WEIGHT CUTTING: A BIOMECHANICAL INVESTIGATION OF THE EFFECT ON MARTIAL ARTS STRIKING PERFORMANCE JARED SCOTT EVANS BSc, Exercise Science, University of Lethbridge, 2008 A Thesis Submitted to the School of Graduate Studies of the University of Lethbridge in Partial Fulfilment of the Requirements for the Degree MASTER OF SCIENCE Department of Kinesiology University of Lethbridge LETHBRIDGE, ALBERTA, CANADA © Jared Evans, 2013 Abstract Weight cutting is a phenomenon that exists in combative weight-class-based sports. The goal of this research was to investigate the effect of weight cutting on striking performance parameters amongst mixed martial arts practitioners. Participants were tested on common strikes using a method specifically developed for the investigation of reaction time, power, and accuracy. These tests were performed prior to a self-selected weight-cut procedure and 24 hours after making weight, with the hypothesis that weight cutting would exhibit a negative effect on the tested parameters. The findings demonstrated a negative effect on peripheral reaction time, a positive effect on central reaction time, and mixed results on power and accuracy. No previous work has been performed on weight cutting and reaction time or accuracy. Future research should look to investigate the phenomenon closer to its real sport setting and to further the investigation of reaction time and accuracy. iii Acknowledgements There are many people who were involved with this study and deserve thanks. Firstly I would like to thank Lee Mein, owner and operator of the Canadian Mixed Martial Arts Center, and the athletes involved in local mixed martial arts. Without them, this research would not be possible. I wish to express my gratitude to Dr. Gongbing Shan for his mentorship, expertise, support, patience, and guidance. Without the biomechanics laboratory, equipment, and his belief in the research this would not have been possible. Also, a thanks to all the students passing through the biomechanics laboratory who helped with collection and analysis. A special thanks to my entire committee for their patience and support. I would also like to thank Shao-Tsung Chang for his help programming the analysis software in matlab and helping with the collection. Without this program, analysis by hand would have been near impossible. Thanks to Dr. Hua Li as well for his support and patience with me in all things mathematical. A special thanks to my parents, Dr. R. Scott Evans and Sarah Evans, for their never-ending love, support, encouragement, editing, and statistical knowledge. When I felt like giving up, they were there to push me forward. Another special thanks to Karen Graham for her professional editing services and patience with my writing. Without her, the final push would have been much harder. These acknowledgements do not begin to express how thankful I am to this team and more for helping me complete this project. Without this support network, I could not have finished. Thank you from the bottom of my heart. iv Table of Contents Abstract ............................................................................................................................. iii Acknowledgements ........................................................................................................... iv List of Tables....................................................................................................................vii List of Figures..................................................................................................................viii Chapter 1: Introduction........................................................................................................1 Background/Theme ........................................................................................................1 Purpose.......................................................................................................................... 4 Significance................................................................................................................... 4 Hypothesis..................................................................................................................... 5 Limitations.................................................................................................................... 5 Delimitations................................................................................................................. 6 Chapter Summary......................................................................................................... 6 Chapter 2: Literature Review.............................................................................................. 7 Weight Cutting and Dehydration.................................................................................. 7 Exercise-Induced Dehydration...................................................................................... 8 Hypo-Hydration............................................................................................................ 8 Hypo-Hydration and Weight-Class Based Sports........................................................10 The Consequences of Weight Cutting.........................................................................12 Full-Contact Forms of Martial Arts.............................................................................15 Barriers to Consensus on the Effects of Weight Cutting.............................................17 Martial Arts Striking Performance...............................................................................18 Chapter Summary........................................................................................................19 Chapter 3: Methodology................................................................................................... 20 3D Motion Capture and Laboratory Set-Up............................................................... 20 Power Quantifications................................................................................................. 23 Linear power calculations..................................................................................... 23 Angular power calculations.................................................................................. 25 EMG Measurement and Reaction Time Calculations................................................ 30 Accuracy Calculations................................................................................................ 32 Pre- and Post-Test Design........................................................................................... 32 Participant Information............................................................................................... 33 Statistical Analysis...................................................................................................... 35 Chapter Summary....................................................................................................... 35 Chapter 4: Results............................................................................................................. 