Is nerve-directed stretching effective for improving of ankle joint flexibility and tissue stiffness in older men?

Age-related decrease in joint flexibility leads to difficulties in activities of daily living and an increased risk of falls. The current study investigated whether nerve-directed stretching, which focuses on stretching neural tissue, could acutely improve joint flexibility and tissue stiffness more than muscle-directed stretching or not. Twenty-seven older men performed muscle- and nerve-directed stretching for 400 ‍s (40 s × 10 times) on separate days. Before and after stretching, maximum ankle dorsiflexion angle was measured as range of motion (ROM). Shear wave propagation velocity (SWV) was also assessed as tissue stiffness of the sciatic nerve, medial gastrocnemius, posterior thigh fascia, and posterior leg fascia in anatomical position. In both stretching conditions, increment of ROM and reduction of sciatic nerve SWV were observed after stretching. The extent of these changes did not differ between the stretching conditions. The SWVs of tissues other than the sciatic nerve did not change before and after the stretching. These results suggest that acute effects of nerve-directed stretching on joint flexibility and tissue stiffness are not superior to muscle-directed stretching.