The Effects of Downhill Slope on Kinematics and Kinetics of the Lower Extremity Joints During Running

Publication date: Available online 12 November 2018

Source: Gait & Posture

Author(s): Sang-Kyoon Park, Hyun-Min Jeon, Wing-Kai Lam, Darren Stefanyshyn, Jiseon Ryu

ABSTRACT

Background

The purpose of this study was to investigate how lower extremity kinematics and kinetics change when running downhill.

Methods

Fifteen male recreational runners ran on an instrumented treadmill with three different slope conditions [level (0º), moderate (-6º), and steep (-9º)] at a controlled speed of 3.2 m/s. Ten consecutive steps were selected for analysis for each of the slope conditions and the order of slope conditions was randomized. Synchonized motion analysis and force plate was used to determine joint kinematics and kinetics.

Results

Compared to level running, participants demonstrated significantly larger knee flexion and smaller ankle plantar-flexion and hip flexion during downhill running (Ps < 0.05). Significantly smaller peak propulsive ground reaction forces and posterior impulses were found during downhill running (Ps < 0.05). Furthermore, participants experienced significantly larger extension moment and negative joint power at the knee (Ps < 0.05) but smaller plantar-flexion moment and negative joint power at the ankle during downhill running (Ps < 0.05). Negative net joint work increased for all joints with increased declinations and the knee joint showed the greatest increase in negative net joint work amongst the three joints (Ps < 0.05).

Significance

These findings indicate that runners modify their running mechanics resulting in greater kinetic demand on the knee during downhill running. Differences in lower extremity injury mechanisms with different running slopes may be linked to the changes in loading at the knee but further investigation using clinical trials is needed to support the potential relationship.

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