36 Overall Effect of Weight Cutting................................................................................ 36 Overall Effect by Hand and Foot Strikes.................................................................... 37 Effect of Weight Cutting by Strike Style.................................................................... 40 Effect of Weight Cutting by Participant..................................................................... 53 v Chapter Summary....................................................................................................... 60 Chapter 5: Discussion....................................................................................................... 61 Pilot Investigation....................................................................................................... 61 Overall Trends............................................................................................................ 61 Trends by Hand and Foot Strikes................................................................................ 63 Trends by Individual Strike........................................................................................ 63 Reaction time components.................................................................................... 63 Power components................................................................................................ 64 Accuracy............................................................................................................... 64 Trends by Individual Participant................................................................................. 65 Conclusion.................................................................................................................. 66 Implications for Practitioners...................................................................................... 67 Implications for Future Research................................................................................ 68 References......................................................................................................................... 69 Appendix A: Ethics Application Approval....................................................................... 81 Appendix B: Consent Form.............................................................................................. 90 Appendix C: SPSS Statistical Results for Over All Effect............................................... 93 Appendix D: SPSS Tables for Overall Hand and Foot Strikes......................................... 95 Appendix E: Tables by Individual Strike Style................................................................ 99 Appendix F: Tables for Individual Participants...............................................................123 vi List of Tables Table 1. Participant Information................................................ 34 Table 2. Results of the Overall Effect of Weight Cutting.......... 37 Table 3. Results of the Overall Effect Isolated by Hand Strikes 38 Table 4. Results of the Overall Effect Isolated by Foot Strikes.. 39 Table 5. Results of the Left Hooks to the Body N= 7 ............... 41 Table 6. Results of the Left Hooks to the Head......................... 42 Table 7. Results of the Left Straights to the Head..................... 43 Table 8. Results of the Right Hooks to the Body...................... 44 Table 9. Results of the Right Hooks to the Head....................... 45 Table 10. Results of the Right Straights to the Head................. 46 Table 11. Results of the Left Kicks to the Head........................ 47 Table 12. Results of the Left Kicks to the Leg.......................... 48 Table 13. Results of the Left Kicks to the Body........................ 49 Table 14. Results of the Right Kicks to the Head...................... 50 Table 15. Results of the Right Kicks to the Leg........................ 51 Table 16. Results of the Right Kicks to the Body...................... 52 Table 17. Results of Participant 1.............................................. 53 Table 18. Results of Participant 2 .............................................. 54 Table 19. Results of Participant 3 .............................................. 55 Table 20. Results of Participant 4 .............................................. 56 Table 21. Results of Participant 5 .............................................. 57 Table 22. Results of Participant 6 .............................................. 58 Table 23. Results of Participant 7 .............................................. 59 vii List of Figures Figure 1. The set-up of synchronized 3D data collection................................................ 21 Figure 2. Punching bag set-up (2a) and Euler angle principles (2b) used to represent the angular rotation of the punching bag...........................................25 Figure 3. Typical power generation of a 185 lb athlete during a left straight punch (right column) and a left hook (left column). As shown in the data presented in this figure, a hook generated higher maximal power than a straight one.........................................................................................................29 Figure 4. Quantification of reaction time using our synchronized device and EMG enveloping method.............................................................................................31 Figure 5. Weight changes during individualized weight-cut process................................34 viii Chapter 1: Introduction My goal for this chapter is to briefly introduce the phenomenon of weight cutting in sport. I will also present the study purpose, significance, hypothesis, and limitations. Background/Theme The sport of mixed martial arts is a free-form, one-on-one combative sport that has its origins in contests attempting to determine which martial art and/or fighting styles were superior. Examples of commonly used styles or disciplines include, but are not limited to, wrestling, boxing, Muay Thai kickboxing, judo, sambo, karate, tae kwon do, and Brazilian jiu-jitsu. Three main areas of empty-handed combat are generally involved: striking/stand up, take downs/throws, and grappling. This sport has developed into a full- contact combat sport with regulations and sanctions, variations of which are becoming popular all over the world. Athletes have shifted from a focus on singular disciplines and have developed into a hybrid mixture of various styles or mixed martial arts. Over the years, the sport of mixed martial arts has become increasingly popular in both spectatorship and participation (Lenetsky & Harris, 2012; Ngai, Levy, & Hsu, 2008; Seidenberg, 2011). The phenomenon of weight cutting, or cycling, is associated with weight class- based sports where athletes will “choose to reduce their body mass to a weight class lower than their normal weight” (Horswill, 2009, p. 22). This is an intentional body mass reduction prior to a competition’s weigh-in and subsequent regain of as much as possible, if not all, of the mass between the weigh-in and the actual competition. Due to the weight class-based nature of mixed martial arts competitions and approximate 24-hour time window between weigh-ins