Biomechanical Changes and the Time Course of Recovery in Lower Extremities of Recreational Runners Following a Simulated Treadmill Half-Marathon

BACKGROUND: Providing runners with injury prevention suggestions from a biomechanical perspective is crucial in light of the increased incidence of running-related injuries forecasted with the rising popularity of the half-marathon. Previous research has demonstrated associations between running injuries and patterns of lower extremity biomechanics, as well as indicating that inadequate rest between training sessions can result in injuries and underperformance. However, whether half-marathon running elicits lower extremity biomechanical changes and the recovery time remains largely unclear. This study aimed to investigate the acute changes (pre-run and immediately post-run) and the time course of recovery (pre-run, day 1, and day 2) in neuromuscular function, landing strategies, and lower extremity joint mechanics of recreational runners following a simulated half-marathon protocol on a treadmill. RESULTS: Compared to pre-half-marathon measurements, we observed significant reductions in concentric (Flexors: Pre: 1.49 ± 0.50Nm/kg, Post: 1.34 ± 0.54Nm/kg, p < 0.001; Extensors: Pre: 2.19 ± 0.73Nm/kg, Post: 2.00 ± 0.82Nm/kg, p < 0.001) and eccentric (Flexors: Pre: 1.67 ± 0.68Nm/kg, Post: 1.34 ± 0.62Nm/kg, p < 0.001; Extensors: Pre: 2.44 ± 0.13Nm/kg, Post: 1.96 ± 0.12Nm/kg, p < 0.001) torques of the knee flexors and extensors, reductions in eccentric knee flexor to concentric knee extensor torque ratios (Pre: 0.78 ± 0.27, Post: 0.68 ± 0.22, p < 0.001), and impaired knee (Pre: 1.6 ± 0.1°, Post: 3.0 ± 0.2°, p < 0.001) and hip (Pre: 1.5 ± 0.2°, Post: 2.6 ± 0.2°, p < 0.001) joint position sense immediately post running. Additionally, we observed an increase in contact time (p = 0.006), decreases in peak vertical ground reaction force (p < 0.001) and impulse (p < 0.001), and changes in lower extremity joint kinematics and kinetics during the stance phase of running immediately after the half-marathon. Most measured parameters recovered within one day, except hip joint position sense, which was restored within two days. By the second day, we also observed super-compensation in thigh muscle torques. CONCLUSION: The study revealed that simulated treadmill half-marathon induces alterations to neuromuscular function, impacts landing strategies, and elicits changes in lower extremity joint mechanics. However, these effects are temporary and resolve within two days post-run. These findings provide valuable insights to optimize training responses and prevent overtraining in recreational runners.