Landing-Takeoff Asymmetries Applied to Running Mechanics: A New Perspective for Performance

摘要

Background: Elastic bouncing is a physio-mechanical model that can elucidate running behavior in different situations, including landing and takeoff patterns and the characteristics of the muscle-tendon units during stretch and recoil in running. An increase in running speed improves the body’s elastic mechanisms. Although some measures of elastic bouncing are usually carried out, a general description of the elastic mechanism has not been explored in running performance. This study aimed to compare elastic bouncing parameters between the higher- and lower-performing athletes in a 3000 m test. Methods: Thirty-eight endurance runners (men) were divided into two groups based on 3000 m performance: the high-performance group (P _(high); n = 19; age: 29 ± 5 years; mass: 72.9 ± 10 kg; stature: 177 ± 8 cm; 3000 _(time): 656 ± 32 s) and the low-performance group (P _(low); n = 19; age: 32 ± 6 years; mass: 73.9 ± 7 kg; stature: 175 ± 5 cm; 3000 _(time): 751 ± 29 s). They performed three tests on different days: (i) 3000 m on a track; (ii) incremental running test; and (iii) a running biomechanical test on a treadmill at 13 different speeds from 8 to 20 km h ~(?1). Performance was evaluated using the race time of the 3000 m test. The biomechanics variables included effective contact time ( t _(ce)), aerial time ( t _(ae)), positive work time ( t _(push)), negative work time ( t _(break)), step frequency ( f _(step)), and elastic system frequency ( f _(sist)), vertical displacement ( S _(v)) in t _(ce) and t _(ae) ( S _(ce) and S _(ae)), vertical force, and vertical stiffness were evaluated in a biomechanical submaximal test on treadmill. Results: The t _(ae), f _(sist), vertical force and stiffness were higher ( p & 0.05) and t _(ce) and f _(step) were lower ( p & 0.05) in P _(high), with no differences between groups in t _(push) and t _(break). Conclusion: The elastic bouncing was optimized in runners of the best performance level, demonstrating a better use of elastic components.