Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
Views
4648
Download
206
 
©Journal of Sports Science and Medicine (2014) 13, 715 - 717

Letter to editor
Theoretical Model Describing the Relationship between the Number of Tackles in Which A Player Engages, Tackle Injury Risk and Tackle Performance
Sharief Hendricks , Mike I. Lambert
Author Information
UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa

Sharief Hendricks
✉ UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa .
Email: sharief.hendricks01@gmail.com
Publish Date
Received: 20-01-2014
Accepted: 11-02-2014
Published (online): 01-09-2014
Share this article
 
Dear Editor-in-Chief

The tackle is a physical contest between opposing players contending for territory and ball possession. During an 80 minute rugby union match, a player will physically engage in the tackle contest, whether as a ball-carrier or tackler, between 10 to 35 times depending on the position of the player (Deutsch et al., 2007; Quarrie and Hopkins, 2008). During a match, tight forwards (position numbers 1-5, who primarily compete in the set phases such scrums and lineouts) engage in the tackle approximately 10-25 times, loose forwards (position numbers 6-8, who mainly competes for possession of the ball at rucks and assist the tight forwards in set pieces) are involved in 25-35 tackles, inside backs (position numbers 9,10,12,13, whose key responsibility is to execute tactics and distribute the ball) competes in 20-25 tackles, and outside backs (position numbers 11,14,15, who are typically quicker and expected to run into open spaces to cross the advantage line and score points) engage in 10-15 tackles (Deutsch et al., 2007; Quarrie and Hopkins, 2008). It follows that a player requires a high level of skill, physical tolerance and resistance to fatigue to repeatedly engage safely and effectively in the tackle. Understanding the physical demands of a tackle is important with many applications. Examples of these applications include the design and development of proper training drills and equipment, planning and management of training and recovery between training sessions and matches. Also, a better understanding of the physical demands contributes to the implementation of strategies designed to reduce the risk of injury and enables replicating the event in the laboratory for research (Austin et al., 2011; Frechede and McIntosh, 2009; McIntosh et al., 2000; Newman et al., 2005; Pellman et al., 2003b). Recently, methods to estimate the magnitude of impact (energy distributed between ball-carrier and tackler upon contact) in real match tackle contests have been developed to further our understanding of the physical demands of the tackle contest (Hendricks et al., 2014).

