To investigate the protective effects of dimethyl fumarate (DMF), an agonist of nuclear factor erythroid 2-related factor 2 (NRF2), against acute lung injury (ALI) induced by high-altitude hypoxia, in order to found a basis for developing novel preventive strategies against hypoxic pulmonary injury.

① Twenty SPF-grade male Wistar rats (5 to 6 weeks old, 210 to 230 g) were randomly divided into (n=5): normoxic control (intraperitoneal injection of normal saline for 10 consecutive days followed by being placed in a normobaric normoxia chamber), hypoxic lung injury (intraperitoneal injection of normal saline for 10 consecutive days followed by being exposed to a hypobaric hypoxic chamber simulating 5 000 m altitude for 48 h), DMF control (intraperitoneal injection of DMF for 10 consecutive days followed by being placed in a normobaric normoxic chamber), and DMF prophylaxis (DMF preconditioning for 10 d followed by hypobaric hypoxic modelling) groups. HE staining was used to observe the histopathological changes in lung tissues to pathologically score the lung injury. ELISA was employed to detect the inflammatory factors to assess inflammatory responses, immunofluorescence assay was utilized to measure the generation of reactive oxygen species (ROS), and spectrophotometry was performed to determine the glutathione (GSH) and malondialdehyde (MDA) levels, as well as superoxide dismutase (SOD) activity. Western blotting and real-time polymerase chain reaction (RT-qPCR) were applied to analyze ferroptosis-related pathway proteins at protein and mRNA levels. ② Hypoxic lung injury cellular model and normoxic control model were established by co-culturing human bronchial epithelial (BEAS-2B) cells and TNF-α-activated human peripheral blood monocyte (THP-1)-derived macrophages under hypoxic and normoxic conditions for 48 h. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to compare the protein profiles in BEAS-2B cells between normoxic control and hypoxic injury groups. Bioinformatics analysis was carried out to identify the key differentially expressed proteins (DEPs). A hypoxic injury prophylaxis group was established by BEAS-2B cells being pretreated with DMF for 24 h and then co-cultured with THP-1 cells. Then the ferroptosis markers, macrophage polarization phenotypes, and inflammatory cytokines were detected in BEAS-2B cells. ③ Additionally, solute carrier family 7 member 11 (SLC7A11) gene was knocked down under DMF intervention to assess ferroptosis markers and macrophage-related inflammatory responses.

① Compared to the hypoxic injury group, the DMF prophylaxis group exhibited significantly decreased pulmonary ROS level and MDA content (P<0.05), increased SOD activity and GSH level (P<0.05), elevated expression levels of SLC7A11 and glutathione peroxidase 4 (GPX4) (P<0.05), along with markedly reduced lung injury score and inflammatory cytokine levels (P<0.05). ② Proteomic analysis identified 5 377 proteins and 613 DEPs (302 up-regulated, 311 down-regulated) in BEAS-2B cells, and among 9 ferroptosis-related DEPs, SLC7A11 exhibited the most significant alteration. In the cellular hypoxic ALI model, compared to the hypoxic injury group, DMF prophylaxis up-regulated SLC7A11 and GPX4 expression (P<0.05), increased GSH level and SOD activity, decreased the M1 macrophage ratio and inflammatory factor levels (P<0.05). ③ SLC7A11 knockdown reversed DMF’s effects by increasing MDA level (P <0.05), decreasing SOD activity and GSH level (P<0.05), suppressing GPX4 expression (P<0.05), and elevating M1 macrophage proportion and enhancing inflammatory cytokine secretion (P<0.05). Conversely, overexpression of SLC7A11 enhanced the protective effects of DMF. Compared with the hypoxia-DMF group, the hypoxia-DMF-overexpression group showed significantly increased GSH level, SOD activity, and GPX4 expression (P<0.05), along with a marked decrease in MDA content (P<0.05) in BEAS-2B cells. Meanwhile, SLC7A11 overexpression further alleviated the inflammatory response, as indicated by significantly reduced expression of IL-1β, IL-6 and TNF-α (P<0.05).

