Neurosurgeon explains real reason even 'fit' people black out at the gym during heavy weight lifting

If you experience repeated episodes, get checked. As Dr Jagannathan says 'lifting heavy should challenge your muscles — not overwhelm your nervous system'.

It’s a sight often seen in 'gym fail' compilations: a seemingly fit weightlifter completes a massive rep, only to go limp and collapse seconds later. While it looks alarming, Dr Jay Jagannathan, a neurosurgeon at the Jagannathan Neurosurgery Institute in Michigan, has said that it isn’t a sign of weakness — it’s a specific physiological glitch.

According to Dr Jay Jagannathan, a sudden faint at the gym is not a sign of weakness, but a specific physiological glitch called a vasovagal response. (Pexels)

The science of the 'gym fail'

Taking to Instagram on February 4, Dr Jagannathan broke down the science behind these sudden collapses, identifying the culprit as a vasovagal response. According to Dr Jagannathan, the phenomenon is a sudden loss of consciousness triggered by the body's own nervous system – when a lifter is under intense physical strain, the body can overreact to the stress. “It’s not weakness. It’s physiology,” Dr Jagannathan.

He explained. “Under intense strain, the body can trigger a reflex that briefly drops heart rate and blood pressure, reducing blood flow to the brain. The result? A sudden faint — often followed by a quick recovery.”

In many cases, this is exacerbated by the valsalva maneuver — the common practice of holding one’s breath to create internal pressure and stabilise the spine. While effective for power, it can spike blood pressure so rapidly that the body overcorrects by forcing a sudden drop, leading to a 'lights out' moment.

How to stay conscious

The good news for gym-goers is that these episodes are largely preventable, Dr Jagannathan shared; he said that lifting heavy should challenge the muscles without 'overwhelming the nervous system'.

To minimise the risk of a vasovagal episode, he recommended: “What actually helps lower the risk during heavy lifting: controlled breathing instead of breath-holding, adequate hydration, especially in heat, stable blood sugar and electrolytes during long or intense sessions, strong posture, proper form, and smart use of a spotter.”

When to worry

While a one-off fainting spell during a personal record attempt might be explained by physiology, Dr Jagannathan warned against ignoring a pattern: “Lifting heavy should challenge your muscles — not overwhelm your nervous system. Train smart. Respect your body’s signals. And if episodes like this happen repeatedly, it’s worth getting checked.”

Note to readers: This report is based on user-generated content from social media. HT.com has not independently verified the claims and does not endorse them.

This article is for informational purposes only and not a substitute for professional medical advice.