THE RELATIONSHIPS BETWEEN HEXAGONAL BARBELL ONE-REPETITION MAXIMUM DEADLIFT AND MAXIMAL ISOMETRIC PULLS AT THREE DIFFERENT POSITIONS A thesis submitted to the Kent State University College of Education, Health, and Human Services in partial fulfillment of the requirements for the degree of Master of Science By Brandon A. Miller May 2020 © Copyright, 2020 by Brandon A. Miller All Rights Reserved ii Thesis written by Brandon A. Miller B.S.Ed., The Ohio State University, 2016 Approved by , Director, Master’s Thesis Committee Adam R. Jajtner , Member, Master’s Thesis Committee Jacob E. Barkley , Member, Master’s Thesis Committee J. Derek Kingsley Accepted by , Director, School of Health Sciences Ellen L. Glickman , Dean, College of Education, Health and Human James C. Hannon Services iii MILLER, BRANDON A., M.S., May 2020 Health and Human Services THE RELATIONSHIPS BETWEEN HEXAGONAL BARBELL ONE-REPETITION MAXIMUM DEADLIFT AND MAXIMAL ISOMETRIC PULLS AT THREE DIFFERENT POSITIONS (124 pp.) Director of Thesis: Adam R. Jajtner, Ph.D. The purpose of this study was to examine the relationships between hex barbell (HBB) deadlift one-repetition maximum (1-RM) and force-time characteristics of maximal isometric pulls from the floor, knee, and mid-thigh positions. Twenty-three healthy men and women completed an HBB deadlift 1-RM assessment and a series of three maximal isometric pulls at each position on separate days. The bar positions were set at 22.5 cm above the platform to represent the lift-off phase (FLOOR), just superior to the patella to represent the knee-passing phase (KNEE), and the mid-thigh – defined as the mid-point between the center of the patella and the anterior superior iliac spine (MT). Correlation analyses were performed to assess the relationships present between 1-RM and force- time characteristics at each position. Results of this investigation corroborated the results of past research suggesting that PF would be a significant predictor of maximal strength. Peak force (PF) was observed to have large to very large correlation coefficients to 1-RM at each position. Late-phase rate of force development (RFD) time-bands at the floor and mid-thigh were observed to have the largest relationships to 1-RM, with respect for position. Maximal strength has been related to late-phase RFD; thus, it is not surprising to observe large relationships at later time epochs from the FLOOR and MT positions. Impulse was observed to have a large to very large relationship to 1-RM at the three positions, suggesting future research to further investigate this under-researched relationship is needed. ACKNOWLEDGEMENTS I would like to thank Dr. Adam Jajtner for his assistance throughout this study, from study design to participant recruitment and data analysis. I would also like to thank my colleagues, Emily Tagesen and Eliott Arroyo, for their assistance with participant recruitment, and assistance administering 1-RM assessments. iv TABLE OF CONTENTS Page ACKNOWLEDGEMENTS ……………………………………………………………. iv LIST OF FIGURES ……………………………………………………………………. vii LIST OF TABLES ……………………………………...…………………………….. viii CHAPTER I. INTRODUCTION ……………………….………………………………….………..... 1 Specific Aims…………………………….……………………………….……………. 5 II. REVIEW OF THE LITERATURE ……………………………………………………6 The Isometric Mid-Thigh Pull ………………………………………………………… 6 Setup and Technique …………………………………………………………….. 6 Force-time Curve Analysis ……………………………………………………... 19 Isometric Mid-thigh Pull Summary …………………………………………….. 27 The Hexagonal Barbell Deadlift……………………………………………………… 29 Hexagonal Barbell Deadlift Summary …………………………………………. 35 Relationship of IMTP to Performance Variables ……………………………………. 37 Relationship of IMTP to Performance Variables Summary ……………………. 52 III. METHODS …………………………………………………………………………. 54 Experimental Approach to the Problem ………………………………………….… 54 Subjects …………………………………………………………………………..…. 56 Procedures ………………………………………………………………………….. 57 Familiarization ………………………………………………………………….. 57 Anthropometrics ………………………………………………………...……… 57 1-RM Assessment ……………………………………………………...……….. 58 Isometric Pull Assessment ……………………………………………………… 58 Force-Time Curve Analysis ……………………………………………….……. 63 Statistical Analysis ………………………………………………………...…… 64 IV. RESULTS ……………………………………………………………………….…. 69 V. DISCUSSION …………………………………………………………………..…… 76 Limitations ……………………………………………………………...…………… 80 APPENDICES ………………………………………………………………………….. 83 APPENDIX A. KENT STATE APPROVED IRB ………………………………….. 84 APPENDIX B. INFORMED CONSENT ………………………………………….. 104 APPENDIX C. MEDICAL HEALTH HISTORY QUESTIONNAIRE …………... 109 APPENDIX D. RECRUITMENT FLYER ………………………………………… 114 v APPENDIX E. RECRUITMENT SCRIPT ……………………………………….. 116 REFERENCES………………………………………………………………………... 118 vi LIST OF FIGURES Figure Page 1. Study Design ...