Metastatic dissemination is the major cause of death from breast-cancer (BC). Fusobacterium nucleatum (F.n) is widely enriched in BC and has recently been identified as one of the high-risk factors for promoting BC metastasis. Here, with an experimental model, we demonstrated that intratumoral F.n induced BC aggressiveness by transcriptionally activating Epithelial-mesenchymal transition-associated genes. Therefore, the F.n may be a potential target to prevent metastasis. Given the fact that cancer-associated fibroblasts (CAFs) are abundant in BC and located near blood vessels, we report an optogenetic system that drives CAF to in situ produce human antibacterial peptide LL37, with the characteristics of biosafety and freely intercellular trafficking, for depleting intratumoral F.n, leading to a 72.1% reduction in lung metastatic nodules number without affecting the balance of the systemic flora. Notably, mild photothermal treatment was found that could normalize CAF, contributing to synergistically inhibiting BC metastasis. In addition, the system can also simultaneously encode a gene of TNF-related apoptosis-inducing ligand to suppress the primary tumor. Together, our study highlights the potential of local elimination of tumor pathogenic bacteria to prevent BC metastasis.

BACKGROUND:Relatively or absolutely active bone resorption function of osteoclasts is one of the causative factors of osteoporosis. Therefore,how to inhibit the formation of osteoclasts and reduce the bone resorption activity is a key element in the prevention and treatment of osteoporosis. Liquiritin,which is derived from licorice,plays a role in the clinical treatment of bone diseases,but there are fewer studies addressing the application of liquiritin in osteoporosis and the mechanism is unknown.OBJECTIVE:To confirm,through both in vivo and in vitro experiments,that liquiritin inhibits osteoclast differentiation and alleviates bone loss.METHODS:Cell counting kit-8 was used to detect whether Liquiritin exerts toxic or proliferative effects on mouse bone marrow-derived macrophages,and tartrate-resistant acid phosphatase staining was performed to observe the effect of liquiritin in inhibiting osteoclast differentiation. The affinity of liquiritin binding to proteins related to osteoclast differentiation was verified by network pharmacology. RT-PCR and western blot assays were performed to detect the inhibitory effects of liquiritin on osteoclast-specific protein and gene expression as well as relevant signaling pathways. Finally,the mitigating effect of liquiritin on bone loss was verified in the C57BL/6J mouse osteoporosis model.RESULTS AND CONCLUSION:Liquiritin,at concentrations of 20 μmol/L and below,could inhibit the formation and differentiation of osteoclasts. Concurrently,it exhibited a high affinity with osteoclast-specific proteins such as nuclear factor of activated T-cells 1,Cathepsin K,c-Fos,and matrix metalloproteinase 9,and reduced the relative expression levels of these genes and proteins. Liquiritin could also effectively lower the phosphorylation expression level of JNK in the MAPK signaling pathway at the 15th,30th,45th,and 60th minutes,and it could salvage the degradation of nuclear factor-κB inhibitor α in the nuclear factor-κB signaling pathway at the 60th minute. In vivo experiments demonstrated that liquiritin could mitigate bone loss caused by osteoclasts and improve parameters related to trabecular bone. To conclude,liquiritin possesses the capacity to inhibit osteoclast differentiation and alleviate bone loss,thereby exerting a protective role against osteoporosis.

