What is the anti-G straining maneuver used for?

• A. To reduce heart rate
• B. To increase thoracic pressure and venous return, delaying or preventing G-LOC during high-G exposure
• C. To improve oxygen diffusion in alveoli
• D. To prevent dehydration

Answer: (B)

The key idea is that the anti-G straining maneuver is used to keep the brain supplied with blood during high-G exposure. When G forces rise, blood pools in the legs and abdomen, which can drop the amount reaching the brain and lead to G-LOC. By tensing the leg and abdominal muscles and performing a controlled breath-hold and bear-down action, you increase intrathoracic pressure. That pressure helps push blood back toward the heart and toward the brain, raising arterial pressure and preserving cerebral perfusion. Doing this in short, repeated bursts during high-G helps delay or prevent loss of consciousness. It isn’t about slowing the heart rate, improving oxygen diffusion in the lungs, or preventing dehydration.