Using an expert consensus-based approach, a netball video analysis consensus (NVAC) group of researchers and practitioners was formed to develop a video analysis framework of descriptors and definitions of physical, technical and contextual aspects for netball research. The framework aims to improve the consistency of language used within netball investigations. It also aims to guide injury mechanism reporting and identification of injury risk factors. The development of the framework involved a systematic review of the literature and a Delphi process. In conjunction with commercially used descriptors and definitions, 19 studies were used to create the initial framework of key descriptors and definitions in netball. In a two round Delphi method consensus, each expert rated their level of agreement with each of the descriptors and associated definition on a 5-point Likert scale (1—strongly disagree; 2—somewhat disagree; 3—neither agree nor disagree; 4—somewhat agree; 5—strongly agree). The median (IQR) rating of agreement was 5.0 (0.0), 5.0 (0.0) and 5.0 (0.0) for physical, technical and contextual aspects, respectively. The NVAC group recommends usage of the framework when conducting video analysis research in netball. The use of descriptors and definitions will be determined by the nature of the work and can be combined to incorporate further movements and actions used in netball. The framework can be linked with additional data, such as injury surveillance and microtechnology data.
- Sporting injuries
- Women in sport
- Sports medicine
- Exercise training
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This is the first consensus process that defines the many components of netball-specific activity using a diverse range of experts across physical, technical and contextual aspects of netball.
This framework provides descriptors and definitions to standardise netball video analysis to improve the consistency of language used within the netball literature and future investigations.
Video analysis data can be integrated with additional data sources (eg, injury surveillance and microtechnology data), with confidence.
The framework could assist in exploring theorical models to better understand movement dynamics and interactions between players (eg, dynamical systems) in netball to inform injury prevention strategies.
Netball is predominantly played by women and is among the most popular sports for women. Over 20 million people participate in netball, primarily in Commonwealth countries.1 Netball is played across all ages, at the community level and in semiprofessional and professional leagues in Australia, New Zealand, South Africa and the United Kingdom (UK). Despite the popularity and professional status in some countries, there is limited research on netball compared with other sports.2 For example, sports such as rugby league and union, with lower participation numbers, (<500 000 and approximately 9.6 million players worldwide), have an established research evidence base.3–5 Reasons may include increased research interest when the respected sports became professional or the bias towards men’s sports in the sports science and sports medicine literature.6
Netball is predominantly an indoor court sport, with each team consisting of seven players, each with a specific playing position.7 It is a high intensity, intermittent game, typically played for 60 min, over four 15 min quarters, with each position restricted to specific court areas.8 At some levels, netball is played outdoors on various playing surfaces (eg, asphalt tarmac and artificial turf) and can be played for shorter durations. The physical actions of netball involve repeated jumps, accelerations, decelerations and changes of direction,9–12 which can expose players to an inherent risk of injury.13–15 Ankle and knee injuries are the most prevalent injuries in netballers,13 reported as 5.9 per 1000 participation hours in varsity level netballers.16 In a systematic review of ankle injuries within team sports, the incidence of ankle injuries during netball matches was 45.6 per 1000 person-exposure,17 the highest of all sports reported. To prevent injuries, the mechanisms of injury need to be established; however, the literature either does not provide clear definitions of actions or provides different definitions for the same action. For example, Davidson and Trewartha18 define shuffling as ‘a sideways movement of the body using a shuffling action of the feet’; while, Fox et al 19 define a shuffle as ‘a sideways, backwards, or on-the-spot movement requiring effort and shuffling movement of the feet’. Therefore, the standardisation and comparison between studies is problematic. Additionally, standardised definitions would assist in establishing the characteristics and demands of the game to support the development and use of sport science within netball.
In other sports, video analysis frameworks are established to ensure consistency when coding match events for performance-based studies and interventions, and to identify injury risk factors and mechanisms.20–23 For example, Hendricks et al 24 used video analysis to understand the mechanisms of concussion injuries in youth rugby union to develop training interventions to decrease the risk of sustaining a concussive injury. In elite netball, video analysis has been used to identify landing from a jump as a mechanism for anterior cruciate ligament injuries.15 Establishing a video analysis framework could assist in consistent reporting (eg, of injury mechanisms and risk factors), as well as in establishing match characteristics and supporting performance analysis.22 A recent consensus statement provided standardisation of the key actions and events in rugby union,22 but similar statements do not exist for netball despite the popularity of the sport. This is required in netball to ensure consistency in the development of netball-specific evidence-based sports science and sports medicine practices. The netball video analysis consensus (NVAC) group was formed to address the above-mentioned concerns with the aim to establish a framework of descriptors and definitions to improve the consistency and quality of video analysis research in netball.
