While the COVID-19 pandemic is far from eradicated, there are definite signs of hope for a return to normalcy. Vaccine distribution has begun and most adults and teenagers (but not children under 12) are eligible to receive the vaccine in the US (Centers for Disease Control Prevention, 2021). Several studies have demonstrated that policies of universal masking contribute to preventing the spread of COVID-19 (Hendrix et al., 2020; Payne et al., 2020; Van Dyke et al., 2020; Wang et al., 2020), and the Centers for Disease Control and Prevention continues to recommend mask wearing for non-vaccinated individuals (Centers for Disease Control and Prevention) and many institutions continue to have mask mandates, especially for non-vaccinated individuals. With the emergence of contagious variants, considerations other than disease transmission are relevant to decisions about universal masking in youth sports. This is highly relevant as winter approaches and there is a greater emphasis on indoor sports that were largely cancelled or required athletes to wear masks during play (Dergaa et al., 2021).

Although wearing a facemask mitigates the spread of COVID-19, wearing a facemask has also been shown to block the lower visual field (El-Nimri et al., 2020; Young et al., 2020; Klatt and Anson, 2021; Weber et al., 2021). Restricting the peripheral visual field increased reaction times and has been linked to reduced overall sports performance in football and downhill skiing (Loopeker and Rowley, 2001; Ruedl et al., 2011; Miller et al., 2019). Blocking the lower visual field promotes downward head tilt, which reduces how far ahead obstacles can be detected (Timmis and Buckley, 2012). Blocking the lower visual field during walking may lead to a trip or fall. Obstruction of the lower visual field related to wearing a facemask may worsen balance for people with higher fall risk (Kal et al., 2020; Klatt and Anson, 2021). Another arena where facemask wearing may have detrimental consequences related to increased risk for injury is the sport of ice hockey. Ice hockey was designated as a “moderate or high-risk” sport related to the potential for COVID-19 spread in several US states, and rules were developed for players/coaches/officials to wear facemasks (Maine Department of Economic Comminuty Development, 2021; MinnesotaHockey, 2021). In some cases, wearing facemasks was mandated for any on-ice hockey activities at all age levels. However, not all states/countries adopted this mandate for players. Although most early evidence suggests that healthy individuals are only mildly impacted while wearing a FM during exercise (Shaw et al., 2020; Hopkins et al., 2021; Mapelli et al., 2021; Shein et al., 2021), others have reported significant reductions in respiratory capacity in healthy adults (Fikenzer et al., 2020; Lässing et al., 2020; Driver et al., 2021). To date the impact of mask wearing on aspects of exercise or sports participation, such as player safety, has received little attention.

Ice hockey players wearing a FM may have reduced lower field of view and to facilitate seeing the puck may need to tilt their head down. Tilting the head downward reduces the “look ahead” window, effectively shortening the reaction time for contact avoidance (Patla and Vickers, 2003). In fast moving contact sports like ice hockey, not being able to see your opponent soon enough because of downward head tilt may lead to more frequent body contact/checking which is the most common cause of player injury (Brust et al., 1992; Emery et al., 2011; Brenner et al., 2014; Mosenthal et al., 2017; Simmons et al., 2017). The Hockey Equipment Certification Counsel Inc. promotes an education program titled “Heads-Up, Don't Duck” to specifically create awareness of the increased risk of cervical spine injuries when looking downward (HECC). Therefore, a scenario where ice hockey players tilt their head downward to play the puck due to a restricted lower visual field (from wearing a facemask while playing), may lead to unsafe on-ice conditions.

Although it has long been known that blocking the lower visual field impairs walking ability (Marigold et al., 2007; Marigold and Patla, 2008) and reaction times in football and alpine skiing (Ruedl et al., 2011; Miller et al., 2019), the extent to which wearing a mask blocks the lower field of view in the context of ice hockey is unknown. Here we report on whether mask wearing in youth hockey players significantly restricts their lower field of view. We hypothesized that youth ice hockey players would experience a significant reduction in the lower visual field when wearing a facemask. We additionally modeled the relationship between the FM induced reduction in the lower visual field and the ability to see a puck on their stick. We hypothesized that wearing a facemask would impair the ability of youth hockey players to use peripheral vision to see a puck on their stick.

Four participants did not demonstrate staircase convergence (indicating incorrect task performance) and one participant had missing data due to technical problems and were not included in the statistical analyses. The participants were 84.8% male and 45.4% (n = 15) played travel hockey last season, with the remaining participants being house players. Four individuals reported an injury last season, and nine individuals reported wearing a mask during practice or game play at least for some of the season, see Table 1. Six of the nine individuals reported that they had to look down to play the puck when wearing a mask compared to when unmasked.

