Future studies need to include women's hockey
Posted: Sat Nov 11, 2023 12:55 pm
Future studies need to include women's hockey
Simon Fraser University researchers are learning more about how the scenarios for head impacts in hockey—from player clashes to contact with the boards or glass—affect impact severity. Their findings, reported in the journal Scientific Reports, should help to inform improvements in injury prevention.
In a follow-up to their previous study on how hockey head impacts occur, researchers returned to a Burnaby rink to follow 43 university men’s hockey players over another three seasons (2016-2019).
This time they compared video evidence—gleaned from cameras strategically placed around the rink to capture head impacts during play—with data from helmet-mounted sensors, or GForceTrackers, which measured head linear accelerations and rotational velocities. In all, 234 head impact incidents were recorded.
The head impact videos were analyzed with a validated questionnaire that probed situational factors before, during, and after impact to the head. Videos were then paired with corresponding helmet sensor data.
“We found that players with visible signs of concussion—such as clutching the head or slow to get up after the impact—experienced greater head rotational velocities than those without signs,” says Olivia Aguiar, a PhD student in SFU’s Department of Biomedical Physiology and Kinesiology (BPK). “Regardless of whether a hit to the head appears to be big or small, any athlete with visible signs of concussion must be removed from play and assessed by a medical professional.”
Researchers also found that while shoulder-to-head impacts occurred more frequently than hand or elbow contact, glass-to-head impacts were nearly four times more common—and just as severe—as board-to-head impacts.
And while the most severe head impacts resulted in penalties, researchers say rules that focus on “primary targeting of the head” offer a limited solution. “The head was the initial site of contact in 24 per cent of cases, of which only four per cent were penalized,” says Aguiar. “More often we saw some degree of player contact prior to the head being struck and found that these head impacts were just as severe. We suggest that prevention strategies aim to reduce any contact to the head, not just instances where the head is targeted.”
Despite growing evidence of repeated sub-concussive impacts, which are more prevalent than concussions in hockey and associated with structural changes to the brain, including symptoms of depression and cognitive impairment, the researchers say a lack of understanding on the most common and severe types of head impacts prevails.
“This is a barrier to the design and development of strategies for better protecting the brain, such as rule changes, skills training, and improvements to protective equipment as well as rink design,” says Aguiar.
“We’re hopeful that adding to the evidence on head impacts in hockey will lead to better ways to create a safer game and preserve brain health.”
Hockey head impact research highlights need to improve injury prevention
Read more: https://www.sfu.ca/sfunews/stories/2023 ... ry-pr.html
To our knowledge, our study is the first to combine helmet-sensor measures with video footage to classify and examine how head impact severity depended on the circumstances of head impacts in men’s university ice hockey. We collected 234 head impact events and examined observable situational factors before, during and after the collision.
We found that the most severe head impacts tended to result in penalties. Player-on-player collisions resulting in “major infractions” (penalties of longer than two minutes in the box) generated 2.0-fold higher head rotational velocities than cases involving “no infraction.” Similarly, Mihalik et al. (2010b) found that, in male youth hockey, penalized impacts resulted in higher linear accelerations. At the same time, we found multiple lines of evidence to support the notion that rules that focus on primary targeting of the head (e.g., Head Contact Rule 7.6 by Hockey Canada47), while important and in need of improved enforcement, offer a limited solution. First, direct targeting of the head rarely resulted in a penalty, indicating the challenge of reinforcing the rule. Only 4% of events where the head was the initial site of contact were penalized (n = 2 of 54). Second, when compare to primary head impacts, secondary impact to the head was far more common. Of the 234 head impacts we examined, the head was the initial site of contact in only 24% of cases. Finally, the severity of impacts did not depend on whether the head was the initial site of contact. Clearly, strategies are required to reduce the frequency and severity of both primary and secondary contacts to the head.
We found that players who exhibited visible signs of concussion (versus no signs) experienced impacts that produced 1.3-fold greater peak head rotational velocities. This finding casts doubt on the controversial question of whether players tend to purposefully exhibit visible signs of concussion for competitive advantage. The most common signs were “slow to get up” and “clutching of head.” Echemendia et al. (2018) and Bruce et al. (2018) examined the use of visible signs to predict subsequent concussion diagnosis in professional ice hockey. They found that, despite being observed frequently, “slow to get up” and “clutching of head” were poor predictors of diagnosed concussions. Bruce et al. (2018) speculated these signs, rather than reflecting concussive injury, may reflect an attempt to draw a penalty or lesser forces experienced at the head. Although injury diagnosis in the current study was unknown, our finding that players with visible signs experienced greater head impact severity support the notion that any player exhibiting visible sign of concussion should be removed from play and receive appropriate medical attention.