BACKGROUND:Relatively or absolutely active bone resorption function of osteoclasts is one of the causative factors of osteoporosis. Therefore,how to inhibit the formation of osteoclasts and reduce the bone resorption activity is a key element in the prevention and treatment of osteoporosis. Liquiritin,which is derived from licorice,plays a role in the clinical treatment of bone diseases,but there are fewer studies addressing the application of liquiritin in osteoporosis and the mechanism is unknown.OBJECTIVE:To confirm,through both in vivo and in vitro experiments,that liquiritin inhibits osteoclast differentiation and alleviates bone loss.METHODS:Cell counting kit-8 was used to detect whether Liquiritin exerts toxic or proliferative effects on mouse bone marrow-derived macrophages,and tartrate-resistant acid phosphatase staining was performed to observe the effect of liquiritin in inhibiting osteoclast differentiation. The affinity of liquiritin binding to proteins related to osteoclast differentiation was verified by network pharmacology. RT-PCR and western blot assays were performed to detect the inhibitory effects of liquiritin on osteoclast-specific protein and gene expression as well as relevant signaling pathways. Finally,the mitigating effect of liquiritin on bone loss was verified in the C57BL/6J mouse osteoporosis model.RESULTS AND CONCLUSION:Liquiritin,at concentrations of 20 μmol/L and below,could inhibit the formation and differentiation of osteoclasts. Concurrently,it exhibited a high affinity with osteoclast-specific proteins such as nuclear factor of activated T-cells 1,Cathepsin K,c-Fos,and matrix metalloproteinase 9,and reduced the relative expression levels of these genes and proteins. Liquiritin could also effectively lower the phosphorylation expression level of JNK in the MAPK signaling pathway at the 15th,30th,45th,and 60th minutes,and it could salvage the degradation of nuclear factor-κB inhibitor α in the nuclear factor-κB signaling pathway at the 60th minute. In vivo experiments demonstrated that liquiritin could mitigate bone loss caused by osteoclasts and improve parameters related to trabecular bone. To conclude,liquiritin possesses the capacity to inhibit osteoclast differentiation and alleviate bone loss,thereby exerting a protective role against osteoporosis.

BACKGROUND:Osteoporosis vertebral compression fracture is a common fracture secondary to osteoporosis,and there is currently a lack of effective predictive indicators and methods for osteoporosis vertebral compression fracture. OBJECTIVE:To investigate the predictive effects of paravertebral muscle degeneration,functional cross-sectional area,and percentage of fat infiltration on osteoporotic vertebral compression fractures. METHODS:The 224 patients with osteoporosis diagnosed from January 2018 to June 2022 were included.They were followed up for more than 2 years.They were divided into fracture group and non-fracture group according to the presence and absence of vertebral fracture.The detailed information of demographics,body mass index,bone mineral density and so on were collected.The functional cross-sectional area and percentage of fat infiltration of bilateral Psoas major muscle and extensor dorsi(Erector spinae muscles muscle and multifidus muscle)at the level of lower endplate of L2 vertebral body were measured and calculated. RESULTS AND CONCLUSION:(1)224 patients were ultimately included,of which 126 had fractures as the fracture group and 98 had no fractures as the non-fracture group.There was no statistically significant difference in age,gender,height,body mass,body mass index,and fracture segment between the two groups(P>0.05).(2)The bone mineral density of the fracture group was significantly lower than that of the non-fracture group(P<0.05).Functional cross-sectional areas of Psoas major muscle and extensor dorsi in the fracture group were significantly lower than those in the non-fracture group(P<0.05).The percentage of fat infiltration of the extensor dorsi in the fracture group was significantly higher than that in the non-fracture group(P<0.05).There was no significant difference in percentage of fat infiltration of Psoas major muscle between the two groups(P>0.05).(3)Receiver operating characteristic analysis showed that the vertebral bone mineral density,percentage of fat infiltration of extensor dorsi,functional cross-sectional area of extensor dorsi and percentage of fat infiltration of Psoas major muscle were 0.903 g/cm2,35.426%,418.875 mm2,and 6.375%,respectively.The areas under curve were 0.634,0.755,0.876,and 0.585,respectively.(4)These findings indicate that paravertebral muscle degeneration is strongly associated with the occurrence of osteoporotic vertebral compression fractures.The functional cross-sectional area of extensor dorsi muscle can effectively predict the occurrence of osteoporotic vertebral compression fractures,which is helpful for early prevention and treatment of osteoporotic vertebral compression fractures.

