100 g Head Impacts Carried 50% Concussion Risk in Mouthguard Data

Head impacts producing about 100 times Earth’s gravity carried a modeled 50% concussion risk in a new study of instrumented mouthguard data. Straight-line head acceleration predicted diagnosed concussion better than rotational acceleration, challenging a long-standing emphasis in helmet testing and injury models.

Key Number: 100 g. The model placed the probability of concussion at 50% when peak linear acceleration reached roughly 100 times gravitational acceleration, well below an often-cited 192 g estimate derived from older helmet-sensor data.

Mouthguards measured the head rather than the helmet

The study combined data from male and female athletes in seven sports, including American football, lacrosse and mixed martial arts. Motion sensors embedded in custom mouthguards recorded both straight-line and rotational head motion. Because a fitted mouthguard is coupled to the teeth, it can track the skull more directly than a sensor mounted on a helmet that shifts during impact.

The dataset contained 3,804 non-concussive impacts and 47 concussive impacts. Researchers matched the sensor records with video and diagnoses made by medical staff or later video review of visible signs such as disorientation and balance loss. They then tested which measurements best separated concussive from non-concussive events.

Peak linear acceleration was the strongest single predictor. Adding peak rotational acceleration did not improve the model, while adding peak rotational velocity produced a modest gain in precision. The result does not mean rotation is harmless. Nearly every real collision combines straight-line and turning motion, and longer events such as whiplash may give rotational acceleration a different role.

The proposed threshold is lower than older estimates

The new risk curve estimated a 50% concussion probability at 100 g and more than 99% at 150 g. An average football impact is about 25 g, according to the Stanford team, but averages conceal the relatively rare high-energy collisions that matter most for acute injury.

An often-cited older estimate placed the 50% point around 192 g. The researchers argue that helmet-mounted sensors behind some earlier datasets may have measured head motion less accurately. Their result therefore has direct implications for certification tests and rating systems that decide which impacts a helmet must manage.

NewTqnia previously examined how movement, heart measurements and athlete surveys can be combined to evaluate sports performance. The new study applies the same broader principle to safety: measurements closer to the body can change what a model identifies as the most informative signal. A related example is smartwatch screening that combined pulse and motion data, where the value also depended on careful comparison against a clinical reference.

Helmet design may need another target

Recent helmet designs have often emphasized reducing rotation through slip layers and other mechanisms. If linear acceleration is independently important, protective systems may also need to lengthen and cushion the straight-line impulse more effectively.

The researchers tested liquid-filled helmet pads on crash dummies and calculated lower concussion risk than with standard pads at every tested impact level. At the most severe setting, estimated risk fell from 73.3% to 55.7%. That experiment is an engineering result, not evidence that the pads prevent concussions in athletes. Senior author David Camarillo is a co-founder of SoftShox, the company licensing the technology, a relationship that matters when interpreting the product comparison.

What changes next

The immediate consequence is a testable engineering question. Helmet-rating organizations can reanalyze their impact protocols using the new curve, while other research groups can compare it against separate mouthguard datasets. Manufacturers can also evaluate whether designs optimized for rotational motion leave avoidable linear acceleration.

A better model will not turn one sensor reading into a diagnosis. Concussion remains a clinical assessment, and impacts below any threshold can still injure an individual. The useful next milestone is not a lower headline number, but a risk function that reproduces across sports and leads to protective equipment that measurably reduces diagnosed injuries.