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Using video analysis to increase understanding around concussion – Stuart Bailey Research

I am really pleased to be able to release a different type of blog today, as Stuart Bailey has kindly provided an overview of his current PhD research into Concussion in Rugby Union and how Nacsport is being used to collect the data required for his research. I would like to say thanks to Stuart for sharing and hope that his research will help to provide useful information to continue with increasing player safety! Over to you Stuart….

Stuart Bailey

Edinburgh Napier University & Scottish Rugby PhD Student

Most blog articles on this site will undoubtedly be about using video analysis to breakdown and dissect elements of performance, with the eventual aim of improving proficiency.

However, as a PhD student with a research title of “Concussion Injury Patterns in elite Scottish Rugby Union”, the following article will describe the use of Nacsport software in helping to further the understanding of causes of concussive injury in rugby union.

All sporting injuries, including concussion, are caused by a combination of intrinsic (specific to the individual) and extrinsic (related to game/training aspects) risk factors. Examples of generalised risk factors for all injuries are shown in the table below:

Intrinsic Factors

Extrinsic Factors


Type of sport (contact vs. non-contact)


Methods/techniques used during sport

Physical Fitness: Aerobic endurance, strength, speed, flexibility

Equipment (stick/racquet etc.) or protective clothing

Previous injury

Weather conditions and playing surface

Physical Build: Height, weight, joint stability, body fat

Rules of the sport

Technical ability

Role of opponents and team-mates

Concussion in rugby is most likely to be caused in contact events (tackles, rucks, mauls etc.). To further our understating of how concussions occur, it is necessary to know how frequently different risk factors are present when both a concussion is caused in contact situations, and how often risk factors are present when there is no concussion. It can then be determined whether there is a relationship between concussions and the presence of certain intrinsic and extrinsic risk factors.

Previous scientific research demonstrates that intrinsic risk factors such as gender and the number of previous concussions are likely to increase the risk of sustaining a future concussion. However, we also know that extrinsic risk factors such as head placement whilst tackling, certain tackle types, impact force, and speed of colliding players also increase the risk of concussion.

What is not currently known is how intrinsic and extrinsic risk factors interplay to provide an overall concussive risk in rugby. For example, does the number of previous concussions a player has sustained provide the risk factor with the greatest weighting? Or does head placement when tackling increase concussive risk to such an extent that the number of previous concussions that the tackler has suffered is then irrelevant? Do high-impact, front-on tackles only increase concussive risk in players who have had several previous concussions?

The current study is using Nacsport Scout Plus to determine how intrinsic and extrinsic risk factors combine to present an overall risk of concussion in elite Rugby Union players in Scotland.

In order to understand this, a literature search was conducted to provide a list of risk factors which may increase the risk of concussion in rugby union. Whereas intrinsic risk factors surrounding concussive history can be collected from previous medical data for each player, extrinsic risk factors require video analysis to be identified.

Templates were constructed using Nacsport Scout Plus to objectively detail the risk factors present in each form of contact (tackled, tackling, rucks, mauls, scrums, lineouts, off the-ball collisions, and kick contests). Each form of contact has its own template, with its own specific risk factors. To facilitate analysis, each template is divided into three distinct phases: pre-contact; during contact; post-contact, with potential risk factors placed in the appropriate phase.

Stuart Bailey Concussion Research Nacsport Template

The above example depicts the Nacsport template utilised to analyse when Scottish players are tackling their opponents. Categories are used to identify which player(s) are tackling, before descriptor buttons are used to describe the presence of potential extrinsic risk factors for the pre-, during-, and post-tackle phase.

The second example below demonstrates how a Nacsport Scout Plus template is used to describe risk factors which may be present in an attacking ruck scenario. Again, categories are used to identify the active player, before descriptors define the actions of that player in the three phases. The ease of creating templates in Nacsport is something unique and incredibly useful about the software.

Some of the templates that have been created contain a large amount of possible risk factors to be identified. The fact that there is an unlimited amount of buttons that can be added to any template, whether they be categories or descriptors, means that Nacsport is extremely easy to use to collect large amounts of data.

Stuart Bailey Concussion Research Nacsport Template 2

Once all analysis is complete from each match and/or concussion incident, data obtained is exported from Nacsport as a .csv file. It is then entered into a large database containing descriptions of risk factor presence in each contact situation throughout each match analysed.

Exporting the data in this format results in a new line of data each time a category button is used for each contact – this allows each individual player to be identified each time they sustain a contact. Therefore, their individualised intrinsic risk factors can be associated with the extrinsic risk factors experienced in each contact.

By observing the frequency of each risk factor in non-concussive versus concussive contact situations it will be possible to identify whether there is a significant difference in the presence of specific intrinsic and extrinsic risk factors in concussive versus non-concussive episodes. In order to analyse how intrinsic and extrinsic risk factors interact, factors which were identified to increase the risk of concussion, whether intrinsic or extrinsic, can then be analysed in greater detail.

For example, the initial analysis may demonstrate that the number of previous concussions (intrinsic risk factor) shows that players with a greater number of previous concussions were at greater risk of subsequent concussive injury whilst tackling. This can be used as a dependent variable for future analysis. By categorising all tackles into groups based upon differing numbers of previous concussions, we can observe whether concussive incidence is altered by the presence of different extrinsic risk factors across these groups. This would infer an interaction effect of intrinsic and extrinsic factors in concussive risk in rugby union.

All contact situations from a random sample of 40 match videos across the 2017/18 and 2018/19 season from a combined cohort of Scotland International Men’s team, Glasgow Warriors, and Edinburgh Rugby are currently being analysed using Nacsport software. The fact that Nacsport Scout Plus software allows any type of video file to be used for analysis is a real bonus – videos to analyse come from a variety of sources, either from the Scottish Rugby, directly from the clubs, or from television broadcasters.

The ability to use any video file that comes from these different locations is extremely useful. Once all video analysis is complete, further contact situations which resulted in a concussion from across these two seasons in these cohorts (but was not analysed during the original 40 match sample) will be analysed using the same situation-specific templates.

By identifying extrinsic risk factors through Nacsport and combining these with intrinsic risk data, we may be able to alter the risk of concussion, and at least improve our understanding of how or whether these factors interact. If it is found that intrinsic risks and concussive history play the grandest part in altering concussive risks, then it is hoped that future work will look into concussive rehabilitation before returning to play.

On the other hand, if extrinsic risks appear to pose the biggest risk in sustaining a concussion, it would be a great opportunity for future work to investigate possible technique or law changes to reduce concussive risks. It is hoped that this information will inform future guidelines and initiatives to reduce concussive risk, both within Scottish Rugby and rugby union worldwide.

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