<qa>  How many patients will be recruited for a feasibility study?The investigators aim to recruit 5 patients for a feasibility and tolerably study and 30 patients for an interventional study over 24 months from Aintree University Teaching Hospitals NHS Foundation Trust. Consenting patients will undergo a series of tests designed to evaluate the ability of the muscle to take up and utilise oxygen, namely a cardiopulmonary exercise test CPET and VO2 Kinetics tests, all done preCRT and at 3,6,9 and 14 weeks postCRT presurgery. All patients will have their CPET, as well as standard restaging scans at 9 and 14 weeks post NACRT. Outcome, activity and quality of life data will also be collected. 