Protocol, and practical challenges, for a randomised controlled trial comparing the impact of high intensity interval training against standard care before major abdominal surgery: study protocol for a randomised controlled trial

BACKGROUND: Risk factors, such as the number of pre-existing co-morbidities, the extent of the underlying pathology and the magnitude of the required operation, cannot be changed before surgery. It may, however, be possible to improve the cardiopulmonary fitness of the patient with an individualised exercise program. We are performing a randomised controlled trial (RCT) assessing the impact of High Intensity Interval Training (HIIT) on preoperative cardiopulmonary fitness and postoperative outcomes in patients undergoing major abdominal surgery. METHODS: Consecutive eligible patients undergoing elective abdominal surgery are being randomised to HIIT or standard care in a 1:1 ratio. Participants allocated to HIIT will perform 14 exercise sessions on a stationary cycle ergometer, over a period of 4–6 weeks before surgery. The sessions, which are individualised, aim to start with ten repeated 1-min blocks of intense exercise with a target of reaching a heart rate exceeding 90% of the age predicted maximum, followed by 1 min of lower intensity cycling. As endurance improves, the duration of exercise is increased to achieve five 2-min intervals of high intensity exercise followed by 2 min of lower intensity cycling. Each training session lasts approximately 30 min. The primary endpoint, change in peak oxygen consumption (Peak VO(2)) measured during cardiopulmonary exercise testing, is assessed at baseline and before surgery. Secondary endpoints include postoperative complications, length of hospital stay and three clinically validated scores: the surgical recovery scale; the postoperative morbidity survey; and the SF-36 quality of life score. The standard deviation for changes in Peak VO(2) will be assessed after the first 30 patients and will be used to calculate the required sample size. DISCUSSION: We want to assess if 14 sessions of HIIT is sufficient to improve Peak VO(2) by 2 mL/kg/min in patients undergoing major abdominal surgery and to explore the best clinical endpoint for a subsequent RCT designed to assess if improving Peak VO(2) will translate into improving clinical outcomes after surgery. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12617000587303. Registered on 26 April 2017.