Objective:To compare the clinical manifestations,laboratory results,and imaging features between pyogenic spondylitis(PS) and tuberculous spondylitis(TS).Methods:This was a cross-sectional study. A total of 88 patients with infectious diseases of spine(IDS) admitted to Shanghai Sixth People′s Hospital from January 2021 to December 2023 were analyzed,including 61 PS cases(PS group) and 27 TS cases(TS group). The clinical manifestations,laboratory results,and imaging features were compared between two groups. The factors associated with PS were analyzed by multivariate logistic regression. The diagnostic efficacy for pathogen identification was compared between metagenomics next-generation sequencing(mNGS) and bacterial culture methods in PS and TS patients.Results:Compared with the TS group,the PS group had a higher age-adjusted Charlson comorbidity index(aCCI)[3.0(1.5,4.0) points vs. 2.0(1.0,3.0) points, Z=-2.189, P=0.029],shorter onset time of disease[1.0(0.8,3.0) months vs. 6.0(2.0,12.0) months,Z=-4.353, P<0.001],and higher median blood leukocyte counts and serum ferritin(SF) level(7.2×10 9/L vs. 6.3×10 9/L, Z=-2.652, P=0.008; 571.3 ng/ml vs. 266.0 ng/ml, Z=-4.773, P<0.001). The proportions of lumbar spine involvement,non-collapsed involved vertebrae,and bone bridges formed were all higher in the PS group compared to the TS group[68.8%(99/144) vs. 41.4%(29/70), χ2=14.628, P<0.001; 68.9%(42/61) vs. 18.5%(5/27), χ2=19.055, P<0.001; 41.0%(25/61) vs. 7.4%(2/27), χ2=9.921, P=0.002]. The proportions of thoracic spine involvement,severe vertebral collapse,severe narrowing of the involved intervertebral space,sequestrum,and paravertebral soft tissue calcification were all higher in the TS group compared to the PS group[52.9%(37/70) vs. 18.1%(26/144), χ2=27.463, P<0.001; 55.6%(15/27) vs. 13.1%(8/61), χ2=17.462, P<0.001; 74.1%(20/27) vs. 37.7%(23/61), χ2=9.907, P=0.002; 74.1%(20/27) vs. 18.0%(11/61), χ2=25.761, P<0.001; 51.9%(14/27) vs. 6.6%(4/61), χ2=23.599, P<0.001]. Multivariate logistic regression analysis indicated that a symptom duration<5.5 months( OR=30.644,95% CI: 2.022-464.529, P<0.05) and a leukocyte count>7.35×10 9/L( OR=48.653,95% CI: 2.045-1 157.721, P<0.05) indicated a higher likelihood of PS; while the vertebral collapse indicated a higher likelihood of TS( OR=0.025,95% CI: 0.001-0.638, P<0.05). The most common pathogen in the PS group was Staphylococcus aureus(31 cases,50.8%),followed by Streptococcus species(10 cases,16.4%). The positive rates of mNGS testing in the PS and TS groups were 84.1%(37/44) and 12/13,respectively,which were higher than those of conventional bacterial culture[77.8%(42/54)] and Mycobacteriumtuberculosis culture(2/11). Conclusions:Compared with the TS patients,the PS patients have shorter onset time,higher aCCI scores,higher blood leukocyte counts and SF levels,less vertebral collapse and intervertebral space narrowing,and more bone bridge formation. The TS patients have more dead bones and calcifications. The mNGS has a higher diagnostic efficacy than bacterial cultures for PS and TS.

