Virginia Research Day 2021

Whitewater Helmet STAR : Evaluating the Biomechanical Performance and Risk of Head Injury for Whitewater Helmets Brock G. Duma, Mark T. Begonia, Stefan M. Duma Virginia Tech - Institute for Critical Technology and Applied Science - Blacksburg, VA

Graph 1: Linear Acceleration for the 4m/s Front Impact Condition

Introduction

There are more than 6 million people who participate in whitewater kayaking and rafting in the United States each year (Figure 1). 1 Of these 6 million participants, there are over 50 whitewater related deaths each year, which makes it have one of the highest fatality risks of all sports. As the popularity in whitewater activities grows, the number of injuries, including concussions, also increases. The objective of this study was to create a rating system for whitewater helmets by evaluating the biomechanical performance and risk of head injury of whitewater helmets using the STAR system.

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Linear Acceleration (g)

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R FF

FC HL

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Helmet Model

Figures 3: Front Impact Location

Graph 2: Rotational Acceleration for the 4m/s Front Impact Configuration

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Rotational Acceleration

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Figures 4:Side Impact Location

Graph 3: STAR Value

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STAR Value

Figure 1: Whitewater rafting is one of the most deadly sports in the U.S.

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Figures 2: Adjacent view of the custom pendulum impactor positioned for a 2m/s impact speed for the front location site

Helmet Model

Figures 5: Rear Impact Location

Materials and Methods

Conclusions

Results and Discussion

All watersport helmets that passed the EN: 1385: 2012 standard, and that were clearly marketed for whitewater use were selected for this study. A total of 21 helmets were found, and 2 models of each helmet were tested. A custom pendulum impactor was used to test the helmets under conditions which are known to be associated with the highest risk of head injury and death (Figure 2). The struck head consisted of a NOCSAE head and Hybrid III 50 th percentile neck, with the head form instrumented with three linear accelerometers, and a triaxial angular rate sensor. For this study, 126 tests were performed at six different configurations. The helmets were tested at 3.1 m/s and 4.9 m/s with impacts to the front, side, and rear for each speed (Figures 3-5) . The velocities were chosen given that the highest recorded flow rate in a whitewater river is 5 m/s, which implies that it is very unlikely that any underwater head impact will have a head impact speed greater than 5 m/s. 2 Each helmet’s Summation of Tests for the Analysis of Risk ( STAR ) value was calculated using the combination of exposure and injury risk that was determined by the linear and rotational accelerations (Eq. 1). 3

➢ The majority of the whitewater helmets are not recommended given that the star values observed for the helmets indicate an extremely high probability of concussion for each impact. ➢ The helmets should reduce head accelerations by a far greater margin for lower concussion risks. The head accelerations observed should more closely model that of American football helmets. ➢ Higher acceleration values for both linear and rotational acceleration were observed at higher impact speeds. ➢ The helmet manufacturer “Sweet Protection” created the top four best performing helmets.

In the 3.1 m/s front impact condition the 21 helmeted tests resulted in a range of 30.2 – 131.2 (g), and 1601 - 5036 (rad/sec^2). In the 3.1 m/s side impact condition the 21 helmeted tests resulted in a range of 35.7 – 129.7 (g), and 2500 - 3678 (rad/sec^2). In the 3.1 m/s rear impact condition the 21 helmeted tests resulted in a range of 24.7 - 152.6 (g), and 1759 – 6889 (rad/sec^2). In the 4.9 m/s front impact condition the 21 helmeted tests resulted in a range of 82.0 – 282.5 (g), and 4024 - 13069 (rad/sec^2) (Graphs 1 and 2). In the 4.9 m/s side impact condition the 21 helmeted tests resulted in a range of 88.1 – 316.4 (g), and 5609 - 24563 (rad/sec^2). In the 4.9 m/s rear impact condition the 21 helmeted tests resulted in a range of 82.9 – 332.0 (g), and 3336 - 14381 (rad/sec^2). The helmets’ star values resulted in a range of .2518 - 4.8634 (Graph 3). Higher linear acceleration values were observed for the front impact conditions, and higher rotational acceleration values were observed for the side impact conditions. The linear regression relating linear and rotational acceleration is strongly correlated with an r^2 value of .72. The linear regression relating the price of the helmet and star value is not correlated with an r^2 value of 0.11. The linear regression relating the mass of the helmet and the star value is not correlated with a star values of 0.03.

➢ Price is not correlated to performance (r^2 = .11). ➢ Weight is not correlated to performance (r^2 .03) ➢ Linear and rotational acceleration is correlated (r^2 = .72)

References

Equation 1: Whitewater STAR equation where L = location, V = Velocity, E = exposure, R = risk, a = linear acceleration, and α = rotational acceleration.

[1] Spittler, J et al., Sports-Specific Illness and Injury. 19:422-429, 2020. [2] EN 1385: 2012, BSI Standards Publication. 2013. [3] Rowson, S et al., Journal of Neurosurgery. 120:919-922, 2014.

RV: Gath RV

H: Shred Ready Half Cut

FL: Shred Ready Full Cut

O: Shred Ready Outfitter Pro

RF: Sweet Prot. Rocker Full

SR: Sweet Prot. Sweet Rocker

W: Sweet Prot. Wanderer

T: WRSI Trident Composite

C: WRSI Current G: Gath Gedi

SS: Shred Ready Super Scrappy

SE: Shred Ready SESH

ST: Sweet Prot. Strutter

CS: NRS Chaos Side Cut

HL: NRS Havoc Livery

SH: Shred Ready Shaggy

FF: Shred Ready Full Face

CF: NRS Chaos Full Cut

M: WRSI Moment Full Face

R: Sweet Prot. Rocker

CP: WRSI Current Pro

Highest Rated Whitewater Helmets

Lowest Rated Whitewater Helmets

Presented at the 2021 VCOM Virginia Research Recognition Day

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