BACKGROUND:The problem of intervertebral disc injury and degeneration has been studied in many ways.Many studies have shown that intervertebral disc injury and degeneration is driven by mechanical loading factors.However,the potential relationship between common phenotypes of intervertebral disc injury and degeneration and mechanical loading factors has been rarely summarized. OBJECTIVE:To summarize the types of common structural abnormalities exhibited by intervertebral disc injury and degeneration in the published literature,and sum up the potential links to the types of mechanical loading that lead to these structural abnormalities in in vitro and ex vivo experimental studies. METHODS:Using the terms"intervertebral disc failure,intervertebral disc injury,mechanical load,mechanical factor,load factor,biomechanics"as Chinese and English key words in PubMed,CNKI,and WanFang databases,articles related to intervertebral disc injury degeneration and mechanical load factors were retrieved.Literature screening was performed according to the inclusion and exclusion criteria,and 88 articles were finally included. RESULTS AND CONCLUSION:(1)Common structural abnormalities of intervertebral discs include decreased intervertebral disc height,disc bulge,osteophyte formation,annulus fibrosus tear,intervertebral disc herniation or disc prolapse,endplate damage,Schmorl nodes and intervertebral disc calcification.Intervertebral discs are susceptible to mechanical load types such as compression,bending,axial rotation,and compound loads.(2)The compressive load mainly causes the decrease of the proteoglycan content and the water-binding ability of the intervertebral disc,leading to the decrease or swelling of the intervertebral disc and further damage and degeneration of the intervertebral disc.In addition,the excessive compressive load causes greater damage to the endplate.(3)Bending load and axial rotation load damage the annulus fibrosus more than the endplate,and prolonged or repeated bending loads can cause tearing of the fibrous annulus and herniation or prolapse of the intervertebral disc,while pure axial rotation loads can induce less damage to the intervertebral disc and only cause the tear of the annulus fibrosus.(4)However,when different load types act in combination,it is more likely to result in high stress on the disc and a greater risk of disc injury.(5)Injury and degeneration of the intervertebral disc present progressive structural damage,and early prevention and protection are particularly important in clinical practice.Future tissue engineering research can start with early repair of the intervertebral disc.

Objective::This study aimed to determine the likelihood of gestational diabetes mellitus (GDM) in subsequent pregnancy among women without GDM history and to identify risk factors for GDM in subsequent pregnancy.Methods::This retrospective cohort study involved participants who delivered twice in same hospital of 18 research centers when delivered the second baby from January 2018 to December 2018. Finally 6204 women were enrolled and 5180 women without GDM history were analyzed further. Women were categorized as non-GDM or GDM based on the blood glucose values of the subsequent pregnancy, and the characteristics and GDM risk of these groups were compared. A univariate analysis of potential risk factors was performed using the Chi-squared test and/or t-test for qualitative or quantitative variables, respectively. Associations with P values <0.1 were chosen to be included in the multivariate binary logistic regression model. Results::In primary analysis of 6204 women, the incidence of GDM in subsequent pregnancy is 48.9% (490/1002) in women with GDM history and 16.1% (835/5202) in women without GDM history. In a further analysis for 5180 women without GDM at index pregnancy, compared with the non-GDM group, the GDM group had a significantly higher age, prepregnancy body mass index, and blood glucose value at each oral glucose tolerance test (OGTT) timepoint (fasting, 1 h and 2 h) during the index and subsequent pregnancies, as well as higher weight retention during the interval between the two pregnancies ( P<0.001). Age above 35 years in subsequent pregnancy (odds ratio ( OR)=1.540, 95% confidence interval ( CI) = 1.257-1.886, P<0.001), macrosomia in index pregnancy ( OR=1.749, 95% CI=1.277-2.395, P=0.001), OGTT blood glucose values in index pregnancy (fasting, OR=2.487, 95% CI=1.883-3.285, P<0.001; 1 h, OR=1.142, 95% CI=1.051-1.241, P=0.002; 2 h, OR=1.290, 95% CI=1.162-1.432, P<0.001) and weight retention ( OR=1.052, 95% CI=1.035-1.068, P<0.001) were independent risk factors for GDM in subsequent pregnancy. Conclusion::For women without GDM history, GDM risk factors including age, macrosomia history, OGTT value, and weight retention, these can be evaluated before a subsequent pregnancy. Early warning and interventions are needed for women at high risk.

