Neuroscience-inspired exercise to enhance outcomes for people with knee pain: clinical virtual reality exercise

The intervention is supervised by two physiotherapists. The VR intervention is a single session and takes around 15 mins (including the rest periods) and the total testing time for the session takes approximately 1.5 hours. The intervention consists of changing the visual gain (which is the amount people perceive they are moving compared to the real world) via virtual reality goggles during a set of 36 squats. All participants will put on a virtual reality (VR) headset and all will complete the intervention. While wearing the VR headset participants will complete in total 36 bilateral squats plus 3 warm up squats. They will be asked to reproduce their 50% squat depth for all 36 squats. The 50% squat depth will be established in baseline testing prior to the intervention and measured using a biomechanical marker system (VICON). Warm up squats In the virtual environment, participants first see a soccer stadium and complete three warm up squats to get used to moving in the virtual world (no gain change). VR intervention Participants will next see an office environment consisting of a floor, walls, windows, ceiling, desk and chair. In the office environment they will complete the bilateral squat intervention under different gain conditions. The gain conditions manipulate the visual feedback to give the perception that they are moving more or less compared to the real world movement. During the intervention, participants will be asked to squat repeatedly to their 50% squat depth. Each block consists of 4 sets of 3 squats (totalling 12 squats) with a 2 minute rest in between each block. Within the block, each set of three squats will have a gain value applied to either increase gain, no change or decrease gain. There are five possible gain options within each block (2 with gain increases, 2 with gain decreases and one no change) so that within each block of 4 sets, participants will randomly receive 4 out of the five gain conditions. The control condition is where the change in vision in the virtual environment mimics real world movement. Increase in gain refers to two conditions where the change in vision in the virtual environment is greater than reality (moderate increase and maximum increase). Decrease in gain refers to two conditions where the change in vision in the virtual environment is less than in reality (moderate reduction and maximum reduction). The order of gain condition within a block of 12 squats will be randomised, and participants will complete 3 X 12 squats in total. Participants and researchers are blinded during the intervention as to whether the gain is neutral, increased or decreased. Following the completion of 36 squats, all participants will undergo post-session outcome measure testing including reproduction of the 50% squat depth.