Beloved around the world, millions of people play rugby every day, but there is a risk of injury. The scrum has been identified as a part of the game with a risk of injury to the neck and spine.

Our research has had a significant impact on reducing the burden of injury in rugby union, with a specific focus on making the rugby scrum safer. Working in partnership with the international governing body, World Rugby, we carried out research showing a 25% reduction in scrum forces by changing technique.

In 2014, World Rugby announced the global adoption of scrum laws based on our research that would be used by all players at all levels of the game. The new laws have contributed to a reduction in injuries, including the most serious, catastrophic spinal injuries.

This work has contributed to making rugby safer for over 9 million players across the world.

Underpinning research

Of all the spinal injuries that occur in rugby, 40% of these occur in the scrum. Needless to say, these life changing injuries have an incredible impact on the lives of the injured individuals and their families and friends. If the research can prevent even one injury, it is highly valuable.

In addition to the physical toll, there is also a substantial cost implication. It is estimated that the lifetime cost of supporting a young individual in the UK who sustains a spinal injury that results in permanent impairment is £10 million to £20 million.

Analysing the scrum

In the scrum, opposing sides collide together while vying for forward momentum, and players experience considerable forces. These collisions may lead to acute injury, and repeated collisions in training and matches may lead to longer-term degenerative injuries, such as arthritis.

Led by Dr Grant Trewartha and Professor Keith Stokes, the team investigated scrums across a wide range of teams, from schoolboy to international level, to:

• establish the forces that front row players are subjected to when the scrum engages
• test alternative methods of engagement

The work was carried out in two phases. Phase one was carried out by Professor Stokes, with Dr Grant Trewartha and Dr Ezio Preatoni in 2011-12, with teams scrummaging against a modified scrum machine that could measure the forces involved. Phase two was carried out by Trewartha, Stokes and Preatoni, alongside Dr Dario Cazzola and Dr Elena Seminati in 2012-14, with teams scrummaging against each other while wearing sensors to determine the forces.

Going through the phases

Phase one

In phase one 34 teams were tested across 6 different levels (international men, elite men, elite women, community men, academy, schoolboy). Teams were asked to engage, come together at the start of the scrum, in a number of different sequences, including the standard scrum engagement instructions used in rugby at the time, 'Crouch, Touch, Pause, Engage'. Through experimentation of a variety of verbal instructions (for example, 'Crouch, Touch, Engage'), variations of adding players (seven players plus one or five players plus 3) and a fold-in engagement, 'Crouch, Bind, Set' emerged as the technique that most clearly reduced peak forces during scrum engagement.

Overall, there was approximately a 50% reduction at all levels, including 16.5 kilonewtons (kN) to 8.6 kN in international men’s and elite men’s teams, and 8.7 kN to 4.4 kN in elite women’s teams. Crucially, this didn't the competitiveness of the scrum as the levels of sustained force during the pushing phase were unchanged.

Phase two

Phase two further tested the new sequence, and continued to find positive results. Across 5 levels, international men, elite men, elite women, community men, university men, 27 teams were tested during live scrummaging using the standard 'Crouch, Touch, Pause, Engage' engagement, a variation of the verbal instructions, 'Crouch, Touch, Engage', and the sequence that had most effect in phase one, 'Crouch, Bind, Set'.

Again, peak forces on engagement were significantly reduced during the live trials of the 'Crouch, Bind, Set' engagement sequence. Across all levels of testing, a 14% to 25% reduction was recorded. Plainly speaking, bodies were being put under significantly less pressure, chances of injury were going down, and rugby wasn't losing any of the competitiveness that makes it such a compelling sport.

Millions feel the impact of the research

As a result of this study, a global change in the scrum laws was permanently adopted in 2014 such that players at all levels of the game in all countries play under this law. The revised scrum law that is based on this research means that props now pre-bind with their opposition player prior to the engagement of the forward packs, which significantly reduces the force of impact, and reduces collapses and resets. Not only the health of the players was being positively impacted, but also the spectacle of the game itself.

'The scrum is a fundamental and dynamic part of our Game. It is important that we continue to promote the best possible player welfare standards and this trial process is about putting players first and delivering a reduction of the forces on engagement at elite level, which could have significant positive effects on long-term player welfare' - Bernard Lapasset, Chairman of the International Rugby Board (now World Rugby

With over 9 million rugby players worldwide, reducing scrum impact forces reaches a huge population and has a positive impact on the long-term health of many of the world's rugby players.

Preventing injury around the world

Influenced by the research findings, South Africa trialled the revised scrum law from 2012 (prior to the global roll-out). In the four years prior to the law change in South Africa (2008-2011), 14 catastrophic scrum-related spinal injuries occurred, a rate of 3.5 per year. In the eight years after the laws revision (2012-2019), five such injuries have occurred in the scrum in South Africa, corresponding to a rate of 0.6 per year.

Following the change in the law scrum-related injuries of all types in New Zealand that led to claims from a leading national insurer fell from 52 per 100,000 prior to the law change, to 24 per 100,000 in 2014.

And in professional rugby in England there has been a significant 40% reduction in scrum-related injuries that lead to players missing training or playing time before and after the law change.