*4.2. Treadmill Running Protocol*

Based on the study by Dekkers et al. [19], we divided all the induced rats into the following groups: the control group (*n* = 8), which was freely raised at random; and the pre-arthritis intervention short (PAS) (*n* = 8), pre-arthritis intervention long (PAL) (*n* = 8), and therapeutic intervention (T) (*n* = 8) groups, which were made to run on a treadmill (TMS8D; MEQUEST, Toyama, Japan) from day 14 to 28, day 14 to 42, and day 28 to 42, respectively. The running conditions for the PAS, PAL, and T groups were set for efficacy of suppression of joint destruction in rat OA models and rat RA models from a previous study: 5 times/week, speed of 12 m/min, 30 min/day [17,31]. Rats with CIA may have reduced activity due to inflammation and pain. To ensure uniform activity, we applied slightly electric stimulation to encourage the rat from behind if it stopped on the treadmill machine. In this study, all rats ran without electric stimulation, so they all had the same performance. The running protocols for each group are shown in Figure 6. The rats were raised in 12-h light:dark cycles and allowed free access to food and water. All the rats were sacrificed on day 42.

**Figure 6.** Experimental protocols. Eight-week-old male Dark Agouti rats were randomly divided into four groups: control, PAS, PAL, and T groups. PAS (*n* = 8), run from day 14 to 28; PAL (*n* = 8), run from day 14 to 42; and T (*n* = 8), run from day 28 to 42.
