Effect of Exposure Type and Timing of Injuries in Division I College Football: A 4-year Single Program Analysis

The Effect of Bye Weeks on Injury Event Rates in the Canadian Football League

OBJECTIVE

To determine the effect of bye weeks (no practices or games) on the injury event rate in the Canadian Football League (CFL).

DESIGN

Historical (retrospective) cohort study.

SETTING

CFL.

PARTICIPANTS

CFL athletes between 2011 and 2018.

INTERVENTION

CFL pseudorandom assignment of bye weeks each season (2011-2013: 1; 2014-2017: 2; 2018: 3).

MAIN OUTCOME MEASURES

Game injury incident rate ratio (IRR) in the week following a bye week compared with non-bye weeks. Sensitivity analyses: IRR for the 2 and 3 weeks following a bye week. We conducted exploratory analyses for combined game and practice injury events because we did not have the number of players exposed during practice.

RESULTS

The IRR was 0.96 (0.87-1.05), suggesting no meaningful effect of a bye week on the post-bye week game injury event rate. We obtained similar results for cumulative game injury events for subsequent weeks: IRR was 1.02 (0.95-1.10) for the 2 weeks following the bye week and 1.00 (0.93-1.06) for the 3 weeks following the bye week. The results were similar with 1, 2, or 3 bye weeks. However, the combined game and practice injury event rate was increased following the bye week [IRR = 1.14 (1.05-1.23)]. These results are expected if the break period results in medical clearance for preexisting injuries; increasing pain in these locations following the bye week would now be considered new injuries instead of "exacerbations."

CONCLUSIONS

Bye weeks do not appear to meaningfully reduce the injury event rate. Furthermore, there was no injury reduction when adding additional bye weeks to the schedule.

Do Sport-Related Concussions Later in the Season Take Longer to Recover From?

OBJECTIVE

In a cohort of high-school football athletes with sport-related concussion (SRC), we sought to investigate the role of seasonality, defined as time of injury during a season, on recovery.

DESIGN

Retrospective cohort study.

SETTING

Regional sport concussion center.

PARTICIPANTS

High-school football athletes ages 14 to 19 -years old who sustained an SRC from 11, 2017 to 04, 2022.

INTERVENTION

Athletes were divided into 3 groups based on seasonality: early, middle, and late season.

MAIN OUTCOME MEASURES

The primary outcomes were initial Post-Concussion Symptom Scale score and recovery, as defined by time to return-to-learn (RTL), symptom resolution, and return-to-play (RTP). Descriptive statistics, analysis-of-variance, t tests, and multivariable regressions were performed.

RESULTS

Of our cohort of 273 high-school football players who sustained an SRC, 97 (35.5%) sustained an SRC during early season, 107 (39.2%) during middle season, and 69 (25.3%) during late season. Compared with late-season concussions, early-season concussions took less days to symptom resolution (early = 11.5 ± 12.9 vs late = 25.5 ± 27.0, P = 0.03), but no differences were found in days to RTL (early = 5.3 ± 4.8 vs late = 7.2 ± 15.8, P = 0.51) and RTP (early = 13.5 ± 11.8 vs late = 23.0 ± 22.8, P = 0.08). Seasonality was not a significant predictor for any recovery metric in multivariable regressions.

CONCLUSION

Sport-related concussions occurring in the early third of the season took significantly less time to symptom resolution than those occurring in the later third of the season; however, this was not statistically significant in multivariable analyses. No association was observed between seasonality and time to RTL and RTP. A trend of worse recovery with concussions later in the season may be present.

Prevention strategies and modifiable risk factors for sport-related concussions and head impacts: a systematic review and meta-analysis

OBJECTIVES

To evaluate prevention strategies, their unintended consequences and modifiable risk factors for sport-related concussion (SRC) and/or head impact risk.

DESIGN

This systematic review and meta-analysis was registered on PROSPERO (CRD42019152982) and conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

DATA SOURCES

Eight databases (MEDLINE, CINAHL, APA PsycINFO, Cochrane (Systematic Review and Controlled Trails Registry), SPORTDiscus, EMBASE, ERIC0 were searched in October 2019 and updated in March 2022, and references searched from any identified systematic review.

