Evaluating Whether Soft-shell Padded Caps Reduce Linear And Angular Acceleration Impacts

PURPOSE: The use of soft-shell padded caps to be worn over helmets have been promoted to decrease the force of impact experienced from head contact and decrease forces sustained with repetitive head impact. The goal of this study was to measure the linear and angular acceleration of impacts experienced by players wearing custom-fitted instrumented mouthguards in those who wore caps to those who did not to evaluate if caps were effective in reducing the force of impact players experienced. METHODS: Forty NCAA Division I players were fitted with mouthguards for the 2022 football season. Data were collected from any player wearing a mouthguard and whether they wore a soft-shell padded cap during practices (the only time caps are worn). Mann-Whitney U and Chi-Square tests were used to compare independent groups of those who wore caps to those who did not in the number of significant hits, peak linear acceleration, peak angular acceleration, and head impact severity as measured by the head acceleration response metric (HARM). RESULTS: There were 3,328 total hits during practices over 487 player practice-days, with 556 (17%) meeting criteria for significant impacts. Of those hits, 2,559 happened to players wearing caps (77%). We found significant differences between those who wore caps with those who did not in the number of significant hits experienced (p < 0.001), peak angular acceleration (p < 0.001), and HARM (p = 0.002). We did not find a significant difference in peak linear acceleration (p = 0.28). CONCLUSION: Using soft-shell padded caps over helmets helps reduce the force of angular acceleration and reduces the number of significant hits. Players should utilize these tools when possible. Additional work is needed to reduce the force of impact from linear acceleration and other metrics which contribute to head impact injuries. - Total Caps – Yes Caps – No Significant Hits Hits 3328 2559 (77) 769 (23) 556 (17) Position Group Defensive Back 53 (2) 0 (0) 53 (2) 16 (0) Defensive Line 460 (14) 460 (14) 0 (0) 68 (2) Linebacker 1156 (35) 942 (28) 214 (6) 215 (6) Offensive Line 881 (26) 881 (26) 0 (0) 85 (3) Running Back 281 (8) 0 (0) 281 (8) 65 (2) Tight End 276 (8) 276 (8) 0 (0) 59 (2) Wide Receiver 221 (7) 0 (0) 221 (7) 48 (1) Peak Linear Acceleration (g; median) 15.58 15.51 15.97 30.40 Peak Angular Acceleration (rad/s/s; median) 1012.38 991.51 1094.03 2224.57 HARM (median) 1.60 1.59 1.69 3.04 Football Research, Inc.