What are the effects of friction movements in sports massage?

Friction movements in sports massage are primarily used for their ability to penetrate deeper into the muscle tissue, which can lead to a variety of physiological responses. One of the key effects is the stimulation of nerve tissues. This stimulus can enhance the proprioceptive feedback to the brain, helping to improve body awareness and muscle coordination.

Additionally, friction can help to break down adhesions and scar tissue, resulting in increased flexibility and release of tight muscles. By applying friction to a tight area, the massage provides both a stimulation of the nerves and a tightening effect by activating the muscle fibers in response to the manipulation, which can enhance the overall function of the muscle.

While the other options present useful effects of massage, they do not specifically capture the unique qualities of friction techniques. For instance, softening and soothing muscles is more related to gentle techniques such as effleurage, whereas improving circulation causing reflex reaction could apply to various massage techniques but doesn't encapsulate the specific benefits of friction. Therefore, option D is the most fitting description of the specific effects of friction movements in sports massage.