How does heat application increase range of motion?

Heat application increases the range of motion primarily by enhancing tissue extensibility and decreasing joint stiffness. When heat is applied to soft tissues, such as ligaments, tendons, and muscles, it causes a rise in temperature that enhances the elasticity of these tissues. As the temperature increases, the collagen fibers within the tissues become more pliable, allowing for greater flexibility and extensibility. This change enables the muscles and surrounding structures to accommodate a greater range of movement without causing injury.

Additionally, heat helps alleviate stiffness in the joints by promoting blood flow and relaxing the muscles surrounding the joint. Increased circulation leads to improved delivery of oxygen and nutrients while also aiding in the removal of metabolic waste products. This combination of increased pliability and reduced stiffness contributes to an enhanced range of motion and improved overall function.

While inflammation can play a role in the healing process, in the context of heat application, it is not conducive to increasing range of motion and can instead restrict movement. Promoting hypoxia, or a deficiency in oxygen, would be counterproductive to both healing and improving range of motion. Therefore, the correct answer recognizes that tissue extensibility and decreased stiffness are key factors in utilizing heat for mobility enhancements.