Ash,

You are dead wrong about the US research. Most was done without any involvement of the NFL or NHL. They actually fought against the research. It is the injured community that pushed the research, against the insurance companies and other financial interests. Concussions are not a fad issue. The internet just made it so more people can access information without the financial interests getting in the way. A few researchers were able to get their research in front of enough people to achieve critical mass. Motor vehicle, falls, assaults and other causes have always been an issue here.

The increased popularity of soccer, your football, and Title 9 access to sport for women/girls has brought injured girls into the public sphere. Parents often take a greater interest in the health of their daughters than their sons. Mother's have driven much of the public interest.

The 20 G concussion and the 120 G non-concussion are debatable issues. There has been a world wide struggle to define a concussion and MTBI. The 20 G concussion likely happens to a subject with quite a history of concussions. The 120 G non-concussion is likely somebody who has never suffered a concussion. Some are more tolerant of impacts. But then, as has been stated here many times, If you have seen one brain injury, you have seen ONE brain injury. There are a myriad of mitigating factors and differences. Neck issues, etc. can make a big difference.

As you claimed, the research can be flawed. The 2 G concussion claim could be just as flawed. I'm not saying it was. I read research regularly that is not flawed but limited in what it can address. People take the research and make assumptions based on misunderstanding the limits of the research.

Just as you contest the research, you do not have all of the answers either. This forum is not about exacting concepts. They do not exist regarding these issues. Research is a system of compiling evidence with models that are intended to reduce the errors. Often, they only find errors as they do the data collection. As they eliminate these errors or abstracts, they can become more exacting. But, they can't do that with concussions. So, they use a broad cohort.

There is currently a controversy about how to properly collect the concussion data needed to fully understand concussions. The US Veterans' Administration has spent millions trying to identify concussions vs similar clusters of symptoms that may be due to other causes.

So, there is no perfect answer. All we have is the research being done. Most of life is based on similar concepts. If we live life based on the outlier ideas such as " a concussion from 2 G's" we will be paralyzed. If we use common sense and reasonably moderate our behavior based on what we observe personally, we can hopefully move forward. Fretting about involuntary head jerks in bed is problematic when one can currently not do anything to end those head jerks. Stopping compulsive head jerks or head banging to music is worth the effort.

If you will read my comments, I said, "They usually use 60 G's " and "20 to 40 G's." Somebody who can not tolerate 2 G's would need to stay in bed. Walking can impart 2 G's to the head. I know the physics and have run the numbers. G's relate to acceleration and deceleration. Both are changes in speed over time. A sudden stop against a fixed object can cause high G forces for very small time increments. A jerk of the head does not not have that sudden change. It would be near impossible to achieve 20 G's with a simple head jerk. The muscles are just not strong enough to start and stop in the time and distance needed to reach those levels. The repetitive effect of shaking can cause trauma at lower G forces.

The research says that the brain can often tolerate extremely high G forces for miniscule time periods. It is the G force sustained over time that is most problematic.

But, when a question is asked, the available answer is usually based on research or at least a large amount of anecdotal evidence.

btw, You said "-The articles in that search are more often than not, with players wearing helmets ect which would require a greater force to overcome such protection." You ignored the fact that the research is based on G forces at the surface of the skull, not at the exterior of the helmet. There are accelerometers that are less than 5 mm thick by 10 to 15 mm square that are fitted against the skull with the helmet and padding holding them tight against the skull. They are set to measure G forces in multiple axis. Some use piezoelectric effect to sense movement. These are accelerometers similar to those in an iPhone that sense position.