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.

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 study the application value of multi-parameter imaging of Revolution energy spectrum CT in identifying the tumor-lung interface between central lung cancer and accompanying atelectasis.Methods The spectral CT imaging data of 73 patients with central lung cancer and accompanying atelectasis confirmed by pathology were collected.The polychromatic image,the best monochromatic image,the best monochromatic image combined with iodine concentration map and the effective atomic number(Eff-Z)of the tumor-lung interface in the arterial,venous and delayed phases were compared,and the CT value,iodine concentration(IC)value,Eff-Z and the slope of energy spectrum curve(λHU)of tumors and atelectasis in the venous phase were also compared.Results(1)On tri-phase CT,the subjective score of the tumor-lung interface in the venous phase was the highest.(2)There were differences among the subjective scores of tumor-lung interface on polychromatic image,best monochromatic image,best monochromatic image com-bined with iodine concentration map and Eff-Z on tri-phasic enhanced CT.The subjective score of the best monochromatic image combined with iodine concentration map was the highest,followed by the best monochromatic image.(3)There were significant differences in CT values,IC values,Eff-Z and λHU between tumors and atelectasis in venous phase,with the highest difference of IC value.Conclusion Revolution energy spectrum CT can identify the tumor-lung interface between central lung cancer and accompanying ate-lectasis through multi-parameter imaging,which may provide helpful information for the diagnosis and therapeutic evaluation of the disease.

Objective:To provide references for promoting the anti-G ability of flying cadets and improving the training methods by testing the flying cadets′ relaxed +G z tolerance and analyzing the related factors. Methods:Fifty-seven healthy male flying cadets were tested for anti-G ability by cluster sampling. The indicators included relaxed +G z tolerance, maximal pedal force of lower limbs, maximal expiratory pressure (MEP) and maximum inspiratory pressure (MIP). The subjects were divided into high and low tolerance groups, and the low tolerance group was divide into 2 groups by judging if they were with or without visual change. The subjects were divided into high and low limbs strength groups by measured maximal pedal force. The questionnaire was used to get the information of human centrifuge test and the physical training of flying cadets at ordinary time. According to the results of the questionnaires, the subjects were divided into low strength (≤3 times/week) and high strength (>3 times/week) physical training groups by aerobic training intensity. Results:Relaxed +G z tolerance test results of the flying cadets were 3.5 G and 4.0 G, with an average of (3.56±0.17) G. Maximal pedal force of lower limbs was averagely (449.3±105.6) kgf (1 kgf=9.806 N). MEP was averagely (20.1±3.5) kPa. MIP was averagely (10.5±2.3) kPa. MEP of 4.0 G group was higher than that of 3.5 G group, and the difference was significant ( t=2.08, P=0.043). In the subjects of 3.5 G relaxed +G z tolerance, MEP of unchanged vision group was higher than that of changed vision group, and the difference was significant ( t=2.35, P=0.023). Relaxed +G z tolerance of high pedal force group (≥449.3 kgf) was higher than that of low pedal force group (<449.3 kgf), and the difference was significant ( t=2.20, P=0.035). 66.7% of the subjects did not learn correct anti-G maneuver; 91.2% of the subjects took long-distance running; 82.5% of the subjects took strength training; 57.9% of the subjects did lower limbs strength training, but 45.6% of them did not understand the correct methods of training muscle groups. MEP of the high training group was higher than that of low training group, and the difference was significant ( t=3.25, P=0.002). Maximal pedal force of lower limbs in the high training group was lower than that in the low training group, and the difference was significant ( t=2.35, P=0.022). Conclusions:The flying cadets′ anti-G ability is not good in centrifuge. They should be arranged to experience and trained in human centrifuge as early as possible. Anti-G physical training should be enhanced based on anaerobic exercise.

