How do helmets help prevent injury to the head?

[Anthony Lu]

Hi. So I've got an essay I have to write on sports equipment and how they increase safety. I know that in football, equipment to increase safety includes helmets, shoulder pads or paddings and cleats. Unfortunately, I have no idea how each of those equipment work to increase safety.

Okay, let's say for helmets, it helps reduces chances of having a concussion/severe brain injury. How does it do it? Like apart from its material, is there any physics stuff (perhaps related to momentum/Newton's laws) that were applied to the helmet to reduce the force of impact? By the way, this is for Y9 IB level thanks!

 

[Anthony Lu]

My essay question is "How has science been applied to contact sports equipment to increase safety?" and I am focusing on the equipments in american football and the science applied to these equipment to increase safety and prevent injuries.

 

[russ_watters]

It's all about acceleration.

 

[Drakkith]

Okay, let's say for helmets, it helps reduces chances of having a concussion/severe brain injury. How does it do it? Like apart from its material, is there any physics stuff (perhaps related to momentum/Newton's laws) that were applied to the helmet to reduce the force of impact? By the way, this is for Y9 IB level thanks!

Like Russ said, it's all about acceleration. Specifically the helmet and pads reduce acceleration by increasing the time over which the collision takes place, which reduces the force of the impact.
See this video:

 

[sophiecentaur]

My essay question is "How has science been applied to contact sports equipment to increase safety?" and I am focusing on the equipments in american football and the science applied to these equipment to increase safety and prevent injuries.

The general idea of spreading an impact over a greater distance comes from the definition of Work, which is Force times Distance. The kinetic Energy of your moving head causes Work to be done on the helmet and that dissipates the Energy. Double the Distance to come to a halt from a given speed and the Force will be halved. There is another factor too. If you land on a sharp edge, the skull can be penetrated because the local pressure is high. The casing of a helmet spreads the impact force over a large area and the skull is not penetrated. So it's a double win win situation.

Protective gear in sport can be a two edged sword and it would be worth while mentioning that in your essay. The 'safer' a situation appears to be, the more will people 'push their luck'. It's the same with modern cars with quiet interiors seat belts and air bags; they tend to encourage people to drive faster. A well padded football player will feel invincible and throw himself (herself?) at the opposition, harder and faster than he would with just a shirt and shorts on.
But that's not Physics; it's the psychology of the players and the audience.

 

[Andy Resnick]

My essay question is "How has science been applied to contact sports equipment to increase safety?" and I am focusing on the equipments in american football and the science applied to these equipment to increase safety and prevent injuries.

The reality is counter-intuitive: modern sports equipment results in *more* injuries because players feel more protected, leading to harder impacts:

http://bjsm.bmj.com/content/bjsports/30/4/289.full.pdf

Until recently (when the NFL gave some cash due to CTE prevalence), none of the major helmet manufacturers employed a single engineer.

 

[sophiecentaur]

Until recently (when the NFL gave some cash due to CTE prevalence), none of the major helmet manufacturers employed a single engineer.

Typical. It would be the same with aircraft and cars if they could get away with it.

 

[Windadct]

The reality is counter-intuitive

I agree with intent - but the point is, an unintended consequence of safety equipment is the way the game changes (is played) due to the protection. I guess a subtle point - but the problem is behavioral not directly due to the equipment.

This has significant factors in all safety related discussions.

Consider day 0 no safety equipment vs day 1 with all of the safety equip. The incidents ( say concussion in this case ) is drastically reduced, it will take time ( behavioral modification) before the long term changes and impact are seen.

In an industrial/commercial setting - it is critical that safety equipment application include behavioral consideration.

Lastly - from a physical/behavioral standpoint, the likelihood of a singular major event, say being knocked unconscious, which is dramatic and visible to all maintains awareness of the issue - add a helmet, this is greatly reduced. As we are seeing now - the cumulative effect of many smaller events is likely to be far more debilitating long term, but also "invisible" to the public ( fans) reducing the public pressure to continue to regulate the game, in fact many fans strongly arguing against additional changes and regulation to address this issue. The Hernandez case is truly a tragedy on all fronts, but IMO is shows the problem on many fronts.