DMF attenuates high-altitude hypoxic ALI by suppressing ferroptosis in pulmonary epithelial cells via up-regulating the NRF2/SLC7A11 axis, modulating macrophage polarization, and mitigating inflammatory response, and thus, exerts a protective effect against hypoxic pulmonary injury.

To investigate the impact of a high-altitude and cold environment on skeletal muscle function and the pathological processes of osteoarthritis (OA),to elucidate the interaction mechanisms between skeletal muscle atrophy,fibrosis,and joint degeneration under cold condition,aiming to found a theoretical basis for the health protection of the musculoskeletal system in military personnel stationed in high-altitude cold regions.

Destabilization of the medial meniscus (DMM) was established on C57BL/6 mice (11 weeks old) by cutting the attaching point at the anterior intercondylar region where anterior cruciate ligament blends with the medial meniscus. Forty male C57BL/6 mice (11 weeks old) were stratified by 2 postoperative time points (8 and 12 weeks). At each time point, the mice were divided randomly divided into 4 groups (n=5):22 ℃ sham operation (22 ℃ Sham),4 ℃ sham operation (4 ℃ Sham),22 ℃ DMM,and 4 ℃ DMM. From 2 weeks after DMM modelling,the 4 ℃ Sham and 4 ℃ DMM groups were placed in a cold chamber [4 ℃,humidity (50±5)%] for 12 h per day until the respective endpoint,meanwhile,the 22 ℃ Sham and 22 ℃ DMM groups were kept at room temperature. At 8 and 12 weeks after intervention,the following assessments were carried out:① Behavioral tests:Gait parameters were quantified using the CatWalk system;Limb load-bearing capacity was evaluated with bipedal balance test;Spontaneous activity distance and time were recorded in the open field test;Twitch force and tetanic force in the quadriceps were measured,and the force-frequency curve was plotted. ② Histopathological analysis:Quadriceps and knee joint tissues were harvested,embedded in paraffin,sectioned and stained with HE and safranin O-fast green to assess synovial inflammatory cell infiltration,cartilage surface integrity,and OARSI score from Osteoarthritis Research Society International System. Additionally,Masson’s trichrome staining was applied to observe collagen deposition in muscle fibers. ③ Molecular detection:Immunofluorescence assay for dystrophin antibody was used to label muscle fiber boundaries and calculate cross-sectional area;Immunohistochemistry assay was employed to determine the expression levels of IL-1β and TNF-α in synovial tissue.

