Safety and legal requirements for sports drone photography: you must have explicit permission from the athlete and ideally a signed release. You must not fly directly over uninvolved spectators.
At organized events (trail races, surf competitions), work with event organizers to establish designated drone operating areas and announce to spectators when the drone is operating. For motorsports, the FAA prohibits drone operation near outdoor events with more than 30,000 attendees without a waiver.
Check the FAA UAS Event Safety Checklist before any organized sporting event. Failure to do so can result in fines and, more importantly, injury to spectators from an uncontrolled drone in a crowded environment.