The Effects of Changing Running Stride A Major Qualifying Project Report Submitted to the Faculty of WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the Degree of Bachelor of Science By: Chelsea Cook Heather Lewis Alicia Turner Date: April 24, 2013 Project Number: BJSGA13 Submitted to: Brian Savilonis Project Advisor Abstract This study explores the effects of changing someone’s running stride by analyzing the forces exerted on the knee and ankle joints. Over a 5 week training period, 13 subjects were observed using video and force-plate analysis in order to estimate the landing load on the ankle and knee upon initial foot strike for two different stride forms. Various kinematic variables, such as landing force, joint moments, and landing angles were compared for two different stride forms to determine if stride change is beneficial. Based on the findings of this study, the benefits of stride change are dependent on the individual. i Table of Contents ABSTRACT ................................................................................................................................................ I 1. INTRODUCTION .............................................................................................................................. 1 2. BACKGROUND .................................................................................................................................. 2 2.1 BIOMECHANICS OF RUNNING .......................................................................................................................... 2 2.1.1 Running Styles .......................................................................................................................................... 3 2.1.2 Running Body Positioning ................................................................................................................... 4 2.2 LOWER LEG ANATOMY: KNEE AND ANKLE ................................................................................................... 5 2.2.1 Knee ............................................................................................................................................................... 5 2.2.2 Ankle ............................................................................................................................................................. 6 2.3 COMMON RUNNING INJURIES AND PREVENTION ......................................................................................... 7 2.3.1 Knee/Leg Injuries and Prevention ................................................................................................... 8 2.3.2 Foot/Ankle Injuries and Prevention ................................................................................................ 9 2.3.3 Fatigue and Fatigue Prevention ....................................................................................................... 9 2.4 CONDUCTING THIS TYPE OF STUDY ............................................................................................................ 10 2.4.1 Determining Volunteer Group, Size of Group, and Study Duration ................................. 10 2.4.2 Instruments and Equipment ............................................................................................................. 11 3. METHODS ....................................................................................................................................... 12 3.1 TESTING OF A NEW RUNNER’S COMFORTABLE STRIDE ........................................................................... 12 3.2 LEARNING A NEW, DEFINED STRIDE .......................................................................................................... 13 3.2.1 Teaching the New Stride .................................................................................................................... 13 3.3 TESTING RUNNER’S USING A NEWLY LEARNED STRIDE .......................................................................... 13 3.3.1 Observing Stride Change .................................................................................................................... 13 4. ANALYSIS ........................................................................................................................................ 15 4.1 VIDEO ANALYSIS ............................................................................................................................................ 15 4.2 FORCE PLATE ANALYSIS ............................................................................................................................... 16 4.2.1 Ground Reaction Force Testing ....................................................................................................... 16 4.2.2 Computational Bio-Analysis Testing ............................................................................................. 17 4.3 LOAD ANALYSIS .............................................................................................................................................. 17 4.3.1 Determining the Forces on the Ankle ........................................................................................... 17 4.3.2 Determining the Forces on the Knee ............................................................................................. 20 5. RESULTS ......................................................................................................................................... 24 5.1 VIDEO ANALYSIS ............................................................................................................................................ 24 5.2 FORCE ANALYSIS ............................................................................................................................................ 25 5.2.1 Force Plate Analysis ............................................................................................................................. 25 5.2.3 Force Equation Analysis ..................................................................................................................... 27 5.3 COMPARISONS ................................................................................................................................................ 29 6. CONCLUSIONS AND RECOMMENDATIONS ........................................................................... 33 6.1 CONCLUSIONS FROM FINDINGS .................................................................................................................... 33 6.2 OVERALL RECOMMENDATIONS TO IMPROVE FUTURE STUDIES .............................................................. 33 7. DISCUSSION ................................................................................................................................... 35 8. BIBLIOGRAPHY ............................................................................................................................ 36 APPENDIX ................................................................................................................................................ A APPENDIX A: PARTICIPANT TRAINING PACKET .................................................................................................... A APPENDIX B: PARTICIPANT AGREEMENT FORM ................................................................................................... G APPENDIX C: ANALYSIS PROCEDURE DETAILED CHECKLIST ............................................................................... I APPENDIX D: MEASURED ANGLES .......................................................................................................................... K APPENDIX E: VIDEO ANALYSIS OF PARTICIPANTS ................................................................................................ N E.1 Exported Data from Adobe AfterEffects ........................................................................................... n E.2 Exported Data from Photoshop ............................................................................................................ o APPENDIX F: FORCE PLATE ANALYSIS OF PARTICIPANTS ................................................................................... P APPENDIX G: NATURAL STRIKE FREE BODY DIAGRAMS AND EQUATIONS ....................................................... R G.1 Ankle Free Body Diagrams ...................................................................................................................... r G.2 Natural Rested Ankle Equations ........................................................................................................... s G.3 Natural Tired Ankle Equations ............................................................................................................. u G.4 Knee Free Body Diagrams ...................................................................................................................... w G.5 Natural Rested Knee Equations ............................................................................................................. y G.6 Natural Tired Knee Equations ............................................................................................................ aa APPENDIX H: MID-FOOT STRIKE FREE BODY DIAGRAMS AND EQUATIONS ................................................... CC H.1 Ankle Free Body Diagrams .................................................................................................................... cc H.2 Mid-Foot Rested Ankle Equations