Neoadjuvant chemoradiotherapy (NACRT) prior to surgery for lower gastrointestinal (colon and rectal) cancer is associated with improved survival, but also adversely affects physical fitness, potentially rendering patients unfit for major surgery or increasing the risk of adverse outcome (death and serious complications) after major surgery. The investigators aim to obtain pilot data showing that neoadjuvant chemoradiotherapy (NACRT)reduces objectively measured exercise capacity (fitness).