Running vs. Walking: Energy Expenditure, Calorie Burn, and Fitness Goals

How much more energy does running use than walking?

Running generally expends significantly more energy per unit of time than walking due to its higher intensity and mechanical demands. While the energy cost per unit of distance can be surprisingly similar at moderate speeds, running almost always results in a higher total caloric burn for the same distance covered.

Understanding Energy Expenditure in Movement

To quantify the energy difference between running and walking, we must first understand how the body expends energy during physical activity. Energy expenditure is typically measured in calories (kcal) or kilojoules (kJ) and represents the total amount of energy required to perform a given task. This energy is derived from the breakdown of macronutrients (carbohydrates, fats, proteins) through metabolic pathways, ultimately producing adenosine triphosphate (ATP) to fuel muscle contraction.

The primary determinants of energy expenditure during locomotion include:

• Body Mass: Heavier individuals require more energy to move their mass.
• Speed/Intensity: Moving faster or with greater effort demands more energy.
• Mechanical Efficiency: How efficiently the body converts metabolic energy into mechanical work.
• External Factors: Terrain, incline, wind resistance, and even footwear can influence energy cost.

METs: A Standard Measure of Activity Intensity

A common and practical method for estimating energy expenditure is through Metabolic Equivalents of Task (METs). One MET is defined as the energy cost of sitting quietly, equivalent to an oxygen uptake of 3.5 milliliters per kilogram of body weight per minute (3.5 mL/kg/min). Activities are assigned MET values based on their intensity relative to this resting state.

To calculate approximate caloric expenditure using METs: Calories Burned (kcal/min) = METs × 3.5 × Body Weight (kg) / 200

Let's look at approximate MET values for walking and running (these can vary slightly based on source and individual variation):

• Walking:
  • 2.0 mph (3.2 km/h): 2.8 METs
  • 3.0 mph (4.8 km/h): 3.5 METs
  • 4.0 mph (6.4 km/h): 5.0 METs
• Running:
  • 5.0 mph (8.0 km/h): 8.0 METs
  • 6.0 mph (9.7 km/h): 10.0 METs
  • 7.0 mph (11.3 km/h): 11.5 METs
  • 8.0 mph (12.9 km/h): 13.5 METs

From these values, it's immediately apparent that running, even at its slowest common pace, has a significantly higher MET value than walking at its fastest common pace.

Energy Cost Per Unit of Time (Duration)

When comparing the energy expenditure over a set period (e.g., 30 minutes), running consistently burns significantly more calories than walking. This is because running involves a higher intensity, greater oxygen uptake, and more vigorous muscle engagement.

Consider a 70 kg (154 lb) individual:

• Walking at 3.0 mph (4.8 km/h) for 30 minutes:

  • METs = 3.5
  • Calories/min = 3.5 × 3.5 × 70 / 200 = 4.29 kcal/min
  • Total for 30 min = 4.29 kcal/min × 30 min = ~129 calories

• Running at 6.0 mph (9.7 km/h) for 30 minutes:

  • METs = 10.0
  • Calories/min = 10.0 × 3.5 × 70 / 200 = 12.25 kcal/min
  • Total for 30 min = 12.25 kcal/min × 30 min = ~368 calories

In this example, running for 30 minutes burns nearly three times as many calories as walking for the same duration. This makes running a more time-efficient exercise for caloric expenditure goals, such as weight management.

Energy Cost Per Unit of Distance

Here's where the comparison becomes more nuanced and often surprising. While running is clearly more demanding per unit of time, the energy cost per unit of distance (e.g., per mile or per kilometer) can be remarkably similar, especially at moderate running speeds.

Research, including classic studies, has shown that above a certain speed, the energy cost of running per unit of distance tends to plateau. This is often attributed to running economy, which refers to the oxygen cost of running at a given speed. Efficient runners expend less energy to maintain a certain pace.