The physical demand of the tackle was determined by calculating the amount of energy distributed between the ball-carrier and tackler upon contact. This excess of energy may cause muscle damage and injury to the musculoskeletal system (Takarada, 2003). The estimated magnitudes of impact ranged from 902 joules (J) to 7608 J for front-on tackles, and 595 J to 6209 J for side-on tackles (Hendricks et al. 2014). Repeated exposure to these physical collisions during training and matches, and over a long competitive season may influence the injury risk profile and longevity of a player, and if not managed correctly, negatively affect performance (Gabbett et al., 2010a; 2012a). With that said, Hendricks et al. analysed injury-free tackle events, demonstrating player’s ability to tolerate a range of impacts (Hendricks et al., 2014). The range of high impact, injury-free tackle events found in this study lends itself to McIntosh’s multifactorial model for injury prevention in team sports (McIntosh, 2005). In the model, McIntosh proposes that the biomechanics of injury risk can be explained by the event either resulting from an overload of the system’s tolerance levels, or a reduction in the system’s tolerance levels through micro trauma to a point where normal loads cannot be tolerated. Indeed, studies have shown a positive relationship between the number of tackles made during matches and markers of muscle damage (Smart et al., 2008; Takarada 2003). Also, using an instrumented bag to measure tackle forces, Usman et al. found that repeated tackling decreased the amount of force produced by the tackler (Usman et al., 2011). The authors attributed this decrease in force to fatigue, and proposed that fatigue may be an important injury risk factor for tackling, and tackle effectiveness (Usman et al., 2011). Similarly in rugby league, Gabbett et al. has shown a decrease in tackling technique as fatigue levels increase (Gabbett, 2008). Given the impact measurements of the tackles analysed in the Hendricks et al. (2014) study, and considering all tackles were injury-free, the range of magnitudes of impacts found in the study may provide evidence for the physical tolerance levels of players during the tackle. In view of above-mentioned injury model (McIntosh 2005) and tackle studies (Gabbett, 2008; Smart et al., 2008; Usman et al., 2011; Takarada, 2003) and the momentum, impact magnitudes presented in the Hendricks et al. (2014) study, it is theorised that players have an upper limit for being able to endure repeated high energy impact tackles. If this upper limit is exceeded the risk of injury is substantially increased, and tackle performance is noticeably decreased (Figure 1). This upper limit is reached either through one or more very high-energy impact contact situations or, accumulates over a match or season following repetitive lower-energy impact situations. However, effective tackle skill training, proper physical conditioning, strength, power, equipment and attitude/motivation can offset this upper limit (McIntosh, 2005). For example, physically conditioned players with a high level of tackle skill may have the technical ability and physiological capacity to minimise the energy load on the body, thereby increasing their tolerance level for physical loads. Evidence to support this theory can be found in rugby union and rugby league. From physical conditioning perspective, well-developed physical qualities such lower body muscular power (vertical jump) and acceleration (10m sprint) is positively associated with better tackle ability (measured using a tackle technique assessment) (Gabbett et al., 2010b; 2011a). Moreover, physiological characteristics such, as lower body muscular strength (1RM box-squat), lower body muscular power, and speed (10m and 40m sprints) improve tackle performance in matches (Gabbett et al. 2011b; Smart et al. 2011). Also, physical characteristics such upper body muscular strength (1RM weighted chin-up) and prolonged high intensity intermittent running ability has been shown to reduce the risk of injury during contact events in matches (Gabbett et al., 2012b). Interestingly, 40m sprint speeds of ≤5.25 seconds (compared to 40m sprint speeds of >5.25 seconds) decreased the probability of remaining injury free during contact events in matches (Gabbett et al., 2012). From a tackle skill perspective, technically skilled players attempts more tackles, execute more dominant tackles, and miss fewer tackles (Gabbett and Ryan, 2009). Furthermore, quicker decision-making time (≤ 80 milliseconds) during a reactive agility task may reduce the risk of contact injury in matches (Gabbett et al., 2012c).

In conclusion, a theoretical model building on previous work in conjunction with the findings of Hendricks et al. can be proposed (Figure 1). This model describes the relationship between the number of tackles a player engages in (acute or chronic fatigue), magnitude of impact (energy load), markers of muscle damage and how this relationship interacts with injury risk (tolerance overload or reduction) and performance.

AUTHOR BIOGRAPHY

Journal of Sports Science and Medicine Sharief Hendricks
Employment: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town
Degree:
Research interests:
E-mail: sharief.hendricks01@gmail.com
 

Journal of Sports Science and Medicine Mike I. Lambert
Employment: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, Faculty of Health Sciences, University of Cape Town
Degree:
Research interests:
E-mail:
 