ELIGIBILITY CRITERIA

Study inclusion criteria were as follows: (1) original data human research studies, (2) investigated SRC or head impacts, (3) evaluated an SRC prevention intervention, unintended consequence or modifiable risk factor, (4) participants competing in any sport, (5) analytic study design, (6) systematic reviews and meta-analyses were included to identify original data manuscripts in reference search and (7) peer-reviewed. Exclusion criteria were as follows: (1) review articles, pre-experimental, ecological, case series or case studies and (2) not written in English.

RESULTS

In total, 220 studies were eligible for inclusion and 192 studies were included in the results based on methodological criteria as assessed through the Scottish Intercollegiate Guidelines Network high ('++') or acceptable ('+') quality. Evidence was available examining protective gear (eg, helmets, headgear, mouthguards) (n=39), policy and rule changes (n=38), training strategies (n=34), SRC management strategies (n=12), unintended consequences (n=5) and modifiable risk factors (n=64). Meta-analyses demonstrated a protective effect of mouthguards in collision sports (incidence rate ratio, IRR 0.74; 95% CI 0.64 to 0.89). Policy disallowing bodychecking in child and adolescent ice hockey was associated with a 58% lower concussion rate compared with bodychecking leagues (IRR 0.42; 95% CI 0.33 to 0.53), and evidence supports no unintended injury consequences of policy disallowing bodychecking. In American football, strategies limiting contact in practices were associated with a 64% lower practice-related concussion rate (IRR 0.36; 95% CI 0.16 to 0.80). Some evidence also supports up to 60% lower concussion rates with implementation of a neuromuscular training warm-up programme in rugby. More research examining potentially modifiable risk factors (eg, neck strength, optimal tackle technique) are needed to inform concussion prevention strategies.

CONCLUSIONS

Policy and rule modifications, personal protective equipment, and neuromuscular training strategies may help to prevent SRC.

PROSPERO REGISTRATION NUMBER

CRD42019152982.

The Influence of Time of Season on Injury Rates and the Epidemiology of Canadian Football Injuries

OBJECTIVE

To describe injury rates and injury patterns in the Canadian Football League (CFL) according to time during the season, player position, injury type, and injury location.

DESIGN

Prospective, cohort study.

SETTING AND PARTICIPANTS

Eight seasons from CFL injury surveillance database.

INDEPENDENT VARIABLES

Depending on the analysis, time of season (preseason, regular, and playoffs), player position, injury type, and injury location.

MAIN OUTCOME MEASURES

Medical attention and time-loss injury rates per 100 athletes at risk (AAR), and prevalence of time-loss injuries per week.

RESULTS

The average game injury rate was 45.2/100 AAR medical attention injuries and 30.7/100 AAR time-loss injuries. Injury rates declined by 1% per week over the season for both medical attention (rate ratio = 0.99) and time-loss (rate ratio = 0.99) injuries, with a substantial decline during the playoffs compared with preseason (rate ratio = 0.70-0.77). The number of ongoing time-loss injuries increased over the course of the regular season. Quarterbacks, offensive backs, and linebackers had the highest game injury rates. Joint/ligament and muscle/tendon injuries were the most common injury types for games and practices, respectively. The lower extremity was the most commonly affected area, specifically the lower leg/ankle/foot and hip/groin/thigh.

CONCLUSIONS

There was a 1% decline in injury rate per week during the season and a 30% decline during the playoffs. The number of ongoing time-loss injuries increased over the regular season. Current results can aid league officials and medical staff in making evidence-based decisions concerning player safety and health.

Data-Driven Risk Classification of Concussion Rates: A Systematic Review and Meta-Analysis

BACKGROUND

Concussion is a growing public health concern and generating concussion prevention programs depends on identifying high-risk sports and characteristics. Identifying the roles of sport, sex, and participation level (e.g., high school versus collegiate athletics) in concussion risk would facilitate more informed decision-making regarding sports participation and generate better targeted prevention strategies.

OBJECTIVES

The current study's objectives were to: (1) determine the magnitude and hierarchy of sports-related concussion (SRC) risk across an array of events and (2) evaluate the modifying roles of sex, participation level, and session type on SRC rates.

