Is There an Optimal Speed for Economical Running?

Area of Science:

• Exercise Physiology
• Sports Science
• Biomechanics

Background:

• Running economy, a key determinant of endurance performance, is influenced by various factors.
• Previous research on the effects of sex and speed on running economy has yielded inconsistent results, potentially due to methodological limitations.
• Understanding these influences is crucial for optimizing training and performance in runners.

Purpose of the Study:

• To investigate the impact of absolute and relative running speeds on running economy.
• To determine if sex influences running economy when comparing individuals of equivalent performance standards.
• To compare the running economy of high-level and recreational runners across a wide range of speeds.

Main Methods:

• Ninety-two healthy runners (high-level and recreational men and women) underwent discontinuous incremental treadmill testing.
• Measurements included oxygen cost, speed at lactate turn point (sLTP), and maximal oxygen uptake.
• Energy cost was calculated in kcal·kg⁻¹·km⁻¹ across a broad spectrum of running speeds.

Main Results:

• No significant sex-specific differences in running economy were observed for either recreational or high-level runners at absolute or relative speeds.
• High-level runners demonstrated superior running economy compared to recreational runners across all tested speeds.
• A curvilinear, U-shaped relationship between speed and energy cost was identified in high-level runners, with an optimal economical speed around 13 km/h (70% sLTP).

Conclusions:

• Running economy is not sex-dependent when comparing runners of similar performance levels.
• Elite endurance runners exhibit enhanced running economy compared to their recreational counterparts.
• An optimal running speed exists that minimizes energy cost, highlighting its importance for efficient locomotion.