Primary Aim 1: To determine the changes in extent of decline and in recovery of functional activity, strength, and muscle mass resulting from activity training (MAT) Primary hypothesis: Abdominal surgery patients randomized to MAT, as opposed to usual care controls (UC) and compared to their baseline evaluation 4 weeks pre-operatively, will have reduced loss of functional activity and reduced loss of muscle strength and mass in the trunk and thigh 6 weeks post-operatively.