To develop the framework of descriptors and definitions, a two-phase process was used. A systematic review of literature was conducted in phase 1, followed by a two round Delphi method consensus process by the NVAC group in phase 2. The method used is in line with the previous video analysis framework consensus in rugby union.22
In phase 1, the literature review was completed per the search terms used within the recent systematic scoping review by Whitehead et al,2 which returned 957 articles. The search was updated to include papers until 20 April 2022, producing an additional 216 articles. This time-efficient method was used as an extension of the previous review from Whitehead et al,2 by the same research group. Each publication was manually searched for any descriptors and definitions. Only publications that provided descriptors and definitions relating to the physical (eg, player movement), technical (eg, events occurring during match play) or contextual (eg, additional match circumstances) aspects of netball were included. Nineteen articles were identified as having relevant definitions. These were reviewed by the initial research group (LM, BJ, SW, DCJvR and FH) to create the starting framework and definitions. The initial research group discussed any descriptors that resulted in more than one definition in the literature, and a unanimous decision was made to determine which definition to include. Champion Data (Victoria, Australia) provided descriptors and definitions that are used commercially in elite netball. Champion Data is the official data provider to Netball Australia, Netball New Zealand and the timing, scoring and results provider to the Netball World Cup 2015, 2019 and 2023.25 The initial research group added relevant terms not present in the literature or provided by Champion Data. Any additional terms were required to be agreed upon by the initial research group before inclusion. All definitions and descriptors were categorised into physical, technical or contextual aspects. The initial research group also established subcategories (figure 1) for further clarity.
In phase 2, the NVAC group was established. The NVAC group included 15 men and 17 women, senior and less-experienced investigators from a variety of disciplines and different ethnicities. Additionally, the NVAC group included investigators who were black, indigenous, people of colour and LGBTQIA+. The diversity of the group was not prospectively determined and did not consider socioeconomic status or people with disabilities. All experts forming the NVAC group are experienced in or affiliated to netball, or have extensive experience in consensus development. Although no official process was used to form the consensus group, consideration was given to inviting an equal number of experts from each field.26 In addition, consideration was given to ensure the inclusion of multiple national governing bodies and countries, particularly those well-established within international netball. The research group also aimed to ensure representation of different standards of netball (eg, international and elite) and different competitions (eg, Suncorp Super Netball (Australia), ANZ Premiership (New Zealand) and Netball Superleague (UK)) to encompass any potential variation in terminology used. The expert group included both researchers (n=5; 17%) and practitioners (medical staff (n=5; 17%), netball coaches (n=5; 17%), players (n=3; 10%), performance analysts (n=6; 21%) and strength and conditioning coaches (n=5; 17%)), some of whom hold multiple roles (eg, player and coach), with their primary role highlighted. The expert group was from various countries including Australia (n=9; 31%), New Zealand (n=3; 10%), South Africa (n=4; 14%) and UK (n=13; 45%).
A Delphi consensus method27–29 was then used to develop the framework of descriptors and definitions collated in phase 1. Two rounds of data were collected via an online survey (Qualtrics, Provo, Utah, USA). For round 1, each member of the expert group independently rated their level of agreement for each of the descriptors and its definition within the framework on a 5-point agreement Likert scale (1—strongly disagree, 2—somewhat disagree, 3—neither agree nor disagree, 4—somewhat agree, 5—strongly agree). Members of the group were also provided with the opportunity to add any suggestions or comments to the proposed framework, and each of the descriptors and definitions. Consensus was considered to have been reached if ≥80% of the group selected ‘strongly agree’.28 Any descriptors and definitions that did not reach consensus were rephrased based on the comments, and any suggested additions to the framework were put forward for round 2.
In round 2 of the consensus, a second round of agreement ratings were attained for the revised descriptors and definitions. Consensus was reached for each descriptor and definition if ≥80% of the group selected ‘somewhat agree’ and ‘strongly agree’. The level of agreement reached for each descriptor and definition in round 2 is reported as median (IQR). Additional supplementary terms that can be applied to the physical and technical actions to provide further detail are presented within the relevant table (eg, to describe the direction or intensity of movement).
