How Many G's Can Your Body Take?

Flopping into a chair hits your head with about 10 g's, and you're fine. Fighter pilots fight to stay awake at 9. So what actually knocks you out? All sources below. ▶ All full episodes:    • What Happens to Your Body? Full Episodes   🔔 Subscribe for new body explainers every week:    / @redlinebody   This animated explainer climbs the g-force ladder, from your chair to a roller coaster, a fighter jet, a rocket sled and a car crash. You'll see why g's drain blood out of your head, why your eyes quit before your brain, what blacking out (G-LOC) is like, how pilots survive 9 g's with a g-suit and a grunt, why astronauts launch lying on their backs, and why a seatbelt works by buying time. ⏱️ CHAPTERS 0:00 Your g-force ladder 0:33 What is 1 g? 1:20 Roller coasters and your blood 2:29 Why your eyes quit first 3:28 G-LOC: lights out 4:18 How pilots survive 9 g's 5:36 Negative g's and red-out 6:11 Why astronauts lie back 6:40 Crash-level g's 8:13 What your body knows 📚 SOURCES FAA CAMI, Acceleration in Aviation: G-Force (2021). https://www.faa.gov/pilots/safety/pil... NASA SP-3006, Bioastronautics Data Book, 2nd ed. (1973). https://ntrs.nasa.gov/citations/19730... Roller coasters and kids' heart rates: Pieles et al. (2017), Pediatric Cardiology. https://doi.org/10.1007/s00246-016-14... Pillow fight vs roller coasters: Pfister et al. (2009), Am J Forensic Med Pathol. https://doi.org/10.1097/PAF.0b013e318... What limits g tolerance sitting up: Wood (1987). https://pubmed.ncbi.nlm.nih.gov/3304268/ Pressure inside the eye under g's: Eiken et al. (2017), Eur J Appl Physiol. https://doi.org/10.1007/s00421-016-34... Head-artery blood flow and blackout timing: Krutz et al. (1975), J Appl Physiol. https://doi.org/10.1152/jappl.1975.38... Relaxed tolerance, g-suit and straining: Eiken et al. (2007), Aviat Space Environ Med. https://pubmed.ncbi.nlm.nih.gov/17484... Female pilot trainees: Navathe (2002). https://pubmed.ncbi.nlm.nih.gov/12433... G-LOC in 501 blackouts: Whinnery & Whinnery (1990), Arch Neurol. https://doi.org/10.1001/archneur.1990... G-LOC timing: Whinnery (1987). https://pubmed.ncbi.nlm.nih.gov/3619838/ Pilots who didn't know they were out: Whinnery (1988). https://pubmed.ncbi.nlm.nih.gov/3281648/ Recovery in 760 blackouts: Whinnery (2014), Extreme Physiology & Medicine. https://doi.org/10.1186/2046-7648-3-9 The straining maneuver: Behm et al. (2026), Frontiers in Physiology. https://doi.org/10.3389/fphys.2026.18... Centrifuge training: Eiken et al. (2022), Am J Physiol Regul Integr Comp Physiol. https://doi.org/10.1152/ajpregu.00043... Negative g before positive g: Banks et al. (1994). https://pubmed.ncbi.nlm.nih.gov/7980328/ Space Shuttle ascent g-loads: NASA NTRS 19940019731. https://ntrs.nasa.gov/citations/19940... Ordinary people in a centrifuge: Blue et al. (2012), https://doi.org/10.3357/asem.3351.2012 · Blue et al. (2014), https://doi.org/10.3357/asem.3956.2014 Astronaut trainees at 8.5 g: Wu et al. (2012). https://doi.org/10.3357/asem.3109.2012 Flopping into a chair: Allen et al. (1994), Spine. https://doi.org/10.1097/00007632-1994... Rocket-sled volunteers: Eiband (1959), NASA Memo 5-19-59E. https://ntrs.nasa.gov/citations/19980... US crash-test chest limit: 49 CFR 571.208 (FMVSS 208). https://www.ecfr.gov/current/title-49... Where the aorta tears: Shkrum et al. (1999), J Forensic Sci. https://pubmed.ncbi.nlm.nih.gov/9987869/ The aorta in cadaver tests: Baqué et al. (2006), J Trauma. https://doi.org/10.1097/01.ta.0000197... Aortic tears in crash deaths: Richens et al. (2003), Eur J Cardiothorac Surg. https://doi.org/10.1016/s1010-7940(02... Seatbelts: Evans (1987), J Trauma. https://doi.org/10.1097/00005373-1987... Eye-level pressure per g, crash stopping distances and the 3 miles at 400 mph are rounded physics calculations. ⚠️ Educational, not medical advice. The squeeze in the video is a 3-second muscle squeeze while breathing normally. Skip it if you have a heart condition or are pregnant. On rides, follow the posted rules. In the car, wear the lap belt low on your hips and the shoulder belt across your chest. 🎨 Animation & narration: Redline Body #WhatIf #Animation #gforce #fighterpilot #rollercoaster #humanbody #science #physiology #aviation #space #seatbelt #explained #education #redlinebody