When does Korr assert that manipulative therapy is effective?

Korr's assertion that manipulative therapy is effective when it establishes coherent patterns of afferent input is grounded in the interplay between the nervous system and the musculoskeletal system. Afferent input refers to sensory signals that are sent from the body to the brain, influencing how the brain perceives and interprets bodily states. In the context of chiropractic care, manipulating the spine and other joints can restore normal motion and alignment, which in turn optimizes the pathways through which these signals travel.

By ensuring coherent patterns of afferent input, manipulative therapy can enhance body awareness, improve reflexes, and facilitate better communication within the nervous system. This suggests that chiropractic adjustments can significantly influence not just physical symptoms, but also neurophysiological responses, leading to more effective management of pain and improved overall function.

The other answer choices, while they may reflect certain benefits of chiropractic care, do not encapsulate Korr's specific focus on the importance of afferent input in the context of manipulative therapy's effectiveness. Emotional stress, physical fitness, and the instantaneous elimination of pain are not considered foundational principles within Korr's framework regarding the mechanics of how manipulative therapy works.