Objective:To evaluate the effectiveness of anti-G straining maneuver (AGSM) in pilots by surface electromyography (sEMG), and to explore the relationships between characteristics of sEMG and anti-G endurance in pilots.Methods:Thirty-eight male high-performance fighter pilots who completed the human centrifuge test at the Air Force Medical Center were selected. Among them, 25 completed the 8.0 G for 10 s anti-G endurance test and 13 completed the 9.0 G for 10 s anti-G endurance test. The sEMG tester was used to keep track of the changes of sEMG in rectus abdominis, rectus femoris, anterior tibial and gastrocnemius muscles while pilots were engaged in AGSM. The anti-G endurance was evaluated according to the changes of visual fields and consciousness. The pilots were divided into 3 groups: the good vision and consciousness group, peripheral visual field narrowing group and endurance endpoint group. The differences in the integral electromyogram (iEMG), mean power frequency (MPF) and muscle input rates between the 3 groups were investigated.Results:A total of 25 pilots completed the 8.0 G for 10 s anti-G endurance test. Among them, 8 (32.0%) were in the good vision and consciousness group, 13 (52.0%) in the peripheral visual field narrowing group and 4 (16.0%) reached the endurance endpoint. Among the 13 pilots who completed the 9.0 G for 10 s anti-G endurance test, 3 (23.1%) were in the good vision and consciousness group, 6 (46.1%) in the peripheral visual field narrowing group, and 4 (30.8%) in the endurance endpoint group. The results of sEMG showed that the iEMG values of the anterior tibialis muscle in pilots under the 9.0 G for 10 s load were significantly different across endurance groups ( H=7.54, P=0.023), and that the iEMG values of the tibialis anterior muscle in the good vision and consciousness group were higher than those in the endurance endpoint group ( P=0.036). The negative slopes of MPF for the rectus abdominis, rectus femoris, anterior tibialis, and gastrocnemius muscles were higher in the good vision and consciousness group than in the other 2 groups, but the differences were not statistically significant ( P>0.05). During the 8.0 G for 10 s anti-G endurance test, there were significant differences in lower limb muscle contribution rates between the 3 groups ( F=4.19, P=0.029). The endurance endpoint group exhibited a lower contribution rate than the good vision and consciousness group ( P=0.025). During the 9.0 G for 10 s anti-G endurance test, there were significant differences in tibialis anterior muscle contribution rates between the 3 groups ( F=4.16, P=0.049). The endurance endpoint group demonstrated a lower contribution rate than the good vision and consciousness group ( P=0.049). Conclusions:The full and balanced activation of abdominal muscles and lower limb muscles, especially the effective mobilization of calf muscles, plays a pivotal role in improving pilots′ AGSM efficiency in high G environments.

Objective:To compare the clinical manifestations,laboratory results,and imaging features between pyogenic spondylitis(PS) and tuberculous spondylitis(TS).Methods:This was a cross-sectional study. A total of 88 patients with infectious diseases of spine(IDS) admitted to Shanghai Sixth People′s Hospital from January 2021 to December 2023 were analyzed,including 61 PS cases(PS group) and 27 TS cases(TS group). The clinical manifestations,laboratory results,and imaging features were compared between two groups. The factors associated with PS were analyzed by multivariate logistic regression. The diagnostic efficacy for pathogen identification was compared between metagenomics next-generation sequencing(mNGS) and bacterial culture methods in PS and TS patients.Results:Compared with the TS group,the PS group had a higher age-adjusted Charlson comorbidity index(aCCI)[3.0(1.5,4.0) points vs. 2.0(1.0,3.0) points, Z=-2.189, P=0.029],shorter onset time of disease[1.0(0.8,3.0) months vs. 6.0(2.0,12.0) months,Z=-4.353, P<0.001],and higher median blood leukocyte counts and serum ferritin(SF) level(7.2×10 9/L vs. 6.3×10 9/L, Z=-2.652, P=0.008; 571.3 ng/ml vs. 266.0 ng/ml, Z=-4.773, P<0.001). The proportions of lumbar spine involvement,non-collapsed involved vertebrae,and bone bridges formed were all higher in the PS group compared to the TS group[68.8%(99/144) vs. 41.4%(29/70), χ2=14.628, P<0.001; 68.9%(42/61) vs. 18.5%(5/27), χ2=19.055, P<0.001; 41.0%(25/61) vs. 7.4%(2/27), χ2=9.921, P=0.002]. The proportions of thoracic spine