The purpose of this research is to gather data on how exercise can help recovery of muscle mass, strength, and physical function after bedrest. Procedures for this study include gathering medical history information, vital signs, collecting urine, collecting blood, muscle biopsies, adipose (fat) biopsies, a glucose clamp, DEXA scan, staying in bed for approximately 10 days, exercise and exercise testing. You are at risk for pain, bleeding, bruising and infection with blood draws and biopsies. You are also at risk for developing blood clots while in bed for 10 days. There is a risk for change or worsening in glucose tolerance with bedrest. Limited muscle movement during bed rest can cause headache, back pain, joint pain, constipation, and reflux. There are no direct benefits to participating in this study and no alternative procedures.