Evaluating Performance of National Hockey League Players After a Concussion Versus Lower Body Injury.

Abstract

Concussions elicit changes in brain function that may extend well beyond clinical symptom recovery. Whether these changes produce meaningful deficits outside the laboratory environment is unclear. The results of player performance postconcussion within professional sports have been mixed. To determine whether National Hockey League (NHL) players with concussions performed worse after returning to sport than players with lower body injuries or uninjured players. Cohort study. Publicly available Web sites that compiled injury and player statistics of NHL players. Male NHL players who missed games due to a concussion (n = 22), lower body injury (n = 21), or noninjury (ie, personal reason or season break; n = 13) during the 2013-2014 and 2014-2015 regular seasons. Data on concussed athletes were used to identify similar players with lower body injury and noninjury based on (1) position, (2) time loss, (3) time on the ice, and (4) team. The primary performance metric was a modified plus-minus statistic calculated by weighting the players' plus-minus metric by their team's simple rating system to account for varying team performances. Linear mixed models assessed the relationship between injury type (concussion, lower body, or noninjury) and performance (plus-minus score). We observed a quadratic effect for a time2 × group interaction ( \upchi _2^2 = 8.85, P = .01). This interaction revealed that the concussion and lower body injury groups had similar patterns of an initial decrease (ie, 2 weeks after return to play), followed by an increase in performance compared with the uninjured group in weeks 5 and 6. Meanwhile, the uninjured group had an initial increase in performance. We observed no group × linear time interaction (P = .47) or overall group effect (P = .57). The NHL players in the concussion and lower body injury groups displayed similar performance impairments. Both injured cohorts experienced an initial decrease in performance at weeks 1 to 2 after return to play, followed by improved performance at weeks 5 to 6 after return to play, suggesting that the performance implications of concussion may be short lived.