The average unmasked visual angle threshold [11.4 degrees (SD 5.9 degrees)] was significantly smaller (closer to the skates) than the masked visual angle threshold [20.3 degrees (SD 8.0 degrees)], [t(1, 26) = −6.2515, p < 0.0000012, Cohen's d = −1.2], as shown in Figure 2. The average hockey stance visual angle was 29.73 degrees (SD 3.79 degrees). Four of the players had visual thresholds that exceeded their hockey stance visual angle.

The primary result from this novel investigation indicates that wearing a facemask significantly restricts the lower field of view in youth hockey players. Although not surprising, to our knowledge this has not previously been demonstrated in youth hockey players. These thresholds suggest that in a “heads-up” hockey stance, the lower visual field angular thresholds would allow most if not all tested players to visualize their stick blade only when not wearing a mask. When wearing a facemask, the fraction of time that the puck would be visible in the peripheral field of view is significantly reduced. Four of the non-goalie participants had a masked visual angle threshold larger than the visual angle from the eyes to the middle of the stick blade while in a hockey stance. Those four individuals would not be able to use peripheral vision to see the puck on the stick blade while skating with a mask on. Thus, to visualize the puck on the stick players must tilt their head down rather than relying on peripheral vision.

We further examined the potential for on ice change in head tilt behavior by relating the masked visual angle threshold to the calculated visual angles in both a hockey stance and an upright stance. It is unlikely that players maintain the exact hockey position height while in play on the ice. Our model conservatively accounts for this by examining the frequency the puck would not be visible given masking and stance criteria while holding the stick placement relative to the skates constant. While masked we expect the players to be able to see the puck using peripheral vision roughly 96% while in their hockey stance. The probability of seeing the puck when more upright is reduced to about 80%. Often during game play players skate in a more upright position than the hockey stance which is more analogous to the non-skating face off position. An important caveat to the interpretation of these models is that if the stick is not perfectly straight out in front of a masked player, the masked player may have to look down more often as the visual angle will shift closer to the visual threshold. Similarly, if the puck was held to the player's side the distance between puck and player would be shortened, further reducing visibility. Although we employed a conservative model to more closely link the visual angle thresholds to skating performance, additional studies are needed to examine on ice performance including both maintaining puck possession and avoiding body contact while masked.

Overall, the combined visual threshold results and modeling suggest that youth hockey players wearing facemasks would need to adopt head-down behaviors more frequently to see the puck. Head-down positioning increases the chance for player-to-player collision which is the primary cause of on-ice injury (Brenner et al., 2014; Black et al., 2016; Simmons et al., 2017). Restricted peripheral vision has been shown to reduce reaction times for visual targets detection (Miller et al., 2019). Hockey players with only slightly obstructed visual fields from protective equipment (face cages and face shields) also demonstrate slower reaction times to visual targets (Ing et al., 2002; Dowler et al., 2009). Increased oculomotor variability for target tracking and gaze shifting was associated with more frequent high acceleration collision impacts in youth ice hockey (Kiefer et al., 2018). The current results suggest that the on-ice use of FM in youth hockey may increase the risk for on-ice injury. The current results do not address potential for disease transmission during play, but highlight a previously unknown risk to player safety that has relevance to universal masking during participation in youth ice hockey. Ice hockey players appear to be special case population such that facemask wearing during participation may have unintentional effects that increase risk for injury.

The main limitation to this study is the off-ice, non-play oriented determination of a lower visual field threshold. The LEDs represent a stationary target, and thus a player's ability to intercept a moving puck cannot be determined. However, skating while possessing the puck may require at least periodic visual updating. We employed a conservative model to account for the static nature of the testing environment. Despite being well representative of the participants in this study, variations in facemask styles may not represent those used by players not participating in this study. Older youth hockey players or adults may have different results. This study did not address the impact of mask wearing during ice hockey play on disease transmission or respiration. The small sample size prevented within group comparisons to determine effects from position or type of face shield.

Facemask wearing restricted the lower visual field in youth hockey players. Puck on stick visibility was compromised suggesting an increase in downward head tilt would be necessary to see the puck on the stick while playing ice hockey while wearing a FM. The current results suggest that the on-ice use of FM in youth hockey may be associated with increased use of head-down positioning that might lead to greater injury incidence during play. However, the association between FM use and an increase in injury risk should be evaluated directly.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by University of Rochester, Research Subjects Review Board. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin. Written informed consent was obtained from the minor(s)' legal guardian/next of kin for the publication of any potentially identifiable images or data included in this article.

EA and BK conceived and designed the study. EA, KC, and VD collected study data. EA, KC, and BC performed data analysis. EA drafted the initial version of the manuscript. EA, VD, KC, BK, and BC critically edited the manuscript. All authors contributed to the article and approved the submitted version.

EA was supported in part by the National Institutes of Health (NIDCD K23 DC018303).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.