Objective::This study aimed to determine the likelihood of gestational diabetes mellitus (GDM) in subsequent pregnancy among women without GDM history and to identify risk factors for GDM in subsequent pregnancy.Methods::This retrospective cohort study involved participants who delivered twice in same hospital of 18 research centers when delivered the second baby from January 2018 to December 2018. Finally 6204 women were enrolled and 5180 women without GDM history were analyzed further. Women were categorized as non-GDM or GDM based on the blood glucose values of the subsequent pregnancy, and the characteristics and GDM risk of these groups were compared. A univariate analysis of potential risk factors was performed using the Chi-squared test and/or t-test for qualitative or quantitative variables, respectively. Associations with P values <0.1 were chosen to be included in the multivariate binary logistic regression model. Results::In primary analysis of 6204 women, the incidence of GDM in subsequent pregnancy is 48.9% (490/1002) in women with GDM history and 16.1% (835/5202) in women without GDM history. In a further analysis for 5180 women without GDM at index pregnancy, compared with the non-GDM group, the GDM group had a significantly higher age, prepregnancy body mass index, and blood glucose value at each oral glucose tolerance test (OGTT) timepoint (fasting, 1 h and 2 h) during the index and subsequent pregnancies, as well as higher weight retention during the interval between the two pregnancies ( P<0.001). Age above 35 years in subsequent pregnancy (odds ratio ( OR)=1.540, 95% confidence interval ( CI) = 1.257-1.886, P<0.001), macrosomia in index pregnancy ( OR=1.749, 95% CI=1.277-2.395, P=0.001), OGTT blood glucose values in index pregnancy (fasting, OR=2.487, 95% CI=1.883-3.285, P<0.001; 1 h, OR=1.142, 95% CI=1.051-1.241, P=0.002; 2 h, OR=1.290, 95% CI=1.162-1.432, P<0.001) and weight retention ( OR=1.052, 95% CI=1.035-1.068, P<0.001) were independent risk factors for GDM in subsequent pregnancy. Conclusion::For women without GDM history, GDM risk factors including age, macrosomia history, OGTT value, and weight retention, these can be evaluated before a subsequent pregnancy. Early warning and interventions are needed for women at high risk.

Objective:To explore the effects of interpregnancy interval (IPI) on pregnancy outcomes of subsequent pregnancy.Methods:A multicenter retrospective study was conducted in 21 hospitals in China. Information of age, height, pre-pregnancy weight, IPI, history of diseases, complications of pregnancy, gestational age of delivery, delivery mode, and pregnancy outcomes of the participants were collected by consulting medical records of pregnant women who had two consecutive deliveries in the same hospital during 2011 to 2018. The participants were divided into 4 groups according to IPI:<18 months, 18-23 months, 24-59 months and ≥60 months. According to the WHO′s recommendation, with the IPI of 24-59 months group as a reference, to the effects of IPI on pregnancy outcomes of subsequent pregnancy were analyzed. Stratified analysis was further carried out based on age, history of gestational diabetes mellitus (GDM), macrosomia, and premature delivery, to explore the differences in the effects of IPI on pregnancy outcomes among women with different characteristics.Results:A total of 8 026 women were included in this study. There were 423, 623, 5 512 and 1 468 participants in <18 months group, 18-23 months group, 24-59 months group and ≥60 months group, respectively. (1) The age, pre-pregnancy body mass index (BMI), history of cesarean section, GDM, gestational hypertension and cesarean section delivery rate of <18 months group, 18-23 months group, 24-59 months group and ≥60 months group were gradually increased, and the differences were statistically significant ( P<0.05). (2) After adjusting for potential confounding factors, compared with women in the IPI of 24-59 months group, the risk of premature delivery, premature rupture of membranes, and oligohydramnios were increased by 42% ( OR=1.42, 95% CI: 1.07-1.88, P=0.015), 46% ( OR=1.46, 95% CI: 1.13-1.88, P=0.004), and 64% ( OR=1.64, 95% CI: 1.13-2.38, P=0.009) respectively for women in the IPI≥60 months group. No effects of IPI on other pregnancy outcomes were found in this study ( P>0.05). (3) After stratified by age and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of oligohydramnios for women with advanced age ( OR=2.87, 95% CI: 1.41-5.83, P=0.004); and <18 months could increase the risk of premature rupture of membranes for women under the age of 35 ( OR=1.59, 95% CI: 1.04-2.43, P=0.032). Both the risk of premature rupture of membranes ( OR=1.58, 95% CI: 1.18-2.13, P=0.002) and premature delivery ( OR=1.52, 95% CI: 1.07-2.17, P=0.020) were significantly increased in the IPI≥60 months group. After stratified by history of GDM and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would lead to an increased risk of postpartum hemorrhage for women with a history of GDM ( OR=5.34, 95% CI: 1.45-19.70, P=0.012) and an increased risk of premature rupture of membranes for women without a history of GDM ( OR=1.44, 95% CI: 1.10-1.90, P=0.009). After stratified by history of macrosomia and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months could increase the proportion of cesarean section for women with a history of macrosomia ( OR=4.11, 95% CI: 1.18-14.27, P=0.026) and the risk of premature rupture of membranes for women without a history of macrosomia ( OR=1.46, 95% CI: 1.12-1.89, P=0.005). After stratified by history of premature delivery and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of premature rupture of membranes for women without a history of premature delivery ( OR=1.47, 95% CI: 1.13-1.92, P=0.004). Conclusions:Both IPI≥60 months and <18 months would increase the risk of adverse pregnancy outcomes in the subsequent pregnancy. Healthcare education and consultation should be conducted for women of reproductive age to maintain an appropriate IPI when they plan to pregnant again, to reduce the risk of adverse pregnancy outcomes in the subsequent pregnancy.

