The effect of blood flow restriction exercise on pain perception

The study will utilise a repeated measures design, with subjects performing a single acute resistance exercise session under two different conditions. The interventions will differ based on the application of blood flow restriction (BFR), and the volume of resistance exercise being performed. Restrictive cuffs will be fitted to the upper thighs of the participants, which will be inflated to 60% of their individual arterial occlusion pressure. In the low dose trial (LOW), participants will perform 4 x 10 repetitions with 30% of their one-repetition maximum in the barbell back squat. In the high dose trial (HIGH), participants will perform 4 sets consisting of 30, 15, 15, 15 repetitions, respectively, with 30% of their one-repetition maximum in the barbell back squat. All trials will consist of a single session to evaluate the acute effect of pain modulation, as assessed through pain pressure thresholds. Each trial will be roughly 45 minutes in duration and will occur face-to-face at La Trobe University in Melbourne, Australia. Each exercise session will be completed in a randomised order, and there will be a minimum of 72 hours and maximum of 10 days between trials. As this project involves apparently healthy individuals, the sessions for all interventions will be supervised, in a one-on-one format, by an accredited exercise scientist. However, a physiotherapist is involved in the project to advise on collection of pain pressure thresholds. The level of intensity for interventions involving resistance exercise will be prescribed using % of one-repetition maximum, with 30% being selected. Perceived effort will also be monitored during all interventions involving exercise using modified Borg RPE (0-10) and repetitions in reserve (RIR), to estimate proximity to failure. It is anticipated that the level of intensity will be vigorous in the high dose trial, moderate in the low dose trial, and low in the passive trial. Individual arterial occlusion pressure will be determined via doppler ultrasound. The restrictive cuff will be positioned around the proximal thigh and gradually and incrementally inflated until blood flow is no longer detected in the posterior tibial artery. Participants must complete all experimental visits to be included in the study. Adherence will be monitored directly as all sessions will be supervised.