① Progressive deterioration of behavioral function:Compared with the 22 ℃ DMM group,the 4 ℃ DMM group exhibited significantly exacerbated functional impairments at both 8 and 12 weeks after intervention,in a time-dependent worsening trend. a. Loss of gait coordination: At 8 weeks,the relative stance phase time of the right hindlimb was shorten by 0.113 (P<0.001),print area was reduced by 0.102 (P<0.05),swing phase time was extended by 0.115 (P<0.05),and single-limb stand time was prolonged by 0.146 (P<0.01). These abnormalities still existed at 12 weeks,with the difference of print area expanding to 0.154 (P<0.05) and that of swing phase time maintaining an elevated magnitude of 0.113 (P<0.05). b. Decline in weight-bearing capacity:Percentage of right paw weight-bearing was decreased by 2.777% at 8 weeks (P<0.001),with the deficit further expanding to 5.156% at 12 weeks (P<0.000 1). c. Suppression of spontaneous activity:Total locomotor distance was decreased by 1 069 cm at 8 weeks (P<0.000 1) and remained reduced by 429.3 cm at 12 weeks (P<0.05). ② Exacerbation of joint histopathological damage:Cold exposure combined with DMM surgery significantly aggravated synovial inflammation and cartilage destruction. a. Synovial pathology:The 4 ℃ DMM group displayed increased synovial pathological score of 2.133 at 8 weeks (P<0.01) and then 2.833 at 12 weeks (P<0.001) relative to the 22 ℃ DMM group,indicating a sustained inflammatory response. b. Cartilage degeneration:The 4 ℃ DMM group showed the maximum score of OARSI elevated by 1.000 (P<0.05) and total score by 2.000 (P<0.01) at 8 weeks,while,at 12 weeks,the maximum score remained elevated by 0.750,and the total score maintained a differential trend of 2.000. c. Upregulation of pro-inflammatory factors:The synovial expression area of IL-1β in the 4 ℃ DMM group was increased by 1.047% (P<0.05) and 1.892% (P<0.05) at 8 and 12 weeks,respectively,and that of TNF-α expression was increased by 3.850% (P<0.000 1) and 3.806% (P<0.000 1),separately at the same time points. ③ Composite impairment of skeletal muscle structure and contractile function:Cold intervention induced triple pathological changes in quadriceps encompassing atrophy,mechanical performance decline,and fibrotic remodeling. a. Depletion of muscular force reserve:Twitch force was decreased by 34.77 mN·m/kg (P<0.01) and 52.87 mN·m/kg (P<0.05) at 8 and 12 weeks,respectively;Tetanus force was reduced by 115.0 mN·m/kg (P<0.05) and 138.3 mN·m/kg (P<0.000 1) at the same time points,with a downward shift of the force-frequency curve. b. Muscle atrophy:The mass ratio of quadriceps was decreased by 0.076% (P<0.05) and 0.102% (P<0.000 1),and the muscle fiber cross-sectional area (CSA) was reduced by 261.3 μm² (P<0.05) and 233.5 μm² (P<0.01) at 8 and 12 weeks,respectively,accompanied with an increased proportion of small-diameter fibers. c. Fibrotic deposition:Relative collagen fiber area in muscle tissue was increased by 4.072% (P<0.01) and 2.238% (P<0.05) at 8 and 12 weeks,respectively,suggesting abnormal extracellular matrix remodeling.

High-altitude cold environment not only directly aggravates synovial inflammation and cartilage degeneration in OA but also further compromises joint structure and function by inducing quadriceps atrophy, reduced muscle strength, and fibrosis.

To investigate the role and mechanism of hepatic-derived angiopoietin-like 3 (ANGPTL3) in mediating reduced cold tolerance induced by chronic hypoxic exposure.

① Male Sprague-Dawley (SD) rats (7 to 8 weeks old, weighing 220 to 260 g) were randomly divided into a normoxic group (N, housed at an ambient condition of altitude 308 m and 24.0±0.5 ℃) and a hypoxic group (H, housed in a hypobaric hypoxic chamber of simulating an altitude 5 800 m and 24.0±0.5 ℃), with 20 rats in each group. Twelve rats from each group were implanted intraperitoneally with temperature-sensing transponders for subsequent measurement of core body temperature (Tc). ② Male SD rats were randomly divided into (n=20 per group): a hypoxic (H) group and a hypoxic+ANGPTL3 inhibitor [Vupanorsen 2 mg/(kg·w)] intervention (H+V) group. Twelve rats from each group were implanted intraperitoneally with temperature-sensing transponders for subsequent Tc measurement. The rats in the H and H+V groups were all housed in a hypobaric hypoxic chamber (simulated altitude 5 800 m, 24.0±0.5 ℃). After 6 weeks, 8 non-implanted rats per group were anesthetized for blood and liver tissue collection. Serum aspartate aminotransferase (AST) level was measured using an automatic biochemical analyzer. Blood levels of hepatic factors were detected with ELISA. Hepatic mitochondrial morphology was assessed by transmission electron microscopy (TEM). Hepatic ANGPTL3 protein level was quantified by Western blotting. The 12 implanted rats from each group were exposed to either a hypoxic cold environment (5 800 m, 6 ℃ for 24 h) or a normoxic cold environment (308 m, -10 ℃ for 6 h). Tc was monitored using a physiological signal telemetry system to assess cold tolerance. Western blotting was used to detect the protein level uncoupling protein 1 (UCP1) in subcutaneous white adipose tissue as an indicator of browning potential.

