Measuring the Severity of Head Impacts in Sports

It’s well known that repeated high-impact collisions in sports can cause acute concussive brain injury and even permanent brain damage. Unfortunately, there aren’t any simple quantitative tests to determine precisely who has suffered too many high-impact blows to the head. How severe does an impact have to be to cause injury? And how many moderate impacts are too many?

Devices designed to measure the relative severity and direction of head impacts may soon yield some answers. Already, at least one commercial product is available. The Checklight by Reebok is a relatively inexpensive monitoring device embedded into a skullcap that can be worn under a helmet. The Checklight combines a series of three accelerometers (to measure g-forces) with a gyroscope (to measure direction). A mathematical algorithm crunches the numbers and comes up with a relative measure of impact intensity. A green light on the device turns to yellow after a moderate impact and red after a more severe one.

But what do the indicator lights really mean? Reebok is careful not to call the Checklight a device for determining who has actually suffered a concussive blow to the head. They call it a “conversation starter”, meaning that it may allow coaches and medical personnel to decide who might need to be evaluated carefully by a medical professional. There is general agreement that more research is needed before these types of devices could be used to truly define who has suffered a concussion.

Some people worry that the device might lead to a false sense of complacency if too much reliance is placed on it. Others argue that we should be looking for ways to reduce the number and severity of head impacts in sports, instead of looking for better ways to determine who might be at risk of a concussion so that we can bench them. Still, it’s encouraging to see research-and-development efforts like this one being undertaken. There’s no reason we can’t take both approaches at once.

The Checklight is meant to be worn under a helmet. Researchers are working on similar impact-measuring devices that can be incorporated into a headband, for use in sports that don’t use helmets.