we are all given.

Which seems pretty sensible, when facing an object potentially moving at 100 mph plus.

But is it even possible?

The average male tennis pro has a serve of around 125mph.

Baseball pitchers are throwing on average a 100mph fastball.

With cricket fast bowlers coming in at a pedestrian 85mph.

But when considering reaction times, speed isn't the only factor,

we have to take in to account the distance too.

If we take tennis, and consider the server's height and position on the court, the ball

has about 75 feet to travel towards the receiver. Wind resistance, air friction and the impact

of hitting the surface will slow the ball by roughly half, by the time it reaches the

receiver. Meaning the overall journey of the ball takes an estimated 700 milliseconds.

For context, blink twice. That was 700 milliseconds.

But consider now that it takes around 500 milliseconds for the brain to process information received

from the eyes, and 25 milliseconds for the motor cortex

to send a message to the arms and legs. It will take a further 150 milliseconds to

swing the racquet, meaning the receiver has about 25 milliseconds to gauge the flight

of the ball, and act accordingly.

Decent odds if you're a fly, less so for a mere human.

Now add to all this that it is extremely unlikely

for the ball to be visible to the human eye until the point it crosses the net,

which means the receiver really has only around 400 milliseconds to react.

The maths just doesn't add up. If you watch the ball by the time you've

swung the ball will be past you. For big servers like John Isner or present

world record-holder Sam Groth the journey time from the net is reduced to about

300 milliseconds, less than half the time needed to judge and execute the shot.

So watching Groth's delivery to get to it, is impossible

“You cannot be serious man”

And in order to return it, you'll need to predict where the ball is going.

“You cannot be serious!”

Fortunately, your brain is able to do exactly that. With a little practice.

While we've all heard that, practice makes perfect, well this is especially true for

elite athletes. Where practice isn't just about technique

but about cutting down on thinking time. Eight-time Grand Slam winner Andre Agassi

says that his game was at its best when he was able to, stop thinking and start feeling.

Stop thinking. Let things happen.

Practice isn't just about improving your own game. It also helps you to understand

and exploit your opponent's.

The brain contains a catchily-named action observation network

of linked regions, including the cerebellum, which governs motor control

and the superior parietal cortex, that assists hand-eye coordination.

The AON helps us recognise familiar patterns and anticipate future action.

Like Ronaldo here, scoring in the dark. The more an athlete prepares and practices,

the more effective the AON becomes. For example, in a football penalty shootout,

even if the striker isn't known at all to the goalkeeper, they can still look for familiar

gestures and body-shapes in the run-up to help with their prediction.

Elite athletes show enormous capacity for making such predictions, with the best tennis

players able to regularly anticipate the trajectory of their opponent's shot even before they

make contact with the ball.

So how does this even work? The eyes help to determine the trajectory

of the ball through tiny, rapid movements known as saccades.

When we look at a picture, our eyes establish multiple fixation points for us to focus on,

to help us make sense of what we are seeing. When a tennis ball is struck, the brain is

able to draw a line from point of impact, to where it thinks the ball is likely to be

in future, creating, an imaginary fixation point.

The eyes are able to track the ball along this path, and suddenly saccade away to this

imaginary point, allowing the player to prepare for the shot before the ball has arrived.

So with the right amount of training and mental preparation,

returning a 125mph serve is a piece of cake.

In theory.