① Compared to normothermic hypoxia (5 800 m, 24 ℃), the group H exhibited a significant Tc decrease during hypoxic cold exposure (5 800 m, 6 ℃) (P<0.05). ② During normoxic cold exposure (308 m, -10 ℃, 6 h), Tc was significantly decreased in both groups N and H, and it was obviously lower in the group H than the group N (P<0.05). ③ Compared to the N group, serum ANGPTL3 level (t=7.3, df=10, 95%CI: 2.553 to 2.687, P<0.000 1) and hepatic ANGPTL3 protein level (t=6.532, df=10, 95%CI: 26.98 to 54.92, P<0.000 1) were notably elevated in the group H. ④ Compared to the H group, serum ANGPTL3 level (t=7.803, df=10, 95%CI: -196.8 to -109.4, P=0.000 4) and hepatic ANGPTL3 protein level (t=3.514, df=10, 95%CI: -66.14 to -14.81. P=0.006) were remarkably decreased in the group H+V. ⑤ During normoxic cold exposure (308 m, -10 ℃, 6 h), Tc was significantly decreased in both groups H and H+V, with that of the group H+V significantly higher that of the group H (95%CI: -0.629 to -0.452, P=0.000 4). ⑥ Under hypoxic cold exposure (5 800 m, 6 ℃, 24 h), Tc was decreased significantly in both groups H and H+V, with that in the H+V group higher than that of the group H (95%CI: -0.568 to -4.431, P=0.018 1). ⑦ Compared to the N group, hepatocyte mitochondrial morphology was significantly damaged and serum AST level was significantly increased (t=14.15,df=14,95%CI:51.61 to 70.04,P<0.000 1) in the group H. ⑧ Compared to the group H, hepatocyte mitochondrial morphology was significantly improved and the serum AST level was significantly decreased (t=4.879, df=14, 95%CI: -47.24 to -18.39, P=0.000 2) in the group H+V. ⑨ Following hypoxic cold exposure (5 800 m, 6 ℃, 24 h), the protein level of UCP1 in subcutaneous white adipose tissue was significantly increased in the group H+V than the group H (t=2.26, df=10, 95%CI: 0.849 to 118.1, P=0.047).

Chronic hypoxic exposure increases hepatic ANGPTL3 production and release into blood circulation, subsequently impairing cold tolerance. This effect is mediated through ANGPTL3-induced hepatic mitochondrial damage and suppression of white adipose tissue browning potential.

To establish lethal shock models in high-altitude, high-cold, and high-heat environments based on the conventional environment hemorrhagic shock (HS) model established in our laboratory, in order to provide animal models for lethal shock treatment in special environments.

A total of 864 SPF-grade male SD rats (12 weeks old, weighing 200±20 g) were divided into high-altitude environment group (simulated 4 000 m altitude in a low-pressure oxygen chamber, exposed to 22±2 ℃ for 48 h), high-cold environment group (altitude 200 to 300 m, exposure to -20 ℃ for 6 h), high-heat environment group (altitude 200 to 300 m, exposure to 35 ℃ for 12 h), and conventional environment control group (no environmental pretreatment) according to different environmental pretreatment, with 216 animals in each group. After environmental pre-conditioning, 4 types of spleen injury methods were used to induce free intra-abdominal bleeding to construct corresponding uncontrolled HS model. The injury methods were as follows: ① Transverse transection at 3 cm away from the end of the splenic parenchyma; ② Transverse transection separately at 3 and 5 cm away from the end of the splenic parenchyma; ③ Transverse arteriotomy of a small arterial branch at the splenic tail; ④ Transverse arteriotomy of a small arterial branch at the splenic tail combined with transection at 3 cm away from the end of the splenic parenchyma. Free intra-abdominal bleeding was induced by above 4 methods until the mean arterial pressure (MAP) dropped to 40 mmHg, which was defined as successful establishment of the uncontrolled HS model. After successful modeling, lactated Ringer’s (LR) solution was employed to maintain MAP at 50 to 60 mmHg at low pressure for 1 h. After the splenic artery was ligated for complete hemostasis, definitive resuscitation was obtained with LR solution of 2×blood loss volume. MAP, respiratory rate (RR) and heart rate (HR) were monitored, cardiac function [troponin I (TnI)], liver function [aspartate aminotransferase （AST）， alanine aminotransferase（ALT）］、and renal function ［blood urea nitrogen （BUN）， serum creatinine （Scr）］ were evaluated, survival time was observed, and 6-hour survival rate was calculated to screeen the appropriate modeling methods for each environment. Then the obtained modeling methods were applied on Bama pigs to establish HS models for high-altitude, high-cold, and high-heat environments, respectively. After modelling, the pigs were resuscitated according to the aforementioned treatment regimens, and basic physiological indicators (MAP, RR, HR), organ functions (heart, liver, kidney), and survival status were observed to verify the stability of the modeling methods.

