Question: Racing flats, or simply flats, are lightweight athletic shoes designed for "long distance" track and field, cross country, and most often, road running, the sport of running on a measured course, over an established what?
Context: Luke Watson (born August 20, 1980) is a retired long-distance runner who specialized in various track and road running disciplines.  He represented the United States at the IAAF World Cross Country Championships in 2004 and 2006.  He was a member of one of the greatest generations of high school long distance runners in the US, many of whom happened to be from Stillwater High in the late 1990s.  At Notre Dame he studied and also became a very competitive middle and long distance runner, before which he ran at three US Olympic Trials in 2004, 2008, and 2012.  Watson retired from competitive running in 2012.  He is the older brother of Jake Watson. The Foot Locker Cross Country Championships are a series of annual cross country running races held in various regions of the United States to determine the premier cross country runner in various age groups, but mainly serves to find the best prep (high school) cross country athlete in the country.  The event began in 1979 by the F. W. Woolworth Company, which initially branded it as the Kinney Cross Country Championships, (for the Kinney Shoes division) in Balboa Park, San Diego, California before Woolworth rebranded the event in 1993 to its present title, the Foot Locker Cross Country Championships, as it still is today, for Woolworth's sporting goods company.  For most people associated with the sport, the name is just shortened to Foot Locker or even abbreviated in agate results as FL (the ticker symbol of the company today).  The event is the longest-running national cross country race for high school students. Obstacle course racing (OCR) is a sport in which a competitor, traveling on foot, must overcome various physical challenges that are in the form of obstacles.  Mud and trail runs are combined and the races are designed to result in mental and physical collapse.  Obstacles include, but are not limited to, climbing over walls, carrying heavy objects, traversing bodies of water, crawling under barbed wire, and jumping through fire.  Many obstacles are similar to those used in military training, while others are unique to obstacle racing and are employed throughout the course to test endurance, strength, speed and, dexterity.  Races vary in both distance and challenge level, combining trail running, road running, and cross country running.  With race venues typically in large cities, organizers encourage athletes of all types to participate.  All Obstacles were introduced into Cross Country Running at Tough Guy, recorded on video 1989 - 2007.  Most signature obstacles were actually created by Mr Mouse.  According to the "Los Angeles Times" in 2012, the number of events—typically all-day festivals—rose rapidly.  In accordance with the sub-culture's fast rate of growth, the "Obstacle Race Magazine" was launched. Trail running is a sport which consists of running and hiking over trails.  In the United Kingdom and Ireland it is also called mountain or fell running although the two types do differ.  It differs from road running and track running in that it generally takes place on hiking trails, often in mountainous terrain, where there can be much larger ascents and descents.  It is difficult to definitively distinguish trail running from cross country running.  In general, however, cross country is an IAAF governed discipline that is typically raced over shorter distances (rarely over 12 kilometers), whereas trail running is loosely governed, and run over longer routes. Inês Alexandra das Neves Monteiro (born 18 May 1980) is a Portuguese athlete who competes in middle and long distance track running, as well as road running and cross country.  She started out as a cross country runner, winning a silver and a gold medal at the 1998 and 1999 European junior race.  She has represented Portugal at the 2004 and 2008 Summer Olympics, and has competed twice at the World Championships in Athletics.  She is a regular performer at the IAAF World Cross Country Championships, generally finishing around 30th place. Road running is the sport of running on a measured course over an established road (as opposed to track and field and cross country running). Abera Kuma Lema (born 31 August 1990) is an Ethiopian long distance runner, who competes in track, cross country and road running events.  An African junior champion over 5000 m, he won his first senior international medal (a team bronze) at the 2010 IAAF World Cross Country Championships. Racing flats, or simply flats, are lightweight athletic shoes designed for "long distance" track and field, cross country, and most often, road races.  They differ from normal training shoes mainly by the lack of a substantial heel (hence the name). Cross country running shoes are made for both cross country running and long distance running.  Season-specific trainers are available for different types of training. Track and field is a sport which includes athletic contests established on the skills of running, jumping, and throwing.  The name is derived from the sport's typical venue: a stadium with an oval running track enclosing a grass field where the throwing and jumping events take place.  Track and field is categorised under the umbrella sport of athletics, which also includes road running, cross country running, and race walking.
Answer: road