Preoperative High Intensity Interval Training: The PHIIT Trial

Colorectal and thoracic surgical patients are susceptible to poor postoperative outcome. In colorectal surgery the rate of post-op complications is between 15-20% and the rate of 30 day mortality is 2.3%. Thoracic surgery also carries significant risk, 30 day mortality is 2.2% while the rate of post-op complications is 29.3%. Poor postoperative outcome significantly affects the patients recovery and increases hospital costs. Reducing postoperative risk therefore conveys significant benefit to the patient and the hospital.

Preoperative physical fitness is predictive of postoperative outcome in intra-abdominal and thoracic surgery. In a systematic review of 6 studies preoperative exercise interventions improved pre-op physical fitness in patients undergoing abdominal surgery, however it is unclear if this translates into an improvement in postoperative outcome.

An updated systematic review and meta-analysis was performed on the effects of pre-habilitation on postoperative outcome. While the results demonstrated that preoperative exercise interventions of 4-6 week duration reduced post-op complications a significant amount of work is still to be performed in this area.

The current colorectal/thoracic pathway from diagnosis to surgery is about 2 weeks and therefore interventions of longer duration are not feasible. Clinicians may be presented with a difficult choice in delaying surgery to perform prehab or cancel the pre-op intervention.

To create greater improvements in aerobic fitness, participants are required to exercise at high levels of VO2peak (e.g. ≥80% VO2peak). High intensity interval training (HIIT) requires participants to exercise at high levels of VO2peak (≥80% VO2peak). Participants exercise for short periods (15 seconds) followed by 15 seconds of rest and typically continue this pattern for 30 minutes or until exhaustion.

A recent review reported HIIT programmes to be safe in individuals with coronary artery disease and stable heart failure. In agreement with this paper a recent meta-analysis noted that HIIT produced a more pronounced incremental gain in participants' mean VO2peak when compared with continuous moderate intensity exercise There are a number of factors to take into account when designing a HIIT programme e.g. duration and intensity of exercise phase and type of recovery period (active vs. passive). Two papers compared a selection of HIIT protocols for safety and time at a high percentage of VO2peak (≥ 80% VO2peak). Protocols with rest periods (passive recovery) allowed patients to exercise for longer and had lower perceived difficulties. In one study of 20 patients with CAD, HITT was prescribed with 15s exercise and passive recovery intervals at 100% Peak Power Output (PPO) or Maximal Aerobic Power (MAP) with no adverse events. PPO or MAP is the power of the last completed stage during a maximal exercise test (watts). This intervention had the highest duration above 80% VO2peak (819s) and a high completion rate of 63%. This protocol was chosen for this study.

HITT has not been investigated as a preoperative intervention to either optimize fitness prior to surgery or reduce postsurgical complications. Preoperative HIIT is an intense intervention which will require significant participant adherence. The safety, cost and clinical application of such a programme needs to be performed. This feasibility study aims to assess the ability of HIIT to improve aerobic fitness two weeks prior to surgery and determine its feasibility.

Inclusion criteria

• Patients scheduled for colorectal or thoracic surgery
• Able to give informed consent
• Ability to understand English

Exclusion criteria

• Acute myocardial infarction
• Unstable angina
• Uncontrolled arrhythmias causing symptoms or hemodynamic compromise
• Syncope
• Active endocarditis
• Symptomatic severe aortic stenosis
• Uncontrolled heart failure
• Acute pulmonary embolous or pulmonary infarction
• Thrombosis of lower extremities
• Suspected dissecting aneurysm
• Uncontrolled asthma
• Pulmonary edema
• Room air desaturation at rest ≤85%
• Respiratory failure
• Acute noncardiopulmonary disorder that may affect exercise performance or be aggravated by exercise (i.e. infection, renal failure, thyrotoxicosis)
• Cognitive impairment leading to inability to cooperate
• Left main coronary stenosis or equivalent
• Moderate stenotic valvular heart disease
• Severe untreated arterial hypertension at rest (>200 mmHg systolic, >120 mmHg diastolic)
• Tachyarrhythmias or bradyarrhythmias
• High-degree atrioventricular block
• Hypertrophic cardiomyopathy
• Significant pulmonary hypertension
• Pregnancy
• Electrolyte abnormalities
• Orthopaedic impairment that compromises exercise performance
• Individuals with pacemakers or defibrillators
• Epilepsy
• Past history or MRI evidence of brain damage, including significant trauma, stroke, transient ischaemic attack (TIA), hydrocephalus, mental retardation, or serious neurological disorder
• Non resectable disease
• Emergency surgery