A century of anti-G straining maneuvers. Are there further changes in AGSM physical training that can improve +Gz tolerance? A scoping review.

High +Gz force tolerance is vital for pilot survival and aircraft performance capabilities. Over the last century, devices such as anti-G suits, pressurized breathing, seat configurations, audio-visual displays to monitor physiological responses, and other techniques have been developed. Anti-G straining maneuvers (AGSM) were also developed to combat the cerebral blood flow reductions that could lead to vision loss, +Gz-force induced loss of consciousness (G-LOC), and pilot performance impairments. Centrifuge conditioning is a very effective task-specific +Gz tolerance training but with few facilities to support it. The recovery breath during AGSM's "hook" breathing can compromise elevated arterial pressures needed to maintain consciousness. Hence it might be fruitful to use breath hold training techniques to prolong the Valsalva maneuver and decrease recovery breath frequency. In addition, the lower body and trunk isometric contractions force output during AGSM can diminish due to fatigue effects. There are contradictions in the literature regarding the effectiveness of muscle endurance and strength training as well as aerobic versus anaerobic training. Very little information is published regarding integrated physical and cognitive training as operating an aircraft does not just involve physiological processes. Is it possible after many decades of AGSM research to make meaningful improvements to pilot +Gz tolerance training? The objective of this scoping review is to examine the AGSM literature and find AGSM components that may allow for advancements that either in isolation or in combination could enhance +Gz tolerance, preventing or delaying visual impairments, performance deficits, and G-LOC.