and competition, weight cutting as a practice is deeply 1 embedded in the sport. Athletes who do not make their contracted weight class may be subject to monetary penalty and/or disqualification. The practice of weight cutting is sometimes discussed openly prior to and during competitions as well as in deciding future match ups. Weight manipulation practices were first mentioned in the 1940s in relation to wrestling, and they are described as having changed little from that time despite the increasing knowledge on the negative effects of such weight loss practices. While weight classes exist to promote fair and matched competition, they also encourage athletes to compete at lower classes in an attempt to increase the chances of success. As there was very limited literature across combat sports, researchers noted the need for further investigations into all areas related to the practice of weight cutting, including: health, longitudinal effects, growth and maturation, performance, psychology, and general success as well as safe practices (Brownell & Steen, 1992; Horswill, 2009; Steen & Brownell, 1990). Koral and Dosseville (2009) explained the phenomenon of body mass reduction in weight class-based sports, summarizing, Most athletes participating in combat sports with specific body mass categories such as wrestling, boxing, and judo can compete in a class 10% below their usual body mass. Thus body mass control may be as important an issue as performance. In sports in which body mass plays a decisive role, the athletes can resort to passive (sauna) and active sweating (through intensive exercise in plastic suits) as well as reducing the amount of food and liquids they consume. Rapid body mass loss (i.e., in 3-4 days) has been reported to be detrimental to performance in terms of power, force, resistance, flexibility, and skilfulness. . . . Moreover, such a procedure may influence cognitive performance and mood negatively. (p. 115) The limited research across combat sports was not necessarily conclusive, although Horswill (2009) stated that “short-duration high-intensity performance is less likely to be affected adversely. If the effort is extended and repeated, i.e., requires an 2 element of endurance, performance deteriorates. For submaximal efforts of longer duration, performance is clearly impacted in a negative way” (p. 29). This summary demonstrated the need for more research in general and a move from laboratory-based physical performance to sport-specific physical performance studies. It also demonstrated the need to broaden and expand the combative sports studied: an example being that no studies focused on mixed martial artists. In the position paper on exercise and fluid replacement for the American College of Sports Medicine, Sawka et al. (2007) wrote specifically on boxing and wrestling as examples of weight-based sports at risk for dehydration. They went on to state that “dehydration greater than 2% body weight degrades aerobic exercise and cognitive/mental performance in temperate-warm-hot environments” (p. 381). The act of weight cutting is not just a performance issue; in its extreme cases, dehydration related to weight cutting may lead to serious medical issues such as heat- related illnesses and stress on the kidneys (Horswill, 2009; Sawka et al., 2007). In 1997, three NCAA wrestlers in different states died from complications associated with dehydration from rapid weight loss procedures (Hoey, 1998; Remick et al., 1998). The Team USA Olympic wrestling captain was barred from competition at the 2008 Beijing Olympics given his deteriorated physical state at the weigh in. He claimed he would be fine at the competition, but physicians barred him from competition (Mihoces, 2008). There was even one alarming case of a 5-year-old wrestler receiving pressure to drop weight (Sansone & Sawyer, 2005). Weight cutting is a very real part of combat sports, and the practice continues today, even in extreme cases, in the presence of modern health and athletic performance knowledge. 3 Athletes may ignore potential long-term health warnings or threats for a potential increased chance of success. If weight cutting could be shown to decrease athletic performance, prowess, or ability, as well as a potential negative health impact, then the practice might possibly be curtailed. This lead to the question: What is the influence of a self-selected weight manipulation regimen on biomechanical parameters of martial arts striking performance among mixed martial arts practitioners? Purpose The aim of this study was to initiate an investigation on the effect of weight cutting on striking performance within a mixed martial artist population using state-of- the-art biomechanical equipment. Parameters under exploration include 3D kinematics, power, accuracy, reaction time, and balance. Also, no restrictions were placed on subjects’ weight-loss protocols; the athletes were allowed to utilize their preferred methods and timing strategies of weight reduction and regain. Such an effort preserved the tested subjects’ normal “style” in a competitive preparation and made the results more realistic. Significance Through this study, as the researcher, I looked to fill a gap where there has been limited research on weight cutting across combat sports, even less on biomechanical parameters and/or performance, and no existing literature focused on a mixed martial arts population. Only one study to date has allowed the athletes to use their own methods of weight reduction when researcher-imposed methods could be considered the largest 4 barrier to a research consensus (Timpmann, Oopik, Paasuke, Medijainen, & Ereline, 2008). The research as carried out in the University of Lethbridge Biomechanics Lab in the Kinesiology Department over a one-year period between May 2009 and December 2011. A portion of the subjects completed the testing around and for an actual competition event. This became the first application of sport-specific performance-related weight cutting research to the ongoing real-life phenomenon. The knowledge gained could be useful in providing insight into the real-life phenomenon as it is occurring, guiding future weight loss plans, changing the approach to rapid weight loss, changing athlete’s attitudes towards weight cutting, and possibly even leading to rule changes that prevent the “need” for dangerous procedures as was done in the National Collegiate Athletic Association wrestling program (Davis et al., 2002; Oppliger, Utter, Scott, Dick, & Klossner, 2006; Schnirring, 1998; Utter, 2001). Hypothesis A self-selected weight cutting regimen of 5% body weight will negatively affect the chosen parameters of striking performance (i.e., the reaction would be slowed; the explosive power generation ability, and the accuracy of punches and/or kicks, would be reduced). Limitations 1. It was assumed that the subjects accurately recorded their weight-loss procedures and weights. 2. It was assumed that both professional and amateur mixed martial artists have a consistency within their own striking habits and technical approaches. 