Stiff Knee Gait Pattern Is Metabolically Inefficient due to Mechanical and Physiologic Mechanisms (2011)

Undergraduates: Abigail Osborn, none Clinton J. Wutzke Michael D. Lewek

Faculty Advisor: Michael Lewek
Department: Exercise & Sport Science

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Individuals with stroke, cerebral palsy, and acquired brain injury often exhibit deficits in hip, knee, and ankle flexion during the swing phase of gait, termed “spastic paretic stiff-knee gait pattern”. The purpose of this project was to determine whether a stiff-knee gait pattern requires greater energy expenditure, and whether the increase in metabolic cost is due to the altered mechanics of the movement, or the increased muscle activity that stiffens the knee. Twenty unimpaired individuals walked on a dual-belt ‘instrumented’ treadmill for three randomly ordered conditions: (1) control, (2) mechanically imposed stiff-knee gait (SKG-M) using a lockable knee brace, and (3) physiological imposed stiff-knee gait (SKG-P) using electrical stimulation to the quadriceps during late stance/early swing. Using a motion capture system and indirect calorimetry, we confirmed that stiff-knee gait produces a metabolically inefficient style of walking, with a significantly greater net metabolic power during the imposed stiff knee gait conditions (p<0.001). Further, SKG-P required greater metabolic power than SKG-M (p<0.001). Body weight support had no influence on metabolic cost (p=0.319). While approximately 50% of the increased metabolic cost came from the altered gait mechanics (SKG-M), the remaining 50% appeared to be due to quadriceps activity during late stance/early swing (SKG-P). Whether treatments to increase knee flexion during swing can reduce metabolic cost remains unknown.