Fig. 1

HITT attenuates OA-induced hyperalgesia. A Research design and timeline. Twelve rats received an MIA injection to build an OA model after 1 week of adaptive feeding and exercise. Six rats received saline injections as control group. After 4 weeks, OA-HIIT rats were subjected to the HIIT treatment for six consecutive weeks, and control rats and OA rats exercised freely on the closed treadmill. Pain thresholds were assessed weekly in all rats, and the right knee joint and spinal cord was extracted after the 10th week. B The von Frey testing detected rats' mechanical withdrawal threshold (MWT). n = 6/group, repeated measures analysis of variance. Tukey and Bonferroni tests method was used as a post hoc test. C,D Representative Safranin-O Fast green staining image (scale bar = 100 μm) and Mankin score of cartilage (n = 6 /group). Blue staining for bone and red staining for cartilage. One-way analysis of variance, the Tukey and LSD tests method was used as a post-hoc test. E Representative western blot image of spinal cord tissue ( L4–L5) and quantitative analysis of c-Fos, Vglut2, and SP (n = 6 /group). One-way analysis of variance, the Tukey and LSD tests method was used as a post hoc test. * P < 0.05, ** P < 0.01, *** P < 0.001 as indicated