Question: Besides the length of Charles Grethen's primary race event, which two race lengths are standard in middle-distance running?

Related documents: [0]  [DOC] Middle-distance running events are track races longer than sprints, up to 3000 metres. The standard middle distances are the 800 metres, 1500 metres and mile run, although the 3000 metres may also be classified as a middle-distance event. The 1500 m came about as a result of running three and 3/4 laps of a 400 m outdoor track or 7 and a half laps of a 200m indoor track, which were commonplace in continental Europe in the 20th century. [END] 
[1]  [DOC] Charles Grethen (born 2 June 1992 in Tuntange) is a Luxembourgian middle-distance runner competing primarily in the 800 metres. He represented his country at three consecutive European Championships. [END]  
Answer: 1500 metres and mile
1500 metres and mile