This is the second key result. Combining with our first key result from the previous section, we see that Δ Δ X ′ = Δ Δ X = − − Δ Δ X → → Δ Δ X = 0. We see that a swimmer that reverses its motion by reversing its sequence of shape changes leads to the opposite distance traveled. In addition, since the swimmer exhibits reciprocal body deformation, the sequence of motion is the same between t 2 and t 3 and t 0 and t 1 . Thus, the distance traveled should be the same independently of the direction of time, meaning that reciprocal motion cannot be used for net motion in low Reynolds number environments.