METHODS

A literature search was conducted on PubMed, searching concussion studies published between 2001 and December 2019. Inclusion criteria for studies required: (1) concussion occurred during sport, (2) that the SRC was clinically diagnosed, and (3) athlete exposures and concussions could be extracted or estimated. A study was excluded if it: (1) was not an original research article, (2) was not written in English language, (3) was an animal study, (4) did not have enough data to calculate SRC rates, (5) included professional or youth sample, and/or (6) contained data collected prior to 2001. The meta-analysis and meta-regression analyses were fit using a random effects model.

RESULTS

Search results returned 2695 unique research articles, with 83 studies included in analyses. Sport, sex, participation level, and session type all significantly influenced SRC rates. Overall, rugby had the highest concussion rate and was classified as the highest risk sport (28.25 concussions per 10,000 athlete exposures). Overall, females had a higher concussion rate than males. Only lacrosse demonstrated a higher concussion rate for males compared to females. Collegiate athletes had higher concussion rates than high school athletes. Games were associated with 2.01 more concussions per 10,000 AEs than practices.

CONCLUSIONS

This meta-analysis demonstrated rugby has the highest concussion risk, followed by American Football, ice hockey, and wrestling. Concussion risk was influenced by sport, sex, participation, and session. Identifying the factors and environments that influence concussion risk can facilitate risk reduction and prevention strategies.

Analysis of Football Injuries by Position Group in Division I College Football: A 5-Year Program Review

OBJECTIVE

The purpose of this study was to evaluate injury characteristics by position groups.

DESIGN

Prospective, observational study.

SETTING

A single, major Division I collegiate football program.

PARTICIPANTS

All players on a collegiate football program each fall regular season.

INDEPENDENT VARIABLES

Exposure to Division I collegiate football and position groups.

MAIN OUTCOME MEASURES

Injury rates (IRs) per 1000 athlete exposures (AEs) and injury rate ratios (IRRs) were calculated and analyzed for all monitored injury variables, which included time in the season, body part, type of injury, game and practice injuries, mechanism of injury, and type of exposure.

RESULTS

During the 2012 to 2016 fall regular seasons, there were 200 reported injuries sustained from 48 615 AE. The overall 5-year IR was 4.11 per 1000 AEs (3.57-4.72 95% confidence intervals). Skill players sustained the highest IR in the preseason (IR, 7.56) compared with line (IR, 4.26) and other (IR, 4.10) position groups. In addition, skill players demonstrated a significantly higher IRR compared with the line (IRR, 1.75, P < 0.05) and other (IRR, 1.85, P < 0.05) position groups.

CONCLUSIONS

Skill players sustained most of their injuries in the preseason, whereas the linemen and other position groups suffered most of their injuries in the first half of the regular season. Skill players demonstrated a significantly higher IR in preseason, noncontact mechanism injuries, and injuries to the upper leg and thigh compared with line and other position groups. Efforts to reduce soft-tissue muscle strains in skill players targeting the preseason may provide one of the best opportunities to significantly decrease current football IRs, whereas efforts to reduce contact exposures may have the greatest effect on concussions and contact mechanism injuries for the other position group. There were no significant differences in IRs between position groups and type of exposure.

Repetitive Head Impact Exposure in College Football Following an NCAA Rule Change to Eliminate Two-A-Day Preseason Practices: A Study from the NCAA-DoD CARE Consortium

Repetitive head impact exposure sustained by athletes of contact sports has been hypothesized to be a mechanism for concussion and a possible explanation for the high degree of variability in sport-related concussion biomechanics. In an attempt to limit repetitive head impact exposure during the football preseason, the NCAA eliminated two-a-day practices in 2017, while maintaining the total number of team practice sessions. The objective of this study was to quantify head impact exposure during the preseason and regular season in Division I college football athletes to determine whether the 2017 NCAA ruling decreased head impact exposure. 342 unique athletes from five NCAA Division I Football Bowl Subdivision (FBS) programs were consented and enrolled. Head impacts were recorded using the Head Impact Telemetry (HIT) System during the entire fall preseasons and regular seasons in 2016 and 2017. Despite the elimination of two-a-day practices, the number of preseason contact days increased in 2017, with an increase in average hourly impact exposure (i.e., contact intensity), resulting in a significant increase in total head impact burden (+ 26%) for the 2017 preseason. This finding would indicate that the 2017 NCAA ruling was not effective at reducing the head impact burden during the football preseason. Additionally, athletes sustained a significantly higher number of recorded head impacts per week (+ 40%) during the preseason than the regular season, implicating the preseason as a time of elevated repetitive head impact burden. With increased recognition of a possible association between repetitive head impact exposure and concussion, increased preseason exposure may predispose certain athletes to a higher risk of concussion during the preseason and regular season. Accordingly, efforts at reducing concussion incidence in contact sports should include a reduction in overall head impact exposure.

