Fig. 1

Eighteen SD rats underwent adaptive training on a treadmill for 1 week at an intensity of 10 m/min, 10 min/d, and 5 d/week. After one week of training, rats were randomly divided into three groups: Sham/sedentary (Sham/Sed), PTOA/sedentary (PTOA/Sed), and PTOA/treadmill-walking (PTOA/TW). The PTOA model was established by transection of anterior cruciate ligament (ACLT) and destabilization of medial meniscus (DMM). While the rats in the sham group were sutured after opening the right knee capsule and no extra surgery was undertaken. The PTOA/TW group performed 8 weeks of treadmill exercise at an intensity of 15 m/min, 30 min/d, 5 d/week. All SD rats were euthanized within 48 h of the last treadmill exercise, blood supernatant was collected after cardiac puncture, and tissue samples were collected and weighed