Modifications in the hardness and compressibility of softballs and baseballs have been developed for use by children of different ages with the intent of reducing the force of impact while maintaining performance characteristics. The NOCSAE has developed standards for these softer baseballs. An expert review indicated that softer balls that meet the NOCSAE standard are less likely to result in serious head injury or commotion cordis (chest injury) attributable to ball impact. See Youth Baseball Protective Equipment Project: Final Report. CPSC.

The helmet evaluation tests for softer baseballs have limited validation for direct head impacts. Independent tests of softer baseballs and a check of the NOCSAE standard as a safety test for unprotected head impacts was conducted by the Institute for Preventative Sports Medicine and Orthopedic Surgery Associates in Ann Arbor, Michigan. See Analysis and Comparison of Head Impacts Using Baseballs of Various Hardness and a Hybrid III Dummy. This study explored the direct baseball impact on the front and side of the head to a nonhelmeted youth baseball player.

This study used a pneumatic baseball gun to impact a test dummy's head at 60 mph as specified in NOCSAE standard for helmet impact protection. Baseball impacts were delivered to three head locations: frontally on the forehead, frontally between the eyes, and laterally on the right temple above the level of the nasion. Commercially available baseballs were tested in the three-head impact configurations. The relative impact energies were identified. Data was analyzed for the "head injury criterion" (HIC) to determine head injury risk, utilizing skull fracture and brain injury data for forehead impacts to calculate the probability of serious injury during frontal impact. The results indicated that softer baseballs resulted in progressively greater reductions in acceleration and head injury criterion (HIC) and showed a reduced injury factor.

Of note, frontal impact areas that had a greater thickness of skin covering the metal skull of the dummy in the testing, showed a lower acceleration and HIC (less risk of injury). In addition, lateral impact areas showed greater acceleration and HIC than frontal impacts in part related also to a thinner head skin covering the temple region.

This was explained by the fact that skin bottoms out with a hardball impact, the skull remains stiff, and high acceleration occurs. The study found that the softer balls significantly reduce the risk of skull fracture and head injury. The study concluded that a validated procedure is required to measure the underlying risk of direct impact by baseballs and soft balls used in sport.