The conversation needs to change from g force only to neck strength, g force, body mass relative to Newtons of force exposure……and how that can reduce reaching the Intracranial Pressure (ICP) and shear strain thresholds that result in concussions – not strictly g forces.

Intracranial Pressure

Recent Research Misses the Obvious in a recent post by Dr. Cameron Marshall – “A recent (November 2019) study published by Campolattano and colleagues examined children 9 to 14 years of age on the magnitude of their concussion injuries. It was found that the average linear acceleration was only 62 G’s. This is significantly lower than the usual 98 G’s found with high school or college-aged athletes.”

Recent research Dr. Cameron Marshall posted showing that children suffer concussions at less force (62 Gs) then high school and college athletes (98 Gs), is due to the brains’ tolerance to ICP 47.4 kPa and shear strain 3.71 kPa threshold for mTBI. These pressures are created by the acceleration and stopping distance during an impact and the ability to resist and dampen the force. To put this in perspective, 62 Gs converts to 760 Newtons of force and 98 Gs converts to 1,201,314 Newtons of force that would need to be absorbed through the musculoskeletal system, assuming the stopping distance is ~ 4mm e.g. hitting the turf or another helmet.

Based on extensive testing CAP has conducted, the average 9-year-old can perform a neck extension with ~15 lbs, whereas the average high school or college athlete can lift ~35 lbs. Obviously, there is a dramatic difference in body mass between these two groups. In sports like football, hockey, soccer and rugby, a larger body mass can be an advantage to better dissipate the force through the bodies’ tendons and muscles, which act as shock absorbers. However, a larger body mass would likely be a disadvantage in equestrian and cycling sports where the athlete usually flies over the horse’s head or the handlebars landing on their head.

The research did not take into consideration rotational forces which create much higher shear strain resulting in sustaining brain trauma at much lower acceleration rates. Furthermore, the forces discussed assume an average skull mass of 10 lbs. It’s important to note that skull mass is already full size by the age of 4 to 6 years old. Strength, body mass and connective tissue development is under- developed compared High School and College athletes which would explain the disparity.

To summarize, to minimize concussion risk, the neck musculature needs to be conditioned to train the connective tissues to 1. reduce peak acceleration during impact, and 2. absorb the impact force and disperse it throughout the body to mitigate increases in ICP and shear strain.

Examination of Brain Injury Thresholds in terms of the Severity of Head Motion and the Brain Stresses International Brain Injury Association – IBIA