A handheld tissue stretching device combined with an extremity flexibility number, stretchscore, enables users to independently evaluate and treat the flexibility of their extremity tissue minimizing physical therapist intervention to evaluate and treat tissue. The distance between handheld stretching devices and the extremity supports changes with a high degree of variability during home treatments; whereas, medical professionals monitor stretch intensity visually and manually. Patients performing home-based stretches impart variable intensity that leads to inconsistent tissue treatment resulting in increased tissue stiffness. The present inventors have discovered when the slack is automatically retracted, the distance between the users hands and the extremity support is continuously proportional to the flexibility of the extremity. This “distance matching” between the handheld stretching device and the extremity support provides a reliable, repeatable, and independent evaluation of extremity flexibility by directly relating this change in distance to the user's flexibility.