A Stanford Medicine team reports in the Annals of Biomedical Engineering that motion-sensing mouthguards recorded 3,804 impacts without concussion and 47 that led to concussion in 203 athletes across seven sports. Peak linear head acceleration was the single most predictive factor of concussion in the team's model. A 100 g impact carried a 50 percent risk of concussion, and 150 g carried more than 99 percent.