If you wear a helmet, ski or snowboard as if you’re not wearing one.

If you wear a helmet, ski or snowboard as if you’re not wearing one.

By Jasper E. Shealy, PhD (updated Feb 2011)

Jasper Shealy, PhD, has been studying ski injuries for 40 years and snowboard injuries for 25 years. His interest in head injuries in skiing and helmets stems from the Sugarbush Resort in Vermont, where he has been a co-researcher with Dr. Robert Johnson and Carl Ettlinger for more than 30 years. Dr. Shealy is currently the vice-chair of the ASTM F27 Committee for snow skiing, and is a U.S. technical delegate for International Standards Organization (ISO) standards relating to snow skiing.

The use of helmets in alpine sports is on the rise. As of 2009/10 season 57% of all skiers and snowboarders used a helmet. We know that helmets can be an effective means of reducing the potential severity of a head injury if the wearer is struck in the head, or if the head strikes something. As a person who has devoted the majority of my professional life to research aimed at making skiing safer you might think that I would be happy with the trend of increased helmet use. Well I am, but I do have a few reservations. Why, you might ask, do I have reservations about more skiers using helmets on the slopes? Let me tell you why. The answer is complex and perplexing.

A little known and poorly appreciated fact is that helmets may not be as effective as you might think. By virtue of the design of helmets, they are more effective at preventing, or moderating skull fractures (0.1 percent of all skiing injuries) than concussions (2.4 percent of all skiing injuries). Alpine sports helmets have a hard outer shell that serves to blunt the concentration of force that is characteristic of a fracture. The helmets typically have a relatively soft inner liner that serves to cushion the blow and thus reduce the severity of the deceleration that the brain experiences. The evaluation criterion used by ASTM (others are similar) usually involves measuring the impact deceleration resulting from a free drop of 2.0 m, (which is equivalent to 14.1 miles per hour) onto a solid fixed object. The headform (equivalent to your brain) impact attenuation requirement is that the deceleration should not exceed 300 g. Most medical authorities believe that significant brain damage will begin to occur at about 150 g and go up from there; by 250 g, serious brain injury is practically a certainty. That is a modest level of protection given that the average maximum speed of skiers and riders on well groomed blue cruiser trails (where most of the fatalities take place) is on the order of 27 mph. It is clear that a helmet is not a panacea, particularly if the threat is that of a head impact with a tree on the margins of the trail (the most common fatality scenario).

Numerous studies show that increased use of a “safety device” like a helmet can alter the behavior of the user and in some cases may even ultimately lead to the unintended consequence of increased overall injuries in the long run. Insurance underwriters and actuaries use a term “moral hazard” to describe the behavior of humans, when they do things that they might not do if they did not have insurance, such as building houses on flood plains or on hurricane-prone coastal zones. This same behavior has been noted in virtually all areas of human endeavor. In general, when the cost (financial or physical risk) of some activity is reduced, there is a tendency on the part of human to be less careful in the pursuit of that activity. If padding, helmets and body armor in ice hockey reduces the perceived cost of playing in a very aggressive manner, players will increase the level of aggressive play. Since helmets and other protective gear became mandatory in the 1970s, the number of catastrophic injuries in ice hockey has increased dramatically. Numerous examples abound to demonstrate this point. Cars equipped with antilock brakes systems (ABS) are involved in more single car collisions than cars without ABS. Not because cars equipped with ABS are less capable, but because humans drive cars equipped with ABS differently than cars without ABS.

The U.S. Consumer Product Safety Commission (CPSC) has found to their dismay that as the use of helmets for bicyclists went from less than 18 percent in 1991 to 50 percent in 1998, the per capita rate of head injuries increased (not decreased) by 50 percent over that same period of time. This finding certainly contradicts the logical notion that increased use of bicycle helmets would result in decreased number of head injuries. In 1999 the CPSC predicted that if all skiers used a helmet there would not be any head related fatalities in skiing. The fact of the matter is that the rate of fatalities in skiing has not changed from the time when virtually no one wore a helmet to the present time (2010) when almost 60% of the population uses a helmet. Among the fatally injured skiers, the helmet utilization is equal to or greater than the general population. Head injury deaths do occur to helmeted skiers and riders. This is stark evidence that the circumstances of the typical fatality scenario is so violent that it overwhelms any mitigating benefit the helmet might have; not that helmets are not a good idea, they just have significant limitations.

