Preoperative exercise, also know as prehabilitation, has been shown to improve physical fitness and potentially reduce postoperative complications in patients undergoing surgery. Patients are often labelled high risk for surgery due to their existing ill-health e.g. heart and lung disease. High risk patients comprise approximately 12% of all elective cancer cases, but account for 80% of all post-operative mortality. Complications significantly affect the quality of life of each CRC patient, both in the short and long-term, and can also impact on survival. It is critical that patients who are deemed at high risk of complications are optimised in the preoperative period. Exercise in the period before surgery is therefore one potential method of improving high risk patients' physical fitness levels while potentially reducing their risk of postoperative complications and subsequent mortality.