………………………………………………………………………. 55 2. Photo of squat stand outfitted for isometric pull assessments ……………………….. 65 3. Participant at the floor position ……….……………………………………………... 66 4. Participant at the mid-thigh position …..…………………………………………...... 67 5. Participant at the knee position ……...……………………………………………….. 68 6. Relationship of one-repetition maximum to peak force at the floor position ……….. 71 7. Relationship of one-repetition maximum to peak force at the knee position …...…… 72 8. Relationship of one-repetition maximum to peak force at the mid-thigh position …... 73 vii LIST OF TABLES Table Page 1. Participant Descriptive Characteristics ………………………………………………. 56 2. Average Hip and Knee Angle at Each Position ……………………………………… 60 3. Average Coefficient of Variation (CV) for Each Position …………………………... 62 4. Average Isometric Force-Time Characteristics at Each Position ……………………. 74 5. Correlation Coefficients between 1-RM and Force-Time Characteristics …………... 75 viii 1 CHAPTER I INTRODUCTION The conventional deadlift is an exercise during which a standard Olympic barbell is lifted from the floor by performing hip, knee, and ankle extension until the torso reaches a fully erect position and is subsequently eccentrically lowered to the floor (Haff & Triplett, 2015). The deadlift is frequently used for strength and power development due to the recruitment of large muscle groups and the high total loads that may be imposed (Haff & Triplett, 2015). The hexagonal barbell (HBB) deadlift is a common variation to the conventional deadlift which is used to distribute the total load between the joints of the body, thereby reducing stress on muscles of the posterior chain (i.e. erector spinae and biceps femoris), creating an upright posture (Camara et al., 2016; Swinton et al., 2011), and supporting claims of improved safety (Gentry et al., 1987; Shepard & Goss, 2017). In addition to potentially enhanced safety, an improved peak force, velocity, and power during submaximal HBB deadlift have also been reported when compared to conventional deadlifting (Camara et al., 2016; Lake et al., 2017; Swinton et al., 2011). Swinton and colleagues (2011) observed greater maximal strength using the HBB compared to conventional deadlift in powerlifters, while Camara et al. (2016) observed no difference between conventional deadlift and HBB deadlift in “resistance trained” men. The discrepancies between studies may be due to a difference in training status, as 2 powerlifters were capable of completing a HBB deadlift 1-repetition maximum (1-RM) of approximately 81 kg more than “resistance trained” men (Camara et al., 2016; Swinton et al., 2011). Despite this, further research is needed to better understand the effect of training status on HBB deadlift maximal strength. Moreover, maximal strength testing using the 1-RM protocol has inherent limitations such as time constraints, the accumulation of fatigue, and a potentially increased risk of injury which impact its efficiency and possibly efficacy (Abernethy et al., 1995; Comfort et al., 2019b; Niewiadomski et al., 2008). With these limitations, a reliable alternative method to assess HBB deadlift 1-RM is warranted. Maximal isometric testing has become popular amongst researchers and practitioners for the examination of performance and monitoring adaptations to various training stimuli (Comfort et al., 2019b; Haff et al., 1997). When compared to traditional maximal strength assessments (i.e. RM protocols), isometric testing is considered potentially safer due to the biomechanical simplicity, reduced fatigue, and improved time-efficiency (Comfort et al., 2019b). Of importance to strength and conditioning coaches, multi-joint isometric tests have demonstrated greater relationships to dynamic movements and are preferred over single-joint isometric tests (Guppy et al., 2019). One such multi-joint isometric test that has been thoroughly researched in is the isometric mid-thigh pull (IMTP). During the IMTP, participants pull against an immovable bar located at a position that mimics the second pull position of the clean exercise (Comfort et al., 2019b). With this test, unlike during a 1-RM assessment, practitioners and researchers are able to assess peak force (PF) and time-specific force values, in addition 3 to the rate of force development (RFD) (Comfort et al., 2015; Dos’ Santos et al., 2017b; Haff et al., 1997, 2005, 2015). Previous research using trained individuals experienced with the IMTP has shown this test to be highly reliable with low variability and low measurement error (Beckham et al., 2018; Comfort et al., 2015; De Witt et al., 2018; Dos’ Santos et al., 2017b; Haff et al., 2015). To the authors’ knowledge only Beckham and colleagues (2018) have utilized a sample of inexperienced weightlifters