Trousers and methods for reducing muscle fatigue, and overcoming range of motion restrictions in the legs caused by the friction created by trouser legs rubbing against the knee portion of a person's leg when they are moving are disclosed. In certain embodiments, the trousers and methods use (1) an engineered dart in the mid-thigh region of the trouser, or (2) a zipper to decrease the vertical linear fabric surface in the mid-thigh region of the trouser such that the resulting tension causes the trouser fabric in the knee region to lift out and away from the knee portion of the wear's leg, thusly eliminating or greatly reducing contact between the trouser leg and the wearer's knee and the resulting strain.