We found no evidence to indicate that the severity of head impacts depended on the playing zone where the hit occurred. More head impacts occurred in the offensive zone, but there were no differences in head impact severity between playing zones. Previous studies have reporting conflicting evidence on whether the severity depends on playing zone. Swenson et al. (2022) reported that male youth athletes reached higher speeds in the neutral zone resulting in greater head linear accelerations and rotational velocities at impact48. However, Hutchison et al. (2015b) found that concussive impacts in male professional hockey most often occurred in the injured player’s defensive zone (45%), followed by the offensive (34%) and neutral (21%) zones. Further investigation is required on whether hits tend to be more severe in specific playing zones at different levels of play.
We also found no evidence that head impact severity depended on the object striking the head. Collectively, over 80% of head impacts involved the head being struck by an opponent’s upper limb (44% of all cases) or the head striking the boards or glass (36% of cases). There were no differences in the severity of impacts to the head from being struck by an opponent’s “shoulder/upper arm,” “elbow/forearm,” or “hand.” Potvin et al. (2019) examined the severity and duration of linear and rotational head accelerations when players delivered padded shoulder-, elbow-, and hand-to-head impacts “as hard as they were comfortable in delivering” to an instrumented kickboxing dummy. They found that mean peak linear and rotational head accelerations were up to 2.1-fold greater for the hand and 1.9-fold greater for the elbow than shoulder. Our current results suggest that, during real-life game play in men’s university hockey, impacts delivered by the shoulder, elbow, and hand create similar peak head accelerations and rotational velocities. Head-to-glass collisions were just as severe, and much more common, than head-to-board collisions. Tuominen et al. (2017) and Schmitt et al. (2018) showed that modifications to the rink may reduce impact severity and injury risk. Our findings suggest that additional studies are required to evaluate the stiffness of the glass/boards and its effect on head accelerations. Previous studies which found differences in head impact severity either (1) reported small differences in mean magnitudes (< 2 g or < 200 rad/s2), where the clinical significance is unclear, or (2) examined factors at high impact magnitudes (e.g., > 20 g threshold or at the 95th percentile), excluding common low-magnitude impact events.
We found no association between head impact severity and anticipation of the collision. Mihalik et al. (2010a) also reported no differences in mean head accelerations between anticipated and unanticipated head impacts in youth hockey (aged 14). Furthermore, Eliason et al. (2022) found that more experience in delivering and receiving body checks did not protect minor hockey players (aged 15–17) against injury, including concussion53. Future research is required to evaluate the protective value of anticipatory responses and player training in reducing the frequency and severity of head impacts and injury in hockey.
Our study has several strengths. While previous studies had examined male youth hockey, ours is the first to combine head kinematics from helmet sensors with video footage to identify the most common and severe head impact scenarios in men’s university ice hockey. We also extend previous research by examining how impact severity depended on the specific object that impacts the head, puck possession, and visible signs of concussion. We recorded game play with a five-camera system, whereas most studies have used only one camera, and we used the video footage to verify that every case we examined involved a direct impact to the head.
Our study also has important limitations. First, we only analyzed data from the home games of a single men’s university ice hockey team. Therefore, results from this study may not apply to other contexts (e.g., practices; women’s ice hockey; other teams, leagues, and levels of play). Second, we observed substantial to perfect inter-rater reliability (kn > 0.60) for most questionnaire items used in our analysis. However, caution should be used when interpreting “looking in the direction of the collision,” as only fair agreement was achieved (TPA = 67%, kn = 0.31). Third, we included only the portion of head impacts having verified matches between video and sensor data. However, we have no reason to believe that the head impacts analyzed in the current study are not representative of all head impacts in the games we studied. Fourth, we reported peak head kinematics as proxy measures for head impact severity and consequently the degree of brain trauma. Future research should consider estimating brain tissue strain, using finite element models, which has been shown to have the closest association with brain injury. Fifth, we only included head impacts observed by six research assistants who watched the game from different angles around the rink, and it is likely some head impacts were missed by the observers. However, our approach ensured that we only included direct head impact events in our analysis. We did not review all sensor-recorded events using the video footage, since previous research has shown that sensor-recorded events often do not correspond to a direct head impact. For example, Wilcox et al. (2014b) used helmet-mounted sensors (HITS) and recorded 1965 impact events across 12 home games in a single season, yet only 270 head impacts were verified on video. Finally, the accuracy of helmet-mounted sensors in reflecting head accelerations and velocities may be affected by factors such as helmet fit, sensor location, and vibration of the helmet shell. To minimize these effects, we standardized the helmet model and sensor placement. Future studies should consider using instrumented mouthguard sensors, which are less error prone and are associated with improved skull coupling.
