O-shaped leg if you are wearing orthotics is not suitable for swimming, other cases can swim. O-shaped legs can swim, swimming process will produce a certain degree of buoyancy of the water, the knee joint is less stressed, in general, will not have a bad effect on the knee joint, swimming can also effectively exercise the whole body muscles. When swimming, try not to choose breaststroke, because breaststroke requires the legs to pinch the water inward and stir the water outward, the amount of movement is too large may increase the weight of the knee ligaments. Swimming is not suitable for O-shaped legs if they are wearing orthotics, because the fabric of the orthotics will become wet after going into the water, which may cause deformation. O-shaped leg should go to the hospital in time, under the guidance of the doctor for treatment and selection of appropriate sports.