General state and pain threshold of rats
During the experiment, no rats in any of the groups died. The control
rats had well-grown fur that was white and shiny. The fur of the rats
with OA appeared haggard and yellow, and they exhibited signs of
irritability. Within one week of the MIA injection, the OA rats showed a
limp, but their movement gradually improved after three weeks. The
OA+HIIT rats also exhibited limp movement and irritability one week
after the MIA injection. After six weeks of HIIT training, it was
expected that the OA+HIIT rats would show improved movement in their
right knee joint, but four rats suffered from serious infections in
their paws and tails. The OA+C-A1 and OA+C-A1+HIIT rats showed a limp
during the first week after the MIA injection, but their condition
gradually improved after the third week. After six weeks of HIIT
training, the fur of the OA+C-A1+HIIT rats became shiny, but three rats
had severe infections in their paws and tails. The body weight of the
rats in each group increased significantly over the feeding period, with
no significant difference in the rate of weight gain (P > 0.05, Figure 2 A, C).
OA rats manifested a lower threshold when the von Frey test stimulated
the hind paw. OA rats exhibited significantly decreased MWT from the
third and tenth week compared with control rats, but HIIT treatment
reversed the OA-induced trend (P < 0.001, Figure 3 B).
There was no significant difference in the MWT of rats in each group
before MIA injection (P > 0.05). From the seventh to
tenth week, the MWT of OA+HIIT rats was significantly higher than that
of OA rats (seventh week: P < 0.01; eighth to tenth
week: P < 0.001). The MWT of OA+C-A1 rats was
significantly lower than that of OA rats (P < 0.05). At
the eighth to tenth weeks, the MWT of OA+C-A1+HIIT rats was
significantly lower than that of OA+HIIT rats (P <
0.05, Figure 2 B, D).