Cardiovascular response is a criterion in determining suitability and safety in exercise testing and training. Howbeit, there is a paucity of studies on cardiovascular response to back muscles' endurance tests in health and disease. Considering that the back extensor muscles are one of the largest muscle groups in the body, and that the magnitude of cardiovascular response to contraction to muscular endurance is reportedly greater than muscular strength testing, it is therefore important to determine the cardiovascular entropy to static and dynamic endurance testing and training of back...