A new patent awarded to Google outlines a system built into a wearable device like Google Glass, that uses motors and motion detectors to automatically tighten or loosen the glasses' arms depending on what the wearer is doing.

The new glasses would have an actuator - a little motor for controlling movement - in each arm that could bend the arms in or out as needed, rather like the way a bendy straw works.

When the glasses detect that their wearer is bobbing up and down at an increased rate - while running, for example - the arms contract to grip the wearer's head, 'Quartz' reported.

This could be a massive boon for athletes who choose not to wear their glasses when active, for fear of breaking them. The actuators could also help solve the one-size-fits-all approach that many glasses have to fitting.

In case the glasses are too wide for someone's face, the actuators could automatically resize the glasses so that they fit snugly.

However, there is no guarantee that Google will be looking to implement this particular patent in Glass.

According to a Google spokesperson, some patents turn into products, and some do not.