involvement,severe vertebral collapse,severe narrowing of the involved intervertebral space,sequestrum,and paravertebral soft tissue calcification were all higher in the TS group compared to the PS group[52.9%(37/70) vs. 18.1%(26/144), χ2=27.463, P<0.001; 55.6%(15/27) vs. 13.1%(8/61), χ2=17.462, P<0.001; 74.1%(20/27) vs. 37.7%(23/61), χ2=9.907, P=0.002; 74.1%(20/27) vs. 18.0%(11/61), χ2=25.761, P<0.001; 51.9%(14/27) vs. 6.6%(4/61), χ2=23.599, P<0.001]. Multivariate logistic regression analysis indicated that a symptom duration<5.5 months( OR=30.644,95% CI: 2.022-464.529, P<0.05) and a leukocyte count>7.35×10 9/L( OR=48.653,95% CI: 2.045-1 157.721, P<0.05) indicated a higher likelihood of PS; while the vertebral collapse indicated a higher likelihood of TS( OR=0.025,95% CI: 0.001-0.638, P<0.05). The most common pathogen in the PS group was Staphylococcus aureus(31 cases,50.8%),followed by Streptococcus species(10 cases,16.4%). The positive rates of mNGS testing in the PS and TS groups were 84.1%(37/44) and 12/13,respectively,which were higher than those of conventional bacterial culture[77.8%(42/54)] and Mycobacteriumtuberculosis culture(2/11). Conclusions:Compared with the TS patients,the PS patients have shorter onset time,higher aCCI scores,higher blood leukocyte counts and SF levels,less vertebral collapse and intervertebral space narrowing,and more bone bridge formation. The TS patients have more dead bones and calcifications. The mNGS has a higher diagnostic efficacy than bacterial cultures for PS and TS.

Objective:To evaluate the effectiveness of anti-G straining maneuver (AGSM) in pilots by surface electromyography (sEMG), and to explore the relationships between characteristics of sEMG and anti-G endurance in pilots.Methods:Thirty-eight male high-performance fighter pilots who completed the human centrifuge test at the Air Force Medical Center were selected. Among them, 25 completed the 8.0 G for 10 s anti-G endurance test and 13 completed the 9.0 G for 10 s anti-G endurance test. The sEMG tester was used to keep track of the changes of sEMG in rectus abdominis, rectus femoris, anterior tibial and gastrocnemius muscles while pilots were engaged in AGSM. The anti-G endurance was evaluated according to the changes of visual fields and consciousness. The pilots were divided into 3 groups: the good vision and consciousness group, peripheral visual field narrowing group and endurance endpoint group. The differences in the integral electromyogram (iEMG), mean power frequency (MPF) and muscle input rates between the 3 groups were investigated.Results:A total of 25 pilots completed the 8.0 G for 10 s anti-G endurance test. Among them, 8 (32.0%) were in the good vision and consciousness group, 13 (52.0%) in the peripheral visual field narrowing group and 4 (16.0%) reached the endurance endpoint. Among the 13 pilots who completed the 9.0 G for 10 s anti-G endurance test, 3 (23.1%) were in the good vision and consciousness group, 6 (46.1%) in the peripheral visual field narrowing group, and 4 (30.8%) in the endurance endpoint group. The results of sEMG showed that the iEMG values of the anterior tibialis muscle in pilots under the 9.0 G for 10 s load were significantly different across endurance groups ( H=7.54, P=0.023), and that the iEMG values of the tibialis anterior muscle in the good vision and consciousness group were higher than those in the endurance endpoint group ( P=0.036). The negative slopes of MPF for the rectus abdominis, rectus femoris, anterior tibialis, and gastrocnemius muscles were higher in the good vision and consciousness group than in the other 2 groups, but the differences were not statistically significant ( P>0.05). During the 8.0 G for 10 s anti-G endurance test, there were significant differences in lower limb muscle contribution rates between the 3 groups ( F=4.19, P=0.029). The endurance endpoint group exhibited a lower contribution rate than the good vision and consciousness group ( P=0.025). During the 9.0 G for 10 s anti-G endurance test, there were significant differences in tibialis anterior muscle contribution rates between the 3 groups ( F=4.16, P=0.049). The endurance endpoint group demonstrated a lower contribution rate than the good vision and consciousness group ( P=0.049). Conclusions:The full and balanced activation of abdominal muscles and lower limb muscles, especially the effective mobilization of calf muscles, plays a pivotal role in improving pilots′ AGSM efficiency in high G environments.

