During summer 2019, I was lucky enough to be selected for a Research Masters investigating head impacts in women’s rugby, funded partly by the Welsh Government’s European Social Fund (ESF) and Keytree. Through this scheme, local organisations can benefit from product research, and the financial support given to the student provides the capacity to invest in the equipment and training needed to conduct high-quality investigations.
The popularity of women’s rugby has rapidly increased, and governing bodies are making great strides to welcome women into a historically male-dominated sport. Whilst the physicality of rugby and involvement in the tight-knit rugby community is of great value to players, the concussion incidence within the sport is currently far too high.
A concussion is a type of traumatic brain injury that can be caused by a direct head impact or from a collision to the body that accelerates the head. This acceleration of the head can cause microstructural damage within the brain and may explain the common symptoms of concussion, such as dizziness and memory loss. Reportedly, 75% of community and 85% of elite players have experienced concussion during their playing careers, which could negatively affect cognitive function later in life and increase the likelihood of neurodegenerative disease.
Highlighting research needs for women’s rugby
Recent research carried out with male rugby players has facilitated improved concussion reporting and injury management protocols. However, few studies include female players within their study populations. The safety policy later developed from this male-centric data is generalised for women, without addressing that sex differences influence head injury mechanisms, recovery times and symptom burden.
Due to alterations in neuronal microstructure, the female brain is less tolerant to accelerative forces, meaning women are 1.4 times more likely to be concussed during sport than men. Comparatively weaker neck musculature reported in women also contributes to this concussion incidence. Players with sufficient neck strength may be able to stabilise the head during a tackle, thus minimising the concussive forces experienced by the brain.
As women have been found to have just 56% of male neck strength, it is likely that they are less able to stabilise the head and are therefore more vulnerable to concussion. In addition to these biological differences, social differences may contribute to the high concussion incidence in women.
Generally, most women begin playing rugby at university and may progress to full-contact matches in a matter of weeks. This inexperience puts women at greater risk of both musculoskeletal and concussive injury.
Boys are more likely to have the opportunity to play rugby in childhood, meaning that they can be gradually introduced to contact, becoming conditioned to withstand the frequent collisions during matches. As such, projects focused specifically on female players are pivotal for the development of sex-specific injury prevention strategies.
This project, therefore, focused on using instrumented mouthguards created and developed by Keytree and Protecht to investigate mechanisms of concussion in women’s rugby. These high-tech instrumented mouthguards record the acceleration of the head during a head impact. By encasing an accelerometer within custom moulded mouthguards, the acceleration of the teeth, and therefore, the skull, can be measured – minimising soft tissue artefact and allowing for the recording of more accurate data.
Understanding the impact of Protecht
Our study began in September 2019 when a team of collegiate women’s rugby players began wearing Protecht™ instrumented mouthguards at matches all around the UK. During these matches, we obtained video footage of these players from multiple angles, which allowed the data from each head impact recorded by the mouthguard to be matched to the video of the event. Subsequently, the video footage was analysed for the type of head impact mechanism in addition to the tackle and fall technique used by players.
As the Coronavirus outbreak meant that several collegiate games were cancelled, we decided to supplement our data with the analysis of pre-recorded video of elite women’s international matches. Two matches between the world ranked first and second teams, and between the world ranked fourth and ninth teams were observed for the presence of head impacts. Findings from collegiate and elite video were compared to investigate how head impacts differ across playing levels.
Data recorded by the mouthguards revealed that the average head impact in rugby was 12g and ranged from 10 – 44g. But when this was combined with the video data of the head impacts, it revealed that women experience head impacts via a different mechanism to that reported in men’s rugby. Generally, male rugby players are concussed as the head is hit by another player during the initial stages of contact. Our collegiate players instead experienced 56.2% of head impacts as they fell from the tackle, 25.5% during the initial phases of contact and 18.3% post fall from contact.
Additionally, novel head impact kinematics were discovered in our collegiate players. It appeared that the majority of collegiate women were unable to stabilise their neck as they fell, resulting in the head experiencing a whiplash style motion into the ground. In comparison, these whiplash style motions during the fall have not been observed in male rugby players. The greater neck strength in men likely allows them to stabilise their heads as they fall and prevent their heads from hitting the floor.
When video of collegiate and elite players was compared, collegiate players were found to experience head impacts at double the rate of elite players. Collegiate players experienced whiplash style kinematics in 31.5% of all contact events, compared to an average of 4.2% in elite players. Interestingly, as the world ranking of elite teams increased, the incidence of whiplash style kinematics decreased. Elite players likely experienced fewer whiplash style head impacts as they are stronger and better conditioned to contact than collegiate players (see figure below).
Pie charts showing the proportion of different types of head impacts experienced by collegiate and elite women rugby players
Future research into head impact in women’s rugby
These results may mean that female rugby players may require the development of sex-specific concussion mitigation strategies to protect them from avoidable injury. As the majority of head impacts occurred as players fell, players may benefit from learn-to-fall interventions. These interventions generally teach players to fall onto their front or side in a controlled manner, allowing players to keep their heads off the floor. Female players may also benefit from neck strength training programs that may allow players to better stabilise their heads as they fall.
Although the concussion incidence in rugby is high, this study has highlighted some areas where targeted intervention is urgently needed. In future studies, we will be investigating how neck strength training and fall interventions may reduce the magnitude of head impacts in women’s rugby and are expecting some exciting results. The generous funding of this project by Keytree and the European Social Fund has enabled the discovery of novel head impact mechanisms that will lead to countless positive interventions in women’s rugby.
This study has also highlighted the general absence of female participants in sports science research. In response to this, our research team has developed a global women’s rugby survey that has already had over 1300 respondents from over 30 countries. This survey investigates the physical characteristics of rugby players (such as height and weight), playing experience and concussion history.