Craniology, Part I: What Your Helmet Will (and Won’t) Do To Protect You

About the author: “I am a very low level adult amateur eventer, sometime DQ, “horse wife,” AKA groom for my husband at horse trials, and a huge fan of upper level eventing and other horse sports. Being a glutton for punishment, I am getting a master’s degree at night and on weekends from Harvard. I researched helmets as part of a class assignment and found out how little I actually knew about the round things we wear on our heads. Here’s the information. Hope you find it useful!”

Katherine Coleman and Longwood at Luhmühlen 2017. Photo by Leslie Wylie.

Part 1: The Basics

From a safety perspective, equestrian helmets are designed to do three main things:

  1. Help protect your head from being cut by something sharp or jagged. The hard, although somewhat pliable, outer shell of your helmet is primarily responsible for this part of the protection. In safety tests, the helmet must prevent a sharp object, designed to resemble a horse’s hoof, from reaching the helmet’s lining.
  2. Slide. Your helmet’s outer shell is smooth to allow it to slide along the ground or another surface, giving your head more stopping room if there is some available.
  3. Reduce the force on your skull on impact.
    The inner liner of your helmet is a critical part of your helmet. It is responsible for keeping your skull safe when it hits the ground or another object. The inner liner is made of hard foam (think of a Styrofoam cooler) that crushes when the helmet experiences a hard impact. When the liner crushes, it gives your head an extra .003 second to stop on hard ground, and it provides an extra .007 or .008 of a second to stop on a softer surface like turf. Assuming your helmet meets ASTM standards, the extra stopping time is designed to keep the force on your skull under 300g (or 300 times the force of gravity). 300g is the internationally accepted threshold for serious brain injury. According to the National Bicycle Safety Institute, a force of 300g is approximately the equivalent of your head hitting a hard, flat surface like a wall, while traveling in a straight line at 14 miles per hour – it’s a lot of force.

There are two critical things that equestrian helmets are NOT designed to do: protect your head against multiple falls and protect your head against concussions and other traumatic brain injuries.

The photos below show the foam liner in British Olympic event rider Pippa Funnell’s helmet after she fell from Sandman 7 at the Withington Manor Horse Trials in 2016. The foam liner did its job and protected Pippa’s head. Note how much the foam liner cracked and crushed as a result of the fall. As the photos show, once cracked or crushed, the foam liner inside your helmet stays cracked and crushed. Consequently, the helmet needs to be replaced.

Source: Riders4Helmets.org, 2016.

Helmet tests by Dr. Carl Mattacola of the University of Kentucky provide additional insight into how a helmet’s foam liner responds when a rider falls.

Being a rider himself, and knowing that riders sometimes get up after a fall and keep riding, Dr. Mattacola studied how much protection a helmet provides after a fall. In a laboratory, he subjected a variety of cross-country/jockey helmets to a succession of four hard impacts on the same part of the helmet. The next set of photos show a cross section of the liner in the Champion brand helmet (called a pad in the photos) before and after the four impacts. The photo on the left shows what the foam liner looked like before any impacts. The photo on the right shows what the liner looked like after four impacts.

Source: Mattacola, 2015.

After four impacts the pad’s thickness was less than half of its original thickness and the gap between the shell of the helmet and the pad almost doubled in size. This particular helmet would have kept the force on the rider’s skull below 300g for the first and second impacts. For the third and fourth impacts, the force on the rider’s skull would have exceeded the 300g international threshold for serious brain injury.

The table below shows the results of the four impacts on all of the ASTM certified cross-country/jockey helmets included in the tests. All of the ASTM certified helmets met the 300g standard for the first and second impacts. After two impacts, all but one of the helmets failed to meet the 300g standard. A helmet’s ability to withstand more than one impact is important because riders can have more than one impact in the same fall. For example, a rider might hit a jump and then the ground or hit the ground and then be hit by the horse’s leg or hoof.

Source: Mattacola, 2015. Red numbers indicate the force was greater the 300g internationally accepted standard for brain injury.

The outside of Pippa Funnell’s helmet demonstrates that a visual examination of a helmet does not show what happens to the foam liner inside. Aside from a bit of chipped paint, Pippa’s helmet looks fine, yet from the photos above we know the liner is damaged.

 

Photo: Riders4helmets.org, 2016.

After testing the cross-country/jockey helmets, Dr. Mattacola’s advice was:

  • When you fall off, replace your helmet even if it does not look damaged.
  • No matter how much you love your old hunt cap or any other non-ASTM certified helmet, don’t ride in it. In addition to testing ASTM certified helmets, he also subjected a non-ASTM certified helmet to a single impact. Thankfully, the test was in the lab because the helmet would have allowed the rider’s head to experience over 900g of force – enough force to be fatal.

In addition to knowing your helmet may not protect you through multiple falls, it is important to know that equestrian helmets are NOT designed to protect you against a concussion or other types of traumatic brain injuries. Before concussions started getting so much public discussion, I was sometimes skeptical when I heard that a rider suffered a concussion while wearing a helmet. In the process of trying to convince athletes of the benefits of wearing helmets, the benefit claims were sometimes overblown and a lot of misinformation entered the marketplace.

The reality is that the ASTM does not test helmets for their ability to prevent concussions or traumatic brain injuries (TBI), and scientists are still working to pinpoint the biomechanics that cause TBI so they can design helmets that can influence those biomechanics. It is clear that protecting riders against straight line impacts is not enough to protect them against traumatic brain injuries. As Dr. Mattacola’s work illustrates, ASTM certified helmets are quite good at mitigating even a straight line impact that could result in death without the helmet. Yet, riders wearing helmets keep suffering from concussions and other traumatic brain injuries.

Practicing Safe Riding

While we are waiting for a helmet that protects against more hazards, the best thing to do is follow the same best practices we learned in driver’s education (adjusted for horses, of course).

  • Plan ahead for the unexpected
  • Ride a horse whose speed and direction you can control (OK, at least most of the time)
  • Be prepared to respond to other riders, horses and other animals you may encounter
  • Do not expect other horses and riders to do what you think they should do
  • Respect other horses and riders that are sharing your space
  • Be aware of footing and weather conditions, especially when they are changing, and respond to the changes
  • Be alert and avoid distractions such as texting, eating, and watching videos while mounted.

Wear your helmet, replace it if you fall, practice safe riding, and Go Eventing!

Stay tuned for Part II, which will discuss ventilation, helmet replacement, and what to expect in helmet technology in the future.

 

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