Objective:To investigate the differences in programmed death-ligand 1 (PD-L1) expression and immune cell infiltration characteristics in different molecular subtypes of endometrial cancer.Methods:A retrospective case series study was conducted. Ninety primary treated EC patients who underwent surgery without preoperative neoadjuvant therapy at the Second Hospital of Tianjin Medical University from November 2016 to May 2022 were collected. The surgical paraffin-embedded tissues were selected, and the molecular subtypes of endometrial cancer were classified according to 2020 World Health Organization (WHO) molecular subtypes using POLE gene Sanger sequencing and immunohistochemical staining. The expression of PD-L1, CD3, CD4, CD8, CD68, and CD20 proteins were detected by immunohistochemistry. Stained slides were digitally scanned for quantitative analysis of PD-L1 and immune cell infiltration density. The PD-L1-related scores were evaluated, including tumor cell score (TCS, the percentage of PD-L1 positive tumor cells among total tumor cells ≥1% was TCS positive, <1% was TCS negative), immune cell score (ICS, the percentage of PD-L1 positive tumor-associated lymphocytes and macrophages among total tumor-associated lymphocytes and macrophages ≥1% was ICS positive, <1% was ICS negative) and combined positive score [CPS, PD-L1 positive stained cells (including tumor cells, lymphocytes and macrophages)/total number of viable tumor cells ×100 ≥ 1 was CPS positive, < 1 was CPS negative]. Clinicopathological characteristics, PD-L1 scores and immune cell infiltration densities among different molecular subtypes were analyzed. Kaplan-Meier method was used to plot disease-free survival (DFS) curves for molecular subtypes, PD-L1 scores and immune cell infiltration densities, with subgroup comparisons using log-rank test. Cox proportional hazards models were used for univariate and multivariate analyses of poor DFS in endometrial cancer patients.Results:The median age of 90 patients was 58 years old (range: 33-72 years old); endometrioid carcinoma was present in 78 cases (86.7%), and non-endometrioid carcinoma was present in 12 cases (13.3%). Molecular subtyping identified POLE-mutated subtype in 6 cases (6.7%), mismatch repair deficient (MMRd) subtype in 23 cases (25.6%), p53 abnormal subtype in 14 cases (15.6%), and non-specific molecular profile (NSMP) subtype in 47 cases (52.2%). Significant differences were observed among the 4 molecular subtypes in International Federation of Gynecology and Obstetrics (FIGO) stage, histological grade, morphological subtype, tertiary lymphoid structures, estrogen receptor expression, and progesterone receptor expression (all P < 0.05). Among the 90 cases, 18 cases (20.0%) were positive for TCS, 31 cases (34.4%) were positive for ICS, and 39 cases (43.3%) were positive for CPS. Significant differences were found among the 4 molecular subtypes in PD-L1 + cell density, distribution of patients with ICS positivity, and distribution of patients with CPS positivity (all P < 0.01), but not in distribution of patients with TCS positivity ( P = 0.090); compared to NSMP subtype, the proportions of ICS-positive patients in POLE-mutated and MMRd subtypes were higher, the proportion of CPS-positive patients and PD-L1 + cell density in MMRd and p53 abnormal subtypes were higher, and the differences were statistically significant (all P < 0.05). Significant differences in immune cell densities were observed among the 4 molecular subtypes (all P < 0.01); compared to NSMP subtype, POLE-mutated, MMRd and p53 abnormal subtypes