The surgical process is a major stressor because of the psychological distress, tissue trauma, lack of activity, and quasi-starvation and it produces immediate systemic changes and both short- and long-term effects on activity and quality of life. However, there is mounting evidence that many of the negative immediate effects of surgery such as pain, fatigue, and weakness are amenable to intervention. If proper interventions are carried out, these symptoms may be readily controlled allowing for a faster recovery and early home discharge. But the effects of surgery are felt far beyond the immediate convalescent period and patients can feel fatigued for many weeks and this delays return to usual function and reduces quality of life. Thus, it would be of great practical benefit if ways of improving post-surgery physical function and quality of life could be identified.

Traditionally efforts have been made to improve the recovery process by intervening in the post-operative period. However, the post-operative period may not be the most opportune time to introduce interventions to accelerate recovery. Many of these surgical patients are concerned about perturbing the healing process as well as being depressed and anxious if they await further treatment. The pre-operative period may be a more emotionally salient time to intervene in the factors that contribute to recovery. The process of enhancing functional capacity of the individual to enable him or her to withstand an incoming stressor has been termed prehabilitation The purpose of this study is to address the following research question: Among persons scheduled for colorectal surgery, does a pre-operative program of aerobic and muscle strength training (prehabilitation) compared to a standard peri-operative educational protocol affect functional exercise capacity and health-related quality of life? The trial will be a single blind, stratified (on cancer diagnosis or not), randomized, two-group (prehabilitation or standard care), parallel design. Both groups will receive the same peri-operative education program. In conformity with current practice, all subjects will also be advised on nutritional support during the preoperative period. Persons with albumin \< 38 gm./l will receive an adequate supply of protein and calorie nutritional supplement bars. In addition to this standard care, the prehabilitation group will be prescribed a program of exercise training consisting of daily stationary cycling from the start of the intervention to the day prior to surgery (minimum 3 weeks) combined with an individualized program of muscle strength training.

Both groups will be evaluated for exercise tolerance, walking capacity and health and emotional status at enrolment and after 3 three weeks of training as well as at 4 weeks, 8 weeks and 24 weeks (6 months) post-surgery. The main outcome measure will be the 6 Minute Walk Test - a valid and reliable measure of functional walking capacity. The estimator of effect will be the proportion of people in each group who, at 8 weeks post-surgery, achieve or exceed their baseline value on this test (± 20m). The proposed sample size is 200. This is based on 80% power to detect a difference of 22% in the proportion recovering to baseline values (40% in standard and 62% in prehabilitation). The results of this trial will be used to inform practitioners and patients alike of the benefits (or risks if any) of exercise in preparing for surgery.