Over the past 10 years, lacrosse has grown increasingly popular, making it one of the fastest growing team sports in the country. Similar to other sporting activities, head injuries in lacrosse can and do occur, and the number of lacrosse-related head injuries has increased in recent years. In women's lacrosse, protective headgear is not required, but U.S. Lacrosse and the American Society for Testing and Materials are currently working to develop a headgear standard for the women's game. In the interim, some female lacrosse programs and individual players are wearing soft headgear during play. The effectiveness of this headgear is unknown. Testing was conducted to better understand the material properties of various types of headgear that may be used in lacrosse and the effect of this headgear on head impact response and head injury potential. For the evaluation of head impact response, an instrumented Hybrid III anthropomorphic test device (ATD) was impacted on the side of the head with lacrosse balls and the front and side of the head with a lacrosse stick. The linear and rotational impact response of the head and corresponding acceleration-based injury metrics are reported. Testing was then repeated with the ATD wearing different types of headgear. Tested headgear included a men's lacrosse helmet and two brands of commercially-available soft headgear. For the higher velocity ball impacts, there was no statistically-significant difference in the measured linear and rotational response of the head for the no headgear and soft headgear test conditions. For the lower velocity ball impacts, there was a small, yet statistically-significant, reduction in head linear acceleration for one of the soft headgears tested in comparison to the no headgear test condition, but there was not a statistically-significant difference in the rotational impact response with this headgear. These results indicate that the soft headgear would not be effective in reducing head injury potential during higher velocity ball impacts, such as ball speeds associated with shooting in women's lacrosse. The men's lacrosse helmet reduced both the linear and rotational response of the head for the higher and lower velocity ball impacts. Material testing showed that the padding in the hard helmet exhibited larger strain energy than the padding within the soft headgears when tested in compression. These results correlate with the larger reductions in head accelerations during ball impacts by the hard helmet. For the stick impacts, there were no statistically-significant differences in the lateral impact response of the head for the helmeted and soft headgear test conditions in comparison to the no headgear test condition, but there were statistically-significant, albeit small, differences in the frontal impact response of the head. The similar impact responses of the head during the stick impacts with and without headgear can be attributed to the relatively low severity of these impacts and the characteristics of the impactor.
Ice hockey body checks involving direct shoulder-to-head contact frequently result in head injury. In the current study, we examined the effect of shoulder pad style on the likelihood of head injury from a shoulder-to-head check. Shoulder-to-head body checks were simulated by swinging a modified Hybrid-III anthropomorphic test device (ATD) with and without shoulder pads into a stationary Hybrid-III ATD at 21 km/h. Tests were conducted with three different styles of shoulder pads (traditional, integrated and tethered) and without shoulder pads for the purpose of control. Head response kinematics for the stationary ATD were measured. Compared to the case of no shoulder pads, the three different pad styles significantly (p < 0.05) reduced peak resultant linear head accelerations of the stationary ATD by 35-56%. The integrated shoulder pads reduced linear head accelerations by an additional 18-21% beyond the other two styles of shoulder pads. The data presented here suggest that shoulder pads can be designed to help protect the head of the struck player in a shoulder-to-head check.
We tested the hypothesis that diaphragm muscle shortening modulates volume displacement and kinematics of the lower rib cage in dogs and that posture and mode of ventilation affect such modulation. Radiopaque markers were surgically attached to the lower three ribs of the rib cage and to the midcostal region of the diaphragm in six dogs of ∼8 kg body masses, and the locations of these markers were determined by a biplane fluoroscopy system. Three-dimensional software modeling techniques were used to compute volume displacement and surface area of the midcostal diaphragm and the lower three ribs during quiet spontaneous breathing, mechanical ventilation, and bilateral phrenic nerve stimulation at different lung volumes spanning the vital capacity. Volume displaced by the diaphragm relative to that displaced by the lower ribs is disproportionately greater under mechanical ventilation than during spontaneous breathing in the supine position (P < 0.05). At maximal stimulation, diaphragm volume displacement grows disproportionately larger than rib volume displacement as lung volume increases (P < 0.05). Surface area of both the diaphragm and the lower ribs during maximal stimulation of the diaphragm is reduced compared with that at spontaneous breathing (P < 0.05). In the prone posture, mechanical ventilation results in a smaller change in diaphragm surface area than spontaneous breathing (P < 0.05). Our data demonstrate that during inspiration the lower rib cage moves not only through the pump- and bucket-handle motion, but also rotates around the spine. Taken together, these data support the observation that the kinematics of the lower rib cage and its mechanical interaction with the diaphragm are more complex than previously known.
Traumatic brain injury may occur in baseball due to a head impact with a thrown, pitched, or batted ball. It has been shown that the average pitching speed of youth pitchers and high school pitchers is approximately 63 mph (28 m/s) and 74 mph (33 m/s), respectively. At pitching speeds of approximately 52 mph (23 m/s), the bat exit velocity (BEV) for metal bats has been shown to be approximately 100 mph (45 m/s). Head kinematics, such as linear and angular head accelerations, are often used to establish head injury risk for head impacts. With a possible ball impact velocity reaching speeds in excess of those typically tested for baseball headgear, it is necessary to understand how the head will respond to high velocity impacts in both helmeted and non-helmeted situations. In this study, head impacts were delivered to the front and side of a Hybrid III 50th percentile male anthropomorphic test device (ATD) by a baseball traveling at speeds of 60 mph (27 m/s), 75 mph (34 m/s), and 100 mph (45 m/s). Head impacts were performed on the non-helmeted ATD head and with the ATD wearing a standard batting helmet certified in accordance with the NOCSAE standard. The Hybrid III headform was instrumented with a nine accelerometer array to measure linear accelerations of the head and determine angular accelerations. Peak resultant linear head accelerations for the non-helmeted ATD were approximately 200–400 g for frontal impacts and approximately 220–480 g for lateral impacts. Peak resultant angular head accelerations for the non-helmeted condition were approximately 17,000–32,000 rad/s2 for frontal impacts and approximately 30,000–60,000 rad/s2 for lateral impacts. For the helmeted ATD, peak resultant linear accelerations of the head were approximately 70–300 g for frontal impacts and approximately 80–360 g for lateral impacts. Peak resultant angular head accelerations for the helmeted ATD were approximately 5,000–14,000 rad/s2 for frontal impacts and approximately 7,500–30,000 rad/s2 for lateral impacts. HIC values for the non-helmeted ATD were approximately 193–1,025 for frontal impacts and approximately 241–1,588 for lateral impacts. SI values for the non-helmeted ATD were approximately 235–1,267 for frontal impacts and approximately 285–1,844 for lateral impacts. HIC values for the helmeted ATD were approximately 16–415 for frontal impacts and approximately 23–585 for lateral impacts. SI values for the helmeted ATD were approximately 25–521 for frontal impacts and approximately 32–708 for lateral impacts. In comparison to the non-helmeted condition, the results demonstrate the effectiveness of a batting helmet in mitigating head accelerations for the frontal and lateral impact conditions tested.
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