had higher densities of CD3 + and CD8 + cells, MMRd subtype had higher CD4 + cell density, and POLE-mutated and MMRd subtypes had higher CD68 + and CD20 + cell densities (all P < 0.05). The median follow-up was 43 months (range: 7-75 months). Among the molecular subtypes, p53 abnormal patients had the worst DFS, and POLE-mutated patients had the best DFS, and the difference in DFS among the 4 subtypes was statistically significant ( P = 0.046). Grouping according to the median density of immune cells in the entire group, patients with high CD8 + cell density (45 cases) had better DFS than those with low density (45 cases) ( P = 0.010), PD-L1 ICS-positive patients had worse DFS than negative patients ( P = 0.019), and NSMP subtype patients with high CD4 + cell density (24 cases) had better DFS than those with low density (23 cases) ( P < 0.001). There was no statistically significant difference in DFS among patients grouping with other PD-L1 scoring modes and other immune cell infiltration density (all P > 0.05). Cox regression analysis indicated that high CD8 + cell density ( HR = 0.335, 95% CI: 0.113-0.990, P = 0.048) was an independent protective factor for poor DFS in endometrial cancer patients, and high CD4 + cell density was an independent protective factor for poor DFS in NSMP subtype patients ( HR = 0.035, 95% CI: 0.003-0.345, P = 0.004). Conclusions:There are significant differences in PD-L1 expression and immune cell infiltration density among the different molecular subtypes of endometrial cancer, which are correlated with the prognosis of patients, and may provide reference for the selection of immunotherapy strategies and prognosis judgment.

Background::Liver cancer is largely resistant to chemotherapy. This study aimed to identify the effective chemotherapeutics for β-catenin-activated liver cancer which is caused by gain-of-function mutation of catenin beta 1 ( CTNNB1), the most frequently altered proto-oncogene in hepatic neoplasms. Methods::Constitutive β-catenin-activated mouse embryonic fibroblasts (MEFs) were established by deleting exon 3 ( β-cateninΔ(ex3)/+ ), the most common mutation site in CTNNB1 gene. A screening of 12 widely used chemotherapy drugs was conducted for the ones that selectively inhibited β-cateninΔ(ex3)/+ but not for wild-type MEFs. Untargeted metabolomics was carried out to examine the alterations of metabolites in nucleotide synthesis. The efficacy and selectivity of methotrexate (MTX) on β-catenin-activated human liver cancer cells were determined in vitro. Immuno-deficient nude mice subcutaneously inoculated with β-catenin wild-type or mutant liver cancer cells and hepatitis B virus ( HBV); β-cateninlox(ex3)/+ mice were used, respectively, to evaluate the efficacy of MTX in the treatment of β-catenin mutant liver cancer. Results::MTX was identified and validated as a preferential agent against the proliferation and tumor formation of β-catenin-activated cells. Boosted nucleotide synthesis was the major metabolic aberration in β-catenin-active cells, and this alteration was also the target of MTX. Moreover, MTX abrogated hepatocarcinogenesis of HBV; β-cateninlox(ex3)/+ mice, which stimulated concurrent Ctnnb1-activated mutation and HBV infection in liver cancer. Conclusion::MTX is a promising chemotherapeutic agent for β-catenin hyperactive liver cancer. Since repurposing MTX has the advantages of lower risk, shorter timelines, and less investment in drug discovery and development, a clinical trial is warranted to test its efficacy in the treatment of β-catenin mutant liver cancer.

