BackgroundRisk 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.MethodsConsecutive 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 VO2) 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 VO2 will be assessed after the first 30 patients and will be used to calculate the required sample size.DiscussionWe want to assess if 14 sessions of HIIT is sufficient to improve Peak VO2 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 VO2 will translate into improving clinical outcomes after surgery.Trial registrationAustralian New Zealand Clinical Trials Registry, ACTRN12617000587303. Registered on 26 April 2017.

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The purpose of this experiment was to explore the operational behavior of hydrodynamic thrust bearings machined from various composite materials (PTFE-Filled Delrin Acetal Resin and MDS-Filled Nylon) and general Aluminum under a set of different axial loading conditions. Since thrust bearings allow mechanical components subjected to axial loads to rotate more freely, they must counter a great deal of friction which can cause bearing failure in order to maintain proper movement. In order to reduce friction and weight, this research posits that thrust bearings machined from composite materials of lower friction coefficients and densities to that of conventionally used materials such as aluminum may provide some advantages. This hypothesis was tested by machining three thrust bearings, all to the same geometric specifications (two composites and one Aluminum) and subjecting them to thrust loads of 25, 50, 75, and 100 pounds while rotating them at a constant rotational speed of 3050 RPM for 10 minutes at each load using a customized test rig. A thermocouple implanted into the bearings themselves recorded the operation temperatures at a sampling rate of 20 Hz. Based on the average temperatures recorded at the 100 pound axial/thrust load, the experiments suggest that the PTFE-Filled Delrin Acetal maintains the lowest average operating temperature of 29.5 °C, followed by the MDS-Filled Nylon at 41.6 °C and lastly the Aluminum at 54.4 °C — a trend that is observed at each axial load albeit less pronounced. These results suggest that composite materials such as PTFE-Filled Acetal and MDS-Filled Nylon to be used in lieu of conventional metals and operate at lower temperatures and lower friction.

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