Doa El-Ansary

1 INTRODUCTION Poor recovery outcomes following major surgery are associated with reduced quality of life, increased complications, increased length of stay, mortality, and patient and provider costs. Yet, an individual patient's recovery trajectory from major surgery can be difficult to predict given the many factors and recovery domains involved in the restitution of preoperative function following the treatment of disease.

1. Introduction The lumbar extensor (LE) muscle group is comprised of the multifidi, erector spinae and short and intersegmental muscles and is involved in controlling lumbar posture and movements [1]. The LE muscle group is capable of generating forces directed in the sagittal, frontal and axial planes, resulting in compression and posterior shear forces on the spine [2].

1. Introduction A squat is a functional and dynamic movement that is used in clinical and sport-specific settings to assess leg extension strength [1], range of motion [1], and movement quality [2]. The double-leg squat (DLS) is performed when both feet are hip-width and on the ground while the single-leg squat (SLS) is performed when standing on one foot pointed straight forward and the other, non-weight-bearing leg raised in the air above ground.