Running economy and lower extremity stiffness in endurance runners: A systematic review and meta-analysis

Abstract

Background: Lower extremity stiffness simulates the response of the lower extremity to landing in running. However, its relationship with running economy (RE) remains unclear. This study aims to explore the relationship between lower extremity stiffness and RE.Methods: This study utilized articles from the Web of Science, PubMed, and Scopus discussing the relationships between RE and indicators of lower extremity stiffness, namely vertical stiffness, leg stiffness, and joint stiffness. Methodological quality was assessed using the Joanna Australian Centre for Evidence-Based Care (JBI). Pearson correlation coefficients were utilized to summarize effect sizes, and meta-regression analysis was used to assess the extent of this association between speed and participant level.Result: In total, thirteen studies involving 272 runners met the inclusion criteria and were included in this review. The quality of the thirteen studies ranged from moderate to high. The meta-analysis results showed a negative correlation between vertical stiffness (r = −0.520, 95% CI, −0.635 to −0.384, p < 0.001) and leg stiffness (r = −0.568, 95% CI, −0.723 to −0.357, p < 0.001) and RE. Additional, there was a small negative correlation between knee stiffness and RE (r = −0.290, 95% CI, −0.508 to −0.037, p = 0.025). Meta-regression results showed that the extent to which leg stiffness was negatively correlated with RE was influenced by speed (coefficient = −0.409, p = 0.020, r2 = 0.79) and participant maximal oxygen uptake (coefficient = −0.068, p = 0.010, r2 = 0.92).Conclusion: The results of this study suggest that vertical, leg and knee stiffness were negatively correlated with RE. In addition, maximum oxygen uptake and speed will determine whether the runner can take full advantage of leg stiffness to minimize energy expenditure.

Effect of Strength Training Programs in Middle- and Long-Distance Runners’ Economy at Different Running Speeds: A Systematic Review with Meta-analysis

“…A greater RFD after HL interventions would allow athletes to generate higher levels of force in short periods of time, allowing a rapid transition from the braking phase to the propulsion phase of the gait cycle, promoting favourable muscular conditions [ 123 ] that maximise the force–velocity relationship [ 125 ] and, thus, RE. On the other hand, HL may improve RE due to changes in lower limb stiffness [ 123 , 126 , 127 ], which would result in more efficient energy storage and release from the lower limbs, thus reducing the energy cost of running [ 128 ]. For example, a study by Millet et al [ 103 ] reported significant increases in RE after 14 weeks of HL and this was accompanied by an increase in leg stiffness.…”

“…8 ). Indeed, it has been observed that the correlation between leg stiffness and RE increases with V O 2 max [ 127 ]. Given that more highly trained athletes make more efficient use of elastic energy (i.e., the Achilles tendon) to minimise muscle energy cost [ 140 ], coupled with a possible increase in tendon stiffness generated by HL [ 133 ], it is possible that athletes with higher levels of performance (i.e., higher initial V O 2 max) may be better able to transfer these adaptations to running at a lower energy cost.…”