A State-of-the-art Review on the Underlying Mechanisms of Running Economy

Running economy is determined by multiple physiological, biomechanical, and neuromuscular variables. Lower extremity stiffness has been identified as a primary factor in the determination of running economy due to its role in the utilization of elastic energy. Recent research exploring fascia has uncovered new insights into the underlying mechanisms driving the storage and utilization of elastic energy during running. New insights coupled with improvements in musculoskeletal modeling techniques and in instrumentation, allowing for accurate non-invasive quantification of passive stiffness, has opened the door for further exploration of running economy. The intention of this state-of-the-art review is to summarize the established conventions regarding the underlying mechanisms of running economy, and specifically stiffness, while reviewing current advancements in research on the topic to identify potential directions for future primary research. An electronic search of PubMed, Google Scholar, Semantic Scholar, and Mendeley databases was conducted, and the results were screened. Forward and backward citations were evaluated, and relevant literature was included to establish context, scope, and an accurate chronology of the development of the topic. A review of the relevant literature highlighted the crucial role that the modulation of stiffness plays in running economy and revealed strong evidence that fascia plays a significant role in the utilization of elastic energy. Additionally, the shortcomings of previous research and methodology was evaluated revealing avenues for further exploration of running economy.