Purpose: To examine the influence of sagittal plane trunk posture on lower extremity energetics during running.
Methods: Forty asymptomatic recreational runners (20 males, 20 females) ran overground at a speed of 3.4 m/s. Sagittal plane trunk kinematics and lower extremity kinematics and energetics during the stance phase of running were computed. Subjects were dichotomized into High-Flexion (HF) and Low-Flexion (LF) groups based on the mean trunk flexion angle.
Results: The mean (+/-SD) trunk flexion angles of the HF and LF groups were 10.8[degrees] +/- 2.2[degrees] and 3.6[degrees] +/- 2.8[degrees], respectively. When compared to the LF group, the HF group demonstrated significantly higher hip extensor energy generation (0.12 +/- 0.06 J/kg vs. 0.05 +/- 0.04 J/kg, p<0.001) and lower knee extensor energy absorption (0.60 +/- 0.14 J/kg vs. 0.74 +/- 0.09 J/kg, p=0.001) and generation (0.30 +/- 0.05 J/kg vs. 0.34 +/- 0.06 J/kg, p=0.02). There was no significant group difference for the ankle plantar flexor energy absorption or generation (p>0.05).
Conclusion: Sagittal plane trunk flexion has a significant influence on hip and knee energetics during running. Increasing forward trunk lean during running may be utilized as a strategy to reduce knee loading without increasing the biomechanical demand at the ankle plantar flexors.
(C) 2014 American College of Sports Medicine