This is the 10627th most frequent German word.
rennais
The word "rennais" is not German; it is French and refers to something or someone from Rennes, a city in France.
In this sentence, 'rennais' is used as the verb to indicate the habitual action of running for fitness.
Ich rennais durch den Park jeden Morgen um fit zu bleiben.
I run through the park every morning to stay fit.
Here, 'rennais' is used to describe a spontaneous action of running caused by an external condition.
Er rennais nach Hause, sobald der Regen begann.
He ran home as soon as the rain began.
'Rennais' in this sentence is used to express a planned future action of running during a competitive event.