ANZCTR - Registration

Registration number

ACTRN12624000657527

Ethics application status

Approved

Date submitted

2/04/2024

Date registered

21/05/2024

Date last updated

21/05/2024

Date data sharing statement initially provided

21/05/2024

Type of registration

Retrospectively registered

Titles & IDs

Public title

Effectiveness of empirically based tackle technique intervention to reduce the in-game risk of injury

Scientific title

Effectiveness of empirically based tackle technique intervention to reduce the in-game risk of injury in healthy sub-elite/elite rugby league and rugby union athletes

Secondary ID [1]

Nil known

Universal Trial Number (UTN)

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Concussion

Shoulder musculoskeletal injury

Breast tissue injury

Knee musculoskeletal injury

Ankle musculoskeletal injury

Condition category

Condition code

Musculoskeletal

Other muscular and skeletal disorders

Neurological

Other neurological disorders

Physical Medicine / Rehabilitation

Other physical medicine / rehabilitation

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

There will be three cohorts:
Cohort 1 male rugby league and/or rugby union sporting organisations will be recruited to this study.
Cohort 2 junior (boys and girls) representative and pathways rugby league and/or rugby union sporting organisations will be recruited to this study.
Cohort 3 women rugby league and/or rugby union sporting organisations will be recruited to this study.
Participants will undergo 1 (potentially 2) observational seasons and then 1 intervention season, a maximum total of 3 annual seasons.
Video recording (i.e. 2D movement data) of every game will occur across Season 1 and 2 with high speed video cameras and global positioning units. Season 1 and 2 will both involve in-season monitoring of player statistics during each game (tackles, tackle breaks, missed tackles, ineffective tackle) training load (number, duration and rate of perceived exertion of session), and epidemiological data on sport injury and illness. Participants who are suspected of sustaining a concussion will have the SCAT6 performed within 7 days, these results will be compared to their baseline SCAT6 assessment. Players will complete five 3D tackle motion sessions across the two seasons. Season 1 will measure players’ self-selected tackle technique at pre- and post-season. Season 2 will record tackle technique in the pre-season at 0-weeks, 6-weeks post-intervention, and post-season. 3D tackle motion of each participant performing 12 torso tackles will be recorded in each session via 3D motion capture and the instrumented mouthguard. A retro-reflective whole body marker set will be attached to each participants and recorded by 20 motion capture cameras. Retroreflective markers will be attached to the participant using double sided sticky tape and the 3D location of the markers will be the data stored. The kinematic data are required for the analysis in this study; the participants will not be identifiable from the 3D kinematic data. Six high speed cameras will record 2D movement data to calculate laboratory tackle proficiency by video coding characteristic of the participants tackle technique; the participants will be identifiable from the video coding data. Video coding will use a predefined coding matrix of 16 categorical variables in the pre-contact, contact and post-contact phases of the tackle using the 2D movement; this protocol is utilised extensively within this field of research. Female participants will be asked to wear or bring along the bra they most often use during rugby union training and/or games. They will also be given a special crop top to wear over your sports bra, exactly like the GPS crop top they wear during their training and/or games. The crop top is lined with a special wearable sensor to record the impact forces sustained by their breasts when they are performing the tackles. They will be then asked if you have any perceived breast pain during the tackles to their breasts. Female participants will also be complete a breast injuries questionnaire. The magnitude of forces experienced by the breast during these impacts within any sport is yet to be investigated. To ensure our program is safe for females in regards to injuries, including breast injuries, we are measuring breast impact forces.

Pre/post intervention design will be employed; the participants will act as their own controls in Season 1 (i.e., observation season) and the tackling intervention will be implemented in Season 2 (i.e., intervention season). Participants will not be provided with any results during Season 1 as this will act as the observation season. In Season 2, participants will undertake the tackle re-education intervention. Training of the tackle technique will be performed by the rugby league/union team coach(es) with coaching and mentoring support from our Indigenous expert coach and skill acquisition expert who will deliver 1x 60-mins introductory tackle session attended by players, coaches, and medical staff to upskill all individuals. A 15-mins tackle drills will occur during the teams’ weekly training sessions, 2x/week for 6 weeks during the pre-season and fortnightly within season. During these sessions, the participants will receive feedback on their tackle technique by the team’s coach(es) and our Indigenous expert coach. The intervention provided will be variable and dependant on the findings of the video coding. Tackle sessions and the drills used are not pre-set but designed on an ad-hoc basis, based upon the findings of the data. Participants will be involved in rugby league/union tackling drills, which can potentially cause physical injury. However, each participant will not be requested to do anything outside of their normal training and match play activities, and therefore participation in this study poses no greater risk than their normal risk of injury in participating in their sport. In fact, the tackling techniques that will be used in this study are considered to be safer, with less of a risk of injury to the ball carrier and the tackler.
The length of the intervention is on a seasonal basis, which is variable based upon the number of teams in a competition and the success of the team in graduating through the premiership.

