the starting area. While poor form during the initial push can lose a team the heat, it is otherwise rarely, if ever, decisive. Over the rest of the course, a sleigh's speed depends on its weight, aerodynamics, runners, the condition of the ice, and the skill of the pilot. Race times are recorded in hundredths of seconds, so even seemingly minor errors – especially those at the beginning, which affect the remainder of the heat – can have a measurable impact on the final race standings. The men's and women's standings for normal races are calculated over the aggregate of two runs or heats. At the Olympic Winter Games and World Championships, all competitions (for both men and women) consist of four heats. Olympic medal table Safety Brain trauma Sledding at a competitive level involves sledders repeatedly subjecting themselves to high-G forces and multiple small collisions of their head into their helmet as sharp turns are taken. Additionally, when mistakes happen and the sled crashes, there are no "seatbelts" or other protections; the sledders can simply be falling down the course at high speed with their helmet grinding along the surface or bouncing off the interior of the sled. One sledder described his experience during crashes as being equivalent to his head being inside a jet engine. Even ignoring crashes, repetitive shaking from small imperfections in the course is hypothesized to cause small tears in the brain, especially if performed repeatedly. The culture of competitive bobsledders (especially before this danger was recognized) also made injured participants hesitant to speak up and request breaks, fearful of being dropped from the team. Bobsledders who train frequently have reported issues such as chronic headaches, a heightened sensitivity to bright lights and loud noises, forgetfulness, a "mental fog", and psychological problems. Repeated mild brain trauma has caused issues for boxers, rugby players, and football players with chronic traumatic encephalopathy, and fears have arisen that bobsledding carries a similar danger, at least with the steeper and faster courses used in competitions. A brain scan of one bobsledder, Christina Smith, revealed damage to the rear and frontal lobes, consistent with micro-tears in the brain's white matter. A significant number of athletes have either committed suicide or died of drug overdoses. Examples include medal-winning bobsledders Eugenio Monti and Pavle Jovanovic, who committed suicide; Steven Holcomb died of an overdose. Since 2013, three North American former bobsledders have