5 Delimitations 1. Due to the small nature of this athletic population, the sample was limited to 12 male subjects in Southern Alberta of varying ages and weight classes. Chapter Summary This chapter presented a brief overview of the phenomenon of weight cutting. The investigation was also introduced with its purpose, significance, and limitations. In the next chapter, an in-depth review of appropriate literature will be conducted. 6 Chapter 2: Literature Review In this chapter, the body of literature regarding intentional dehydration for competitive purposes will be reviewed. This includes a description of the phenomenon of weight cutting, why athletic populations are using such practices, and which athletic populations are engaged in the practice. As well, I will discuss the prevalence and magnitude of the practice, how the practice is utilized, and the effect of weight cutting on a variety of physiologic, performance, and health variables. The limitations and barriers to a consensus of opinion on effect will also be presented. Martial arts striking performance is briefly summarized as a way of investigating the phenomenon of weight cutting. Weight Cutting and Dehydration Dehydration can be assessed in many ways, and body weight reduction is one such marker (Shirreffs, 2000). Even though weight cutting can and does involve more than just water loss, caloric restriction for example, the weight loss is primarily water weight (Timpmann et al., 2008). Therefore, a self-imposed reduction in body weight is predominately a form of dehydration that can be exacerbated by caloric restriction and/or heat exposure. In relation to sport, exercise, and performance, dehydration can occur in two forms: exercise-induced dehydration and hypo-hydration. Exercise-induced dehydration is body weight loss during exercise brought on by sweating as a reaction to the exercise itself. Hypo-hydration in this case is the situation where athletes intentionally dehydrate themselves prior to competition or performance (Barr, 1999; Shirreffs, 2009). 7 Exercise-Induced Dehydration Exercise-induced dehydration has been found to unequivocally affect performance in a negative manner (American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada, 2000; Gauchard, Gangloff, Vouriot, Mallie, & Perrin, 2002; McGregor, Nicholas, Lakomy, & Williams, 1999; Sawka, Montain, & Latzka, 2001; von Duvillard, Arciero, Tietjen-Smith, & Alford, 2008; Yoshida, Takanishi, Nakai, Yorimoto, & Morimoto, 2002). The body weight reduction of approximately 2-3% through dehydration appears to be the threshold for a variety of functional decrements, including: basketball skills, tennis skills/sprinting, throwing accuracy, anaerobic strength/power, muscular power and endurance, aerobic endurance, as well as general decreases in performance capacity (Barr, 1999; Casa et al., 2000; Coyle, 2004; Devlin, Fraser, Barras, & Hawley, 2001; Dougherty, Baker, Chow, & Kenney, 2006; Jones, Cleary, Lopez, Zuri, & Lopez, 2008; Magal et al., 2003; Maughan, 2003; Montain, 2008; Murray, 2007; Rodriguez, Di Marco, & Langley, 2009; Sawka et al., 2007; Shirreffs, 2005, 2009; Walsh, Noakes, Hawley, & Dennis, 1994; “Water Deprivation and Performance of Athletes,” 1974). Hypo-Hydration There is not a clear consensus about hypo-hydration as was found with exercise- induced dehydration, but the practice has still been found to negatively affect many aspects of performance. Hypo-hydration was found to negatively affect aerobic performance (M. Fogelholm, 1994; Sawka et al., 2001), reaction time, balance, and postural sway (American Academy of Pediatrics Committee on Sports & Fitness, 2005; Patel, Mihalik, Notebaert, Guskiewicz, & Prentice, 2007). Hypo-hydration has also been 8 found to negatively affect general exercise performance (American Academy of Pediatrics Committee on Sports & Fitness, 2005; Caldwell, 1987; Paik et al., 2009), particularly in rowing (G. Slater et al., 2006; G. J. Slater et al., 2005; G. J. Slater et al., 2006), and more specifically in basketball, rowing, and cycling performance with a 2% body weight reduction (Baker, Dougherty, Chow, & Kenney, 2007; Burge, Carey, & Payne, 1993; Walsh et al., 1994). Intermittent sprint time has also been found to be negatively affected (Maxwell, Gardner, & Nimmo, 1999) as well as explosive power. It should be noted that although this particular study of explosive power found that 1-2% body weight reduction affected women and not men, the researchers postulated that it would with more weight lost (Gutierrez, Mesa, Ruiz, Chirosa, & Castillo, 2003). Muscular strength and endurance have also been found to be decreased by hypo-hydration (G. M. Fogelholm, Koskinen, Laakso, Rankinen, & Ruokonen, 1993), although these decreases have been found to be far less detrimental to aerobically trained populations as compared with anaerobically trained populations at a 3% body weight reduction (Caterisano, Camaione, Murphy, & Gonino, 1988). More recently, hypo-hydration has been found to negatively impact strength, power, resistance exercise, and high-intensity exercise performance (Judelson, Maresh, Anderson, et al., 2007; Judelson, Maresh, Farrell, et al., 2007). However, there was some contradiction about performance decrements within the literature. Aerobic performance, anaerobic performance, rowing performance, muscular strength, and endurance were found to recover with at least five hours of adequate rehydration and re-feeding (G. M. Fogelholm et al., 1993; M. Fogelholm, 1994; G. J. Slater et al., 2005). More confounding studies that detracted from a consensus included 9 finding that hypo-hydration decreases muscular endurance but not strength (Montain et al., 1998) and that sprint or vertical jump performance were not impaired (Watson et al., 2005). Furthermore, in direct contradiction, hypo-hydration has been found to both increase oxidative stress and DNA damage (Paik et al., 2009), but also to not enhance muscle damage after resistance exercise (Yamamoto et al., 2008). Hypo-Hydration and Weight-Class Based Sports This phenomenon of hypo-hydration or weight cutting has been explored directly from many research angles in a variety of previously mentioned weight class sports, such as wrestling, judo, boxing, tae kwon do, and MMA for example. Some of the research streams included the effect of weight cutting on long-term growth and anthropometrics, psychological measures, work capacities, metabolism, muscular strength, muscular endurance, immune function, aerobic power, anaerobic power, physiological parameters (blood metabolites for example), its relation to winning or success, and even to academic grades. The bulk of this research has involved wrestling because it has the most common and longest usage of the phenomenon. The practice received special interest after the three NCAA deaths referred to in chapter one (Hoey, 1998; Remick et al., 1998). More recently, judo is becoming more researched. This intentional and purposeful loss of body weight to compete in a lower weight class may be achieved through a variety of active or passive methods with the primary objective of losing water weight, which involves the athlete rapidly reducing body weight for a competitive weigh in to gain a size, leverage power, and/or strength advantage (Brownell, Steen, & Wilmore, 1987; Horswill, 1992, 1993, 2009; Oopik et al., 2002; Oppliger, Case, Horswill, Landry, & Shelter, 1996; Oppliger, Steen, & Scott, 2003; 10 “Water Deprivation and Performance of Athletes,” 1974; Wroble & Moxley, 1998b). As mentioned, weight cutting exists in weight-class-based combative sports such as wrestling, boxing, and martial arts such as judo, tae kwon do, karate, and mixed martial arts. The practice even exists in non-combative weight-based sports such as power lifting, rowing, and horse racing (Beljaeva & Oopik, 2001; Horswill, 1992; Kazemi, Shearer, & Choung, 2005; Schoffstall, Branch, Leutholtz, & Swain, 2001; M. S. Smith, Dyson, Hale, Harrison, & McManus, 2000; Waslen, McCargar, & Taunton, 1993). Combative weight class athletes will routinely lose between 5 and 10% of their body weight to compete in lower classes (American College of Sports Medicine, 1976; Artioli et al., 2010; Brownell et al., 1987; Hall & Lane, 2001; Horswill, 1993; Kiningham & Gorenflo, 2001; Ribisl, 1975; M. S. Smith et al., 2000; Steen & Brownell, 1990). This weight loss is achieved through a variety of potential methods, including increased exercise, decreased caloric intake/ energy restriction, fluid restriction, heat exposure (e.g., sauna/steam), exercising in heat exposure, diuretics, laxatives, and even vomiting (Clarkson, Manore, Oppliger, Steen, & Walberg-Rankin, 1998; Horswill, 1992, 1993; Kiningham & Gorenflo, 2001; Oppliger et al., 2003; Wroble & Moxley, 1998b). Weight cutting can be very frequent, based on competitive needs. Essentially, the prevalence of weight cutting will parallel the frequency of competition. The practice has been described in wrestlers as occurring approximately 10 to 15 times per season with a range of 2.0 to 2.9 kilograms lost on a weekly basis (Oppliger et al., 1996; Oppliger, Landry, Foster, & Lambrecht, 1993; Oppliger, Landry, Foster, & Lambrecht, 1998; Oppliger et al., 2003). Judokas were found to have reduced their weight roughly two to 11 five times a year, although many reduced their weight six to 10 times a year and were found to have started the practice generally before 15 years old (Artioli et al., 2010). The percentage of wrestlers who practice weight cutting has varied in research, but with a range of 32% to 89%, the phenomenon is real and a part of weight class sports (Artioli et al., 2010; Horswill, 1993; Kiningham & Gorenflo, 2001; Lakin, Steen, & Oppliger, 1990; Oppliger et al., 1998; Steen & Brownell, 1990). Most recently, 82% of judokas were found to engage in the practice (Artioli et al., 2010). Weight cutting is also prevalent in boxing, tae kwon do, and general combative sports or mixed martial arts (Hall & Lane, 2001; Kiningham & Gorenflo, 2001; M. Smith et al., 2001; M. S. Smith et al., 2000). The Consequences of Weight Cutting Weight cutting has been found to have little or no effect on anthropometrical or long-term growth in judokas (Waslen et al., 1993) and wrestlers (Housh et al., 1997; Housh, Johnson, Stout, & Housh, 1993; Nelson, 1962; Nitzke, Voichick, & Olson, 1992; Roemmich & Sinning, 1997; Singer & Weiss, 1968). Although it should be noted that weight cutting has been linked to long-term weight development in boxers, wrestlers, and weight lifters and that the practice may enhance weight gain or predispose to obesity in later life (Saarni, Rissanen, Sarna, Koskenvuo, & Kaprio, 2006). Weight cutting has been investigated in relation to success or winning in wrestlers and found to have a mixed effect. Utter and Kang (1998) were the only researchers who found no affect, while weight cutting was found to have a positive correlation to success in two other studies (Wroble & Moxley, 1998a, 1998b). While weight cutting may have 12 contributed to winning, it had no effect on academic grades of wrestlers (Burcham, Gerald, Hunt, & Pope, 2006). There have been mixed results regarding the effect of weight cutting on metabolism. While there was no effect found in judokas (Waslen et al., 1993) and for the most part in wrestlers (McCargar & Crawford, 1992; Melby, Schmidt, & Corrigan, 1990; Schmidt, Corrigan, & Melby, 1993), weight cutting has been found to slightly decrease resting energy expenditure (Oopik et al., 1996; Steen, Oppliger, & Brownell, 1988). In other research, weight cutting has been found to consistently have a negative effect on psychological and cognitive function in judokas (Degoutte et al., 2006; Filaire, Maso, Degoutte, Jouanel, & Lac, 2001; Koral & Dosseville, 2009; Yoshioka et al., 2006) and in wrestlers (Choma, Sforzo, & Keller, 1998; Landry, 1998). It should be noted that Landry (1998) found a decrease in psychological variables, but no change in cognitive function. Another stream of research with a consensus was that of various indices of immune function. While it has not been well researched in wrestlers, with only one study (Whiting, Gregor, & Finerman, 1988) finding a negative impact, this damaging effect has been well documented in judokas (Finaud et al., 2006; Kowatari et al., 2001; Ohta et al., 2002; Suzuki et al., 2003; Umeda, Nakaji, Shimoyama, Kojima, et al., 2004; Yaegaki et al., 2007). A similar health-related stream of research that only appeared in studies related to judokas is that of bone health. Unlike previous areas, results were mixed. Some of the research documented the negative effect of weight cutting on bone health markers, contrasted with no effect in light of mediation from heavy training (Prouteau, Benhamou, & Courteix, 2006; Prouteau, Pelle, Collomp, Benhamou, & Courteix, 2006). 13 Yet another stream of research in uniform agreement was that of physiological blood and substrate parameters. There was an undisputed negative effect in judo (Degoutte et al., 2006; Filaire et al., 2001; Prouteau, Benhamou, & Courteix, 2006) as well as in wrestling (Hickner et al., 1991; Horswill, Park, & Roemmich, 1990; Karila et al., 2008; Strauss, Lanese, & Malarkey, 1985; Tarnopolsky et al., 1996; Webster, Rutt, & Weltman, 1990). Weight cutting has also been investigated in relation to performance measures. The phenomenon has been found to have a unanimous negative effect on judo performance (Degoutte et al., 2006; Filaire et al., 2001; Koral & Dosseville, 2009; Prouteau, Ducher, Serbescu, Benhamou, & Courteix, 2007). It has been found to negatively impact anaerobic output in both wrestlers and judokas (Maffulli, 1992; Umeda, Nakaji, Shimoyama, Yamamoto, et al., 2004; Webster et al., 1990). There is also an overwhelming negative impact found in relation to physical work capacity in wrestling (Herbert & Ribisl, 1972; Hickner et al., 1991; Horswill, Hickner, Scott, Costill, & Gould, 1990; Klinzing & Karpowicz, 1986; Maffulli, 1992; Oopik et al., 1996; Oopik et al., 2002; Rankin, Ocel, & Craft, 1996; Ribisl & Herbert, 1970). However, some studies have found working capacity to not be affected (Kraemer et al., 2001; McMurray, Proctor, & Wilson, 1991), or even improve with weight cutting (G. M. Fogelholm et al., 1993). In relation to strength, the effect of weight cutting is uncertain. Both a negative influence and mixed results have been found in relation to wrestlers (Maffulli, 1992; Webster et al., 1990). Strength has also been investigated in power lifters, and it was found that weight cutting negated strength (Schoffstall et al., 2001). 