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 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.

Retinal vein occlusion (RVO) is a common retinal vascular disease, and macular edema (ME) is the most common cause of visual impairment in eyes with RVO.Intravitreal injection of anti-vascular endothelial growth factor (VEGF) has been advocated as a first-line therapy for ME secondary to RVO.After anti-VEGF treatment, the patient's visual function recovers well in the short term, but the long-term efficacy is unstable and the recurrence rate of ME is high.Therefore, it is of great clinical value to predict the factors influencing the recurrence of ME, which would help determine which patients should receive frequent follow-up and more aggressive treatment to achieve better clinical outcomes.In this paper, the influencing factors of recurrence of ME secondary to RVO are summarized, including disorganization of retinal inner layer, change in the macular microvascular structure, change in choroid thickness, the non-perfusion area between different areas of the retina, inflammatory cytokines, retinal blood flow and blood flow velocity, etc., which can provide an important basis for patient counseling, clinical diagnosis and treatment and prognostic follow-up.

Retinal vein occlusion (RVO) is a common retinal vascular disease, and macular edema (ME) is the most common cause of visual impairment in eyes with RVO.Intravitreal injection of anti-vascular endothelial growth factor (VEGF) has been advocated as a first-line therapy for ME secondary to RVO.After anti-VEGF treatment, the patient's visual function recovers well in the short term, but the long-term efficacy is unstable and the recurrence rate of ME is high.Therefore, it is of great clinical value to predict the factors influencing the recurrence of ME, which would help determine which patients should receive frequent follow-up and more aggressive treatment to achieve better clinical outcomes.In this paper, the influencing factors of recurrence of ME secondary to RVO are summarized, including disorganization of retinal inner layer, change in the macular microvascular structure, change in choroid thickness, the non-perfusion area between different areas of the retina, inflammatory cytokines, retinal blood flow and blood flow velocity, etc., which can provide an important basis for patient counseling, clinical diagnosis and treatment and prognostic follow-up.

Objective To explore the value of free mitochondrial deoxyribonucleic acid(DNA)and micro ribonucleic acid(miRNA,miR)-146a expression in peripheral blood in assessing short-term prognosis of sepsis.Methods Totally 145 patients with sepsis admitted to the hospital from March 2021 to February 2023 were selected to detect the free mitochondrial DNA and miR-146a expression in peripheral blood.The incidence of poor prognosis after 28 days was counted,and the patients were then divided into poor prognosis group and good prognosis group.The general data and the free mitochondrial DNA and miR-146a expression in peripheral blood of the two groups were compared.Logistic regression analysis was used to explore the influencing factors of poor prognosis in patients.Receiver operating characteristic(ROC)curve was drawn to analyze the predictive efficacy of free mitochondrial DNA and miR-146a expressionin assessing the short-term prognosis of sepsis.Results The incidence of poor short-term prognosis in the 139 patients who completed the study was 28.78％.Concurrent diabetes(OR=1.765,95％CI:1.181～2.637),acutephysiology and chronic health evaluation(APACHE Ⅱ)score(OR=1.972,95％CI:1.317～2.953),free mitochondrial DNA in peripheral blood(OR=2.416,95％CI:1.524-3.829),and miR-146a expres-sion(OR=2.462,95％CI:1.431～4.237)were risk factors for poor short-term prognosis of patients with sepsis(P＜0.05).The sensitivity,specificity and area under curve(AUC)of free mitochondrial DNA and miR-146a expression in peripheral blood to predict poor short-term prognosis were higher than those of APACHE Ⅱ score(P＜0.05),and the sensitivity and AUC of free mitochondrial DNA and miR-146a expressions in peripheral blood to predict poor short-term prognosis were higher than those of both alone(P＜0.05).Conclusions Free mitochondrial DNA and miR-146a expression in peripheral blood are related to poor short-term prognosis of sepsis.The efficacy of both of them in assessing poor short-term prognosis of sepsis is better than that of APACHE Ⅱ score,and their combined prediction efficacy is even 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.

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.