Movement Patterns and Injury Incidence in Cross-Country Skiers: A Prospective Cohort Study Sonya G. Anderson Worth A thesis submitted to Auckland University of Technology in partial fulfilment of the requirement for the degree of Masters of Health Science October 2016 Faculty of Health and Environmental Sciences School of Clinical Sciences ii Abstract Purpose of the Work This 12-month prospective study describes the characteristics of a group of elite cross- country skiers using subject demographics; intake physical measurements (Movement Competency Screen—MCS, hamstring length, and trunk muscle endurance); and monthly injury, training, and racing reports. The primary hypothesis is that new injury is associated with poor movement competency. Secondary hypotheses are that new injury is associated with (a) a history of injury, (b) a long career in cross-country skiing, (c) high training hours, (d) high running training hours, (e) high roller ski training hours, (f) poor trunk muscle endurance, and (g) reduced active straight leg raise (ASLR). Mean injury incidence will be used to examine differences between the injury incidence rates of (a) the ski season and off-season, (b) traumatic and nontraumatic injuries, and (c) injuries by anatomic location. Introduction Cross-country ski injury incidence studies have employed variable methodologies, using retrospective injury and training surveillance. Standardised injury incidence measures will improve the understanding of cross-country ski injury incidence. Studying the relationship between movement patterns and new injury may identify risk factors for future injury, and eventually reduce injury rates with appropriate intervention strategies. Methods At enrolment, 71 professional or collegiate cross-country skiers (35 men, 36 women) provided demographics and injury history, then performed the Movement Competency Screen (MCS), hamstring length, and trunk muscle endurance tests. Self-report electronic injury and training surveillance occurred monthly for 12 months. Spearman’s correlation determined the relationship between new injury and MCS score, past injury, iii total training time, and run training time. A t-test compared injury incidence (the mean number of injuries per subject per 1,000 training/exposure hours) between anatomic regions, type of injuries, and seasons. Results/Main Points The study was completed by 58% of subjects (18 men, 23 women). There were 3.18 injuries per subject per 1,000 training/exposure hours. New injury was not correlated with MCS score, but was correlated with previous injury (p < .05). New injury did increase as the time spent running increased, although not significantly (p = .08). New injury was not correlated with any other variable. Risk factor analysis found previous injury was a significant predictor of new injury when accounting for overall training time, run time, and MCS score. Lower-extremity injury incidence (2.13) was significantly higher than upper extremity (0.46) or trunk injury incidence (0.22). Nontraumatic/overuse injury incidence (2.76) was significantly higher than acute injury incidence (1.05) (p < .05). Off-season injury incidence (5.25) was higher than ski season (2.27), although not significantly (p = .07). Conclusion This is the first examination of the relationship between MCS score and new injury in cross-country skiers. New injury positively correlated with previous injury, but not with MCS score, hamstring length, trunk endurance ratio, or training/exposure hours. Lower- extremity and nontraumatic/overuse injuries had the highest incidence rates. Previously injured skiers are at greater risk for further injury. The results lay the foundation for further movement and injury studies and future injury prevention strategies. Keywords: Movement Competency Screen (MCS), cross-country skiing, injury incidence iv Table of Contents Abstract ............................................................................................................... ii Table of Contents ............................................................................................... iv List of Figures ................................................................................................... xii List of Tables .................................................................................................... xiii List of Abbreviations ........................................................................................ xiv Attestation of Authorship ................................................................................. xvi Acknowledgments ........................................................................................... xvii Ethics Approvals .............................................................................................. xix 1Introduction ....................................................................................................... 1 1.1Statement of the Problem ............................................................................ 1 1.2Purpose of the Study .................................................................................... 5 1.3Significance of the Problem ........................................................................ 7 2Review of Literature ......................................................................................... 8 2.1A Brief Overview of the Development of Competitive Cross-Country Skiing ................................................................................................................ 8 2.1.1Cross-country skiing competitions. ........................................................ 9 2.1.2Kinematics of cross-country skiing techniques. ................................... 10 2.1.2.1 Classic technique. ........................................................................ 11 2.1.2.2 Skate technique. .......................................................................... 12 2.1.3Cross-country ski training. ................................................................... 13 2.2Framework for Injury Prevention Research .............................................. 14 2.3Review of Cross-Country Ski Injuries....................................................... 17 2.3.1Literature search strategy. .................................................................... 17 v 2.3.2 ............................................. Definition of injury types used in this review. ...................................................................................................................... 18 2.3.2.1 Definition of an injury. ................................................................ 19 2.3.2.2 Definition of injury severity. ....................................................... 19 2.3.2.2.1 Acute injuries. ........................................................................ 19 2.3.2.2.2 Chronic injuries. .................................................................... 19 2.3.2.2.3 Traumatic injuries. ................................................................. 20 2.3.2.2.4 Nontraumatic injuries. ........................................................... 20 2.3.2.2.5 Time loss injuries. .................................................................. 20 2.3.3Types of cross-country ski injuries. ...................................................... 20 2.3.3.1 Cross-country ski injuries by anatomic location. ........................ 21 2.3.3.2 Cross-country ski injuries by severity (time lost to injury). ....... 21 2.3.3.3 Cross-country ski injuries by acuity (acute traumatic or chronic overuse). ..................................................................................................... 22 2.4Risk Factors for Injuries in Cross-Country Skiing .................................... 29 2.4.1Intrinsic risk factors for injury in cross-country skiing and other endurance sports. .......................................................................................... 29 2.4.1.1 Hamstring length and low back pain. .......................................... 30 2.4.1.2 Trunk muscle endurance and low back pain. .............................. 31 2.4.2 ........... Extrinsic risk factors for injury in cross-country skiing and other endurance sports. .......................................................................................... 31 2.4.3Summary............................................................................................... 32 2.5Screening Tests in Sports Medicine ........................................................... 33 2.6Whole Body Movement Screening ............................................................ 34 vi 2.6.1Movement Competency Screen (MCS). .............................................. 35 2.6.2Functional Movement Screen (FMS). .................................................. 36 2.6.3Athletic Ability Assessment (AAA). .................................................... 38 2.6.4Whole body movement screens and injury prediction. ........................ 38 2.6.4.1 MCS and injury prediction. ......................................................... 40 2.6.4.2 FMS and injury prediction. ......................................................... 42 2.6.5Summary............................................................................................... 43 2.7Justification for the Use of the MCS in This Study ................................... 44 2.8Conclusion ................................................................................................. 45 2.9Statement