There were differences in the appropriate modeling methods for different environments: the conventional environment preferred method ④, the high-altitude environment preferred method ③, the high-cold environment preferred method ①, and the high-heat environment preferred method ②. All the above methods met the model standards of a 6-hour mortality rate >70% after shock, a blood loss >50% after low-pressure resuscitation, and a survival rate >50% after definitive resuscitation. In the state of shock, the MAP of rats was significantly reduced in each group (P<0.001), RR and HR were abnormally changed, the indicators of cardiac, liver, and renal functions (TnI, AST, ALT, BUN, Scr) (P<0.05) were significantly increased, and the survival time was obviously shortened. After LR low-pressure resuscitation combined with definitive resuscitation, the MAP was notably recovered (P<0.01), the organ function indicators were significantly improved, and the survival time was greatly prolonged. The verification results in Bama miniature pigs showed that in the shock group, MAP was decreased to approximately 40 mmHg, RR was significantly reduced, HR was increased, the 6-hour survival rate was 0%, and the indicators of cardiac, liver, and renal functions (TnI, AST, ALT, BUN, and Scr) were notbly elevated (P<0.001). In the resuscitation group, the MAP was significantly increased to 58.6 to 68.4 mmHg (P<0.01), the 6-hour survival rate reached 50.00% to 56.25%, and organ functions were significantly improved. All these findings confirmed the reliability of each model.

Lethal shock models under high-altitude, high-cold, and high-heat environments are successfully established, respectively, and the appropriate standardized modeling methods are identified for each environment. The modelling methods are further verified on Bama miniature pigs, and the constructed models have advantages of stability and reliability for laboratory requirements.

To systematically investigate the metabolic characteristics of hemorrhagic shock (HS) under simulated high-altitude conditions by integrating metabolomics and machine learning algorithms, and screen the biomarkers for predicting HS under these conditions.

Eighty SPF-grade male SD rats (10 to 12 weeks old, weighing 180 to 220 g) were randomly divided into a sham operation group (Sham) and an uncontrolled HS group (UHS), with 40 animals in each group. All rats were placed in a hypobaric hypoxia chamber to simulate an altitude of 5 000 m for 48 h. After removal from the chamber, the rats were given an injection of oleic acid immediately via tail vein, and then in 30 min latter, those from the UHS group were induced to free bleeding by splenic artery transection, with the endpoint set at a mean arterial pressure (MAP) of 40 mmHg. Thus, a rat model of HS under stimulated high-altitude conditions was established. Metabolomic analysis was performed on the serum samples to identify differential metabolites between the Sham and UHS groups. Weighted gene co-expression network analysis (WGCNA) was carried out to identify metabolites associated with UHS. Three machine learning methods, including least absolute shrinkage and selection operator (Lasso) regression, random forest (RF), and support vector machine-recursive feature elimination (SVM-RFE) were employed to identify relevant biomarkers for HS at high-altitude. Based on 10-fold cross-validation, the diagnostic performance of the biomarkers was evaluated with receiver operating characteristic (ROC) curve analysis, and the area under the curve (AUC) was calculated.

