A half marathon is a road running event of 21.1 km, or 13 7⁄64 miles, about 13.1 miles. It is half the distance of a marathon and usually run on roads. Participation in half marathons has grown steadily recently.One of the main reasons for this is that it is a challenging distance, but does not require the same level of training that a marathon requires. In 2008, Running USA reported that the half marathon is the fastest growing type of race. A 2010 article by Universal Sports echoed the growing popularity of the distance.New York Road Runners CEO Mary Wittenberg and noted running author and coach Jeff Galloway have also commented on the popularity of the distance.It is common for a half marathon event to be held concurrently with a marathon, using almost the same course with a late start, an early finish or shortcuts. Most people tend to run a half marathon before running a full marathon. A half marathon will help to physically prepare the body for the 42.195 kilometers (26.2 miles) that makes up a marathon. Running a half marathon is both physically and mentally demanding. For those who have never run this distance before, it is imperative to train correctly. It is advised to slowly build up endurance over a three month period; decreasing the intensity of the training in the last couple of weeks before the event. If the body is over-worked, injury is more likely to occur. It is also important to eat correctly and stay hydrated before, during, and after the race.