A Deep Dive into Running Efficiency: The Scientific Relationship Between Vertical Oscillation, Ground Contact Time, and Running Economy

Running Economy: The Runner’s “Fuel Efficiency”

Running Economy is defined as the amount of oxygen consumed per kilogram of body weight per kilometer at a specific pace (mlO₂/kg/km). A lower value indicates greater efficiency, allowing you to run faster with the same aerobic capacity.

If two runners have the same VO2max, the one with better running economy can maintain the same pace with less effort—this is why, with identical physical training, runners with better technique improve faster.

Key Biomechanical Metrics

Modern running sensors (Garmin watch running dynamics sensors, Stryd power meters, Runscribe, etc.) can provide the following biomechanical data:

Vertical Oscillation

The vertical distance your center of mass moves with each step (in centimeters), representing how high you “bounce.”

Excessive vertical oscillation means energy is wasted on “bouncing up” rather than “moving forward.” Improvement methods include: core stability training, consciously lowering your center of gravity, and increasing cadence.

Ground Contact Time

The duration your foot remains in contact with the ground per step (in milliseconds).

Excessively long ground contact time is usually related to the following:

• Heel striking instead of midfoot striking
• Insufficient ankle joint stiffness, lacking rebound capability
• Weak glutes and hamstrings, resulting in insufficient propulsion

Ground Contact Balance

The ratio of ground contact time between your left and right feet (ideal: 50%/50%). An imbalance exceeding 52%/48% may indicate running asymmetry, which could lead to overuse injuries on one side over the long term.

Cadence

Steps per minute; elite runners typically range between 170–185 steps/minute.

Relationship between cadence and ground contact time:
A 10% increase in cadence usually shortens ground contact time and reduces vertical oscillation. For most runners, increasing cadence is the single most effective technical adjustment for improving running efficiency.

Vertical Ratio

Vertical oscillation ÷ stride length, representing the ratio of “bouncing” to “moving forward.”

• A lower value means less vertical energy expenditure per unit of forward distance
• Target: below 7% (elite runners commonly see 5–6%)
• Common values for amateur runners in Taiwan: 8–12%

How to Use These Metrics to Improve Running Technique

Step 1: Establish a Baseline
Run for 30 minutes at your usual aerobic pace (e.g., 5:00–5:30/km) and record the average values of each metric.

Step 2: Identify the Biggest Issue
The following two problems are most common:

• Ground contact time >260ms + cadence <165: Prioritize increasing cadence, aiming to raise it by 1–2 steps/minute per week until reaching 170+
• Vertical oscillation >9cm: Strengthen your core, improve your landing point (your foot should land directly beneath your center of mass, not ahead of your body)

Step 3: Practice Targeted Drills

Drills to improve ground contact time:

• Quick in-place ankle hops (100 reps × 3 sets)
• Fast high knees (emphasizing quick ground contact and rebound)
• Jump rope (emphasizing ankle stiffness and fast rhythm)

Drills to improve vertical oscillation:

• Core planks and lateral core training
• While running, imagine there’s a ceiling above your head that you must not touch
• Shorten your stride and increase cadence (both usually improve together)

Special Considerations for These Metrics on Taiwan’s Mountain Roads

Road races in Taiwan often feature climbing sections, and biomechanical data naturally changes on hilly terrain:

• When climbing: ground contact time lengthens, cadence decreases, and vertical oscillation may decrease (normal)
• When descending: ground contact time shortens and vertical oscillation increases (watch out for knee stress)

During hill training, don’t force the flat-road standards; instead, focus on comparisons within similar gradients.

Conclusion

Running efficiency data isn’t just for showing off numbers—they are tools for diagnosing your technique. When you see a high ground contact time after your next workout, that’s not bad news; it’s a clear direction for improvement. With targeted technical training, you’ll find that at the same fitness level, running can become increasingly effortless and faster.

Related Reading

• Vertical Oscillation and Ground Contact Time: Two Key Metrics of Running Efficiency
• Interpreting Garmin Running Dynamics Data: Training Applications of Vertical Oscillation, Ground Contact Time, and Stride Length
• A Guide to Improving Running Economy: Run Faster with Less Energy
• Running Economy: The Secret to Running Faster with Less Energy