Epidemiology of Hand and Wrist Injuries in NCAA Men's Football: 2009-2010 to 2013-2014

Background:

Participation in National Collegiate Athletic Association (NCAA) football is at an all-time high. This population of athletes experiences a substantial injury burden, with many injuries affecting the upper extremities.

Purpose/Hypothesis:

The purpose of this study was to describe the epidemiology of hand and wrist injuries in college football players from the academic years 2009–2010 to 2013–2014. We hypothesized that variables such as event type (practice vs game), mechanism of injury, and player position would have an effect on the injury incidence.

Study Design:

Descriptive epidemiological study.

Methods:

An epidemiological study utilizing the NCAA Injury Surveillance Program was performed to investigate rates and patterns of hand and wrist injuries in participating varsity football teams from 2009–2010 to 2013–2014.

Results:

A total of 725 hand and wrist injuries were captured in 899,225 athlete-exposures. The observed practice injury rate was 0.51 injuries per 1000 athlete-exposures, compared with a game injury rate of 3.60 (P < .01). Player-on-player contact was the most common injury mechanism reported, with blocking being the most common activity at the time of injury. Offensive linemen were most likely to experience an injury. Of all injuries sustained, 71.4% resulted in no time loss from competition, whereas 9.8% of injuries resulted in longer than 7 days of time loss. A fracture resulted in the greatest time loss from competition (mean ± SD, 8.3 ± 24.0 days; median, 0 days [range, 0-148 days] for injuries sustained in a practice setting) (mean ± SD, 7.7 ± 15.8 days; median, 0 days [range, 0-87 days] for injuries sustained in a game setting).

Conclusion:

Hand and wrist injuries were found to be significantly more common in games when compared with practices. This study provides valuable prognostic data regarding expected time loss on a per-injury pattern basis. Further investigation on specific injury subtypes and expected time loss as a result of these injures would provide trainers, players, and coaches with useful information on an expected postinjury recovery and rehabilitation timeline.

Effect of Concussions on Lower Extremity Injury Rates at a Division I Collegiate Football Program

Background:

Football has one of the highest injury rates (IRs) in sports, ranging from 4.1 to 8.6 per 1000 athlete-exposures (AEs). Previous research has reported that athletes may be at an increased risk of suffering lower extremity (LE) injuries after a concussion.

Purpose/Hypothesis:

The purpose of this study was to evaluate the rate of LE injuries in collegiate football athletes after a concussion. We predicted that the overall LE IR would increase after a concussion and that each position group would also demonstrate a similar increase in LE injuries after a concussion.

Study Design:

Cohort study; Level of evidence, 2.

Methods:

Daily attendance and injury records were prospectively collected by licensed team medical providers for the 2012 through 2016 college football regular seasons. Each injury report included the date of injury, position group, body part injured, and type of injury. IRs per 1000 AEs with 95% CIs were calculated to evaluate LE injuries at different time points after a concussion (remainder of season, next season, any additional seasons) and by months (<6 months, 6-12 months, >12 months). Mid-P exact tests were utilized to establish injury rate ratios (IRRs) to compare the IR between variables.

Results:

There was no significant difference in LE IRRs between the athletes post- versus preconcussion (P = .20) or between the postconcussion and no concussion (control) athletes (P = .08). There was an increased LE IR beyond 12 months in the postconcussion group (IR, 9.08 [95% CI, 3.68-18.89]) compared with the no concussion group (IR, 2.88 [95% CI, 2.04-3.96]) (IRR, 3.16 [95% CI, 1.21-7.15]; P = .02). Line position players had an increase in LE injuries after a concussion (IRR, 6.22 [95% CI, 1.31-23.68]; P = .03) compared with linemen with no concussion.

Conclusion:

There was no initial increase in LE IRs immediately after a concussion; however, there was an increased LE IR more than 12 months after a concussion. There was no increase in LE IRs demonstrated by skill and other position groups. Line position players experienced an increased LE IR the next season after a concussion or greater than 12 months after the injury.