Before running, Jim always stretches.
Is the gerund phrase before running or just running?
It's not a phrase; the gerund is "running" and it's the object of the preposition.
The gerund phrase in the sentence is "before running".
To identify the gerund phrase, we need to understand what a gerund is. A gerund is a verb form ending in "-ing" that functions as a noun in a sentence. It is derived from a verb but acts as a noun.
In this sentence, "running" is a gerund because it ends in "-ing" and is functioning as a noun. However, "before" is not a gerund, but rather a preposition that introduces the gerund phrase. So, the entire gerund phrase is "before running".