14 Full-Contact Forms of Martial Arts The problem with this volume of research is that it comes from non-contact, non­ striking forms of martial arts or sports as opposed to full-contact striking martial arts and mixed martial arts. Some studies have been performed with mixed populations of both contact and non-contact weight cyclers. Jauhiainen, Laitinen, Penttila, Nousiainen, and Ahonen (1985) investigated the effect of a 5% weight cut by varying methods (e.g., sauna, diuretic, exercise, control) on blood physiology alterations in wrestlers, judokas, boxers, and weight lifters. The researchers found that blood lipids and proteins increased with sauna and diuretic dehydration, but not with exercise. This was most likely related to the moderating effects from increased heavy training. An important note is that different methods of weight loss cause different physiological alterations and that the levels of aerobic and anaerobic training can also create variation. Roots, Timpmann, and Oopik (2000) examined the role of weight cutting on the physiologic blood lipid profile and found no adverse effect of the practice in karatekas, wrestlers, boxers, and judokas. Timpmann et al. (2008) investigated the effect of a 5% weight cut on work, strength, metabolites, and urea in wrestlers and karatekas. A key principle is that this study was one of the first studies to focus on a “self-selected regimen” of weight loss rather than one imposed by the researcher. It was concluded that weight cutting decreased work and strength while increasing metabolites and urea (Jauhiainen et al., 1985; Roots et al., 2000; Timpmann et al., 2008). An even smaller field of research has been conducted exclusively on full-contact striking combative sports. This included research into karate, boxing, tae kwon do, general combative sports, and/or mixed martial arts. 15 In karate, a 5% weight reduction over five days decreased physical working capacity, which was not maintained by creatine supplementation. However, creatine appeared to maintain peak force and angular velocities as opposed to the decrease observed in placebo trials (Oopik et al., 2002). A 6% weight cut in tae kwon do practitioners was found to decrease exercise time, peak blood lactate, maximal running time, heart rate, and muscular endurance. While muscular endurance decreased, strength and power remained. Likewise, while maximal running time and heart rate decreased, maximal oxygen uptake did not change (Lee, 1997). Also, a 5% reduction was associated with a decrease of anaerobic high- intensity performance in lightweight athletes as compared to heavyweights (Kijin & Wookwang, 2004). Although simulated sports performance has become more and more popular in research related to weight cutting, this has not been fully realized in other sports as compared with boxing. It was found that a loss of body mass diminished simulated boxing performance; however, some athletes appeared predisposed to better handle dehydration and not demonstrate performance decrements (M. S. Smith et al., 2000). In a similar boxing performance task, a negative effect was found overall, but with a few outliers who saw no decrement or even improvement (M. Smith et al., 2001). Lastly, weight cutting was found to negatively impact mood and simulated performance (Hall & Lane, 2001). Essentially, all three found performance decreases due to weight cutting. Only one study to date has investigated weight cutting in general combative sporting athletes. They were not designated mixed martial artists, but they were not designated into other sports either. Timpmann, Oopik, Paasuke, Medijainen, and Ereline 16 (2004) examined the effect of a 5% weight cut on strength, work, and blood metabolites in this undefined population of general combative athletes. It was concluded that there was an increase in metabolites as well as urea from protein degradation. Also, work and strength were impaired in a 3-minute variable intensity exercise, attempting to replicate the high intensity and aerobic demands of combative sports (Timpmann et al., 2004). Barriers to Consensus on the Effects of Weight Cutting Unfortunately, there were barriers to a consensus on the effects of weight cutting. These barriers included the methods used in varying research, researcher imposed protocols, and differing rehydration times. Timpmann et al. (2008) suggested that the main problem was researcher-imposed weight controls and, as such, were the only researchers to use a self-selected weight-loss protocol. Results from previous studies may have been confounded by the fact that the subjects were not allowed to use their own developed and practiced procedure of weight loss. Instead, according to Timpmann et al. (2008), subjects were to use prescribed methods they may not have preferred nor had experience with. Another conflicting issue was the differing tests and measures of performance; as well, these tests were not necessarily being sport specific. While one test might accurately represent one sport, the results and trends may not transfer to a different sport. The last major problem was differing rehydration times between weigh in and competition between sports. Only mixed martial arts of the striking contact sports have the large window of 24 hours. All other sports have resorted to shorter rehydration times; therefore, again, results and trends are not applicable to other timelines from other sports. Large timelines have been used for wrestling, but not the full 24 hours of rehydration as is found in mixed martial arts. 17 Anaerobic power and strength have been vastly studied with mixed results in relation to weight cutting because they have been described as the key to success in wrestling (Horswill, 1992). However, anaerobic power and strength have not been investigated relative to martial arts striking performance and parameters. Dehydration has been associated with negative effects on reaction time and accuracy. Reaction time has been described as negatively affected by dehydration, but this link has not been established directly to hypo-hydration (American Academy of Pediatrics Committee on Sports & Fitness, 2005). These parameters have not only been ignored for the most part in hypo-hydration, they are also absent from research relating to full contact combative striking sports. The effect of weight cutting on strike accuracy has yet to be investigated in contact combative weight class sports such as mixed martial arts, even though accuracy has been found to decrease in relation to exercise induced dehydration (Devlin et al., 2001). Essentially, factors such as reaction time and accuracy have not been fully investigated in relation to hypo-hydration for making weight. Martial Arts Striking Performance Power, speed, and timing are some of the most important factors for martial arts striking performance. Power can be thought of as explosive force (i.e., the product of force and speed) or an athlete exerting their strength quickly. Speed and timing include both muscular speed and reaction time. Aspects of the fundamental