PURPOSE:This study investigated MMPs/TIMPs balance in the rat skeletal muscle extracellular matrix after acute eccentric exercise to elucidate the effects of acupuncture on exerciseinduced skeletal muscle damage and remodeling of the skeletal muscle extracellular matrix. METHODS: Eight-week-old Sprague-Dawley rats (n= 96, body wt 220 ± 6.9 g) were randomly assigned to four groups: sedentary control (C), acupuncture control (CA), exercise (E) and acupunctured exercise (EA). Animals were made to run on a motor-driven treadmill with −16° downhill tracks at a speed of 16 m/min for 90 minutes. Tissues were collected from the vastus intermedius muscle immediately, and at 24 hours, 48 hours, 72 hours and 120 hours after exercise. Western blotting was used to detect protein expression of matrix metalloproteinases-2 (MMP2), MMP9, tissue inhibitor of metalloproteinases-1 (TIMP1) and TIMP2. All animal experiments were approved by the Animal Welfare and