Head Kinematics During Experimental Snowboard Falls: Implications for Snow Helmet Standards

Abstract

A study by Nakaguchi and Tsutsumi [“Mechanisms of Snowboarding-Related Severe Head Injury: Shear Strain Induced by the Opposite-Edge Phenomenon,” J. Neurosurg, Vol. 97, 2002, pp. 542–548] showed that 68 % of all snowboarders’ head injuries were associated with backward falls, with beginner and intermediate snowboarders constituting the majority of the injured. We previously fabricated a test apparatus that replicated the fall kinematics of a snowboarder during a back-edge trip. A Hybrid-III anthropomorphic test device (ATD) outfitted with a snowboard and snowboarding gear was accelerated to a typical intermediate snowboarder’s speed (30.5 ± 1.5 kph) and tripped resulting in a backward fall that terminated in a head-to-slope impact. This test protocol produced repeatable fall kinematics under realistic on-slope conditions. In this study, we characterized the fall kinematics and quantified head velocity in order to evaluate the helmet energy management requirements associated with a back-edge trip. Digital high-speed video recorded at 500 frames per second was used to quantify the snowboarder’s head kinematics: (i) prior to the trip; (ii) during trip phase; (iii) during free fall; and (iv) at ground impact. Translational energy of the ATD was rapidly converted to a combination of linear and angular energy during the trip phase. Although the speed of the ATD’s center of gravity decreased during the trip phase, the test data showed the absolute speed of the head increased rapidly during the fall as a result of the body’s induced angular rotation. The mean head velocity normal to the slope increased from approximately zero at fall initiation to as much as 37.1 kph during the fall (122 % of the initial velocity), and was 29.1 kph at snow contact (95 % of the initial velocity). Resultant head velocity peaked at 54.3 kph (178 % of the initial velocity), and was 38.2 kph at snow contact (125 % of the initial velocity). The data presented here may be useful for assessing drop height requirements for snow helmet evaluations.

Head impact in a snowboarding accident

“…a) and head velocity (Fig. b–d) of the numerical model (NM) were consistent with those recorded with the ATD (Scher et al., ; Richards et al., ). Experimental and numerical head acceleration peaks were equivalent on soft snow [ATD: 74 (±39 g), NM: 86 g].…”

“…Kinematics comparison (a) and head resultant (b), normal (c), and tangential (d) velocity comparisons between anthropomorphic dummy (Scher et al., , Richards et al., ) (exp.) and multi‐body model (num.)…”

“…() and Richards et al. () were replicated numerically. In 2006, they projected an anthropomorphic dummy (ATD) outfitted with snowboarding equipment on an indoor simulated gentle ski slope at a speed of 30 km/h, the typical speed of an intermediate snowboarder.…”

Head impact velocities in FIS World Cup snowboarders and freestyle skiers: Do real-life impacts exceed helmet testing standards?

“…In contrast, the observed gross injury mechanism in our study involved the following sequence: edge catch, buttock contact with snow, back contact and finally head contact with snow (figures 6 and 7). Richards et al 25 reported that the mean normal-to-slope head impact velocity was 8.11 m/s, corresponding to a helmet drop height of 3.4 m, and the resultant velocity was 10.6 m/s, which despite the differences in study approach and crash mechanism is very similar to our results.…”

Head injury mechanisms in FIS World Cup alpine and freestyle skiers and snowboarders

“…This information is important to increase the ecological validity of future head impact injury reconstructions. For example, a previous laboratory reconstruction of snowboarding back edge catches with anthropomorphic test devices presented them as being flipped up in the air after the edge catch, with the hips and spine in full extension and landing directly onto the head 17. This is not a realistic reconstruction of a snowboarding back-edge catch event, based on our findings (see figure 4).…”