Ski Helmets and Reaction Time

Ski season is upon us. Many experts (including myself) are of the opinion that helmets should be worn by all downhill skiers and snowboarders to help prevent head injuries. One of the “con” arguments proposed by some persons who object to wearing helmets is that they interfere with skiing in such a way as to perhaps make it more dangerous. In their opinion, this might occur by obscuring peripheral vision or diminishing the perception of sound. A very important article entitled article entitled “Do Ski Helmets Affect Reaction Time to Peripheral Stimuli?” (Wilderness & Environmental Medicine:22,148-150,2011) has recently been published by Gerhard Ruedl and colleagues from the Department of Sports Science at the University of Innsbruck in Austria.   

The investigators sought to determine whether or not ski helmet use affects reaction time to peripheral stimuli. They used the Compensatory-Tracking-Test (CTT) in a laboratory situation to study 10 men and 10 women during four conditions in a randomized order: wearing a ski cap, wearing a ski helmet, wearing a ski cap and goggles, and wearing a ski helmet and goggles.

The CTT is performed by using a video projector that projects on a screen. The subjects being studied are seated at a table and instructed to respond to visual stimuli that appear on the screen, notably including the periphery of vision. The results were interesting. The lowest (quickest) mean reaction time (approximately 477 milliseconds) was noted for persons wearing only a ski cap. This was not statistically significantly different from the mean reaction time noted for persons wearing a ski helmet (approximately 478 milliseconds). The persons wearing both the goggles and cap or helmet had longer mean reaction times (514 milliseconds and 498 milliseconds, respectively). Note that all of these times are around one-half second.

What are the take-aways from this study? First, it is important to note that this is a simulation that involved only one measure—peripheral vision. It did not take into account the influence of sound. It was not a field experiment, so the influences of extraneous factors were not included. Such factors might be sounds (e.g., ski and wind noise, talking, etc.), thickness of helmet or design of goggles, ambient weather (e.g., sunshine or cloud cover), speed of travel on skis and snowboard, and so forth. However, it somewhat counters the notion that wearing a helmet per se diminishes reaction time to external visual stimuli, regardless of the situation. Furthermore, in a very controlled setting, the differences in reaction time are very, very small—approximately 30 milliseconds (30/1000 of a second), which would not seem to be a huge factor in causing ski accidents. So, while more studies need to be somehow accomplished in more realistic field settings, this is a good start to dispelling the automatic notion that wearing protective helmets is harmful to skiers wishing to avoid the sorts of accidents that cause head injuries.