A total of 19 studies on netball provided physical (table 1), technical (table 2) or contextual descriptors (tables 3–6) with definitions which were extracted to develop the framework. Overall, 35 of the descriptors and their definition (plus 5 of the supplementary terms) reached agreement after round 1. The remaining 45 descriptors and definitions (and 5 supplementary terms) were rerated in round 2, with the addition of a further 14 descriptors and definitions included in round 2 following suggestions from the NVAC group made in round 1. The median (IQR) rating of agreement was 5.0 (0.0) overall for the physical category; and 5.0 (0.0), 5.0 (0.0), 5.0 (0.0) for the locomotor, non-locomotor and jumping and landings physical subcategories, respectively. For technical aspects, the overall mean rating of agreement was 5.0 (0.0); and 5.0 (0.0), and 5.0 (0.0) for the attacking and defensive subcategory descriptors and definitions. Within the contextual category, the overall mean rating of agreement was 5.0 (0.0); and 5.0 (0.0), 5.0 (0.0), 5.0 (0.0) and 5.0 (0.0) for the time-based, team information, court areas and additional information contextual subcategories, respectively. Supplementary terms had an overall agreement rating of 5.0 (0.0) (tables 1 and 2).
This consensus aims to create a framework of physical, technical and contextual descriptors and definitions to standardise and improve the consistency of language used within the netball literature. The NVAC group recommends using these descriptors and definitions when conducting netball research incorporating any physical, technical or contextual element. The descriptors and definitions used should be determined by the aims of the study. Additionally, descriptors and definitions may be combined to further describe an action or event in netball. For example, to describe a ‘step change’ in netball, the definitions of ‘step’ (table 1) and ‘change of direction’ (table 1) can be combined. The supplementary terms located in tables 1 and 2 can be applied to the relevant physical (table 1) and technical (table 2) descriptors to provide further detail to the action. For example, the ‘shuffling’ (table 1) action can be further described as ‘backwards shuffling’ using the direction of movement descriptor components (table 1). Qualitative descriptive intensity components have been provided and can be applied to relevant physical aspects. Further research is required to provide quantitative thresholds for women athletes using microtechnology units.
The framework of descriptors and definitions can be used to assist with various aspects of netball research and is an important methodological advance for research in netball for return to play from injury/illness/leave, injury surveillance and the sports sciences. Developing a consensus statement defining the most common actions observed in netball contributes to a more stable methodological platform for people to conduct both academic research and practical/clinical experiments. For example, coaches, sports scientists and researchers alike will more easily compare findings, pilot novel interventions with appropriate evaluations and generalise pooled findings to the appropriate levels of granularity. Coaches and performance analysts will be able to map these characteristics across time, while this may allow skill acquisition specialists to improve the skills associated with specific subcomponents of performance. Physiologist and strength and conditioning experts can explore mediating factors to these subcomponents while refining and evaluating the training process. These data can also be integrated with epidemiological injury data that will inform the medical team. Recommendations and considerations from the NVAC group for the use of the descriptors and definitions to improve the quality of future research and practice are discussed below.
Integration with additional data sources
Video analysis in netball can be integrated with data from external sources, such as injury surveillance and wearable microtechnology data. Video data can supplement injury surveillance data (eg, count and classification) to provide in-depth information, such as identifying injury mechanisms to further understand the injury risk factors and inform prevention strategies.
The use of wearable microtechnology within elite netball is increasing, with developments in the technology enabling research into the movement characteristics through the use of Local Positioning Systems (LPS) and Inertial Measurement Units with accelerometer-derived ‘load’ metrics at the elite level in Australia.10 30 31 However, it is limited compared with other team sports such as rugby league, rugby union and soccer which extensively use Global Navigation Satellite Systems (GNSS).4 10 32 Given that netball is played indoors at the elite level, GNSS cannot be used and LPS is required. However, the cost and set up of LPS currently limit its use and practicality across different environments. If the use of LPS continues to grow within elite netball, the locomotor and intensity of movement definitions (table 1) could be further developed to include objective thresholds. To provide more insight into netball, microtechnology data can be used concurrently with video analysis data to provide further information and context when quantifying the movement characteristics and monitoring of external workload rather than analysing data in isolation.33 Integration of video analysis data with injury surveillance and microtechnology data will further enhance the understanding of netball and also standardise the reporting of netball literature.
