Biomechanics of Rugby Union Scrummaging

Abstract

In the game of ruby union, the scrum epitomises the physical nature of the game. It is both a powerful offensive skill, affording a base for attacking play, and a defensive skill in denying the opposition clean possession. However, the scrum has also been implicated in a large proportion of serious spinal injuries in rugby union. The majority of injuries are found to occur at engagement where the forces experienced by front-row players (more than two-thirds of a tonne shared across the front-row) can exceed the structural limits of the cervical spine. These large forces are a consequence of the speed of engagement and the weight (and number) of players involved in the scrum. This highlights not only the need for physical preparation of all forwards but particularly player restraint at engagement, and justifies the 'crouch-pause-engage' sequence recently introduced to 'depower' the scrum. As the hooker is the player exposed to the greatest loads throughout the scrum and subsequently most at risk, he should determine the timing of engagement of the 2 front-rows. Stability of the scrum is an indication of front-row players' ability to utilise their strength to transmit the force to their opponents as well as the push of second-row and back-row players behind them in the scrum. This appears to be independent of the size of players. Equally, it reflects the risk of chronic degeneration of the musculoskeletal system through repeated exposure to these large stresses. However, not only are older and more experienced players better able to generate and transmit these forces, they are also able to maintain the integrity of the scrum. A large proportion of individual players' efforts to generate force is lost in their coordinated effort in a normal scrum. It is assumed these forces are dissipated through players re-orientating their bodies in the scrum situation as well as to less efficient shear forces and to the elastic and compressive tissues in the body. It again reinforces the importance of physical preparation for all forwards to better withstand the large forces involved in scrummaging. Despite negative publicity surrounding the risk of serious spinal injury in rugby union, limited research has been conducted to examine either the mechanisms of injury or techniques implicated in causing injury. Biomechanical information can provide systematic bases for modifying existing techniques and assessing the physical capacities necessary to efficiently and safely play in the serum. This will both improve performance of game skills and minimise the potential for injury.

BokSmart: Safe and effective techniques in rugby union

“…23,24 This indicates poor technique in non-international front-row forwards. Maintenance of a flat straight neutral spine with natural lordosis (spine-in-line) will ensure maximal forward force transfer and no downward force generation.…”

BokSmart: Preventive rehabilitation for rugby injuries to the lower back and core

“…18 The forces involved in scrumming and the positioning of the players have always been a concern when it comes to spinal injuries. 37 However, thanks to a greater awareness of the dangers involved in scrumming, the risk of spinal injury in the scrum has decreased. 20 Due to improvements in refereeing and laws governing the scrum, the number of injuries as a result of scrumming has decreased in comparison with the number of injuries sustained during the ruck and maul phases.…”

The cervical spine of professional front-row rugby players: correlation between degenerative changes and symptoms

“…The earliest published reference to the relationship between rugby and spinal injuries dates back to a report in The Times of London from November 1869 [2]. A consistent finding from several studies is the high proportion of injuries sustained by players in the front-row of the scrum [1,[3][4][5][6][7]. The scrum is a phase of play in rugby union used as a method of re-starting the game.…”

“…The moment of engagement between the two packs of forwards is known as the ''Hit'' and is used as an attempt to intimidate and unsettle the opposing pack. The scrum and particularly the ''Hit'' is the phase of play most commonly associated with spinal injuries [1,4,8].…”

“…While some studies have suggested that younger players make up a large proportion of spinal injuries [4], most have reported the incidence of injuries to be higher among adults and especially those playing at higher grades [1,9]. Factors such as greater size, increased physical strength and heightened aggression in senior rugby are suggested as reasons for this [3,10].…”