Evaluating the Effectiveness of Boxing Headguards in Mitigating Head Impact Accelerations That Cause Concussions by Using a Dynamic Head Model

Introduction

Giza and Hovda (2001) described a concussion as “any transient neurologic dysfunction resulting from a biomechanical force” (p.1). More specifically, a concussion is a “clinical syndrome of biomechanically induced alteration of brain function typically affecting memory and orientation, which may involve a loss of consciousness” (Giza et al., 2013, p. 2250). Concussions or mild traumatic brain injuries (mTBI) that occur while playing the sport of boxing, for example, cause short and long-term traumatic neurologic impairments on athletes and represent one of the major occurrences of head injuries for athletes at the amateur and professional levels.

In the sport of boxing, athletes scores points by landing finishing shots on their opponents with the intention to disable them (World Boxing Association, 2012). Consequently, the magnitude of the acceleration induced to the athlete’s head plays a significant role in the risk of concussions, brain injuries, and the severity of the damage (Rowson et al., 2016).

Boxing headguards provide a mean to reduce the risk of concussion on athletes by mitigating the magnitude of linear accelerations induced to the athlete’s head while playing the sport (McIntosh & Patton, 2015). There is a need to understand, however, the behaviour of boxing headguard materials in minimizing not only the magnitude of linear impact accelerations induced to the head but also rotational accelerations caused by oblique impacts to the head. Oblique impacts generate shear forces and consequently rotational accelerations producing a “jarring” effect to the head, which deforms the brain tissue and causes a concussion (Meaney & Smith, 2011). Furthermore, there is a lack of information in the literature regarding the effect of linear and rotational accelerations causing concussions on athletes in the sport of boxing.

Based on the need to further investigate the protective capabilities of boxing headguards, this study examined the static and dynamic properties of two commercial boxing headguards (Adidas® and Century® Drive) and a modified TPU liner insert model implemented into a Century® Drive headguard. The TPU material has become attractive in helmet design for its elastic, high tensile, and flexural strength properties (Lin et al., 2017). The first objective of this study was to determine the energy absorption capacity of boxing headguard materials across different locations during static testing. The second objective was to examine the combined effect of headguard type and impact location on measures of linear and rotational accelerations during simulated dynamic impacts.

Background

Meaney et al. (1995) stated that during a head impact, the combination of linear and rotational accelerations causes the brain to accelerate and decelerate inside the skull, which may result in a concussion. Linear accelerations produced during a head impact cause the brain to elongate and deform by putting a stretch on various structures of the brain including neurons, glial cells, and blood vessels. This elongation and deformation of the brain alters membrane permeability and decreases blood flow (Mckee & Daneshvar, 2015), which in turn can lead to a variety of symptoms affecting the physical and cognitive performance of the athlete (Giza & Hovda, 2001). Symptoms of concussion may include confusion, disorientation, unsteadiness, dizziness, headache, and visual disturbances (Giza & Hovda, 2001).