REFERENCES
Journal of Sports Science and Medicine Austin D., Gabbett T., Jenkins D. (2011) The physical demands of Super 14 rugby union. Journal of Science and Medicine in Sport 14, 259-263.
Journal of Sports Science and Medicine Deutsch M.U., Kearney G.A., Rehrer N.J. (2007) analysis of professional rugby union players during match-play. Journal of Sports Sciences 25, 461-472.
Journal of Sports Science and Medicine Frechede B., McIntosh A.S. (2009) Numerical reconstruction of real-life concussive football impacts. Medicine & Science in Sports & Exercise 41, 390-398.
Journal of Sports Science and Medicine Hendricks S., Karpul D, Lambert M (2014) Momentum and kinetic energy before the tackle in rugby union. Submitted to. Journal of Sport Science and Medicine 13, 557-563.
Journal of Sports Science and Medicine McIntosh A.S. (2005) Risk compensation, motivation, injuries, and biomechanics in competitive sport. British Journal of Sports Medicine 39, 2-3.
Journal of Sports Science and Medicine McIntosh A.S., McCrory P., Comerford J. (2000) The dynamics of concussive head impacts in rugby and Australian rules football. Medicine & Science in Sports & Exercise 32, 1980-1984.
Journal of Sports Science and Medicine Newman J.A., Beusenberg M.C., Shewchenko N., Withnall C., Fournier E. (2005) Verification of biomechanical methods employed in a comprehensive study of mild traumatic brain injury and the effectiveness of American football helmets. Journal of Biomechanics 38, 1469-1481.
Journal of Sports Science and Medicine Pellman E.J., Viano D.C., Tucker A.M., Casson I.R., Waeckerle J.F. (2003b) Concussion in professional football: reconstruction of game impacts and injuries. Neurosurgery 53, 799-812.
Journal of Sports Science and Medicine Smart D.J., Gill N.D., Beaven C.M., Cook C.J., Blazevich A.J. (2008) The relationship between changes in interstitial creatine kinase and game-related impacts in rugby union. British Journal of Sports Medicine 42, 198-201.
Journal of Sports Science and Medicine Smart D, Hopkins W.G., Quarrie K.L., Gill N (2011) The relationship between physical fitness and game behaviors in rugby union players. European Journal of Sport Science 14, S8-S8.
Journal of Sports Science and Medicine Takarada Y. (2003) Evaluation of muscle damage after a rugby match with special reference to tackle plays. British Journal of Sports Medicine 37, 416-419.
Journal of Sports Science and Medicine Quarrie K.L., Hopkins W.G. (2008) Tackle injuries in professional Rugby Union. The American Journal of Sports Medicine 36, 1705-1716.
Journal of Sports Science and Medicine Usman J., McIntosh A.S., Frechede B. (2011) An investigation of shoulder forces in active shoulder tackles in rugby union football. Journal of Science and Medicine in Sport 14, 547-552.
Journal of Sports Science and Medicine Gabbett T.J. (2008) Influence of fatigue on tackling technique in rugby league players. Journal of Strength and Conditioning Research 22, 625-632.
Journal of Sports Science and Medicine Gabbett T.J., Jenkins D.G., Abernethy B. (2010a) Physical collisions and injury during professional rugby league skills training. Journal of Science and Medicine in Sport 13, 578-583.
Journal of Sports Science and Medicine Gabbett T.J., Jenkins D.G., Abernethy B (2010b) Physiological and anthropometric correlates of tackling ability in junior elite and subelite league players. Journal of Strength and Conditioning Research 24, 2989-2995.
Journal of Sports Science and Medicine Gabbett T.J., Jenkins D.G., Abernethy B (2011a) Correlates of tackling ability in high performance rugby league players. Journal of Strength and Conditioning Research 25, 72-79.
Journal of Sports Science and Medicine Gabbett T.J., Jenkins D.G., Abernethy B. (2011b) Relationships between physiological, anthropometric, and skill qualities and playing performance in professional rugby league players. Journal of Sports Sciences 29, 1655-1664.
Journal of Sports Science and Medicine Gabbett T.J., Jenkins D.G., Abernethy B. (2012a) Physical demands of professional rugby league training and competition using microtechnology. Journal of Science and Medicine in Sport 15, 80-86.
Journal of Sports Science and Medicine Gabbett T., Ryan P. (2009) Tackling Technique, Injury Prevention, and Playing Performance in High-Performance Collision Sport Athletes. International Journal of Sports Science and Coaching 4, 521-533.
Journal of Sports Science and Medicine Gabbett T.J., Ullah S., Finch C.F. (2012b) Identifying risk factors for contact injury in professional rugby league players - Application of a frailty model for recurrent injury. Journal of Science and Medicine in Sport 15, 496-504.
Journal of Sports Science and Medicine Gabbett T.J., Ullah S., Jenkins D.G., Abernethy B. (2012c) Skill qualities as risk factors for contact injury in professional rugby league players. Journal of Sports Sciences 30, 1421-1427.
 
 
 
Home Issues About Authors
Contact Current Editorial board Authors instructions
Email alerts In Press Mission For Reviewers
Archive Scope
Supplements Statistics
Most Read Articles
  Most Cited Articles
 
  
 
JSSM | Copyright 2001-2020 | All rights reserved. | LEGAL NOTICES | Publisher

It is forbidden the total or partial reproduction of this web site and the published materials, the treatment of its database, any kind of transition and for any means, either electronic, mechanic or other methods, without the previous written permission of the JSSM.

This work is licensed under a Creative Commons License Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.