None of Bruno's statements represent a specific fitness training goal, as they are all vague. However, if we are looking for the statement that could potentially be developed into a more specific goal, "I want to run faster" is the closest.
To make it specific, Bruno could specify a time or distance, such as "I want to run a mile in under 7 minutes."
So the response that is MOST accurately leaning towards a specific fitness goal is: I want to run faster.