The Indigenous pedagogy framework and collaborative engagement with the Wollotuka Institute will facilitate the integration of the research outcomes into the rugby league community by developing new evidence-based coaching manuals for the wider rugby league community that is respectful of the high proportion of Indigenous and Pacifika players in the rugby league community. This research initiative continues to support the NRL’s three core pillars of Health, Learn, and Respect for positive change within the community.

The intervention between groups may differ, depending on the skill level and baseline abilities of the teams and players. All interventions will follow the Indigenous pedagogy framework and collaborative engagement as above.

The minimum duration of intervention in any given cohort is 6 months and the maximum intervention period in any given cohort is 4 years.

Written tackle reports will be provided to coaching staff, as part of the collaborative engagement strategy, with assistance to create clips via our video coding platform to be provided to players for individual feedback.

Intervention code [1]

Behaviour

Comparator / control treatment

The participants will act as their own controls in Season 1 (i.e., observation season) and the tackling intervention will be implemented in Season 2 (i.e., intervention season).

Control group

Active

Outcomes

Primary outcome [1]

The primary outcome will be a summative index of tackle proficiency as a measure of in-game risk of injury.

Timepoint [1]

Data will be collected for this outcome during each training session and sports game from the time of enrolment until the completion of one to two observational seasons and one intervention season (three years post-enrolment).
Each cohort is up to a three-year cycle of data collection comprising of one to two observational seasons and one intervention season. Final follow up will be the end of season for the final cohort, estimated to be 2028. Final publication estimated for Cohort 2 2029.

Secondary outcome [1]

If re-training a player to tackle with our safer tackle techniques alters the tackler’s 3D tackle motion measured via the gold-standard of 3D motion capture.

Timepoint [1]

Commencement of the study began with initial recruitment of Cohort 1 and 3 in 2022 and commenced in the 2023 rugby league and rugby union seasons. Each cohort is up to a three-year cycle of data collection comprising of one to two observational seasons and one intervention season. Each cohort will have data collected at each training session and sports game for up to three-years post-enrolment, comprising of one to two observational seasons and one intervention season. Final follow up will be the end of season for the final cohort, estimated to be 2028. Final publication estimated for Cohort 2 2029.

Secondary outcome [2]

Inertial head kinematics (i.e., peak linear and angular head acceleration) of both players.

Timepoint [2]

Commencement of the study began with initial recruitment of Cohort 1 and 3 in 2022 and commenced in the 2023 rugby league and rugby union seasons. Each cohort is up to a three-year cycle of data collection comprising of one to two observational seasons and one intervention season. Each cohort will have data collected at each training session and sports game for up to three-years post-enrolment, comprising of one to two observational seasons and one intervention season. Final follow up will be the end of season for the final cohort, estimated to be 2028. Final publication estimated for Cohort 2 2029.

Secondary outcome [3]

Laboratory tackle proficiency scores.

Timepoint [3]

Commencement of the study began with initial recruitment of Cohort 1 and 3 in 2022 and commenced in the 2023 rugby league and rugby union seasons. Each cohort is up to a three-year cycle of data collection comprising of one to two observational seasons and one intervention season. Each cohort will have data collected at each training session and sports game for up to three-years post-enrolment, comprising of one to two observational seasons and one intervention season. Final follow up will be the end of season for the final cohort, estimated to be 2028. Final publication estimated for Cohort 2 2029.

Eligibility

Key inclusion criteria

1. Healthy sub-elite and elite rugby league/rugby union male and female athletes who are currently playing in a NSW, ACT, National Rugby League or Rugby Australia competition.

2. Junior male or female participants aged 14 to 18 years who are competing in competitions such as one of the following competitions: SG Ball cup (Male U18 years), SLE Laurie Daley Cup (U18s), Harvey Normal Tarsha Gale Cup (Women U18 years), Harold Matthews Cup (Male U16s years), SLE Andrew Johns Cup (U16s years). Male and female rugby union players will be competing in NSW School 7s and XVs pathway and Sydney Junior Club Competition as outlined in https://www.nswjuniors.com.au/post/nsw-rep-rugby-roadmaps-u10s-to-u18s

3. Female participants in Cohort 3 will be aged over 17 years of age

4. Willingness to give written informed consent prior to participation in the study

5. Willingness to comply with the study

Minimum age

14 Years

Maximum age

No limit

Sex

Both males and females

Can healthy volunteers participate?

