Exercise ball a chair because of ergonomic considerations or biomechanical reasons. This large plastic ball, known as a "birth ball", can also be used during labour to aid the descent of the fetal head into the pelvis. Sitting in an upright position will also aid fetal positioning and is more comfortable for the woman. Sitting on the ball with arms placed on a bed, table or otherwise sturdy object for support and gently rocking the hips may help the woman during contractions and aid the natural physiological process of birth. Exercise ball An exercise ball, also known as a Swiss Ball, is
Water polo ball Water polo ball A water polo ball is a ball used in water polo and canoe polo, usually characterized by a bright yellow color and ease of grip ability, so as to allow it to be held with one hand despite its large size. Ball weight is 400-450 grams (14-16 ounces) and inflated to 90-97 kPa (kilopascals) gauge pressure (13-14 psi) for men and 83-90 kPa (12-13 psi) for women. Water polo balls come in two main sizes: a size 5 (68-71 cm in circumference), intended for use by men, and a size 4 (65-67 cm in circumference), intended for