) at a consistent, moderate effort. Track your finish time and average heart rate. Over time, a faster finish time at the same average heart rate (or lower heart rate for the same time) indicates improved economy.

Wearable Technology Metrics

Many modern GPS watches and running pods provide advanced running dynamics that can indirectly reflect efficiency. These are not direct calculations of energy cost but indicators of biomechanical efficiency.

• Ground Contact Time (GCT): How long your foot spends on the ground with each stride. Shorter GCT generally indicates more efficient propulsion and less braking.
• Vertical Oscillation (VO): How much your body moves up and down with each stride. Lower vertical oscillation means less energy is wasted moving vertically and more is directed horizontally.
• Stride Length and Stride Rate (Cadence): While optimal values vary by individual, an appropriate balance is key. Often, increasing cadence (shorter, quicker steps) can reduce GCT and VO, leading to better efficiency for many runners.
• Power Meters (e.g., Stryd): These devices estimate running power (in watts) by combining force, velocity, and other biomechanical data. While still an evolving metric, for a given speed, a lower power output suggests greater efficiency.

Factors Influencing Running Efficiency

Running efficiency is a complex interplay of physiological, biomechanical, and neurological factors.

• Biomechanical Factors:
  • Running Form: Optimized posture, arm swing, foot strike, and leg mechanics.
  • Stiffness and Elasticity: The ability of muscles and tendons to store and release elastic energy (e.g., Achilles tendon stiffness).
  • Limb Segment Mass: Lighter lower limbs require less energy to swing.
• Physiological Factors:
  • Muscle Fiber Type: Higher percentage of slow-twitch fibers can be advantageous for aerobic efficiency.
  • Mitochondrial Density & Capillarization: More mitochondria for aerobic energy production and better capillary networks for oxygen delivery.
  • Neuromuscular Coordination: Efficient recruitment and firing patterns of muscle fibers.
• Training Factors:
  • Strength Training: Improves muscular force production and reduces energy cost.
  • Plyometrics: Enhances elastic energy return and muscle stiffness.
  • Running Drills: Improve specific aspects of form and coordination.
  • Pacing Strategies: Consistent pacing minimizes energy fluctuations.

Improving Your Running Efficiency

Improving running efficiency is a critical goal for any serious runner, as it allows you to sustain faster speeds with less effort.

• Strength Training: Focus on compound movements that strengthen the core, glutes, hamstrings, and calves. Examples include squats, lunges, deadlifts, and calf raises. Stronger muscles are more efficient at producing force and stabilizing the body.
• Plyometrics: Exercises like box jumps, bounds, and skipping drills improve the stretch-shortening cycle, enhancing the elastic properties of muscles and tendons, leading to more "spring" in your step.
• Running Drills & Form Work: Incorporate drills like A-skips, B-skips, butt kicks, and high knees into your warm-up. Focus on maintaining a tall posture, slight forward lean, relaxed shoulders, and a higher cadence (170-180 steps per minute is often cited as efficient for many).
• Pacing and Strategy: Practice even pacing during training runs. Avoiding surges and significant fluctuations in speed can optimize energy expenditure.
• Hill Training: Running uphill strengthens leg muscles and improves power, while downhill running can improve eccentric strength and stride mechanics.
• Cross-Training: Activities like cycling or swimming can improve cardiovascular fitness without the high impact of running, allowing for recovery while maintaining aerobic capacity.
• Adequate Recovery and Nutrition: Proper fueling and sufficient rest ensure your body can adapt to training stimuli and perform optimally.

Limitations and Considerations

While calculating and improving running efficiency is beneficial, it's important to acknowledge certain limitations:

• Individual Variability: Optimal running form and efficiency metrics vary significantly between individuals based on genetics, body composition, and training history. There's no single "perfect" running style for everyone.
• Cost of Lab Testing: Gold-standard laboratory testing is expensive and not readily accessible to all.
• Practical vs. Scientific Accuracy: Field-based methods provide useful estimates but lack the precision of lab-based indirect calorimetry.
• Focus on Submaximal Efforts: Running efficiency primarily relates to submaximal aerobic efforts. It doesn't directly predict performance in maximal sprint events.
• Interaction with Other Factors: Running performance is a complex interplay of VO2 max, lactate threshold, muscle strength, and psychological factors, not solely dependent on running efficiency.

Conclusion

Calculating running efficiency, whether through precise laboratory measurements of oxygen consumption or practical field-based observations, provides invaluable insight into an athlete's energy economy. By understanding how efficiently your body converts oxygen into forward motion, you can identify areas for improvement in your training, biomechanics, and overall performance strategy. Ultimately, enhancing your running efficiency means you can run faster, for longer, with less effort, unlocking your full potential as a runner.