Optimally flexible muscles support ideal postures, basic movements of Activities of Daily Living (ADL) and advanced skills of Exercise, Sports and Occupation. But flexibility of muscles usually gets diminished due to lack of exercise, adaptation of incorrect postures, and restricted mobility caused by injuries, diseases and ageing. Inflexibility of muscles in turn could cause unpredictable deterioration of functional capabilities. Inflexible muscles have the potency to impair the neuromuscular coordination and mechanical efficiency of ADL, Squats, Lunges, Forward bending, Single leg balance, Locomotion and athletic traits that are usually evident in thorough fitness evaluations. Stretch postures can be used in clinical diagnosis, prophylactic regimens and therapeutics. Stretching exercises have been an inevitable component in structured physical activity for general health, maximizing exercise performance and various disease rehabilitation. Maintenance of full range of motion of all the moveable axial and appendicular joints ensures adequate exposure of the neuromusculoskeletal system to gravitational forces, and help preventing the debilitating effects of Gravitational Torque Deficiency Syndrome. Though plenty of explanations and evidences already exists to understand and apply stretch science, one important ‘biomechanical fundamental’ has been found neglected. This article aims at concisely explaining that ‘neglected biomechanical fundamental’ of stretch biomechanics with the help of logical reasoning and innovative illustrations. Keeping these innovative biomechanical interpretations as a foundation, it is possible to elicit comprehensive research pursuits among Exercise Professionals to explore stretch mechanics of all the skeletal muscles at an arthrokinematic level, and upgrade the standards of stretching exercise prescriptions. Keywords: Flexibility, Inflexibility, Stretching Exercise, Range of Motion, Stretch Biomechanics, Muscle Tightness, Subluxation, Arthrokinematics