Objective To explore the relationship between training burnout, sleep quality and heat regulation response, severe heatstroke in people performed 5-km armed cross-country training. Methods 600 male officers and soldiers who participated in 5-km armed cross-country training in summer from 2017 to 2018 were enrolled. All trainees participated in 5-km armed cross-country training in environment with ambient temperature > 32 ℃ and (or) humidity > 65%. They were divided into two groups according to whether severe heatstroke occurred during 5-km armed cross-country training. The age, military age, body mass index (BMI), physical fitness score, external environment (such as ambient temperature, relative humidity, wind speed, heat index), training burnout score and Pittsburgh sleep quality index scale (PSQI) score, heart rate (HR), core temperature (Tc), sweating volume and serum Na+, K+, Cl- levels were compared between the groups. The risk factors of severe heatstroke during 5-km armed cross-country training were screened by binary multivariate Logistic regression analysis. Results There were 26 cases of severe heatstroke in 600 trainees who participated in 5-km armed cross-country training, with an incidence of 4.33%. There was no significant difference in age, military age, BMI, physical fitness score and external environment of 5-km armed cross-country training between people with or without severe heatstroke. Compared with those without severe heatstroke, the dimensions of training burnout and the total average scores of training burnout of severe heatstroke personnel before 5-km armed cross-country training were increased significantly (physical and mental exhaustion score: 12.4±2.5 vs. 9.4±3.5, training alienation score: 8.8±2.8 vs. 5.8±2.3, low sense of achievement score: 8.2±2.7 vs. 5.6±2.3, total score of training burnout: 9.8±3.2 vs. 6.9±3.2, all P < 0.01), all factors except daytime dysfunction (DD) of PSQI and total PSQI score were also increased significantly [sleep quality (SQ) score: 1.0 (1.0, 2.0) vs. 1.0 (1.0, 1.0), fall asleep time (SL) score: 2.0 (1.0, 3.0) vs. 1.0 (1.0, 1.0), sleep time (SH) score: 1.0 (0.8, 2.0) vs. 1.0 (0, 1.0), sleep efficiency (SE) score: 1.0 (0, 1.0) vs. 0 (0, 0.8), sleep disorder (SD) score: 2.0 (1.0, 3.0) vs. 1.0 (0, 2.0), total PSQI score: 1.0 (1.0, 2.0) vs. 1.0 (0, 1.0), all P < 0.01], HR was increased significantly at onset (bpm: 120.00±10.57 vs. 86.49±14.91, P < 0.01), Tc was increased significantly (℃: 41.46±0.57 vs. 37.97±0.83, P < 0.01), serum electrolyte contents were decreased significantly [Na+ (mmol/L): 130.54±5.97 vs. 143.15±10.56, K+ (mmol/L): 3.72±0.44 vs. 4.37±0.50, Cl- (mmol/L):97.58±4.80 vs. 102.10±2.39, all P < 0.01], and the amount of sweat during training was increased significantly (g: 395.81±16.16 vs. 371.88±40.76, P < 0.01). Binary multivariate Logistic regression analysis showed that total score of training burnout [odd ratio (OR) = 0.653, 95% confidence interval (95%CI) = 0.563-0.757], total PSQI score (OR =0.693, 95%CI = 0.525-0.916), HR (OR = 0.871, 95%CI = 0.838-0.908), Tc (OR = 0.088, 95%CI = 0.043-0.179), sweating volume (OR = 0.988, 95%CI = 0.979-0.997), Na+ (OR = 1.112, 95%CI = 1.069-1.158), K+ (OR = 13.900, 95%CI = 5.343-36.166), Cl- (OR = 1.393, 95%CI = 1.252-1.550) were independent risk factors for severe heatstroke during 5-km armed cross-country training (all P < 0.01). Conclusion Increase in training burnout, total PSQI score, excessive changes of body heat regulation response and excessive loss of Na+, K+, Cl- in serum are independent risk factors for severe heatstroke during 5-km armed cross-country training under the same conditions with high temperature and humidity environment.