Associations between the circumstances and severity of head impacts in men’s university ice hockey
Read the study: https://www.nature.com/articles/s41598-023-43785-5
Simon Fraser University researchers are learning more about how the scenarios for head impacts in hockey—from player clashes to contact with the boards or glass—affect impact severity. Their findings, reported in the journal Scientific Reports, should help to inform improvements in injury prevention.
In a follow-up to their previous study on how hockey head impacts occur, researchers returned to a Burnaby rink to follow 43 university men’s hockey players over another three seasons (2016-2019).
This time they compared video evidence—gleaned from cameras strategically placed around the rink to capture head impacts during play—with data from helmet-mounted sensors, or GForceTrackers, which measured head linear accelerations and rotational velocities. In all, 234 head impact incidents were recorded.
The head impact videos were analyzed with a validated questionnaire that probed situational factors before, during, and after impact to the head. Videos were then paired with corresponding helmet sensor data.
“We found that players with visible signs of concussion—such as clutching the head or slow to get up after the impact—experienced greater head rotational velocities than those without signs,” says Olivia Aguiar, a PhD student in SFU’s Department of Biomedical Physiology and Kinesiology (BPK). “Regardless of whether a hit to the head appears to be big or small, any athlete with visible signs of concussion must be removed from play and assessed by a medical professional.”
Researchers also found that while shoulder-to-head impacts occurred more frequently than hand or elbow contact, glass-to-head impacts were nearly four times more common—and just as severe—as board-to-head impacts.
And while the most severe head impacts resulted in penalties, researchers say rules that focus on “primary targeting of the head” offer a limited solution. “The head was the initial site of contact in 24 per cent of cases, of which only four per cent were penalized,” says Aguiar. “More often we saw some degree of player contact prior to the head being struck and found that these head impacts were just as severe. We suggest that prevention strategies aim to reduce any contact to the head, not just instances where the head is targeted.”
Despite growing evidence of repeated sub-concussive impacts, which are more prevalent than concussions in hockey and associated with structural changes to the brain, including symptoms of depression and cognitive impairment, the researchers say a lack of understanding on the most common and severe types of head impacts prevails.
“This is a barrier to the design and development of strategies for better protecting the brain, such as rule changes, skills training, and improvements to protective equipment as well as rink design,” says Aguiar.
“We’re hopeful that adding to the evidence on head impacts in hockey will lead to better ways to create a safer game and preserve brain health.”
Hockey head impact research highlights need to improve injury prevention
Read more: https://www.sfu.ca/sfunews/stories/2023 ... ry-pr.html
To our knowledge, our study is the first to combine helmet-sensor measures with video footage to classify and examine how head impact severity depended on the circumstances of head impacts in men’s university ice hockey. We collected 234 head impact events and examined observable situational factors before, during and after the collision.
We found that the most severe head impacts tended to result in penalties. Player-on-player collisions resulting in “major infractions” (penalties of longer than two minutes in the box) generated 2.0-fold higher head rotational velocities than cases involving “no infraction.” Similarly, Mihalik et al. (2010b) found that, in male youth hockey, penalized impacts resulted in higher linear accelerations. At the same time, we found multiple lines of evidence to support the notion that rules that focus on primary targeting of the head (e.g., Head Contact Rule 7.6 by Hockey Canada47), while important and in need of improved enforcement, offer a limited solution. First, direct targeting of the head rarely resulted in a penalty, indicating the challenge of reinforcing the rule. Only 4% of events where the head was the initial site of contact were penalized (n = 2 of 54). Second, when compare to primary head impacts, secondary impact to the head was far more common. Of the 234 head impacts we examined, the head was the initial site of contact in only 24% of cases. Finally, the severity of impacts did not depend on whether the head was the initial site of contact. Clearly, strategies are required to reduce the frequency and severity of both primary and secondary contacts to the head.
We found that players who exhibited visible signs of concussion (versus no signs) experienced impacts that produced 1.3-fold greater peak head rotational velocities. This finding casts doubt on the controversial question of whether players tend to purposefully exhibit visible signs of concussion for competitive advantage. The most common signs were “slow to get up” and “clutching of head.” Echemendia et al. (2018) and Bruce et al. (2018) examined the use of visible signs to predict subsequent concussion diagnosis in professional ice hockey. They found that, despite being observed frequently, “slow to get up” and “clutching of head” were poor predictors of diagnosed concussions. Bruce et al. (2018) speculated these signs, rather than reflecting concussive injury, may reflect an attempt to draw a penalty or lesser forces experienced at the head. Although injury diagnosis in the current study was unknown, our finding that players with visible signs experienced greater head impact severity support the notion that any player exhibiting visible sign of concussion should be removed from play and receive appropriate medical attention.
