Reebok’s Checklight: A Standout in Wearable Devices

Whether you are counting how many steps you’ve taken a day with your fitness band or measuring your heart rate with a smart watch, technological advances in wearable devices are satisfying consumers’ cravings for their own personal health data.  In July 2013 Reebok unveiled a revolutionary wearable device called Checklight, which provides data concerning the severity of head impact in contact sports.

How Checklight works

Checklight is a thin skullcap, which fits underneath a helmet and has a small light that hangs by the player’s neck. A green flashing light indicates that Checklight is on and functional, whereas a yellow or red flashing light indicate that the player has had a head impact above the threshold that could potentially cause a traumatic head injury. Reebok is clear in establishing that Checklight is not an injury predictor or a diagnostic tool. Just because a player’s light turns yellow, or even red, that player does not necessarily have a concussion. Rather, it provides actionable information with which a player or coach can then make a more informed decision about how to proceed. Checklight provides one extra piece of data which players previously did not have that will help players and coaches decide whether to pull someone from a game or seek medical attention.

Development of Checklight technology

Checklight was developed as collaboration between Reebok and Boston-based MC10. The project took 4 years in development, which is long for Reebok standards, partially because it diverges dramatically from the company’s typical products. Checklight considers both linear and rotational force in its assessment of impact severity. Inventors tested many materials and designs to insure that no matter where on your head the hit comes it will be accurately assessed by the device.  he threshold for head injury was defined by the Head Injury Criterion (HIC) value used by the automotive industry in crash tests for dummies. The HIC value is calculated using a formula that takes into account the acceleration of a head over time after impact [1]. 

Importance of Checklight in the prevention of permanent brain damage

The importance of a product like Checklight has become apparent in recent years, as the long-term impact of traumatic head injuries has received national media attention. Parents today are asking the question; should I let my child play football or are the risks of head injury too great? This is probably not a question many people were asking 20 years ago, but it is certainly a reasonable one. Playing high impact sports has real risks; the Sports Concussion Institute in LA estimates that the risk of concussion is 75% playing football [2]. Having a concussion also increases your risk of a subsequent concussion, with each following concussion making another more likely. Multiple concussions can lead to the development of long-term damage including mild cognitive impairments, chronic traumatic encephalopathy (CTE), or post-concussion syndrome.

More professional athletes have spoken out about the dangers of CTE. CTE is caused by a buildup of protein in the brain that blocks the normal function of neurons, and can ultimately, in severe cases, lead to progressive dementia. A challenge in CTE research is that CTE can only be diagnosed posthumously. In September of 2014 the Department ofVeterans Affairs, which houses the largest brain bank in the United States, reported that 101 of 128 football players from any level of the sport (high school, college or professional) showedpositive diagnoses for CTE, and 76 of 79 NFL players [3]. Sample bias should be noted in this study becauseplayers who suspected brain damage from football may have been more likely to donate their brains to research, but even assuming the percentages are inflated here, the correlation is still quite alarming.

Reebok piloted Checklight with a football team in Wayland, MA. Over the course of the season a warning light went off 18 times.  In most cases the player was pulled from the game and after monitoring was determined to be fine. One case was an obvious concussion; even in the absence of Checklight the protocol for that player would have been the same, he would have been pulled from the game and directed to seek medical attention. One player fell into a gray zone, and it is these gray zone hits where Checklight can make the most impact. This player had a yellow light and he insisted that he was fine, but because of the light the coach insisted that he sit out. While sitting on the sidelines, that player developed symptoms of concussion. He had, in fact, incurred a concussion from the impact. Promptly pulling a player to the sidelines following a suspected concussion is particularly important because any further impact in the time directly following a concussion can be much more damaging in the long run.

Why Checklight implementation may be slow

If Checklight can provide one more piece of health data for the tech-savvy consumer, why aren’t we seeing children on sports teams everywhere sporting Checklight underneath their helmets? Unfortunately, the answer is probably the same as why seatbelts and helmets took so long to be accepted by the general public: it can take a long time for the adoption of safety measures. Players may feel that they will stand out if they are wearing Checklight and other team members are not. Reebok also is gearing their product more towards youth sports teams over professional leagues. It’s possible that a trickle-down approach may be more successful – if professional athletes started wearing Checklight and showed that they were concerned about brain safety, it may become more accepted by the masses.

Ultimately, Checklight stands out amongst other wearable devices in its ability to provide actionable data that could dramatically affect the safety of children everywhere. We can only hope that Checklight itself, or similar safety products, are adopted in the near future to protect young and old athletes from the dangers of repetitive head injury.



  1. McHenry, Brian G. HIC and ATB. 2004.

  2. Sports Concussive Institute. ‘Concussion Facts’.

  3. Breslow, Jason M. 76 of 79 Deceased NFL Players Found to Have Brain Disease. Frontline, September 30 2014.

Rachel Liberman

Rachel Liberman is postdoctoral research fellow at Massachusetts General Hospital where she works in the Nephrology division within the Program in Membrane Biology.  She is currently investigating the regulation of proteins involved in renal acid base homeostasis.  She received her PhD in Molecular Physiology from Tufts University Sackler School of Biomedical Sciences in 2014.  She is particularly interested in translational research and scientific communications.