Why do I feel faint at the gym?

The gym stacks all the usual faint triggers into one hour, and the NHS's faint-cause list reads like a workout log: not eating or drinking enough, being too hot, standing up too quickly (a sign of low blood pressure), and - the one to rule out - heart problems. Exercise shifts blood into your working muscles; if you also skipped lunch, a hard set can leave your brain briefly under-supplied, and the grey tunnel-vision feeling arrives. Standing up fast after floor exercises or leg press does a similar thing - blood pools in dilated leg vessels and pressure dips before your body catches up. Heat multiplies all of it. Prevention is concrete: eat a light meal or snack 1 to 2 hours before training, drink water before and through the session, take rests between hard sets, cool the room or your clothing where you can, and change positions slowly - sit for a few seconds before standing from the mat. The moment you feel faint: stop, sit or lie down, and lift your legs if you can - riding it out seated is how you avoid the fall. The pattern that needs a doctor, not a snack: actually fainting during exercise (rather than after), feeling faint with chest pain, palpitations, or unusual breathlessness, or fainting episodes that repeat despite eating and drinking properly. Exercise-induced fainting deserves a heart check, and the NHS says anyone who faints should see a GP. Pymander is a free AI doctor, 24/7 by text, that can help you sort the pattern.