“…The remaining studies represented various sports, including track and field (47) , aesthetic sports (39) , endurance sports (34,35) and various team and individual sports (25)(26)(27)36,42,45,46) . Sporting levels included competitive (9,(21)(22)(23)26,30,32,34,35,39,40,42,49) , regional/state/national competitors (27)(28)(29)(36)(37)(38)43,47) , high school/college (19,24,27,33,41,45,57) , elite (20,44,46) and one study did not report sporting level (25) . NK was assessed using twenty-one questionnaires across thirty-two studies.…”