Football (soccer) is a team sport with high physical demands (jumping, sprinting, heading, quick changes of direction, tackling) that puts its players at increased risk of both contact (e.g., concussion) and non-contact (e.g., Anterior Cruciate Ligament (ACL) injuries (López-Valenciano et al., 2020). Indeed, a professional football team with a squad of 25 players typically suffers about 50 injuries each season that result in substantial time-loss from play [5] (Ekstrand, Hägglund, & Waldén, 2011). This comes at a significant performance cost to a football organization where player availability has been found to correlate very strongly (r > 0.85) with on-pitch success metrics such as games won, goals scored, total points and final league position [12] (Hägglund et al., 2013; Eirale et al., 2013).

Furthermore, injuries also pose a significant financial burden to football organizations. A recent study calculated that the cost of lost wages and lost prize money, means an English Premier League team could lose an average of £45 million per season as a consequence of injury-related decrements in performance (Eliakim, Morgulev, Lidor, Meckel, 2020) [6].

These finding provide professional football organizations with a strong economic and performative incentive to invest in injury prevention and rehabilitation programs and technologies. One emerging technology that is being proposed as a method of augmenting traditional rehabilitation practices for both head [23] (Santos, Yamaguchi, Buckley, & Caccese, 2020) and musculoskeletal (Vogt, Skjæret-Maroni, Neuhaus, & Baumeister, 2019) injuries is Virtual Reality (VR). Through a head-mounted display (HMD), an immersive virtual environment can be presented where there is one-to-one mapping between movement in the real world and movement in the virtual world. This direct correspondence between how a person feels their movement in the real world and sees their movement in VR is critical for optimising rehabilitation and training. Preserving this behavioural realism ensures that the virtual environment (VE) allows users to interact with 3D generated models in real time while using their natural senses and skills (Craig, 2013) [13].

Indeed, since the beginning of the 21st century, the use of VR as an augmentative tool has shown utility in many domains including surgery [11] (Gurusamy, Aggarwal, Palanivelu, & Davidson, 2008), sport [8] (Gray, 2017; Neumann et al., 2018) and education [7] (Falah, 2014). As the technology has become increasingly accessible and the hardware components have become more powerful, sports performance has emerged as a key area of interest. For physiotherapists, one major opportunity has been created by the significant advancements in VR hardware, both in terms of performance and reduced cost. The Oculus Quest 2, currently retailing at £299, uses inside out movement tracking that has levels of precision (c. 0.18mm) that are comparable to other sophisticated, high-cost light-based motion capture systems such as Qualisys or Vicon [14] (Holzwarth, Gisler, Hirt, & Kunz, 2021). As a result, motion data can be easily captured, analyzed and presented back to the user in real-time with high levels of accuracy.

What’s more, the power of virtual reality to create a perceptual context (through visual and auditory content) that invites certain kinds of game play interactions (e.g., moving to pop a ball) offers physiotherapists the opportunity to change these contexts (customise the games) to encourage different forms of movement. By using the power of game play, the user’s attention is drawn away from the types of movements they are making and more towards the goal-directed nature of the interactions needed to successfully play the game. Customised VR games will encourage the appropriate level of movement, while VR motion sensors will record the quality of these interactions to produce game scores that objectively reflect where the player is on their recovery journey. Indeed, a recent study has shown that motion data collected from the sensors embedded in the Oculus Quest headset can be used to measure postural sway and quantify improvements in stability rather than the physiotherapist relying solely on the power of observation [21] (Masoner et al., 2020).

VR can enhance physiotherapy by transforming rehabilitation exercises from a decoupled task – such as standing on one leg and asking the player to open and close their eyes - to a coupled task where the player is interacting in real time with moving objects in their surrounding environment in a more naturalistic way. For example, the visual scene in Virtual Reality can be subtly changed to give the perception of forward and/or lateral movement [2] (Burcal & Grooms, 2021). In keeping with Lee & Aronson’s moving room experiments from the 1970s [18] (Lee & Aronson, 1974), perturbations to the virtual optic flow will force adjustments to the balance system to accommodate these. This ability to easily change visual input means that more natural perception-action couplings will be maintained, similar to what is encountered in real life. For instance, by promoting the down-weighting of visual inputs during balance exercises, athletes are being better prepared for the demands of the visually dynamic sporting environment where they are constantly required to monitor the reliability of sensory inputs rather than adapting to the static conditions of eyes open and/or eyes closed.

Another major advantage of VR technology when implementing a rehabilitation plan, is the ability to advance the athlete through progressively more difficult exercises. All-or-nothing approaches are limited because they either eliminate (e.g., eyes closed) or alter (e.g., foam pad) inputs from a sensory system. For example, such manipulations have been shown to be ineffective in reducing reliance on visual cues, as they are not challenging the role of visual perception in a granular way but are rather removing visual input altogether [25] (Song, Rhodes, & Wikstrom, 2018). VR therefore offers a promising new method for physiotherapists to offer more posturally challenging exercises that dynamically adjust the extent to which visual perturbations invoke balance readjustments through proprioceptive input, particularly at later stages of rehabilitation.

There are also important potential barriers to integrating VR into clinical practice. In an interview with several elite football coaches, Thatcher, Ivanov, Szerovay, & Mills (2020) attributed many coaches’ negative perceptions of VR to the notion that the technology is relatively unproven in a football environment leading to early scepticism of the added value VR brings. Indeed, coaches were quoted as describing the technology as “gimmicky” and the technology must provide a clear indication that it holds more value than these existing methods. However, in a recent survey with professional football staff, Greenhough, Barrett, Towlson, & Abt (2021) found that while there was no consensus on whether VR should be used as a talent identification tool, 73% of practitioners agreed that VR could be used in a professional football setting for rehabilitation.

Despite these opinions and proposed benefits, few physiotherapists and rehabilitation specialists in elite football use VR as part of their day-to-day practice. The aims of this study are i) to explore the perceived benefits and barriers to the adoption of VR technology to rehabilitate players in elite football following a trial period of usage and ii) provide a list of recommendations to support the design of virtual reality sessions aimed at rehabilitation in sport, but also outline the practical implications for using VR technology in a professional football setting, such as staff time constraints and player buy-in.