Runners with lower dynamic stability exhibit better running economy

Maintaining dynamic stability during running incurs an energetic cost that does not contribute to forward propulsion. Despite this, dynamic stability has received little attention as a potential factor influencing running economy. To understand the relationship between dynamic stability and running economy and how both can be affected through footwear, twenty-one trained runners were tested on a treadmill across three individualized speeds and five footwear conditions (4 advanced footwear technology (AFT) and 1 non-AFT). Local dynamic stability (LDS) was quantified via maximum Lyapunov exponents from seven segmental angular velocities, aggregated per trial and running economy was measured as cost of transport using metabolic gas-exchange data. Linear mixed-effects models were used to assess relationships between LDS, COT and footwear. Aggregated LDS was negatively associated with COT ( p =  0.036), while footwear condition had no significant effect on LDS ( p =  0.060–0.359). This study is the first to demonstrate that an aggregate of LDS across multiple body segments is negatively associated with COT, indicating that runners with lower dynamic stability exhibit better running economy. AFT did not affect LDS compared to non-AFT, suggesting that the ergogenic effects of AFT are achieved without compromising running stability.