Objective:To provide references for promoting the anti-G ability of flying cadets and improving the training methods by testing the flying cadets′ relaxed +G z tolerance and analyzing the related factors. Methods:Fifty-seven healthy male flying cadets were tested for anti-G ability by cluster sampling. The indicators included relaxed +G z tolerance, maximal pedal force of lower limbs, maximal expiratory pressure (MEP) and maximum inspiratory pressure (MIP). The subjects were divided into high and low tolerance groups, and the low tolerance group was divide into 2 groups by judging if they were with or without visual change. The subjects were divided into high and low limbs strength groups by measured maximal pedal force. The questionnaire was used to get the information of human centrifuge test and the physical training of flying cadets at ordinary time. According to the results of the questionnaires, the subjects were divided into low strength (≤3 times/week) and high strength (>3 times/week) physical training groups by aerobic training intensity. Results:Relaxed +G z tolerance test results of the flying cadets were 3.5 G and 4.0 G, with an average of (3.56±0.17) G. Maximal pedal force of lower limbs was averagely (449.3±105.6) kgf (1 kgf=9.806 N). MEP was averagely (20.1±3.5) kPa. MIP was averagely (10.5±2.3) kPa. MEP of 4.0 G group was higher than that of 3.5 G group, and the difference was significant ( t=2.08, P=0.043). In the subjects of 3.5 G relaxed +G z tolerance, MEP of unchanged vision group was higher than that of changed vision group, and the difference was significant ( t=2.35, P=0.023). Relaxed +G z tolerance of high pedal force group (≥449.3 kgf) was higher than that of low pedal force group (<449.3 kgf), and the difference was significant ( t=2.20, P=0.035). 66.7% of the subjects did not learn correct anti-G maneuver; 91.2% of the subjects took long-distance running; 82.5% of the subjects took strength training; 57.9% of the subjects did lower limbs strength training, but 45.6% of them did not understand the correct methods of training muscle groups. MEP of the high training group was higher than that of low training group, and the difference was significant ( t=3.25, P=0.002). Maximal pedal force of lower limbs in the high training group was lower than that in the low training group, and the difference was significant ( t=2.35, P=0.022). Conclusions:The flying cadets′ anti-G ability is not good in centrifuge. They should be arranged to experience and trained in human centrifuge as early as possible. Anti-G physical training should be enhanced based on anaerobic exercise.

Objective:To establish a new centrifuge G load profile of simulated aerial combat maneuver (SACM).Methods:The +G z load data of fighter aircraft training at home and abroad were analyzed. A +G z profile of SACM was established according to the results of data analysis. Four volunteers wearing anti-G suit were exposed to SACM on the centrifuge and performed PHP maneuver. +G z value, electrocardiograph and the ear-pulse signal of volunteers were measured. The peripheral light loss, G-LOC or almost loss of consciousness (A-LOC) of volunteers were taken as the indicators of the G-endurance end point. The exposure time of volunteers to the endpoints or the completion of 1 group SCAM was taken as G-duration tolerance. The fatigue degree of volunteers was rated according to their subjective feelings. Results:The new 2-8 G SACM was consisted of 7 plateaus which were +4 G z for 20 s, +2 G z for 5 s, +5 G z for 10 s, +2 G z for 5 s, +6 G z for 15 s, +2 G z for 10 s and +8 G z for 5 s with an onset rate of 3 G/s. The total +G z exposure duration was 85 s. Three of 4 volunteers completed SACM centrifuge exposure. The other one experienced A-LOC and G duration tolerance was 60 s (at 6 s of 6 G z). The mean heart rate of 3 volunteers reached (200±7) beat/min at 8 G z 5 s. All volunteers "obviously felt tired" when they finished SACM exposure. Conclusions:The 2-8 G SACM porposed in the centrifuge test can be conducive to furtherly recognize the influences of the changing characteristics of +G z profiles on pilots in fighter typically operational training of this study. The volunteers′ G-duration tolerance could be preliminarily evaluated according to exposure duration, changes of vision and consciousness of SACM.

Objective:To explore the training methods of strengthening pilots′ waist and abdomen muscle strength free-standing exercises and simple equipment (sandbag, weight plates, Roman chair, etc.) exercises.Methods:Eight healthy male volunteers were trained 3 times a week for 3 months and 1.0-1.5 h each time by using the methods of flying like swallows, curling up the abdomen, swinging legs in supine position, using Roman chair and so on. The improvement project was changed every 4 weeks. The pre-and post-tests consisted of waist and abdomen maximum muscle torque (MMT), 10 s torque equivalent (10 s TE) and the surface electromyography signal of erector spine in the forward flexion, back extension, left and right rotation by using the maximum isometric static muscle strength test method. Furthermore, the multi-step endurance test method was used to test the volunteers′ lumbar and abdominal muscles endurance, including the total torque equivalent (TTE), endurance time and the surface electromyography signal of erector spine in the forward flexion and back extension. The software package SPSS 18.0 was applied for self-contrasted t-test.Results:After 3 months systematic training, the MMT of 8 volunteers increased by 24.99%, 27.55%, 82.00% and 47.76% in the forward flexion, back extension, left and right rotation and the 10 s TE increased by 26.05%, 29.43%, 85.64% and 84.59%. They were significantly different from that before in different directions, so was 10 s TE ( t=3.32-20.45, P<0.05). After training, the left and right erector spine′s average electromyography signal increased significantly ( t=4.30, 9.81, P<0.01) in the back extension and the values were 73.73% and 101.21%, however, they didn′t increased so much in the other 2 directions. In the meantime, the median frequency (MF) in 3 directions changed little under the premise of a significant increase in 10 s TE. The TTE increased by 36.28% and 52.03% in the forward flexion and back extension compared with that before training, the differences were statistically significant ( t=1.24, 1.13, P<0.05), although the endurance time and the MF in the last step did not significantly change while the total training load increased. Conclusions:The effects of the waist and abdomen training based on free-standing exercises and simple equipment are effectual. After training, the volunteers′ muscle strength and endurance increased significantly and the anti-fatigue ability of muscles was enhanced. The training method is simple and easy to carry out in the flying troops.