In our studies of potentially serious head injuries in skiing, we have unfortunately seen much the same result. In our study at Sugarbush Resort, a ski area in Vermont, the use of helmets has increased from virtually zero prior to 1995, to approximately 75 percent today (2009/10). While we have seen a decrease in the number of head injuries for helmeted and versus non-helmeted skiers, we have noticed that the severity of the head injury is higher for helmeted skiers that non-helmeted. For non-helmeted skiers, only 23 percent of all potentially serious head injuries are more serious than a mild concussion. For helmeted skiers, 67 percent of their potentially serious head injuries are more severe than a mild concussion. This is due in part to the fact that a helmet essentially rules out several classes of head injury, for example there are no scalp lacerations or skull fractures to helmeted skiers; the overall risk of any injury above the neck has gone down by about 30%. We have also found that helmeted skiers ski faster than non-helmeted skiers, this is true for our control group, it is true for all injuries, and it is true for those skiers sustaining potentially serious head injuries. We cannot say that wearing a helmet makes you ski faster (it may be that people who tend to ski fast are the ones who buy and use helmets). Clearly in our study, the helmeted skiers are sustaining a disproportionate number of the truly serious head injuries, i.e., the moderate to severe concussions, and closed head injuries. From a biomechanical perspective, it is obvious that the users frequently find themselves in a situation where the simple use of a helmet is not enough to prevent serious head injury. Perhaps they are skiing too fast for the circumstances, or taking chances that are ill advised. Maybe they feel that the use of the helmet permits them to engage in activities that they might not engage in if they were not wearing a helmet (skiing in the trees) or at a higher level (skiing faster) than they might otherwise choose. A false, or exaggerated, feeling of security can lead to people increasing their level of risk-taking. This off-setting behavior, especially in young skilled males, appears in skiing and snowboarding to negate to some degree the benefits of wearing a helmet.

What can we take away from this lesson? If you are going to wear a helmet, ski and ride as if you aren’t wearing one. Don’t alter your behavior, don’t take more risks or ski or ride faster because you’re outfitted in a helmet. Make sure that you remain in control and ski and ride responsibly.

Finally, it is important to keep head injuries in perspective. The incidence of serious head injuries in alpine skiing and snowboarding is not as frequent as you might think. During the past 29 seasons in our study, only 2.6 percent of all medically significant injuries in skiing are what we call a potentially serious head injury (PSHI). PSHI’s are defined as any diagnosed concussion, skull fracture, closed head injury, and/or death due to head injury. Of that 2.6 percent, 0.1 percent are skull fractures, 2.4 percent are concussions, and the other 0.1 percent is everything else that has the potential for serious neurological damage. To put this in a context, the comparable figure for bicycles is 32 percent. 32 percent of all injuries to bicyclists that are treated in hospital emergency rooms would meet our PSHI criteria. While the risk of a PSHI in skiing is not zero, nothing in life is risk free. If you are not part of the truly high risk group, i.e., relatively young (late teens to early forties) adult male skiers who are at least intermediate or better in ability, your risk of such an injury is really quite low.

In my opinion, the use of a helmet is an effective part of an individual program to increase one’s safety on the slope. The use of a helmet should only be done if it part of an overall program, and under no circumstances should the use of the helmet be allowed to adversely affect the behavior of the user. Most important, do not have unrealistic expectations as to what a helmet can do, and ski safely and responsibly. Again, wear a helmet, but ski and snowboard as if you aren’t wearing one! I wear one, and would not go skiing without one, so should you.

By lok_admin • March 2, 2011 • 10:58 am

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