The efficiency of walking at incrementally increasing inclines is strongly related to thigh and knee angles at heel strike

Efficiency plateaus during incline walking at slopes above 20%, and is equal to that of concentric muscle activity. We believe that a non-linear increase in leg swing naturally results in the necessary increase in knee angle at heel strike to lift the body as slope increases and minimizes leg swing maintaining an efficiency of uphill walking equal to that of concentric muscle activity at inclines above 20%.