Does visual manipulation of the lifted load within a virtual reality environment influence perceived exertion with resistance exercise?

performance of a leg press exercise in a virtual reality environment in which the observed weight does not match the actual weight All testing occurs with supervision of a Physiotherapy honours student and an academic staff member. Participants will be seated in an incline leg press machine and the manual blocks on the machine adjusted to limit the range of knee flexion and extension to a pre-specified range. Participants will then practice performing the leg press movements with no additional load on the machine (i.e., 50kg). Next, a virtual reality headset, which blocks the real world environment from the user, will be fitted with the participant seated in the machine. Through this headset the participant can view the leg press machine and a female model wearing similar clothes and shoes performing leg press exercises under different weight conditions. For each exercise the video shows the model performing five sets in time to a metronome. A standardised training regimen will then be used that helps the person learn how to use the hand controllers to navigate within the virtual environment. Two practice sets of performing the leg press task in time with the video image they observe in the headset in which actual and visualised load match will then occur as well as practice utilising the outcome measures at the completion of each set. The participant will then remove the headset and have any questions answered. Further familiarisation will occur if the participant does not feel confident to continue. Once the participant is confident to proceed, the formal testing will begin. Participants will be informed that the purpose of the study is to investigate the biomechanics of the leg press exercise under different loads, and whether this differs between the virtual and non-virtual environments. To this end, reflective markers will be placed over that lateral knee, hip and ankle of the person’s right leg and a video camera positioned on the right side of the leg press machine. Participants will be told that they will be asked to lift different weights that correspond to the weights seen on the video and we will compare the biomechanics of lifting in a virtual environment with biomechanical data already collected of lifting the same loads in a normal environment. The measurement of Rate of Perceived Exertion (RPE), Repetitions in Reserve (RIR) and muscular fatigue will be described as process variables to be controlled for when analysing biomechanical differences. The participant will be exposed to four different conditions, four times presented in a randomised, counterbalanced order. The unloaded leg press weight is 50 kg. In all conditions the actual load will be 70 kg (bar weight plus 20 kg added weight) so the four conditions are: A = 20kg on bar initially, observe the removal of 20kg so visualise a lift of 50kg (actual lift 70 kg) B= 0 kg on bar initially, observe the addition of 20 kg so visualise a lift of 70kg (actual lift 70 kg) C = 40Kg on bar initially, observe the removal of 20 kg so visualise a lift of 70 kg (actual lift 70 kg) D = 20 kg on bar initially, observe the addition of 20 kg, so visualise a lift of 90kg (actual lift 70 kg) Participants will perform five repetitions of a condition then immediately provide their RPE and RIR. The RPE and RIR scales are displayed in the headset after each repetition to facilitate this. After a two minutes rest, they will complete the next condition in the randomisation sequence and repeat the assessment process. After four conditions the participant will remove the head set and will be free to move around for five minutes. After this rest period another sequence of four conditions will occur using the same methodology as above. This will be then repeated two more times so that all participants complete all four conditions four times. Total testing time is approximately 60 minutes