High intensity exercise training prior to major elective surgery is well tolerated and associated with impressive cardiopulmonary improvement. George Rose1, Tom Calverly1, Hayato Tsukamoto1, David Byfield1, Richard Davies2, Ian Appadurai2 and Damian M Bailey1 1 Neurovascular Research Laboratory, University of South Wales, Pontypridd , United Kingdom. 2 Department of Anaesthetics, University Hospital of Wales, Cardiff, United Kingdom. Results Background Impaired cardiorespiratory fitness (CRF) is associated with poor post-operative outcome following major elective surgery (Moran et al., 2016). Given its importance, approximately 30,000 preoperative cardiopulmonary exercise tests (CPET) are conducted in the UK each year to assess patient risk and plan care (Levett et al, 2018). Structured aerobic interval-training can improve cardiorespiratory fitness prior to surgery (West et al. 2015), however the current evidence base is lacking. Thus as proof of concept, we conducted a clinical case study to address the feasibility and adaptive benefits of high intensity interval training (HIIT). The HIIT intervention was well tolerated with no adverse events occurring and 29 of 30 sessions completed. After 10 weeks, pulmonary oxygen uptake at peak exercise and anaerobic threshold increased by 36 and 27% respectively (18.6 versus 13.7 and 10.5 versus 8.3 ml.kg-1.min-1) and traversed a fitness stratification threshold of 15 ml O2.kg-1.min-1 for peak oxygen uptake. The patient was subsequently referred for surgery. Methods A 70 year-old female who underwent an oesophagectomy for oesophageal cancer developed ischaemia of the gastric conduit and was left with a pharyngostomy, and a feeding jejunostomy. Further surgery for restoration of the upper gastrointestinal tract with a colonic interposition which involved another major thoraco-abdominal operation was offered, however the patient’s fitness for surgery was stratified as high-risk. The medical history also included a myocardial infarction and coronary artery bypass graft. Following CPET to symptom limited exhaustion to determine baseline fitness, a ten-week supervised HIIT intervention was conducted. Three exercise sessions of 40 minutes duration separated by 48 hours recovery were completed each week using cycle ergometry. Each session comprised six, two-minute bouts of heavy exercise [50% of the difference between power output at peak exercise and anaerobic threshold (AT)] interspersed by three minutes of moderate exercise (80% of the power at AT) in accordance with previous research (West et al. 2015). Heart rate was monitored by 12-lead ECG alongside blood pressure, and rate of perceived exertion recorded. Cardiorespiratory fitness was reassessed by CPET every two weeks and HIIT intensities adjusted accordingly. Discussion Despite the high intensity of exercise, HIIT proved feasible, safe, and well tolerated. Impressive cardiopulmonary adaptation occurred in excess of variation typically observed during repeated measures (Rose et al., 2018). Improved CRF over a short period of time enabled the fitness for surgery classification to move from “unfit” to “fit”, and thus supports investigating HIIT in future trials as an adjunct prior to major surgery. References Levett et al. (2018). Br J Anaesth 120, 484-500. Moran et al. (2016). Br J Anaesth 116, 177-191. Rose et al. (2018). Br J Anaesth 120, 1187-1194. West et al. (2015). Br J Anaesth 114, 244-251. The authors would like to acknowledge The Physiological Society for a travel grant to attend this meeting.