## 4 Discussion  
### Effects of Subalpine Training on the Physical Functions of Cross-Country Skiers  
1.1 The Impact of Subalpine Training on Athletes' White Blood Cells, Red Blood Cells, and Hemoglobin  
Leukocytes are an important component of the body's defenses and protection functions, and the leukocyte count can reflect the body's immune function. Under normal conditions, the total number of leukocytes in the body is relatively stable, and changes in it can reflect the body's disease and immune stress status to a certain extent [32]. The effects of exercise training on leukocytes and their subpopulations have been widely reported, and exercise can cause an increase in peripheral blood leukocytes, depending on the intensity of the exercise and the level of training, with low-intensity exercise unlikely to result in significant changes in the number of leukocytes and their subpopulations [33]. It has been suggested that an important feature of the body's immune system response after acute exercise is an increase in the number of leukocytes in the peripheral blood, and [PERSON] et al. concluded that the effect of exercise in a hypoxic environment on leukocyte immune function is more pronounced during altitude training [34]. [PERSON] et al. reported that ten Australian swimmers and eight non-athletes who participated in the 1996 Atlanta Olympics spent 3 weeks at an altitude of 2102 m, and both groups had reduced leukocyte counts, but the athlete group was more pronounced [35]. The different results of the above studies may be related to factors such as duration and intensity of training at altitude. This study \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Project**} & \multicolumn{3}{c}{**Male**} & \multicolumn{3}{c}{**Female**} \\ \cline{2-7}  & **Before** & **After** & \(p\)**-Value** & **Before** & **After** & \(p\)**-Value** \\ \hline
30 m running/s & 4.23 \(\pm\) 0.17 & 4.23 \(\pm\) 0.16 & 0.899 & 4.84 \(\pm\) 0.11 & 4.83 \(\pm\) 0.11 & 0.847 \\ Squat/kg & 121.86 \(\pm\) 12.97 & 133.41 \(\pm\) 13.22 & 0.006 & 82.75 \(\pm\) 14.89 & 94.75 \(\pm\) 9.71 & 0.037 \\ Deadlift/kg & 79.73 \(\pm\) 7.91 & 84.86 \(\pm\) 8.37 & 0.043 & 52.50 \(\pm\) 7.45 & 53.37 \(\pm\) 6.02 & 0.800 \\
10 km running/min & 34.54 \(\pm\) 1.65 & 32.25 \(\pm\) 1.56 & 0.000 & 32.97 \(\pm\) 0.73 & 30.62 \(\pm\) 0.61 & 0.008 \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Changes in athletes’ physical and athletic performance indicators before and after subalpine training. Figure 6: Before and after training values for (**a**) deep squat and bench press; (**b**) 10 km run. found that the number of leukocytes in male athletes increased slowly with the duration of subalpine training, with a significant increase beginning in month 3 compared to the pre-subalpine period and peaking at month 5, suggesting that subalpine training can cause a significant increase in the number of leukocytes in male cross-country skiers; In female athletes, the changes were not significant in the first two months, but there were significant fluctuations between months 3-6, with a peak in leukocyte count in month 5, which may be related to changes in training intensity or duration of training. The trend of change with each time point was the same for both male and female athletes, indicating that there was no significant difference in the effect of subalpine training by gender. Red blood cells mainly reflect the number of red blood cells in athletes' circulating blood, while hemoglobin is the main component of red blood cells and an important ferritin in red blood cells, which is one of the important indicators to measure blood oxygen carrying capacity and body function [36]. The most critical factors affecting oxygen transport in blood are blood oxygen capacity and hemoglobin affinity. Increasing the number of red blood cells and hemoglobin results in greater oxygen delivery which helps to improve the aerobic exercise ability of athletes.