 

[sophiecentaur]

I am wondering how our supplementary comments are really helping the OP. We have steered the thread away from what the initial brief requires of the essay. We have voiced the caveat about increased protection not being the whole story, but could we be helping more with the Physics of the situation?
Apart from reducing the decelerating force and reducing local pressure, is there anything else that should be said? I can't think of anything.
We could go into the types of injuries that protective clothing may not help with; for instance there is alway the risk of spinal injury when the whole body gets twisted. No amount of cushioning can protect against that.
I know very little of the rules of American Football but I know that the rules of Rugby Union are constantly being changed to lower the risk. Take for instance the rule that forbids you from lifting someone's legs higher than their body - to reduce the risk of neck injury and the constant modification of the rules about procedure in a Scrum or Ruck. Some physics there perhaps.

 

[Khashishi]

It's not all acceleration. There's also the spreading of the impact energy over a larger area. If your head gets hit by a lightweight rock, it isn't going to accelerate your head very much. But a helmet will probably help. So the helmet is a combination of soft material and hard material. The soft material will soften the acceleration, and the hard material will spread the point of impact.

 

[Andy Resnick]

I am wondering how our supplementary comments are really helping the OP. We have steered the thread away from what the initial brief requires of the essay. We have voiced the caveat about increased protection not being the whole story, but could we be helping more with the Physics of the situation?

Your point is well taken, but it's also useful (IMO) to point out when the 'just-so' story fails. The science of safety equipment is much more clear when discussing auto racing: improvements in crumple zones and harnesses have clearly decreased injuries. Similarly, improvements in baseball helmets and pads have likely decreased injuries. In both cases, what is missing is human-to-human contact and behavior; pitchers aren't suddenly hurling the ball faster and drivers aren't suddenly driving faster.

 

[Windadct]

It does happen quite often here(well all online forums really) - perhaps a commentary forum, where the original post can be replicated if it has fostered too much off track commentary, and allow the the off-the-rails comments to continue, but the OPs thread remain cleaner.

 

[Dr.D]

Helmets reduce the likelihood of a hole in the head. They do not do much about head attachment (neck) damage.

 

[gmax137]

none of the major helmet manufacturers employed a single engineer

source please?

 

[Andy Resnick]

source please?

Allegorical, unfortunately- a colleague was involved with an NIH concussion study with the NFL and told me that factoid about the 4 major manufacturers (Riddell, Rawlings, Schutt, one other...).

For supporting evidence, I looked for "football helmet" patents and found almost nothing regarding safety or engineering improvements until about 2005. For example, scroll down to the bottom of this one:

https://patents.google.com/patent/US20110209272A1/en

 

[jbriggs444]

https://patents.google.com/patent/US20110209272A1/en

That's a lot of words for "put padding on the outside of the shell too".

 

[gmax137]

I find it impossible to believe a company can mass produce hundreds of thousands of plastic molded products "without a single engineer."

The Riddell site says they're hiring "Industrial Designer" position. Not quite what you had in mind, I know. But a new-hired designer must report to someone.

 

[sophiecentaur]

I find it impossible to believe a company can mass produce hundreds of thousands of plastic molded products "without a single engineer."

The Riddell site says they're hiring "Industrial Designer" position. Not quite what you had in mind, I know. But a new-hired designer must report to someone.

You would be surprised just how little a person called an 'engineer' needs to know about Engineering. I imagine that @Andy Resnick was referring to a Chartered Engineer or equivalent. After all, it is a safety of life scenario.
"That mould looks good. How thick should we make the plastic? We could fill it with some old socks. Now . . . . for the important bits. What colour shall we make it and how much can we sell it for?"

 

[gmax137]

"That mould looks good. How thick should we make the plastic? We could fill it with some old socks. Now . . . . for the important bits. What colour shall we make it and how much can we sell it for?"

I understand what you're saying, and maybe it is even true in this case. But it's a nearly slanderous thing to say about a company, based on what some guy "Andy" on the internet says he heard from a friend of his.

BTW, the Riddell website history of the company is interesting, apparently they invented the plastic football helmet and provided the "suspension" used in the WWII US army helmet.

 

[russ_watters]

I imagine that @Andy Resnick was referring to a Chartered Engineer or equivalent. After all, it is a safety of life scenario.

That actually only applies to construction work. Product safety isn't something you need a license for. My dad spent an entire career as an engineer in the ste el and industrial gas industries and only worked with a handful.

I'm with @gmax that it is difficult to imagine you could have a company like that with no engineers (besides facilities engineers).

That may be besides the point though; what they probably need more is a biologist or even MD running an R&D department, with engineers below.

 

[berkeman]

Hi. So I've got an essay I have to write on sports equipment

Whelp, I hope we've helped you to copy/paste your homework assignment here in the General Physics forum. Hope you get an "A" with our help. Thread closed.