## 3 Results
### Treadmill Settings Effect  
No significant differences were found at the pre-exercise time point between exercise sessions for any of the measured indicators of physiological response (Tables 1-3). At the final 60 s of each WT session, HR was higher compared to the DT session. Additionally, at this time point, horses exhibited higher HR during the carpal-depth WT+AR session than during both fetlock-depth WT sessions; however, no significant difference was observed between the carpal-depth WT sessions regardless of whether the AR mode was activated. Similarly, immediately post-exercise, LAC was higher for almost all WT sessions compared to the DT session, except for the fetlock-depth WT session, where no significant differences were found between the DT session and the fetlock-depth WT+AR session. No differences in LAC were observed at this time point between the fetlock-depth WT+AR session, carpal-depth WT session, and carpal-depth WT+AR session. At the 30 min post-exercise time point, HR was higher for the DT session than for both fetlock-depth WT \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & **Time** & **DT Session** & **Feltlock-Depth** & **Feltlock-Depth** & **Carpal-Depth** & **Carpal-Depth** & **\(p\)-Value** \\  & **Point** & & **WT Session** & **WT +AR Session** & **WT Session** & **WT +AR Session** & **\(p\)-Value** \\ \hline RBC & before & 7.6 (6.5–9.1) & _7.9_ (7.3–9.2) a & 7.4 (6.4–9.3) a & 7.7 (6.6–9.3) & 7.6 (6.8–9.1) a & \(p\) = 0.12 \\ (\(\times 10^{12}\)/L) & 0 min & 8.9 (6.4–9.9) & 7.5 (6.7–9.4) a & 7.8 (6.7–10.0) a & 7.3 (6.2–9.8) & 7.6 (6.7–9.9) b & \(p\) = 0.89 \\ norm: 2-12 & 30 min & 7.3 (5.4–8.6) & 7.4 (5.7–9.1) b & 7.3 (6.3–8.0) b & 7.1 (6.8–7.7) & 7.0 (5.9–8.0) a & \(p\) = 0.18 \\ \(\times 10^{12}\)/L & 24 h & 7.4 (6.9–8.8) b & 7.0 (5.9–8.5) b & 6.9 (5.9–8.1) b & 7.6 (5.9–6.9) b & \(p\) = 0.11 \\  & \(p\)-value & \(p\) = 0.06 & \(p\) = 0.007 & \(p\) = 0.0003 & \(p\) = 0.11 & \(p\) = 0.01 \\ above N/n: & & & 0 & 0 & 0 & 0 & 0 \\ \hline HGB & before & 11.4 (10.4–12.3) a & 12.6 (10.4–12.3) a & 11.7 (10.2–12.8) a & 11.8 (10.3–13.4) & 11.5 (10.3–14.2) & \(p\) = 0.07 \\ (g/dL) & 0 min & 13.8 (10.1–16.2) b & 12.1 (10.9–14.3) a & 11.9 (10.7–15.6) a & 12.1 (10.8–14.6) & 12.2 (10.1–14.6) & \(p\) = 0.17 \\ norm: & 30 min & 11.6 (8.7–12.9) a & 11.4 (10.0–14.0) b & 11.4 (9.3–12.8) b & 11.5 (9.9–12.7) & 11.1 (10.2–13.7) & \(p\) = 0.62 \\
8–17 g/dL & 24 h & 12.2 (11.3–14.8) a & 11.3 (10.0–13.8) b & 11.0 (9.8–13.1) b & 12.2 (9.6–14.6) b & \(p\) = 0.06 \\  & \(p\)-value & \(p\) = 0.002 & \(p\) = 0.003 & \(p\) = 0.008 & \(p\) = 0.12 & \(p\) = 0.09 \\ above N/n: & & & 0 & 0 & 0 & 0 & 0 \\ \hline  & & & & & & & \\ \end{tabular}  
\end{table} 
Table 2: Red blood cell count (RBC) and hemoglobin concentration (HGB) measured during the following treadmill exercise sessions: dry treadmill (DT) session, water treadmill (WT) session at fetlock-depth water, WT session at fetlock-depth water with artificial river (AR) mode, WT session at carpal-depth water, and WT session at carpal-depth water with AR mode. Data are presented as median and ranges (minimum and maximum values). sessions, with no differences observed between both carpal-depth WT sessions and the remaining sessions. At the same time point, LAC was higher for the carpal-depth WT+AR session compared to the DT session and the fetlock-depth WT session, with no significant differences among the remaining sessions. No significant differences in HR or LAC were observed 24 h post-exercise (Table 1). Immediately and at 30 min post-exercise, no session-related differences in RBC or HGB were observed. However, differences in both RBC and HGB were noted at the 24 h post-exercise time point (Table 2). Immediately post-exercise, CK activity was higher for almost all WT sessions compared to the DT session, except for the carpal-depth WT session, where no differences were found with the remaining sessions. At the same time point, no session-related differences in AST activity were observed. However, differences in LDH activity were noted at this time point.