A joint rotational exercise and stretching tool for strengthening muscles and connective tissues, particularly for shoulder internal and external rotation, with further applicability to the wrist, elbow, and hip. The device includes a mount, torque-generating mechanism, and ergonomic lever arm configured to align with anatomical joint axes. It enables concentric, eccentric, isometric, and passive modes of use. Unlike traditional tools that provide linear resistance or partial-range torque, this invention delivers continuous rotational resistance across the full arc of motion. Configurable mounting and ergonomic adjustments allow use across various joints, limb lengths, and exercise positions. Suitable for rehabilitation, injury prevention, and performance training in clinical, home, or athletic environments.

A cable training assembly disposable within a portable housing includes a cable configured for pulling by a user and a screw mechanism configured to deflect at least one spring. The deflection of the spring exerts a retraction force on the cable in opposition to a force exerted on the cable by the user. A selector assembly includes a knob that is rotatable by the user to select or deselect a spring acting on the cable.