###### Abstract  
Purpose: This study investigated the changes in the blood indices, specific athletic abilities, and physical fitness of outstanding cross-country skiers, trained in the subalpine; Methods: Twenty-eight athletes (twenty males and eight females) from the National Cross-country Ski Training Team completed sub-alpine training during the 2020-2021 snow season. The athletes' physical functions were evaluated by collecting blood from elbow veins and measuring blood biochemical indexes. To compare the treadmill roller-skining athletic ability and physical fitness of athletes before and after subalpine; Results: Male and female athletes showed different trends in red blood cells (RBC), hemoglobin (Hb), cortisol (C), Creatine Kinase (CK) and blood urea (BU) (\(p\) < 0.05 or \(p\) < 0.01). Overall, the female athletes' mean values of RBC, Hb, CK, and BU were lower than that of male athletes, while C was just the opposite. Comparing the athletic performance of athletes before and after the subalpine, it was found that blood lactate concentrations were significantly lower in both male and female athletes at the same load intensity (\(p\) < 0.05 or \(p\) < 0.01), whereas 10 km endurance running and 1 RM deep squat were significantly higher in both male and female athletes (\(p\) < 0.05 or \(p\) < 0.01). Conclusions: After 6 months of subalpine training, cross-country skiers improved their oxygen-carrying capacity and anabolism, and showed significant improvements in specific athletic ability, physical endurance, acid tolerance and 1 RM absolute strength for both male and female athletes. In recent years, many researchers in different sports have started to explore subalpine training (1300-1800 m). From the point of view of combining physiological functions and sports training [10], subalpine training provides a certain degree of hypoxia stimulation while maintaining the intensity of training on the plains, so that athletes receive sufficient intensity stimulation, avoiding the disadvantages of traditional plateau training in terms of degradation of athletic performance [11; 12]. Research has demonstrated that subalpine training can improve the oxygen-carrying capacity of female athletes in the national modern pentathletes and swimmers, having a stimulating effect on their anabolism [13; 14] and can enhance the aerobic capacity of rowers and figure skaters and have a positive effect on their physical function [15; 16]. Currently, not much research has been conducted on cross-country skiing training on subalpine plateaus, except for some early reports on cross-country skiing training on plateaus, which demonstrated that plateau training can effectively promote cross-country skiers' physical function [17]. [PERSON], [PERSON] et al. showed that when athletes stay at subalpine (1500-2000 m) day and night for training, it is very effective for athletes' improvement; it is recommended that when arranging subalpine cycle training, athletes need to follow the basic phase of pre-season training process when they reach the maximum (volume) training load. It is considered that usually the duration of subalpine training is generally 7 to 21 days, depending on the specific goals of the training [18]. In sports training, functional state refers to the level or state of readiness of the athlete's body for training or competition. For endurance sports, the scientific diagnosis of sports fatigue and monitoring of functional state is key to athletic performance, and the use of classical physiological and biochemical indicators to monitor athletes' functional states has become an integral part of training in endurance sports [19].