parameters of power, speed, and timing have been investigated through a wide variety of indirect and direct methods. This body of literature has been summarized, including the existing limitations (Chang, Evans, Crowe, Zhang, & Shan, 2011). It should be noted that none of this 18 summarized literature on martial arts striking performance investigated the phenomenon of weight cutting in any way. Chapter Summary Dehydration negatively effects athletic performance, but the effect of self-induced weight cutting with a subsequent rehydration period remains less clear. There were large gaps across the literature and many barriers to a consensus on the effect of the phenomenon. There was minimal research on weight cutting in general within mixed martial artists as an athletic population, and only one study utilizing non researcher imposed weight loss methods. Also, researchers have yet to utilize a sport-specific performance test for mixed martial arts, with either common strikes, strike parameters, or high-intensity intermittent exercise of five minutes representing one round of mixed martial arts competition. Weight cutting has been investigated from a variety of approaches in a variety of weight-class-based sports; to date, no research has utilized a full-body, three-dimensional motion capture system to quantify changes in striking mechanics and parameters in relation to weight cutting. These striking parameters include velocities and accelerations, which can be equated to strike power or force, reaction time, and accuracy. 19 Chapter 3: Methodology My aim in this chapter is to present the materials and methods used to investigate the effect of weight cutting on martial arts striking parameters. This includes the laboratory set up of a synchronized motion capture system, electromyography unit, and an optical trigger device. As well, I present an explanation of the quantification of power, reaction time, and accuracy based on strike timing, 3D kinematic characteristics of the punching bag and striking limbs, electromyography measurement, and the optical trigger signal. Lastly, a description of the application of the quantifying methods to a pre- and post-test design investigating weight cutting, the characteristics of the subjects tested, and the statistical analysis will be presented. 3D Motion Capture and Laboratory Set-Up Once ethical approval was received from the University of Lethbridge (see Appendix A), the laboratory was set up with a 12-camera VICON 3D motion capture system that was used to quantitatively determine the whole body kinematic characteristics during each striking movement. VICON software (www.vicon.com) was configured to capture movement at a rate of 200 frames per second. Calibration residuals were determined in accordance with VICON’s guidelines and yielded positional data accurate within 1 mm. Each subject was fixed with 39 reflective markers with a diameter of 9 mm. The markers reflected infrared light emitted from the cameras and their positional data were recorded by said cameras. These markers were placed at specific bony and body landmarks to create 15 segments and a full body biomechanical model using previously 20 existing methods (Shan, Bohn, Sust, & Nicol, 2004; Shan & Westerhoff, 2005; see also Figure 1). Figure 1. The set-up of synchronized 3D data collection. 1 The segments consisted of the head and neck, upper trunk, lower trunk, two upper arms, two lower arms, two hands, two thighs, two shanks, and two feet. To create the head segment, markers were placed on the left and right temples and two on the posterior portion of the parietal bone. The upper trunk and arm segments were created by markers on the sternal notch, xiphoid process, C7 and T10 vertebrae, right back, left and right acromion processes, left and right lateral epicondyles of the humerous, styloid processes of the ulna and radius, right and left third metacarpophalangeal joints, as well as the right and left upper and lower arms. The lower torso/pelvis and leg segments were created 1 From “An Innovative Approach for Real Time Determination of Power And Reaction Time in A Martial Arts Quasi-Training Environment Using 3D Motion Capture and EMG Measurements,” by S.-T. Chang, J. Evans, S. Crowe, X. Zhang, & G. B. Shan, 2011, Archives o f Budo, 7, p. 187. Copyright 2011 by Chang et al. Reproduced with permission. 21 from markers placed on both the right and left following landmarks: the anterior superior iliac crest, posterior superior iliac crest, lateral condyle of the tibia, lateral malleolus of the fibula, calcaneal tuberosity, head of hallucis, upper leg/thigh, and tibia. The raw kinematic data were processed using a five-point smoothing filter (1-3-4-3-1 function). In addition, a standard punching bag was outfitted with 15 markers. Four were located on the top and four on the bottom to provide a frame for the bag. Another seven markers were used as targets, with three vertical left markers, three vertical right markers, and one front marker whose height matched the highest side markers. The frame markers were used to determine the striking power of the athlete. The target markers corresponded to the body targets of the most common strikes: left jab (left straight punch) and right straight punch to the head, hooks to the head and body, as well as left and right kicks to the head, body, or legs. These target markers, combined with the carefully placed striking markers on the middle knuckle of the glove and lower shin, allowed for an investigation of accuracy. The shin marker was placed at the lower third of the shank and then adjusted based on the subjects’ preferred contact area. The height of the bag was standardized by hanging it so that the subject’s lowest lateral rib matched the height of the middle or body targets. The high/head and low/leg targets were placed at 20% of body height away from midpoint marker, which was already located at the middle of the bag. Kinematic data of the subject and bag were calculated based on the data collected from the 3D motion capture system using previously mentioned methods. This data included positional changes, velocities, and accelerations. The optical signal system of three LED lights was synchronized to the system and controlled by the researcher. These signal lights were used to initiate the time of strike as 22 well as to indicate to the subject the location of (or style of) strike. The lights were placed at the top of the bag at eye level without interfering with the targets. This allowed for random selection of the strike within the chosen style and when combined with electromyography (EMG) and motion data allowed for a thorough investigation of reaction time. 2 Power Quantifications Power and force were mathematically determined from the kinematic data using the method proposed by Chang et al. (2011). This method was specifically developed for this research project. Using this method, the movement of the punching bag was used to determine the power in the strike. Treating the punching bag as a rigid body and utilizing the related coordinate data, linear and angular power were able to be calculated and, hence, the total power as well. P T = P L + P A [1] Where PTis the total power, PL and PA are the linear and angular powers respectively. Linear power calculations. In order to determine linear power, the velocity of the centre of the bag (v) and the force applied to the bag (F) needed to be quantified. The eight frame markers of the punching bag provided this information. Since the cylindrical punching bag had a uniform density and was symmetric in both vertical and horizontal directions respectively, the centre of mass was determined with coordinates x, y, and z, in their respective planes. 