Quality of video footage
While video footage in netball continues to develop in many countries, the quality of video footage varies widely. This may be due to the limited resources and personnel available. Video footage can range from setups with multiple angle options, suitable vantage points and high-quality resolution to compromised setups (eg, one camera angle with a low vantage point). Additionally, it is not uncommon to have no video footage below the professional level. These limited resources for recording may have a direct impact on analysis. Where possible, matches (and training) should be filmed using at least one camera from behind the goal post from a vantage point that can capture the whole court. If this is not possible, filming can be undertaken from the side of the court in line with the centre circle, from a suitable vantage point. Mount the camera on a tripod for stability and position the lens to have the ball and where possible, at least half of the court in view. All players that can enter the centre third should be in view at the centre pass, as well as the goal shooter of the team in possession (and goal keeper of the team out of possession). If additional cameras are available, these should be setup to increase the coverage of all players’ movement in and out of possession. Out of possession movement can be important for assessing injury mechanisms and analysing physical demands of the game. The software used to analyse the footage should allow control over the time-lapse during the recording to assess movements. Each coded instance should be saved into a database. The recording should allow frame by frame and slow-motion viewing, with the ability to pause and rewind if required for detailed analysis.34 Furthermore, computer vision techniques using pan, tilt and zoom cameras are emerging, which automatically classify movements and player actions. Therefore, these definitions may help with the emergence of this technology in netball.
Video analysis can be used to assist in the use of dynamical systems in team sports.35 Identifying interactions between players and the opposition based on spatial positioning and recognising patterns within the play and formations can be advantageous.35–37 While there are developments in research and practical application of dynamical systems in sports, such as soccer,38 limited research exists on dynamical systems in netball. Recently, a semiautomated process has been used to understand player passing combinations and locations in netball37 as well as the use of computer vision to define player locations using video footage.39 Further developments in automated camera systems may also provide accurate external load data, thus providing one integrated system for physical, technical and tactical data. The use of video analysis with dynamical systems in netball is an area of future research, to support performance and assist in understanding injury mechanisms and risk factors. Video analysis can also be used to assist in using dynamical systems to understand skill-based, technical and tactical aspects of training sessions and be combined with microtechnology data and physical demands of training session findings.10 31 This consensus statement could be used in future research to further inform and develop the use of dynamical systems with video analysis to study complex and dynamical movement interactions in netball.
The framework can be applied to all levels of netball and focuses on a sport, which is played predominantly by women, including in many low-income and middle-income countries therefore has the potential to impact the health of women athletes. The NVAC group includes both athletes and coaches; however, most of the experts currently work in high-performance netball and there is no representation from countries which may be less well resourced. There may thus be potential bias in the recommendations and considerations for the descriptors and definitions within this consensus statement. Consideration was given to include an approximately equal number of experts from each field of work (researchers (n=5; 17%); medical staff (n=5; 17%); netball coaches (n=5; 17%); players (n=3; 10%); performance analysts (n=6; 21%) and strength and conditioning coaches (n=5; 17%)), multiple national governing bodies and countries, representation of a range of standards within netball and different competitions to minimise any potential limitation. Additionally, given the rapid progression of netball and developments in technology, further descriptors and definitions may need to be added to the framework or updated as netball advances to ensure the framework remains up to date.
The aim of this consensus statement was to create a framework of descriptors and definitions to standardise and improve the consistency of language used within netball literature. The nature of the netball research being conducted will determine which of the recommended descriptors and definitions will be used. Additionally, descriptors and definitions can be combined to provide further details of movements and actions used within netball. The framework can link video analysis data with additional data sources, such as microtechnology and injury surveillance data. This can assist in further understanding injury mechanisms and risk factors in netball, and support sport science research and practice.
Patient consent for publication
This project was approved by Leeds Beckett University, Local Ethics Committee (95237).
Twitter @loismackay, @23benjones, @aaron_s_fox, @Sharief_H, @biomechstu, @DrKirstSpencer, @CarelViljoen, @SarahRWhitehead
Contributors LM, BJ and SW conceptualised the research project and designed the study. LM, BJ, DCJvR, FH and SW developed the initial definitions. LM, BJ and SW reviewed round 1 and 2 responses. LM, BJ, DCJvR and SW drafted the manuscript. All authors contributed to the consensus generation, critically reviewed and edited the manuscript prior to submission.
Funding LM’s PhD is part-funded by England Netball.
Competing interests LM is part-funded by England Netball. LL and JT are employed by England Netball. PB, KD, JK and JS work for England Netball through the English Institute of Sport. JC, FH, LL and SW are employed by Leeds Rhinos Netball. DCJvR is affiliated to World Netball. SAM-N is a Vitality Netball Superleague umpire.
Provenance and peer review Not commissioned; externally peer reviewed.
Equity, diversity and inclusion statement Our research and author team included 15 men and 17 women, senior and less-experienced investigators from a variety of disciplines and different ethnicities. The author team included investigators who were black, indigenous, people of colour and LGBTQIA+. The diversity of the group was not prospectively determined and did not consider socioeconomic status or people with disabilities.
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