Lower-extremity joint and muscle group mechanical behavior changes in response to altered task demand

We used uphill walking to test whether lower-extremity joints, and the major muscle groups spanning them, could alter their mechanical functions. We found that the hip, ankle, and knee decreased spring- and damper-like behavior and increased motor-like behavior during uphill walking. These joint-level changes were driven by altered mechanical functions of extensor, but not flexor, muscle groups.