We found no evidence to indicate that the severity of head impacts depended on the playing zone where the hit occurred. More head impacts occurred in the offensive zone, but there were no differences in head impact severity between playing zones. Previous studies have reporting conflicting evidence on whether the severity depends on playing zone. Swenson et al. (2022) reported that male youth athletes reached higher speeds in the neutral zone resulting in greater head linear accelerations and rotational velocities at impact48. However, Hutchison et al. (2015b) found that concussive impacts in male professional hockey most often occurred in the injured player’s defensive zone (45%), followed by the offensive (34%) and neutral (21%) zones. Further investigation is required on whether hits tend to be more severe in specific playing zones at different levels of play.
We also found no evidence that head impact severity depended on the object striking the head. Collectively, over 80% of head impacts involved the head being struck by an opponent’s upper limb (44% of all cases) or the head striking the boards or glass (36% of cases). There were no differences in the severity of impacts to the head from being struck by an opponent’s “shoulder/upper arm,” “elbow/forearm,” or “hand.” Potvin et al. (2019) examined the severity and duration of linear and rotational head accelerations when players delivered padded shoulder-, elbow-, and hand-to-head impacts “as hard as they were comfortable in delivering” to an instrumented kickboxing dummy. They found that mean peak linear and rotational head accelerations were up to 2.1-fold greater for the hand and 1.9-fold greater for the elbow than shoulder. Our current results suggest that, during real-life game play in men’s university hockey, impacts delivered by the shoulder, elbow, and hand create similar peak head accelerations and rotational velocities. Head-to-glass collisions were just as severe, and much more common, than head-to-board collisions. Tuominen et al. (2017) and Schmitt et al. (2018) showed that modifications to the rink may reduce impact severity and injury risk. Our findings suggest that additional studies are required to evaluate the stiffness of the glass/boards and its effect on head accelerations. Previous studies which found differences in head impact severity either (1) reported small differences in mean magnitudes (< 2 g or < 200 rad/s2), where the clinical significance is unclear, or (2) examined factors at high impact magnitudes (e.g., > 20 g threshold or at the 95th percentile), excluding common low-magnitude impact events.
We found no association between head impact severity and anticipation of the collision. Mihalik et al. (2010a) also reported no differences in mean head accelerations between anticipated and unanticipated head impacts in youth hockey (aged 14). Furthermore, Eliason et al. (2022) found that more experience in delivering and receiving body checks did not protect minor hockey players (aged 15–17) against injury, including concussion53. Future research is required to evaluate the protective value of anticipatory responses and player training in reducing the frequency and severity of head impacts and injury in hockey.
Our study has several strengths. While previous studies had examined male youth hockey, ours is the first to combine head kinematics from helmet sensors with video footage to identify the most common and severe head impact scenarios in men’s university ice hockey. We also extend previous research by examining how impact severity depended on the specific object that impacts the head, puck possession, and visible signs of concussion. We recorded game play with a five-camera system, whereas most studies have used only one camera, and we used the video footage to verify that every case we examined involved a direct impact to the head.
Our study also has important limitations. First, we only analyzed data from the home games of a single men’s university ice hockey team. Therefore, results from this study may not apply to other contexts (e.g., practices; women’s ice hockey; other teams, leagues, and levels of play). Second, we observed substantial to perfect inter-rater reliability (kn > 0.60) for most questionnaire items used in our analysis. However, caution should be used when interpreting “looking in the direction of the collision,” as only fair agreement was achieved (TPA = 67%, kn = 0.31). Third, we included only the portion of head impacts having verified matches between video and sensor data. However, we have no reason to believe that the head impacts analyzed in the current study are not representative of all head impacts in the games we studied. Fourth, we reported peak head kinematics as proxy measures for head impact severity and consequently the degree of brain trauma. Future research should consider estimating brain tissue strain, using finite element models, which has been shown to have the closest association with brain injury. Fifth, we only included head impacts observed by six research assistants who watched the game from different angles around the rink, and it is likely some head impacts were missed by the observers. However, our approach ensured that we only included direct head impact events in our analysis. We did not review all sensor-recorded events using the video footage, since previous research has shown that sensor-recorded events often do not correspond to a direct head impact. For example, Wilcox et al. (2014b) used helmet-mounted sensors (HITS) and recorded 1965 impact events across 12 home games in a single season, yet only 270 head impacts were verified on video. Finally, the accuracy of helmet-mounted sensors in reflecting head accelerations and velocities may be affected by factors such as helmet fit, sensor location, and vibration of the helmet shell. To minimize these effects, we standardized the helmet model and sensor placement. Future studies should consider using instrumented mouthguard sensors, which are less error prone and are associated with improved skull coupling.
Associations between the circumstances and severity of head impacts in men’s university ice hockey
Read the study: https://www.nature.com/articles/s41598-023-43785-5