Objective To establish a scientific training program that takes into account both anaerobic and aerobic training for pilots,and to explore the appropriate ratio of aerobic and anaerobic training.Methods According to the physical examination standards for pilots,a total of 16 healthy subjects aged 18-24 were selected from two batches.The two batches of subjects were trained with different aerobic and anaerobic ratios.Training period was 3 months.The changes in cardiopulmonary function of the subjects before and after training were evaluated using the cardiopulmonary function exercise testing system(CPET),and the changes in anaerobic capacity were evaluated using changes in strength as an indicator.Results After training,the weight load of the subjects in the two training programs,including barbell squats,leg flexion and hard pull,and barbell under 10RM and 3RM,was significantly increased(P<0.001),and there was no statistically significant difference in anaerobic strength growth between the two groups.The results of CPET showed that the maximum load,maximum heart rate,and respiratory quotient in the two groups were significantly increased after than before the training(P<0.01).The maximum load(Experiment group 1:29.12±19.69,Experiment group 2:72.00±46.24)and respiratory quotient(Experiment grouop 1:0.11±0.09,Experiment group 2:0.28±0.16)of the subjects in experiment group 2 before and after training were greater than those in experiment group 1.The difference was statistically significant(P<0.05).Conclusion The anaerobic and aerobic capacities of the subjects in the experiment group 2 are effectively improved,indicating that ratio of aerobic and anaerobic of the training scheme is better.

Objective:To discuss the application of gradual-onset rate run (GOR) of human centrifuge on G-tolerance evaluation and training by analyzing the training results of (student) pilots in GOR centrifuge run.Methods:The G-tolerance and anti-G straining maneuver effect of 440 student pilots and 368 pilots participated centrifuge training in recent years were analyzed. The (student) pilots were grouped by age (20-25 years,26-30 years,31-35 years,36-40 years, >40 years). The 392 student pilots and 335 pilots who completed rapid onset rate run (ROR) were divided into 8 G 10 s training high G tolerance group (group A), 8 G 10 s training low G tolerance group (group B), 9 G 10 s training high G tolerance group (group C) and 9 G 10 s training low G tolerance group (group D) according to pass the 8 G 10 s or 9 G 10 s run one-time or not. The relation of G-tolerance and anti-G straining maneuver effect of GOR to ROR was discussed.Results:The average distribution range of relaxed G-tolerance under GOR (GOR tolerance 1) was (4.1±0.7) G, and the average distribution range of anti-G straining maneuver aided G-tolerance under GOR (GOR tolerance 2) was (6.2±0.8) G. The average HP anti-G straining maneuver effect was (2.1±0.6) G. There was a significant difference in GOR tolerance 1 ( H=11.94, P=0.018), no significant difference in GOR tolerance 2 ( H=4.80, P=0.308), and a significant difference in the effect of HP anti-G straining maneuver among pilots in different age groups ( F=3.01, P=0.018). The effect of HP anti-G straining maneuver in the age group over 40 years old was greater than that in other age groups ( P=0.027, 0.034, 0.009, 0.006). There was no significant difference in GOR tolerance 1, GOR tolerance 2 and HP anti-G straining maneuver effect between pilots and student pilots (all P>0.05). There were significant differences in GOR tolerance 2 ( H=15.38, P=0.002) and the effect of HP anti-G straining maneuver ( H=8.22, P=0.041) among group A, group B, group C and group D. The GOR tolerance 2 of group B was lower than that of other anti-G tolerance groups ( P=0.003, 0.001, 0.040). Conclusions:The centrifuge GOR training could reflect the G-tolerance and anti-G straining maneuver effect of (student) pilots and provide references for predicting the human centrifuge training result and improving accelerate training and tolerance evaluating.

