Science

Draymond Green Blames Crotch Kicking on Knee-Jerk Physiology

Human Hitmonlee Draymond Green is out of control: On Sunday, the notorious crotch-kicking Golden State Warrior jammed his foot into the Phoenix Suns’ Marquese Chriss, calling to mind his brutal head-kick to the Houston Rockets’ James Harden only three days before. After being penalized according to the NBA’s “Unnatural Acts” rule, he lashed out at the league for failing to understand “kinesiology.” By invoking the body’s knee-jerk reactions, Green is attempting to get a free pass for his bad behavior.

In his rant during a shootaround on Saturday, the crazy-legged power forward provided a somewhat reasonable explanation for his errant kicks.

It’s funny how you can tell me how I get hit and how my body is supposed to react. I didn’t know the league office was that smart when it came to body movements. I’m not sure if they took kinesiology for their positions to tell you how your body is going to react when you get hit in a certain position.

Given his history of wild leg-kicking, NBA fans probably won’t buy Green’s argument. It’s even less likely kinesiologists will. While it is true that the body does react reflexively to certain physical stimuli, it isn’t always clear that Green’s kicks are reactionary.

Knee-jerk reactions occur when the leg reflexively extends, thereby resembling something like a kick. In an actual knee-jerk reaction — known among physiologists as a “patellar reflex” — the lower leg jerks to extend after the area right below the kneecap is tapped with a hammer. When the patella tendon (the bit of tissue connecting the muscles to the bone) is struck, it causes the quadriceps muscle to stretch, which, in turn, triggers a sudden contraction immediately. Just like an elastic band, a stretched-out muscle always wants to return to its relaxed state to avoid injury.

It is unlikely that the knee-jerk reflex is responsible for Draymond Green's kicking every game.

Under the skin, what’s really happening during a knee-jerk reaction is that a signal travels from the stretched-out quadriceps muscle, through the nerves, and up to the spinal cord, where it is processed; an outward-bound signal from the spinal cord travels back out through a different nerve, telling the quadriceps to contract. These signals, combined with a different, coordinated signal telling the hamstring to relax, is ultimately what causes the knee to jerk upward. Because the amount of time elapsed between the initial hammer tap and the knee-jerk is how long it takes for nerve signals to complete a loop between the muscle and spinal cord, knee tapping is used to test for issues in that nerve signaling circuit.

The knee-jerk reaction isn’t the body’s only stretch reflex. Others include the jaw-jerk reflex, which involves an open mouth snapping shut as the lower jaw is tapped beneath the chin, as well as the ankle-jerk reflex, which happens when a relaxed foot is tapped at the Achilles tendon and reflexively points.

But the reflex that most closely describes what Green does in games is the knee-jerk reaction. Unfortunately for Green, there isn’t much evidence he’s receiving acute blows at the very small, specific sweet spot right below his patella in the moments leading up to his kicks. It definitely did not look this way when he kicked Marquese Chriss in the hand:

And it did not seem to be the case when he kicked James Harden. Poor James Harden.

Of course, with all of the kicking Green has done over his career — and there has been plenty — it’s entirely possible that some of his kicks were in fact elicited by a rapid tap to the lower knee. Just not his most recent ones. Perhaps, as he insinuated when he told the NBA to “Let me know how the body works because clearly mine don’t work the right way,” Green’s body actually does react differently — and more violently — than that of most people. Or maybe the reflexive issue at hand is less physical than it is psychological: Knee-extending and ankle-flexing aside, perhaps what he is dealing with is, straight-up, a jerk reflex.

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