A fit runner may race a 5K every other weekend for 10-12 weeks, working up to a goal race, though this is unlikely to be sustainable in the long run. If your goal race is a marathon, you may supplement your preparation with shorter tune-up events. A recreational runner who races only once or twice a month could even experience health issues if they were to try and go the whole season without stopping. The most common type of race is the "sprint" which usually lasts between 15 minutes and one hour. These races are typically held on road courses or in parks and generally have less than 250 competitors. Some larger cities may have weekly sprint races where all kinds of distances are covered simultaneously. There are also "half-marathons" which cover 13.1 miles and allow about 1 hour 20 minutes to complete. These are commonly used by people who want to test themselves against others who are also training for a big event. There are also "marathons" which cover 26.2 miles and take approximately 3 hours 30 minutes to finish. These are designed for more experienced runners who have prepared over time for their first race of this distance. Finally, there is also the "ultramarathon" which is any race longer than 24 hours. These vary in length from 4 hours to 100 miles or more. The longest race in history was called the "Boston Marathon" and it lasted for 26 miles (42 km).