Principal component analysis (PCA) of the metabolomic data showed clear separation between the samples from the Sham and UHS groups. Orthogonal partial least squares-discriminant analysis (OPLS-DA) further confirmed significant differences in metabolic profiles between the 2 groups. There were 5 398 metabolites identified, with the UHS group having 391 metabolites significantly down-regulated (VIP>1, FC<1/1.5, P<0.05) and 1 181 metabolites obviously up-regulated (VIP>1, FC>1.5, P<0.05) when compared to the Sham group. Among the metabolites, the most altered metabolites were lipids, including FFA (18:2), FFA (18:1), FFA (12:0), FFA (14:0), ergosterol, mesaconic acid, suberic acid, gamma-linolenic acid, and PC [22:5 (4Z, 7Z, 10Z, 13Z, 16Z)/22:6 (4Z, 7Z, 10Z, 13Z, 16Z, 19Z)], and then followed by organic acids and derivatives, such as methionine, citrulline, creatine, L-lactic acid, oxalacetic acid, and 2-acetolactate. Pathway enrichment analysis showed that these differential metabolites were mainly involved in glutamine metabolism, taurine metabolism, alanine, aspartate and glutamate metabolism, as well as glycerophospholipid metabolism. WGCNA analysis found that MEturquoise module exhibited the strongest positive correlation with UHS (R=0.95, P=8e-40), while the MEsalmon module showed the strongest negative correlation with UHS (R=-0.67, P=2e-11). With thresholds of |Gene Significance (GS)|>0.2 and |Module Membership (MM)|>0.8, 344 characteristic metabolites were identified, and all of them were significantly associated with HS in a high-altitude environment. The 3 machine learning algorithms yielded 3 biomarkers, that is, methionine, D-inositol-4-phosphate and phosalone. Significantly increased D-inositol-4-phosphate and phosalone while decreased methionine were observed in the UHS group than the Sham group. ROC curve analysis revealed that the AUC values of D-inositol-4-phosphate, phosalone and methionine were 0.988, 0.950 and 0.988, respectively, indicating that the 3 biomarkers having good predictive efficiency for HS under simulated high-altitude condition.

HS rats under simulated high-altitude conditions present significantly disturbed metabolic profiles, characterized by substantial changes across multiple pathways. The metabolites D-inositol-4-phosphate, phosalone and methionine may serve as potential biomarkers for predicting the occurrence or evaluating the severity of HS in high-altitude environments.

To explore the impact of living at high altitudes for 1.5 years on the retinal blood vessels among healthy non-Tibetan young males and to screen related hematological and physiological indicators, providing a basis for increasing the eye examination items in high-altitude regions.

A cross-sectional survey design was employed. Data screening and collation were conducted between September 2024 and September 2025. The study subjects comprised non-Tibetan young adult males who, by December 2024, had been residing continuously at an altitude of 4 100 m for 1.5 years. Among the 180 participants, 65 had retinal vascular abnormalities and 115 were normal. Two independent samples rank-sum test and multivariate logistic regression analysis were performed to analyze the association between the hematological and physiological indicators and retinal vascular abnormalities.

The incidence of retinal vascular abnormalities was 36.11%. Two independent samples rank-sum test showed no statistical difference between the 2 groups in chronic mountain sickness (CMS) (P=0.527), while the P-values less than 0.2 were observed in term of heart rate (P=0.033), average visual reaction time (P=0.07), γ-glutamyl transferase (P=0.18), total cholesterol (P=0.033), triglycerides (P=0.149), low-density lipoprotein (P=0.095), platelet count (P=0.141), and plateletcrit (P=0.066). Multivariate logistic regression analysis revealed that heart rate (OR=1.033, 95%CI: 1.003 to 1.064, P=0.033) and total cholesterol (OR=1.868, 95%CI: 1.004 to 3.477, P=0.049) were positively, while average visual reaction time (OR=0.035, 95%CI: 0.002 to 0.723, P=0.03) was negatively correlated with the risk of retinal vascular changes.

