White, Andrew2018-03-142018-03-142018-01http://hdl.handle.net/11299/194601University of Minnesota Ph.D. dissertation.January 2018. Major: Kinesiology. Advisor: Diane Wiese-Bjornstal. 1 computer file (PDF); x, 152 pages.Sport participation is one of the leading causes of injury among American youth and poor sportsmanship behavior contributes to the risk of sport-related injury. Theories of behavior modification suggest operant conditioning can lead to behavior change, as can other environmental and personal factors. Additionally, models of sport-related injury show behavioral change can alter injury risk. One context injury prevention research should focus on is youth American football, as the competition injury rates are higher than those of other sports. The current study implemented modified Fair Play rules, which utilize operant conditioning, in a youth football league to determine if, compared to teams using standard rules, teams using Fair Play rules had (a) better sportsmanship behavior and attitudes and (b) lower injury rates; (c) if there was an effect, the study also aimed to determine how Fair Play rules impacted injury rates. These purposes were examined over two football seasons with one group of teams using Fair Play rules both seasons (FP-FP), one group using standard rules both seasons (Std-Std), and one group switching from standard to Fair Play rules after one season (Std-FP). At the beginning of this study, participants were on average 12.19 (±0.44) years old, Caucasian (85.1%), and male (99.4%). Linear mixed models revealed the only statistically significant group difference for injury rates was a significantly higher rate of head/neck injuries for the FP-FP group than the Std-Std group when Fair Play penalty yards per game was not accounted for. Similarly, collapsing across groups, the rate of opponent head/neck injuries significantly increased after the first season, but no other changes over time were significant. A MANOVA revealed no group differences in athlete self-reported sportsmanship behavior and attitudes or athletes’ perceptions of coach sportsmanship behavior. High variability and small group sizes limited the power to detect differences, but examining mean values of injury rates revealed complex patterns across groups and time. Results suggest Fair Play rules and player sportsmanship behavior affect injury rates in youth American football; however, this effect is complex and further research is required to clearly determine the effect of Fair Play rules in this context.enFair Playinjuryinterventionsport-related injuryyouth footballyouth sportThesis or Dissertation