A spectator sport is a sport in which the notional reasonable person  (State v. Cripps, 533 N.W.2d 388 (1995)) cannot take part in due to barriers to entry, such as high level of training required or specialist equipment.
Many popular sports are not spectator sports, for example association football.
1. Negligence and the 'Reasonable Person'. Available at: https://injury.findlaw.com/accident-injury-law/standards-of-care-and-the-reasonable-person.html Retrieved on September 11, 2020.