Endurance Has Been Studied. Most Commonly, These Are(1) Several Types of Methods of Testing Spinal Muscle Measures of Isometric, Orstatic, Endurance, (2) Active Measures of Endurance Within a Nonfixed Range Ofmotion (Isotonic), and (3) Isokinetic Testing That Places Subjects In a Fixedrange of Motion As Well As a Fixed Rate of Joint Motion Acceleration. of Theassessment Strategies Available, Isometric Endurance Testing Seems to Becost-Effective and Requires Little Equipment For Testing. Because of These Features,We Chose to Focus on Isometric Endurance Assessment; We Felt That If There Wasevidence to Support It As a Clinically Useful and Valid Procedure, It Would Bethe Type of Testing That Clinicians Would Choose to Use to Measure Spinalmuscle Endurance. We Also Explored the Literature For Evidence Regarding Theendurance of the Lumbar Spine Extensors Specifically, Because Many Methods Arepurported to Test the Lumbar Spine Extensors.