Patients' ability to tolerate surgery is associated with physical fitness: less fit patients have an increased rate of death and serious complications following major surgery. Combined chemotherapy and radiotherapy (x-rays) prior to rectal cancer surgery is known as neo-adjuvant chemoradiotherapy (NACRT) and is associated with improved cancer removal but adversely affects physical fitness. In Liverpool, the investigators have pre-pilot data showing that NACRT reduces objectively measured physical fitness (measured by cardiopulmonary exercise testing) in patients having surgery. This pre-pilot study investigated the effects of a 6-week structured responsive endurance training programme (SRETP) after NACRT and before cancer surgery. This programme has improved both their fitness and their health related quality of life(HRQL). Now, the investigators are undertaking a randomised controlled trial to compare changes in patient's physical fitness in response to SRETP with a group of patients who will be given exercise advice. The SRETP group will exercise 3 times a week for 9 weeks. The investigators will make objective measurements of physical fitness in both groups. The investigators will monitor patient's perceptions of the training programme, HRQL, daily activity (using an accelerometer), and outcomes after surgery. The investigators believe that, patients in the exercise group will improve their physical fitness prior to surgery, change behaviour towards exercise, improve activity and HRQL following NACRT. These results will contribute to the design of a large, multi-centre trial to determine whether a SRETP increases physical fitness with a reduction in adverse outcome following surgery. The investigators will conduct an adequately powered randomized controlled trial (RCT) comparing a SRETP with 'exercise advice' in 46 rectal cancer patients. Specifically, we will test the following hypotheses and outcomes: PRIMARY HYPOTHESIS A 9-week, structured responsive endurance training programme (SRETP) compared with a control group (no training) will result in a clinically significant difference in physical fitness (2.0ml/kg/min VO2 at LT) post-NACRT prior to surgery.

SECONDARY OUTCOMES

1. A 9-week SRETP compared with a control group (no training) will result in a clinically significant difference in physical fitness (2.0ml/kg/min VO2Peak) in patients who have had NACRT prior to surgery.
2. SRETP following NACRT and prior to cancer surgery will provide psychological health benefits and improve patient's HRQL (assessed by semi-structured interviews and questionnaires -EORTC QLQ-30 and EQ-5D). This will provide vital exploratory information that will inform a future application to deliver a larger appropriately powered RCT exploring the hypothesis that patients with greater pre-operative fitness will encounter lower postoperative morbidity and mortality. Specifically, these exploratory outcomes are:

EXPLORATORY OUTCOMES

1. To investigate whether SRETP following NACRT and prior to surgery is associated with a change in overall physical activity (assessed by the number of steps while active using an accelerometer).
2. To investigate whether there is a change in the day 7 surgical morbidity (using the Post-Operative Morbidity Survey) and mortality.
3. The effect of SRETP on cancer downstaging post-NACRT (Tumour, Node and Metastasis Staging-TNM staging).

Inclusion Criteria:

• All patients listed to undergo elective rectal cancer resection and long course neoadjuvant chemoradiotherapy in the two NHS teaching hospitals (Aintree University Hospital NHS Foundation Trust and Southampton University Hospital NHS Foundation Trust)

Exclusion Criteria:

• Unable to consent.
• Under 18 years of age.
• Unable to perform exercise.
• Any contraindications on the American Thoracic Surgery CPET safety guidelines.