BACKGROUND Flight cadets need to have good physical fitness to cope with the challenges of flying missions.The continuous development of science and technology has led to the constant upgrading of fighter jets and the...BACKGROUND Flight cadets need to have good physical fitness to cope with the challenges of flying missions.The continuous development of science and technology has led to the constant upgrading of fighter jets and the improvement of their performance,which has resulted in new and higher requirements for the physical fitness of flight personnel.The traditional physical training mode,method,and assessment have been used for many years and do not meet current fitness needs.AIM To investigate the impact of a 12-wk comprehensive anti-G fitness training program on the aerobic capacity of aviation cadets and to evaluate its effectiveness.METHODS Fifty-five cadets were randomly assigned to control and experimental groups using a randomized,single-blind design.The control group maintained their existing training regimen,while the experimental group participated in a 12-wk comprehensive training intervention.The training program comprised strength training twice per week,high-intensity interval training three times per week,and supplemental nutritional and psychological support.Maximal oxygen uptake(VO2max),lower limb strength,and hemoglobin levels were measured at baseline,at 6 wk and 12 wk post-intervention.RESULTS Repeated measures analysis of variance revealed significant differences of both VO2max and relative VO2 in both groups across time points(P<0.05).However,no significant time-group interaction was observed(P>0.05).Paired t-tests comparing baseline and 12-wk results showed that VO2max and relative VO2 were significantly higher in the experimental group than the control group(P<0.05).This suggests that the training program effectively enhanced the aerobic capacity of the experimental group.Key indicators of aerobic capacity,bilateral lower limb strength and hemoglobin levels,were also significantly different over time and between groups(P<0.05).No significant differences were noted in heart-rate metrics(P>0.05).CONCLUSION A 12-wk comprehensive anti-G fitness training program significantly improved the aerobic capacity of aviation cadets,thereby enhancing their overall capacity and laying a physiological foundation for enduring high-G flights.展开更多
A series of noninvasive mechanical auxiliary circulation(NMAC)technologies,such as intermittent pneumatic compression(IPC),external counterpulsation(ECP),and anti-G suit,had been widely used to realize noninvasive int...A series of noninvasive mechanical auxiliary circulation(NMAC)technologies,such as intermittent pneumatic compression(IPC),external counterpulsation(ECP),and anti-G suit,had been widely used to realize noninvasive intervention of human cardiovascular system for different purposes,such as treatments of cardiovascular diseases and protecting pilot from G-induced loss of consciousness(G-LOC)during exposure to sustained accelerations.There are lots of similarities among these NMAC technologies,especially on aspects of hardware constitutions and their physiological effects.However,these technologies were almost independently developed in the past few decades.The similarities and differences were summarized on aspects of hardware constitutions and physiological effects of IPC,ECP and anti-G suit in this paper,and a general concept for NMAC technologies was proposed.This concept did not include a restrict definition,but generally focused on the physiological benefits,while any noninvasive mechanical methods that can achieve such benefits are welcomed.Trends for these typical NMAC technologies,especially about the strategies to realize personalized therapy or to meet new challenges,are discussed.This paper provided a unified perspective for non-invasive mechanical technologies aiming at cardiovascular benefits,and might inspire new technologies to be introduced in.展开更多
Galling phenomena in metal forming not only affect the quality of the engineered surfaces but also the success or failure of the manufacturing operation itself.This paper reviews the different galling conditions in sh...Galling phenomena in metal forming not only affect the quality of the engineered surfaces but also the success or failure of the manufacturing operation itself.This paper reviews the different galling conditions in sheet and bulk metal forming processes along with their evolution and the effects of temperature on galling.A group of anti-galling methods employed to prevent galling defects are also presented in detail.The techniques for quantitatively measuring galling are introduced,and the related prediction models,including friction,wear,and galling growth models,are presented to better understand the underlying phenomena.Galling phenomena in other processes similar to those occurring in metal forming are also examined to suggest different ways of further studying galling in metal forming.Finally,future research directions for the study of galling in metal forming are suggested.展开更多
基金the Ethics Committee of Beijing Sport University(No.2019113H).
文摘BACKGROUND Flight cadets need to have good physical fitness to cope with the challenges of flying missions.The continuous development of science and technology has led to the constant upgrading of fighter jets and the improvement of their performance,which has resulted in new and higher requirements for the physical fitness of flight personnel.The traditional physical training mode,method,and assessment have been used for many years and do not meet current fitness needs.AIM To investigate the impact of a 12-wk comprehensive anti-G fitness training program on the aerobic capacity of aviation cadets and to evaluate its effectiveness.METHODS Fifty-five cadets were randomly assigned to control and experimental groups using a randomized,single-blind design.The control group maintained their existing training regimen,while the experimental group participated in a 12-wk comprehensive training intervention.The training program comprised strength training twice per week,high-intensity interval training three times per week,and supplemental nutritional and psychological support.Maximal oxygen uptake(VO2max),lower limb strength,and hemoglobin levels were measured at baseline,at 6 wk and 12 wk post-intervention.RESULTS Repeated measures analysis of variance revealed significant differences of both VO2max and relative VO2 in both groups across time points(P<0.05).However,no significant time-group interaction was observed(P>0.05).Paired t-tests comparing baseline and 12-wk results showed that VO2max and relative VO2 were significantly higher in the experimental group than the control group(P<0.05).This suggests that the training program effectively enhanced the aerobic capacity of the experimental group.Key indicators of aerobic capacity,bilateral lower limb strength and hemoglobin levels,were also significantly different over time and between groups(P<0.05).No significant differences were noted in heart-rate metrics(P>0.05).CONCLUSION A 12-wk comprehensive anti-G fitness training program significantly improved the aerobic capacity of aviation cadets,thereby enhancing their overall capacity and laying a physiological foundation for enduring high-G flights.
基金the National Key R&D Program of China(2020YFC20044400)the National Natural Science Foundation of China(NSFC,Nos.12072018,11602013).
文摘A series of noninvasive mechanical auxiliary circulation(NMAC)technologies,such as intermittent pneumatic compression(IPC),external counterpulsation(ECP),and anti-G suit,had been widely used to realize noninvasive intervention of human cardiovascular system for different purposes,such as treatments of cardiovascular diseases and protecting pilot from G-induced loss of consciousness(G-LOC)during exposure to sustained accelerations.There are lots of similarities among these NMAC technologies,especially on aspects of hardware constitutions and their physiological effects.However,these technologies were almost independently developed in the past few decades.The similarities and differences were summarized on aspects of hardware constitutions and physiological effects of IPC,ECP and anti-G suit in this paper,and a general concept for NMAC technologies was proposed.This concept did not include a restrict definition,but generally focused on the physiological benefits,while any noninvasive mechanical methods that can achieve such benefits are welcomed.Trends for these typical NMAC technologies,especially about the strategies to realize personalized therapy or to meet new challenges,are discussed.This paper provided a unified perspective for non-invasive mechanical technologies aiming at cardiovascular benefits,and might inspire new technologies to be introduced in.
文摘Galling phenomena in metal forming not only affect the quality of the engineered surfaces but also the success or failure of the manufacturing operation itself.This paper reviews the different galling conditions in sheet and bulk metal forming processes along with their evolution and the effects of temperature on galling.A group of anti-galling methods employed to prevent galling defects are also presented in detail.The techniques for quantitatively measuring galling are introduced,and the related prediction models,including friction,wear,and galling growth models,are presented to better understand the underlying phenomena.Galling phenomena in other processes similar to those occurring in metal forming are also examined to suggest different ways of further studying galling in metal forming.Finally,future research directions for the study of galling in metal forming are suggested.