The reasons for this phenomenon include:

• Mechanical Efficiency: At higher speeds, the body adopts a more efficient running gait. While walking involves a continuous support phase with at least one foot on the ground, running includes a flight phase where both feet are off the ground. This "bouncing" motion, when optimized, can be surprisingly energy-efficient per stride.
• Pendulum Mechanics: The leg acts more like a pendulum during running, leveraging elastic energy stored in tendons and muscles, which reduces the metabolic cost compared to the continuous muscle activation required during walking.
• Less Vertical Oscillation per Step: While running involves more vertical oscillation overall, the efficiency of the spring-like action at higher speeds can lead to a more economical forward propulsion per unit of distance.

However, even with these efficiencies, running still generally burns more calories per unit of distance than walking. The difference is simply not as dramatic as the "per minute" comparison might suggest.

For instance, a 70 kg individual walking a mile might burn approximately 90-100 calories, while running the same mile might burn 100-110 calories. The difference is present but less pronounced than the time-based comparison. This means that if your goal is to burn a specific number of calories, you will cover the distance much faster by running, but the total caloric cost per mile might only be 10-20% higher than walking that same mile.

Factors Influencing Energy Expenditure

Beyond the fundamental differences between walking and running, several factors can significantly alter the energy cost of either activity:

• Body Weight: A heavier person will always burn more calories for the same activity than a lighter person because they are moving more mass.
• Speed and Intensity: As shown with METs, increasing speed, whether walking or running, increases energy expenditure.
• Incline/Grade: Walking or running uphill dramatically increases energy demand due to the added work against gravity. Even a slight incline can significantly elevate caloric burn.
• Terrain: Uneven surfaces, sand, snow, or trails require more stabilizing muscle activation and thus more energy than smooth, flat pavement.
• Running Economy/Efficiency: Individual physiological differences in gait, muscle fiber type, and biomechanics mean that some individuals are naturally more efficient runners than others, burning fewer calories for the same speed.
• Wind Resistance: Running into a strong headwind requires more effort and energy.
• Footwear and Clothing: While minor, heavy or restrictive gear can slightly increase energy cost.

Practical Implications for Fitness Goals

Understanding the energy cost differences between running and walking has several practical implications for designing your fitness routine:

• Weight Loss: If your primary goal is to maximize caloric expenditure in a limited amount of time, running is generally more efficient. A 30-minute run will typically burn far more calories than a 30-minute walk.
• Cardiovascular Health: Both activities are excellent for cardiovascular health. Running, being higher intensity, will elevate heart rate and oxygen consumption more significantly, providing a stronger training stimulus for the cardiovascular system.
• Injury Risk: Running imposes higher impact forces on joints (knees, hips, ankles) due to the flight phase and greater ground reaction forces. Walking is a lower-impact activity, making it more suitable for individuals with joint issues, those new to exercise, or during recovery periods.
• Accessibility and Sustainability: Walking is accessible to almost everyone, requires minimal equipment, and can be easily incorporated into daily life. It's often more sustainable for long-term adherence due to lower perceived effort and reduced injury risk.
• Training Adaptation: Running primarily builds cardiovascular endurance and muscular strength/power in the legs. Walking improves cardiovascular health and muscular endurance but to a lesser degree than running.

Conclusion

In summary, running unequivocally uses more energy per unit of time than walking. For instance, a 30-minute run will typically burn two to three times more calories than a 30-minute walk, making it a highly time-efficient exercise for caloric expenditure.

However, when considering the energy cost per unit of distance, the difference is less pronounced. While running still generally burns slightly more calories per mile or kilometer, the efficiency of the running gait means the increase is not proportional to the increase in speed.

Therefore, the choice between running and walking should be guided by your specific fitness goals, current fitness level, available time, and individual considerations regarding joint health and injury risk. Both activities offer significant health benefits, and the best exercise is ultimately the one you can perform consistently and enjoy.