The Effects of a 12 Week Home-based Exercise Intervention on Physical Performance in Patients With Cancers of the Gastrointestinal Tract With Pre- Cachexia or Cachexia

Inclusion Criteria: * Have a primary diagnosis of colorectal, esophageal, gastric, pancreatic or biliary tract cancer and plans to initiate systemic chemotherapy within the next 4 weeks after enrollment. * Have been diagnosed as having an advanced unresectable cancer with no plans for surgical intervention during the active study period (12 weeks). * Have an ECOG performance score of 0 or 1. * Have a life expectancy of \>3 months as determined by their primary oncologist. * Have experienced at least 2% weight loss of the patient's reported previous body weight over the 6 months prior to enrollment. Patients who have 2 - 4.9% weight loss should also have one of the following metabolic changes: a hemoglobin level \<13, an albumin level \<3.5, and/or impaired glucose tolerance within the past year such as a new diagnosis of diabetes, an A1C level \>5.7, a random glucose level \>200 or a fasting glucose level \>100. * Have permission from primary oncologist to engage in low to moderate intensity exercise regimen. * Be able to read English (since the assessment materials are in printed format). * Be able to give written informed consent. Exclusion Criteria: * Have any of the following limitations: unable to walk the 4 meters of the SPPB test, wheel-chair bound, unable to perform low-to-moderate intensity exercise regimen (patients unable to perform 6 minute walk or stair climb test will be allowed to participate, but will be held out of these measurements). * Have had major surgery (excluding diagnostic procedures like laparoscopy, EGD/EUS, esophageal stent placement) in the past 4 weeks. * Be experiencing dysphagia that requires enteral or parenteral feeding for nutrition. * Be enrolled on hospice at time of consent. * Be engaged in an active exercise routine by being identified as in the Active or Maintenance Stage of exercise behavior as assessed by the 1-item Exercise Stages of Change Short Form (40).