Errors in Throwing Actions Finally Explained

For many years, biomechanics experts, mathematicians and physicists have been arguing about which kind of errors underlie failures in reaching targets when humans throw things.

Clearly, one of the most complex aspects of the problem is the fact that the human arm provides its “owner” with nearly endless possibilities of throwing an object.

You can do so either overhand or underhand, and each of these types of throws has its advantages and disadvantages. Determining where errors originate when a throw does not achieve its target is an objective that has been pursued for years.

A team of experts from the Harvard University Applied Math Lab, led by scientists Madhusudhan Venkadesany and Lakshminarayanan Mahadevan, recently conducted a new investigation into this issue.

They say that, when people throw things, they use their hands, arms, shoulders and wrists. Emulating such a multi-jointed system in the lab is extremely complex, and so the team decided to simplify the model.

Additionally, the angle, speed and trajectory of the throw are also important factors, that cannot be compared to each other due to their completely different natures.

But Venkadesany and Mahadevan did not let this get in their way, Technology Review reports.

They produced a system that resembled the human arm, but which could be reduced to two important traits – the angular velocity of the swing and the angle of the arm at the time of release.

The team determined that a very clear trade-off appears to exist between speed and accuracy. They say that slower throws are more precise, even though more prone to interference from the outside.

But the Harvard group also made a groundbreaking new finding – this correlation has nothing to do with the way muscles behave when under pressure.

Until now, experts believed that “noise” building up in muscles' capabilities when they were solicited at full power were responsible for the errors in throwing accuracy.

The new model indicates that his has nothing to do with it, and that many throws fail due to the way in which trajectories amplify errors.