Yes

Key exclusion criteria

1. Female participants in Cohort 3 aged under 17 years of age

2. Female participants in Cohort 3 with a history of epilepsy that is induced by flashing light

3. Participants who do not understand and/or cannot commit to the requirements of the study

4. Participants who are not willing or able to give informed written consent

Study design

Statistical methods / analysis

Each participant will have multiple tackle technique measurements from both Season 1 (pre-intervention) and Season 2 (post-intervention). The impact of the intervention on the primary outcome of tackle proficiency will be assessed using a linear mixed model including a random intercept to account for repeated measures on participants and fixed effects for time (pre- or post-intervention) and additional covariates identified as prognostic for the outcome. Secondary outcomes (individual measures of tackle proficiency) will be analysed using logistic mixed models, including the same terms as above.

The effect of the intervention on inertial head kinematics (3D motion capture, instrumented mouthguard) and 3D tackle motion and kinetics (e.g., breast force for females only) measures will be assessed using generalised linear mixed models (GLMM), with distribution and link function as appropriate to each outcome measure and including a random intercept to allow for repeated measures on participants. GLMMs will also be used to identify 3D tackle motion variables predicting inertial head kinematics and assess whether laboratory measures are associated with in-game tackle proficiency scores. For females only, GLMMs will also be used to identify 3D tackle motion variables predicting breast forces during tackling and assess whether laboratory measures are associated with in-game tackle proficiency scores. To account for potential correlation among explanatory variables, principal component analyses (PCA) will be considered for transforming individual variables into principal components for analysis (Dunteman, 1989).

Recruitment

Recruitment status

Recruiting

Date of first participant enrolment

Anticipated

Actual

6/05/2022

Date of last participant enrolment

Anticipated

Actual

Date of last data collection

Anticipated

4/12/2028

Actual

Sample size

Target

2000

Accrual to date

100

Final

Recruitment in Australia

Recruitment state(s)

NSW

Funding & Sponsors

Funding source category [1]

Government body

Name [1]

National Health and Medical Research Council

Country [1]

Australia

Primary sponsor type

University

Name

University of Sydney

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

The University of Sydney Human Research Ethics Committee

Ethics committee address [1]

https://www.sydney.edu.au/research/research-integrity-and-ethics.html

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

02/05/2022

Approval date [1]

06/05/2022

Ethics approval number [1]

Summary

Brief summary

No evidence exists on whether different tackle techniques could reduce injury risk such as concussion, breast or shoulder injuries. 

Our tackle behaviour re-education intervention is empirically-based on our pilot research (Edwards et al., 2021) and the theoretical framework of the Behaviour Change Wheel (D’Lima et al., 2020) to maximise the intervention’s efficacy (Sullivan et al., 2021). Our success to change in-game tackle behaviour will be assessed using industry standard best practice of qualitative video analysis to measure in-game tackle technique proficiency (Aim 1). We will then use gold standard 3D motion analysis to accurately measure tackle-induced forces and 3D tackle technique in the laboratory across a season (Aim 2). This will provide critical mechanistic understanding of how tackle technique influences these impulse forces to the head (i.e. inertial head kinematics), as there is limited 3D tackle motion studies. By using these technologies, we can establish if impulsive forces delivered to the head during a tackle (i.e., concussion risk exposure) can be reduced by re-training in-game and laboratory tackle behaviour. 

We will focus on Indigenous players, given no published injury research has taken an Indigenous athlete-centred approach despite the higher proportion of National Rugby League (NRL) players identifying as Indigenous/Pasifika (57% vs 3% general population) (League, 2017). We will employ a blended Indigenous pedagogy approach with Western ways of teaching and learning (Yunkaporta, 2009) and will be taught by an Indigenous expert rugby codes coach. 

The outcomes from this research will enable the translation of our empirically validated results into policy and practice in new coaching manuals on how to teach players to change their tackle behaviour that minimise their head impact exposure and injuries (including breast injuries).

Trial website

Public notes

Contacts

Principal investigator

Name

A/Prof Suzi Edwards

Address

Susan Wakil Health Building, University of Sydney, Western Ave, Camperdown NSW 2006

Country

Australia

Phone

+61 2 8627 7895

Email

suzi.edwards@sydney.edu.au

Contact person for public queries

Name

Suzi Edwards

Address

Susan Wakil Health Building, University of Sydney, Western Ave, Camperdown NSW 2006

Country

Australia

Phone

+61 2 8627 7895

Email

suzi.edwards@sydney.edu.au

Contact person for scientific queries

Name

Suzi Edwards

Address

Susan Wakil Health Building, University of Sydney, Western Ave, Camperdown NSW 2006

Country

Australia

Phone

+61 2 8627 7895

Email

suzi.edwards@sydney.edu.au

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