Comparing Impact and Concussion Risk in Leatherhead, Modern Football, and Hockey Helmets

Background: Improvements in the modern helmet have demonstrated beneficial effects in reducing concussion risk in football players. However, previous studies and existing data yield conflicting results regarding leatherhead previous era football helmets. This study compared the head acceleration produced in a leatherhead football helmet (LH) versus a modern football helmet (MF) versus a modified modern football helmet (ModF) (with softer foam placed on the inside after removing original padding) versus a hockey helmet (H) in helmet-to-helmet strikes.

Methods: Each helmet was placed on a Century Bob manikin and struck with various combinations. Accelerometers were placed on the manikin’s head at the apex, frontal, and right temporal locations, and each collected data in X, Y, and Z axes. The striking helmet containing a 4.42KG weight, was hung from a rope at a fixed length (117 cm) and raised 45° from horizontal, then released to strike the left side of the helmet on the manikin. The net vector peak linear acceleration (PLA) for each accelerometer was determined in each helmet-to-helmet strike and repeated for 20 trials.

Results: Mean PLA values of helmet-to-helmet impacts were obtained from the three accelerometer locations on the manikin's head and measured in gravitational G units (9.8 m/sec/sec). The results are summarized in Table 1 and Figure 1.

Each type of helmet was placed on the manikin head and struck with a MF. When LF was struck, significantly greater PLA values in all three locations were produced in comparison to H and MF. Compared to ModF, the LF produced significantly greater PLA values in the apex and frontal locations. ModF had a significantly greater PLA in the frontal and temporal regions compared to H. MF had a significantly greater PLA in the frontal and temporal regions compared to H. MF also had a greater PLA in the temporal region compared to ModF. In the apex and frontal locations, H had the lowest PLA followed by MF and ModF, which were not significantly different from each other. In the temporal location, H had the lowest significant PLA, followed by the MF, then the ModF.

The PLA generated between two of the same type of helmet (one on the manikin head and one as the swinging helmet) demonstrated a significantly greater PLA in a MF to MF strike in all three dimensional locations than in a H to H strike.

Conclusion: The results demonstrated that LF was the least protective in reducing PLA. The ModF did not provide a significant difference compared to MF. A significantly greater PLA was produced between the two MF when compared to two H. These results provide additional insight into the inconclusive evidence regarding the safety of LF and into the design of future football and hockey helmets.