To explore the effects of different fluid replenishment methods on the internal environment, body thermal regulatory response and severe heatstroke of 5-km armed cross-country training soldiers. Methods A Special Force officers and soldiers who participated in 5-km armed cross-country training (2-3 times a week, 25-30 minutes each time for 3 weeks) during summer training from June to July in 2018 were enrolled, and they were divided into three groups according to the random number table, with 300 trainees in each group. 200 mL of drinking fluids were given to each group 15 minutes before and after each 5-km armed cross-country training: A group with boiled water, B group with purified water, and C group with beverage prepared by pharmaceutical laboratory of the 990th Hospital of PLA Joint Logistics Support Force (100 mL containing 6 g carbohydrates, 42 mg sodium, and 11 mg potassium). The venous blood was collected before and after the last training or during the onset of severe heatstroke to do the following tests: serum cardiac troponin I (cTnI, chemiluminescence), MB isoenzyme of creatine kinase (CK-MB, immunosuppressive), serum creatinine (SCr, enzymatic method), urea nitrogen (BUN, enzymatic method), alanine aminotransferase (ALT, tryptase), aspartate transaminase (AST, tryptase), and Na+, K+, Cl- (electrode method). The heart rate (HR) and core temperature (Tc, anal temperature) were monitored at the same time. The amount of sweat in training and the occurrence of severe heatstroke were also recorded. Results There was no significant difference in heart, liver, kidney function, electrolyte and body heat regulation reaction among three groups of 5-km armed cross-country trainees before training. Compared with before training, the levels of serum cTnI, CK-MB, SCr, BUN, ALT, AST, HR and Tc were significantly increased after training or during the onset of severe heatstroke in three groups, while the contents of Na+, K+, Cl- were significantly decreased, but the increase or decrease of group C was relatively smaller compared with group A and group B [cTnI (μg/L): 0.9 (0.6, 1.4) vs. 1.1 (0.7, 2.8), 1.0 (0.6, 3.3); CK-MB (U/L): 7.0 (5.0, 11.0) vs. 9.0 (6.0, 14.5), 8.0 (6.0, 15.0); SCr (μmol/L): 92.09±18.64 vs. 102.78±18.77, 103.64±20.07; BUN (mmol/L): 7 (6, 9) vs. 9 (8, 11), 10 (8, 13); ALT (U/L): 27 (22, 34) vs. 36 (30, 43), 34 (27, 43); AST (U/L): 37 (31, 48) vs. 41 (34, 50), 39 (34, 51); HR (bpm):87.01±17.07 vs. 95.88±21.06, 96.59±22.04; Tc (℃): 37.73±0.81 vs. 38.03±1.05, 38.10±1.04; Na+ (mmol/L):150.14±3.86 vs. 144.18±8.89, 144.04±9.39; K+ (mmol/L): 4.32±0.57 vs. 4.15±0.62, 4.13±0.51; Cl- (mmol/L):100.43±3.71 vs. 98.42±4.24, 98.41±4.58; all P < 0.01]. The incidence of severe heatstroke in group C was significantly lower than that in group A and group B [1.67% (5/300) vs. 5.00% (15/300), 5.33% (16/300), χ2 = 6.424, P = 0.040]. There was no significant difference in sweating volume in groups A, B, C (g: 370.47±48.71, 370.85±50.66, 370.17±50.21, F = 0.014, P = 0.986). There was no significant difference in the above indexes between group A and group B (all P > 0.05). Bi-classification Logistic regression analysis showed that the increase of HR, Tc and excessive loss of Na+, K+, Cl- were risk factors for severe heatstroke [odds ratio (OR) was 0.848, 0.138, 1.565, 17.996 and 2.328 respectively, all P < 0.01]. Conclusions Timely supplementation of carbohydrate, sodium and potassium ions can effectively change the internal environment and body heat regulation reaction of 5-km armed cross-country trainees, so as to reduce the occurrence of severe heatstroke. The increases of HR, Tc and excessive loss of Na+, K+, Cl- are risk factors for severe heatstroke.