" i ran 7 strolls or laps "
The word "stroll" is used more commonly if you just leisurely walk around the park.
"I ran 7 laps" is the most commonly used, for most people use the word 'laps' when your exercising. Stroll doesn't sound proper when you refer to yourself 'running'.
Stroll = leisure walk around the park
lap = running around the park.