Objective:To explore the application of isokinetic muscle strength test in the evaluation of flying cadets′ G-tolerance by investigating the leg strength characteristics of different G-tolerance flying cadets.Methods:G-tolerance test: the AMSACC-4E human centrifuge closed-loop mode was used to test the +8 G z tolerance of 89 male fighter flying cadets. The G-tolerance end point of the flying cadets were determined according to physiological signal monitoring, facial expression characteristics and objective comments. According to the test results, the flying cadets were divided into 3 groups: excellent group, good group and failing group.The grouping criteria: excellent group: could complete the +8 G z 10 s test at one time, with no change in the main complaint light and good consciousness. Good group: could complete the +8 G z 10 s test at one time, the main complaint peripheral light dimmed or disappeared, the central light did not change. Failing group: failure to complete the +8 G z 10 s test at one time, occur G-induced loss of consciousness or almost loss of consciousness. Isokinetic muscle strength test: Biodex System 4 Pro isometric test system was used to test the maximum strength, strength endurance and muscle force balance of the leg flexor and extensor muscles of flying cadets. The test indicators include: peak torque, relative peak torque, average power and peak torque flexion ratio. The test site was knee joint of legs. The test angular speeds were 60°/s and 180°/s. The flying cadets were tested once at each angular speed. They were required to do their best to complete 5 times of consecutive flexion and extension at 60°/s, and 20 times of consecutive flexion and extension at 180°/s. Resting 1 min between different speed, and 3 min between different legs test. The leg strength characteristics were compared among 3 groups. Results:There were 52 flying cadets in excellent group, 29 in good group and 8 in failing group. In terms of leg strength: ①maximum strength: under the test of angular speed 60°/s, there was no significant difference in the peak moment and relative peak moment of leg flexor and extensor muscles among 3 groups (all P>0.05). The peak moment and relative peak moment of flexor muscle of left leg in excellent group were lower than those of right leg, with significant differences ( t=2.14, 2.20, P=0.037, 0.032). ②Strength endurance: under the test of angular speed 180°/s, there was a significant difference in the average power of right leg extensor muscle among 3 groups ( F=3.39, P=0.038). The average power of right leg extensor muscle in excellent group was higher than that in good group, with significant difference ( P=0.015). The average power of the left leg flexor muscle in the excellent group was lower than that of the right leg ( t=2.78, P=0.008). ③Muscle force balance: there were no significant differences between the leg peak torque flexion ratio of flying cadets at 60°/s and 180°/s angular speeds (all P>0.05). The peak torque flexion ratio of the left leg of the excellent group was lower than that of the right leg at both angular speeds ( t=3.96, 3.30, P<0.001,=0.002). Conclusions:The strength endurance of the right leg extensor muscles of the flying cadets with excellent G-tolerance is better, suggesting that under the test of angular speed 180°/s, there may be a certain correlation between the average power of leg extensor muscles and the G-tolerance. Maximum strength and muscle balance of the leg are not significant to the G-tolerance of the flying cadets.

Objective:To explore whether Corona Virus Disease 2019 (COVID-19) has any impact on human centrifuge training of flying cadets and to provide references to the human centrifuge training for the recovered flying personnel by comparing the changes of flying cadets′ G-tolerance and physiological indicators in human centrifuge training.Methods:Twelve flying cadets who underwent the current batch of human centrifuge training in 2022 were selected and divided into rehabilitation group and control group according to whether they had been infected with COVID-19, with 6 in each group. The rapid G onset rate (ROR) and gradual G onset rate (GOR) were respectively chosen for human centrifuge test. At the same time, the changes of their heart rate and respiratory rate during the tests were recorded, and the G-tolerance situations of the subjects were collected.Results:The average relaxed G-tolerance under GOR (GOR tolerance 1) was (4.2±0.8) G in rehabilitation group, and their average anti-G straining maneuver aided G-tolerance under GOR (GOR tolerance 2) was (5.7±0.6) G. Compared with that of the control group, there was no significant difference in GOR tolerance 1 and GOR tolerance 2 (both P>0.05). There was no significant changes in heart rate and respiratory rate in ROR and GOR human centrifuge tests between 2 groups (all P>0.05). Conclusions:COVID-19 didn't impact the recovered flying cadets' performance in human centrifuge training, as well as the anti-G straining maneuver effect and cardiovascular regulation.