Nanogirl Michelle Dickinson: Science reveals most accurate throw

Basketball players didn't adopt the granny throw but the underarm throw might be the most effective. Picture / CMGS Sport

With the World Masters Games in full swing this past week and Auckland's streets filled with athletes, it's no surprise that a study of the science of throwing things caught my eye.

Research published this week in the Royal Society Open Science journal finally answers some of those deep, searching questions you have about throwing - underarm or overarm (as if New Zealand hasn't formed a view on that already), speed versus accuracy, and some fascinating comparisons between the throwing abilities of humans and our close relatives, chimpanzees.

Throwing is a predominantly human trait. Although other primates throw sticks and stones in the wild, they don't do it anywhere near as well as we do.

Chimpanzees are incredibly strong and athletic in many ways, yet adult male chimps can only throw an object at about 32km/h. Contrast this with professional baseball players recorded throwing at speeds of more than 160km/h and the speed difference is clear.

The ability of humans to throw quickly is believed to have developed about two million years ago, with an anatomical advantage that eventually helped us with hunting.

Speed, however, is only one metric when it comes to throwing. Hunting prey using rocks or a spear is only successful if the object actually hits the target.

This need for accuracy in the throw quickly creates challenges when trying to hit a target with force. The faster an object is thrown, the less accurate the throw is likely to be. Scientists have long thought that this inaccuracy came about because throwing faster makes it more difficult it is to release the object at the right time.

This new research, however, shows that even when objects are released in the same way, a faster throw will still be less accurate. Using data from different studies of thrown objects, the researchers from Yale and Harvard discovered that most of the differences in accuracy between a fast throw and a slow one happen after the object has left the hand.

They found that when an object is thrown quickly it travels almost in a straight line which means that any error in the angle that it was thrown at is amplified. Slowly thrown objects however tend to arc and small errors in the throwing angle have little effect on the trajectory of the object, and thus slower throws are likely to be more accurate.

Most of us have evolved to throw cricket and rugby balls at each other now, rather than rocks and spears. But the same success metrics of speed and accuracy still apply.

So to the burning question - what is the ideal way to accurately throw an object? The study found that the ideal overarm or underarm technique depends on factors including the target's shape, height and distance.

After mathematically modelling the trajectories of thrown objects, the study concluded that underarm throws may be the most effective, as they are a perfect trade-off between speed and accuracy. Underarm throwing also requires less moving hinge joints with only the shoulders pivoting, compared to the shoulder, elbow and wrists during an overarm throw.

Despite this advantage, underarm throws are an uncommon sight in sport. In the 1980s NBA player Rick Barry perfected his underarm free throw and became one of the most effective shooters of all time.

The technique earned the nickname of the "granny throw" and other players didn't follow suit. Perhaps these cultural attitudes have a greater impact than accuracy alone?

Darts was the only exception to the rule in the study with an overarm throw at 5.5m/s and release angle of 17-37 degrees calculated as the optimal bullseye strategy.