Reflexes & Reaction Time

NHL goalies have lots of equipment designed to help stop pucks, but their most valuable tool is their brain. It's what sparks the nerve impulses that travel to the limbs, allowing the goalie to see and react quickly enough to make a save. "Science of NHL Hockey" is a 10-part video series produced in partnership with the National Science Foundation and the National Hockey League.

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LESTER HOLT, reporting: In the National Hockey League, no player faces more shots, more action and more pressure than the goaltender. One of the best in the business is Pekka Rinne of the Nashville Predators, a 2011 finalist for the Vezina trophy, awarded to the top goalie in the NHL.

ERIK JOHNSON (Defenseman, Colorado Avalanche): He's a very athletic goalie and he fights through all the traffic and he's just a really tough goalie to beat.

HOLT: At six foot five, 210 pounds, Rinne is a mountain in goal. In 2011, he stopped 93 percent of the shots fired on him. In addition to his size and his elite skills, Rinne also has the incredible gift of speed. Like many NHL goalies, his cat-like reflexes allow him to quickly react to the puck.

PEKKA RINNE (Goaltender, Nashville Predators): I think it's something that comes from back of your mind. The better it is when, when you don't think about anything, you just read and react.

DR. PATRICIA SHEWOKIS (Drexel University): I'm amazed at the multitasking that is done on, on the rink by all the different players, in particular goalies.

HOLT: Dr. Patricia Shewokis, a human movement scientist and statistician at Drexel University, is funded by the National Science Foundation.

SHEWOKIS: The reaction to a stimulus is called reaction time. It's a period of time between the presentation of the stimulus, and in the sense of a goalie, it's the presentation of the puck coming toward him.

HOLT: To calculate how much time the goalie has to react, we divide the distance from the goalie to the puck by the speed at which it travels. If a player takes a shot on Rinne from the blue line - 60 feet from the goal - and he shoots the puck at 90 miles per hour, or 132 feet per second...

SHEWOKIS: What that would mean in terms of a goalie's reaction time is that he has just over point-45 seconds to make the save. If he is any slower than that, there's a goal.

HOLT: To stop the shot in less than half a second, Rinne must rely on his nervous and muscular systems. Rinne first anticipates where the shot is going to go by shifting his weight and moving into position.

RINNE: I try to look at the distance, how, how big of a distance is between the shooter and myself, and then place myself according to that.

HOLT: The shifting of weight in Rinne activates something called a reflex. A reflex is an unconscious muscle response to a stimulus, meaning it does not involve the brain. Rinne literally reacts to the shot without consciously thinking.

RINNE: When you see the puck is coming, if you start thinking about it, it's already by you.

HOLT: Receptors at the end of the sensory neurons fire an impulse that travels at speeds exceeding 100 meters per second, about 225 miles per hour. This impulse moves down something called the sensory afferent pathway, a chain of nerve structures that transmits the nerve impulse toward Rinne's central nervous system, igniting a key component of the reflex.

SHEWOKIS: This is where we have one of the body's natural resources that come into play which is the reflex arc.

HOLT: Think of the reflex arc as shortcut en route to a final destination. Because there is a need for an immediate response, the impulse is re-routed through the reflex arc to the spinal cord to be processed instead of going all the way up to the brain.

SHEWOKIS: At the spinal cord there is this relay station that occurs. It's short-circuiting the brain, going out through the motor neuron, out to the, the muscles and making this change so that the goalie is able to make that save.

HOLT: The best goalies have reflexes as fast as one-tenth of a second - that's how fast impulses travel from the sensory neuron, up and back down the reflex arc from the spinal cord, and then out to his muscles. The reflex allows Rinne to be in position and ready for the shot before the puck gets to him. While goalies have an innate ability to react quickly, they work hard during practice to anticipate shots and improve their reaction time.

RINNE: I think it's something that eventually is going to improve over the time, you know, just practicing and facing a lot of shots. You kind of learn to read the plate of the shooter and the stick of shooter and where he's placing the puck.

BRENDEN MORROW (Left Wing, Dallas Stars): I'm amazed every day at how good the goalies are and how quick they move. I don't know if they somehow know something where the puck's going and not telling us.

HOLT: For the players who must face outstanding NHL goalies like Pekka Rinne, more often than not they're caught on the short end of the stick.