ELI5: Explain Like I'm 5

Jendrassik maneuver

Okay kiddo, imagine you're running a race and you need a boost of energy to help you go faster. That's kind of what the Jendrassik maneuver is.

The Jendrassik maneuver is something doctors do to test your reflexes. They get you to clasp your hands together or interlock your fingers and then pull apart, like you're trying to break a stick. While you're doing this, the doctor will tap your knees with a special hammer.

When the doctor hits your knee with the hammer, your knee will jerk forward. But if you do the Jendrassik maneuver at the same time, which is when you clasp your hands together and try to pull apart, your knee will jerk even more than it would if you didn't do the maneuver.

That's because when you clasp your hands and try to pull apart, it sends a signal to your brain to focus on that task. When your brain is focused on that, it doesn't pay as much attention to the tapping sensation on your knee, so your leg has a bigger reflex reaction.

So, just like a boost of energy helps you run faster in a race, doing the Jendrassik maneuver can help doctors see how strong your reflexes are.