University of Northern Iowa UNI ScholarWorks Dissertations and Theses @ UNI Student Work 2016 Biomechanical differences in the weightlifting snatch between successful and unsuccessful lifts Jack Rummells University of Northern Iowa Let us know how access to this document benefits ouy Copyright ©2016 Jack Rummells Follow this and additional works at: https://scholarworks.uni.edu/etd Part of the Sports Sciences Commons Recommended Citation Rummells, Jack, "Biomechanical differences in the weightlifting snatch between successful and unsuccessful lifts" (2016). Dissertations and Theses @ UNI. 292. https://scholarworks.uni.edu/etd/292 This Open Access Thesis is brought to you for free and open access by the Student Work at UNI ScholarWorks. It has been accepted for inclusion in Dissertations and Theses @ UNI by an authorized administrator of UNI ScholarWorks. For more information, please contact [email protected]. BIOMECHANICAL DIFFERENCES IN THE WEIGHTLIFTING SNATCH BETWEEN SUCCESSFUL AND UNSUCCESSFUL LIFTS An Abstract of a Thesis Submitted in Partial Fulfillment of the Requirements for the Degree Master of Arts Jack Rummells University of Northern Iowa July, 2016 ABSTRACT The purpose of this study was to determine what differences exist between several kinematic variables between failed and successful attempts in the snatch lift. Six female Weightlifters at the 2015 American open were measured for kinematic variables via videotape during competition. The results show that differences existed in the angle of the shoulder at peak barbell height and the catch height, along with the amount of separation between the lifter and barbell at peak height. Significant differences were also found at the angle between the barbell and lifter center of mass. This study was a first step toward understanding the importance of the lifter’s ability to quickly and accurately pull themselves under the barbell. A better understanding of this association may help to improve coaches’ abilities to develop drills to improve consistency in barbell path. BIOMECHANICAL DIFFERENCES IN THE WEIGHTLIFTING SNATCH BETWEEN SUCCESSFUL AND UNSUCCESSFUL LIFTS A Thesis Submitted in Partial Fulfillment of the Requirements for the Degree Master of Arts Jack Rummells University of Northern Iowa July, 2016 ii This Study by: Jack L. Rummells Entitled: Biomechanical differences in the Weightlifting Snatch between Successful and Unsuccessful Attempts has been approved as meeting the thesis requirement for the Degree of Master of Arts ___________ _____________________________________________________ Date Dr. Travis Ficklin, Chair, Thesis Committee ___________ _____________________________________________________ Date Dr. Robin Lund, Thesis Committee Member ___________ _____________________________________________________ Date Dr. Forest Dolgener, Thesis Committee Member ___________ _____________________________________________________ Date Dr. Kavita R. Dhanwada, Dean, Graduate College iii TABLE OF CONTENTS PAGE LIST OF TABLES ...............................................................................................................v LIST OF FIGURES ........................................................................................................... vi CHAPTER I. INTRODUCTION ........................................................................................1 Statement of the Problem ...............................................................................................3 Null Hypotheses .......................................................................................................3 Significance of the Study ...............................................................................................3 Delimitations ............................................................................................................4 Limitations ...............................................................................................................5 Assumptions .............................................................................................................5 Definition of Terms..................................................................................................6 CHAPTER II. REVIEW OF RELATED LITERATURE ..................................................8 History of Weightlifting .................................................................................................8 Phases of the Snatch and Clean and Jerk .....................................................................11 Technique .....................................................................................................................19 Anthropometry .............................................................................................................23 Trajectory .....................................................................................................................28 Conclusion ...................................................................................................................34 CHAPTER III. METHODOLOGY ..................................................................................35 Research Design...........................................................................................................35 Variable Definitions ...............................................................................................35 iv Research Participants ...................................................................................................37 Instrumentation ............................................................................................................37 Procedures for Collecting Data ....................................................................................38 Data Collection ............................................................................................................39 Data Analysis ...............................................................................................................44 CHAPTER IV. RESULTS ................................................................................................45 CHAPTER V. DISCUSSION ...........................................................................................46 REFERENCES ..................................................................................................................49 v LIST OF TABLES TABLE PAGE 1 Descriptive statistics and paired samples t-test results ..........................................45 vi LIST OF FIGURES FIGURE PAGE 1 Weightlifting Setup ................................................................................................24 2 Common Bar Path Styles .......................................................................................31 3 Camera Setup .........................................................................................................38 4 Orthogonal Reference Frame Setup .......................................................................41 5 θpeak .........................................................................................................................42 6 Loop .......................................................................................................................43 1 CHAPTER I INTRODUCTION The sport of Weightlifting has been dominated throughout its history by individuals that are able do display superior physical power and technical mastery. These two aspects seem to lie on opposite ends of the spectrum. Logically, there are weaker individuals that have more perfected positions when performing the lifts. They are able to be successful by having a great efficiency with the strength they possess. Other individuals seem to have great strength, which allows their technique to have a wider margin of error and still able to successfully complete lifts. At the elite/international level this spectrum still holds true, but with a much narrower margin in comparison to novice lifters. Examples of this throughout history have been Chinese Weightlifters falling more toward the technical precision side of the spectrum, and Bulgarian Weightlifters falling on the strength surplus portion of the spectrum (Simmons, 2007). Regardless, throughout history these teams have both been extremely successful in this sport on the international platform. Much research exists on how to improve general strength, even at the highest level of sport, but what is lacking in the literature is research describing the technical flaws of unsuccessful lifts, besides improper height of the barbell from the pulling phases. Some literature suggests that the highest correlation between successful and unsuccessful lifts is the angle of the barbell during the first pull and displacements in barbell trajectory (Musser, Garhammer, Rozenek, Crussemeyer, & Vargas, 2014; Gourgoulis, Aggeloussis, Garas, & Mavromatis, 2009). But before this is examined 2 further, the anatomy of the two events that make up the sport of Weightlifting must be discussed. The movements of Weightlifting are the snatch and the clean and jerk. Each of these movements require an explosive generation of force in order to get the barbell from the floor to its successful overhead, arms locked-out position. The snatch requires a single movement to bring the barbell to the final position. The clean and jerk requires a two-part movement to get the barbell to its final overhead position (Stone, Pierce, Sands, & Stone, 2006). The first movement, known as the clean, takes the barbell