2 The approach and equations used in this presentation follow the collaborative research I completed as reported in “An Innovative Approach for Real Time Determination of Power And Reaction Time in A Martial Arts Quasi-Training Environment Using 3D Motion Capture and EMG Measurements,” by S.-T. Chang, J. Evans, S. Crowe, X. Zhang, & G. B. Shan, 2011, Archives o f Budo, 7(3), 185-196. Copyright 2011 by Chang et al. 23 Using the coordinate data, vectors were produced representing the movement/ position, velocity (first derivative of Equation 2), and acceleration (second derivative of Equation 2) of the rigid body for each frame. v = X v2 = y v3 = z [2] Vox Equation 2, v is the velocity vector of the centre of the punching bag, and Vi, v2, and v3 are the velocities of the bag in their respective x, y, and z directions. Each velocity was determined by the first derivatives: i , y and z, in their respective x, y, and z directions. Basic physics calculations were used to determine the linear force (F) exerted on the bag (Newton’s 2nd Law, Equation 3) and using physics theory, the linear power was able to be determined. F = mvx F2 = mv2 = mv3 [3] Vox Equation 3, F is the force vector applied to the punching bag, rn is the mass of the punching bag, and Vg, v 2, and v3 are the accelerations in their respective x, y, and z directions (or first derivatives of the previously obtained velocities). Accelerations as stated were the derivative of velocities or the second derivative of the positional data. 24 r------- Using Equation 3, Fi, Fz, and Fa were calculated: that is, the applied force in the x, y, and z directions respectively. Therefore, the linear power equation was as follows: PL = F -v = F f\ + F2v2 + F3v3 [4] A program written in MATLAB was used to help determine the linear power. Angular power calculations. To determine angular power, the rotational characteristics of the bag movement during and after contact were of import. Again, using the coordinate data, positional vectors were determined for each frame. Based on engineering physics (Meriam & Kraige, 2008), the rotational characteristics and angular power were calculated using the Euler Angle System and angular dynamics. The marked bag and principles of Euler angles are presented in Figure 2. BTBL BTBR 3 LEDs Lhigh Rhigh Lmid Rmid Low Rlow .............. BBBL BBBFT'h BBFL BBFR Figure 2. Punching bag set-up (2a) and Euler angle principles (2b) used to represent the angular rotation of the punching bag.3 3 From “An Innovative Approach for Real Time Determination of Power And Reaction Time in A Martial Arts Quasi-Training Environment Using 3D Motion Capture and EMG Measurements,” by S.-T. Chang, J. Evans, S. Crowe, X. Zhang, & G. B. Shan, 2011, Archives o f Budo, 7(3), p. 189. Copyright 2011 by Chang et al. Reproduced with permission. 25 The explanation of the bag marker set in Figure 2a is as follows: BTBL = bag top back left, BTFL = bag top front left, BTBR = bag top back right, BTFR = bag top front right, BBBL = bag bottom back left, BBFL = bag bottom front left, BBBR = bag bottom back right, and BBFR = bag bottom front right represent the markers on the eight corners of the bag. Markers were also placed on the sides to provide a target for the participant; Lhigh, Lmid, and Llow, Rhigh, Rmid, and Rlow. The front marker matches the height of the Rhigh and Lhigh markers and is not included in the figure due to overcrowding with the signal lights. The principles of Euler angles used to represent the angular rotation of the punching bag are depicted in Figure 2b. Lower case letters x, y, and z represent the initial axis of an object, and capital lettersX, Y and Z represent the axes after rotation. N represents a common line between the position before and after rotation (an intersection of the xy and the XY planes). The Euler angles a, P, and y represent the angle between the x-axis and N, the angle between the z-axis and the Z-axis, and the angle between N and the X-axis respectively. Any three consecutive rotations of a rigid body can be represented with Euler angles (a, P, and y). Based on previous methods (Trucco & Verri, 1998), an angle between two consecutive vectors needed to be calculated in order to determine Euler angles: that is, the time change of a selected vector. The specific vector chosen was from the centre of the bag to the bag top back right marker (BTBR). As stated, positional vectors were calculated for each frame from the coordinate data. These positional vectors build a rotational matrix by Euler’s theorem, which states that any 3D rotation can be represented by a rotation around a unit vector n = [«,, n2, n3f . The value for n can 26 be determined using the dot product of the vector positions. The angles between vectors were expressed using 9, which, again, were determined from the coordinate data. Once n was determined, the rotation matrix (R) was expressed as follows: n 2 nn2 " 0 - n n 2 R = I cos# + (1 - cos#) nn n 2 n n + s in # n 0 - n 1 n n n3n2 n32 - n2 n1 0 [5] 1 0 0 where I is identity matrix, i.e. 0 1 0 0 0 1 On the other hand, when the rotation matrix R is expressed using Euler Angles (a, P, and y), it has the following form: cos P cos y - cos P sin y sin P R sin a sin P cosy - sin a sin Psiny + cos a cosy -sin a cos P cosasin Pcosy + sinasiny cosasin Psiny + sinacosy cos a cosy [6] From Equation 5 and Equation 6, a, P, and y were determined, and after these Euler angles were obtained, the angular velocity of the bag was calculated based on Equation 7 (Meriam & Kraige, 2008). mx = a sin Psiny+ Pcosy < a 2 = a sin P cos y - P sin y cv3 = a cos P + y 1 [7] For Equation 7, ^ represents the angular velocity on the x-axis, obtained from the first derivative of the related Euler angles. Similarly, wz and represent the angular velocity on the y and z-axis respectively. 27 In order to calculate the angular power, the moment of inertia of the bag needed to be determined. Again, treating the punching bag as a rigid body with a cylindrical shape allowed the quantification of its moment of inertia. I = I7 = 1 m(3r2 + h2) < 1 2 12 [8] L = mr2 [ 3 2 For Equation 8, m is the mass of the punching bag, r is radium of the bag, h is the height of the bag, Ii, I2, and I3 are the moment of inertia in the medial-lateral, anterior- posterior, and vertical directions respectively. Because of the symmetry of the punching bag, they are equal to each other. After the determination of angular velocities (Equation 7) and the moments of inertia (Equation 8), the moment M (torque) applied to the bag could be calculated using Euler equations (Equation 9): M l = I Oj + (I3 - 12 )o2o3 < M 2 = I2 O2 + (I1 - I3)°3°1 M 3 = I3