The incidence of retinal vascular abnormalities is relatively high among healthy young men who have resided in high-altitude areas for 1.5 years. Increased heart rate and elevated total cholesterol level are independent risk factors for retinal vascular changes, while prolonged visual reaction time is associated with a reduced risk of such changes. Countermeasures Regular fundus photography helps identify retinal vascular changes at an early stage, which has important clinical significance for preventing the occurrence and development of high-altitude-related retinopathy and even high-altitude cerebral edema. It is recommended to include fundus photography in the health monitoring system for personnel residing in high-altitude areas.

To investigate the incidence of functional constipation (FC) in troops stationed at plateau, to explore the rules and features of FC occurring in high altitude, and to analyze related factors and develop prevention and treatment measures.

A survey was carried out during May and August 2024 with Rome Ⅲ diagnostic criteria, symptom checklist-90 (SCL-90) and self-designed questionnaires on the soldiers who had been stationed in the highland area (5 100 m) for more than 6 months subjected with stratified cluster random sampling. A total of 770 questionnaires were distributed, and 765 ones were recovered. These questionnaires mainly included a retrospective survey on constipation symptoms, and 9 related factors were evaluated. Univariate and multivariate logistic regression analyses were applied to identify the independent influencing factors for FC.

Totally 765 valid questionnaires were collected, and the incidence of FC was 15.8%. Logistic regression analysis showed that lack of dietary fiber (OR=4.347, 95%CI: 2.749 to 6.873), anxiety (OR=3.625, 95%CI: 2.279 to 5.766), frequent suppression of defecation (OR=2.869, 95%CI: 1.846 to 4.458), insufficient oxygen intake (OR=2.664, 95%CI: 1.712 to 4.145) and lack of exercise (OR=2.346, 95%CI: 1.429 to 3.849) were the potential risk factors for FC (P<0.01).

The incidence of FC is 15.8% among high-altitude officers and soldiers, and its main risk factors are lack of dietary fiber, anxiety, frequent restraint of defecation, insufficient oxygen intake, and lack of exercise. Countermeasures High priority should be given to the issue of FC among plateau-stationed troops. Following comprehensive interventions are recommended: ① Improve environmental and managerial conditions by optimizing accommodation facilities, daily schedules, and ensuring adequate time of oxygen supply; ② Promote healthy behaviors through dietary restructuring, increased fiber and water intake, scientifically planned physical activities, and avoidance of prolonged sitting and deliberate suppression of bowel movements; ③ Strengthen psychological support by implementing mental health counseling to alleviate anxiety; ④ Standardize medical interventions with appropriate pharmacological assistance when necessary. Through multidimensional and systematic health management, the incidence of functional constipation can be effectively reduced, thereby safeguarding both the physical and mental well-being of the troops and maintaining combat readiness.

To explore the group characteristics of emotion regulation strategies and their mediating mechanism between psychological stress and sleep disorders among military personnel stationed at altitudes.

A cross-sectional study was conducted on 401 servicemen subjected with convenience sampling from a troop stationed at Garze Tibetan Autonomous Prefecture, Sichuan Province (3 980 to 4 200 m) during December 2024 and April 2025. Psychological stress self-evaluation test for military personnel (PSET), emotion regulation questionnaire (ERQ), and Pittsburgh sleep quality index (PSQI) were used for evaluation. Structural equation modeling was employed to analyze the mediating effects of emotion regulation strategies between psychological stress and sleep disorders.

The incidence of sleep disorders was 20.2% among ultra-high-altitude military personnel, and the incidence of mild sleep disorder 18.45%. Sleep disorder total score showed significant positive correlations with expressive suppression and psychological stress (r=0.23, 0.53, P<0.01). Expressive suppression played a partial positive mediating role between psychological stress and sleep disorders, accounting for 3.63% of the total effect.

The frequency of using emotion regulation strategy among ultra-high-altitude stationed military personnel is increased with rising psychological stress levels. It is recommended to implement alternative training targeting expressive suppression strategies for high-stress groups in order to improve sleep disorders.