Treptower Park is a good anchor point for running in east Berlin. Our short route combines Treptower Park & the adjacent Spreepark. As an add-on or standalone run, there are lovely paths along Rummelsberger River (See). 
 
Treptpower Park & Spreepark. This 8 km loop starts at the S-Bahn station, through the Treptower Park trails and the Planterwald nature preserve. An important landmark is the Soviet War Memorial, which commemorates the 80,000 Soviet soldiers who were killed in the Battle of Berlin. The route continues into Spreepark, which is the site of an amusement park that operated from 1969–2001. 
 
Spree & Rummelsberger River Paths. For a nice add-on, cross the Parkwegbrücke (bridge) over the river (good pedestrian path) and run on the Uferweg path along Spree & the Rummelsberger rivers. This is mostly waterfront running, with nice views. The full route is 12 km RT possible, and a. A 5.5 loop would be the finger out to Friedhof Alt-Stralau. Nearby is the massive Arena Berlin, and good running options along the Landwehr Canal trails.