Objective:To establish a new centrifuge G load profile of simulated aerial combat maneuver (SACM).Methods:The +G z load data of fighter aircraft training at home and abroad were analyzed. A +G z profile of SACM was established according to the results of data analysis. Four volunteers wearing anti-G suit were exposed to SACM on the centrifuge and performed PHP maneuver. +G z value, electrocardiograph and the ear-pulse signal of volunteers were measured. The peripheral light loss, G-LOC or almost loss of consciousness (A-LOC) of volunteers were taken as the indicators of the G-endurance end point. The exposure time of volunteers to the endpoints or the completion of 1 group SCAM was taken as G-duration tolerance. The fatigue degree of volunteers was rated according to their subjective feelings. Results:The new 2-8 G SACM was consisted of 7 plateaus which were +4 G z for 20 s, +2 G z for 5 s, +5 G z for 10 s, +2 G z for 5 s, +6 G z for 15 s, +2 G z for 10 s and +8 G z for 5 s with an onset rate of 3 G/s. The total +G z exposure duration was 85 s. Three of 4 volunteers completed SACM centrifuge exposure. The other one experienced A-LOC and G duration tolerance was 60 s (at 6 s of 6 G z). The mean heart rate of 3 volunteers reached (200±7) beat/min at 8 G z 5 s. All volunteers "obviously felt tired" when they finished SACM exposure. Conclusions:The 2-8 G SACM porposed in the centrifuge test can be conducive to furtherly recognize the influences of the changing characteristics of +G z profiles on pilots in fighter typically operational training of this study. The volunteers′ G-duration tolerance could be preliminarily evaluated according to exposure duration, changes of vision and consciousness of SACM.

Objective:To explore the training methods of strengthening pilots′ waist and abdomen muscle strength free-standing exercises and simple equipment (sandbag, weight plates, Roman chair, etc.) exercises.Methods:Eight healthy male volunteers were trained 3 times a week for 3 months and 1.0-1.5 h each time by using the methods of flying like swallows, curling up the abdomen, swinging legs in supine position, using Roman chair and so on. The improvement project was changed every 4 weeks. The pre-and post-tests consisted of waist and abdomen maximum muscle torque (MMT), 10 s torque equivalent (10 s TE) and the surface electromyography signal of erector spine in the forward flexion, back extension, left and right rotation by using the maximum isometric static muscle strength test method. Furthermore, the multi-step endurance test method was used to test the volunteers′ lumbar and abdominal muscles endurance, including the total torque equivalent (TTE), endurance time and the surface electromyography signal of erector spine in the forward flexion and back extension. The software package SPSS 18.0 was applied for self-contrasted t-test.Results:After 3 months systematic training, the MMT of 8 volunteers increased by 24.99%, 27.55%, 82.00% and 47.76% in the forward flexion, back extension, left and right rotation and the 10 s TE increased by 26.05%, 29.43%, 85.64% and 84.59%. They were significantly different from that before in different directions, so was 10 s TE ( t=3.32-20.45, P<0.05). After training, the left and right erector spine′s average electromyography signal increased significantly ( t=4.30, 9.81, P<0.01) in the back extension and the values were 73.73% and 101.21%, however, they didn′t increased so much in the other 2 directions. In the meantime, the median frequency (MF) in 3 directions changed little under the premise of a significant increase in 10 s TE. The TTE increased by 36.28% and 52.03% in the forward flexion and back extension compared with that before training, the differences were statistically significant ( t=1.24, 1.13, P<0.05), although the endurance time and the MF in the last step did not significantly change while the total training load increased. Conclusions:The effects of the waist and abdomen training based on free-standing exercises and simple equipment are effectual. After training, the volunteers′ muscle strength and endurance increased significantly and the anti-fatigue ability of muscles was enhanced. The training method is simple and easy to carry out in the flying troops.