They are not equal. "I go to swim" or "I go to hike" seems to indicate that you are now leaving to do those activities, and, if that is the case, would probably be best is used in the present progressive: "I am going to swim" or "I am going to hike" (however, note that these sound more like you're using the verb "to go" as an auxiliary to create the future tense). In my opinion, this construction places more emphasis on the verb "go" than on the infinitive that follows.
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