Latest research in football - week 39 - 2017

As previous literature updates, I have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.

Following studies were retrieved for this week:

#1 Resting metabolic rate of Indian Junior Soccer players: Testing agreement between measured versus selected predictive equations
Reference: Am J Hum Biol. 2017 Sep 30. doi: 10.1002/ajhb.23066. [Epub ahead of print]
Authors: Cherian KS, Shahkar F, Sainoji A, Balakrishna N, Yagnambhatt VR
Summary: Owing to a dearth of research related to Resting Metabolic Rate (RMR) among adolescent athletes in India, our study aimed to document RMR among junior soccer players (JSP) and to identify suitable RMR predictive models for JSP from nine existing equations. Forty Indian JSP (Boys = 21, Girls = 19) representing the under-12 and under-16 age categories were assessed for body composition (skinfold technique) and RMR (oxycon mobile). Two-way ANOVA and ANCOVA were used to examine the differences across age and sex. Bland-Altman plot was used to test agreement between measured vs. predicted RMR using the equations of Cunningham (, The American Journal of Clinical Nutrition, 33), Soares et al. (, European Journal of Clinical Nutrition, 47; 1998, British Journal of Nutrition, 79), Henry (, Public Health Nutrition, 8), and Patil and Bharadwaj (, Journal of Postgraduate Medicine, 59) for non-athletic populations and the equations of De Lorenzo et al. (, The Journal of Sports Medicine and Physical Fitness, 39), Wong et al. (, Singapore Medical Journal, 53), and ten Haaf & Weijs (, PloS One, 9) for adult athletes. RMR showed significant (P < .01) sex differences (Boys: 1343 ± 297.1; Girls: 1135 ± 116.7 kcal·day-1 ). While RMR values adjusted for fat-free mass (FFM) were similar across age and sex. The equation of Soares et al. (, British Journal of Nutrition, 79) for girls and Wong et al. (, Singapore Medical Journal, 53) for boys showed better RMR predictability. FFM explained variation in RMR across age and sex. The FFM-based Soares et al. (, British Journal of Nutrition, 79) equation for girls and body weight-based Wong et al. (, Singapore Medical Journal, 53) equation for boys are best suited for predicting RMR

#2 Effects of age on the soccer-specific cognitive-motor performance of elite young soccer players: Comparison between objective measurements and coaches' evaluation
Reference: PLoS One. 2017 Sep 27;12(9):e0185460. doi: 10.1371/journal.pone.0185460. eCollection 2017.
Authors: Hicheur H, Chauvin A, Chassot S, Cheneviere X, Taube W
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Summary: The cognitive-motor performance (CMP), defined here as the capacity to rapidly use sensory information and transfer it into efficient motor output, represents a major contributor to performance in almost all sports, including soccer. Here, we used a high-technology system (COGNIFOOT) which combines a visual environment simulator fully synchronized with a motion capture system. This system allowed us to measure objective real-time CMP parameters (passing accuracy/speed and response times) in a large turf-artificial grass playfield. Forty-six (46) young elite soccer players (including 2 female players) aged between 11 and 16 years who belonged to the same youth soccer academy were tested. Each player had to pass the ball as fast and as accurately as possible towards visual targets projected onto a large screen located 5.32 meters in front of him (a short pass situation). We observed a linear age-related increase in the CMP: the passing accuracy, speed and reactiveness of players improved by 4 centimeters, 2.3 km/h and 30 milliseconds per year of age, respectively. These data were converted into 5 point-scales and compared to the judgement of expert coaches, who also used a 5 point-scale to evaluate the same CMP parameters but based on their experience with the players during games and training. The objectively-measured age-related CMP changes were also observed in expert coaches' judgments although these were more variable across coaches and age categories. This demonstrates that high-technology systems like COGNIFOOT can be used in complement to traditional approaches of talent identification and to objectively monitor the progress of soccer players throughout a cognitive-motor training cycle.

#3 Comparison of Thigh Muscle Strain Occurrence and Injury Patterns between Male and Female High School Soccer-Athletes
Reference: J Sport Rehabil. 2017 Sep 27:1-35. doi: 10.1123/jsr.2016-0178. [Epub ahead of print]
Authors: Cross KM, Gurka KK, Saliba S, Conaway M, Hertel J
Summary: Thigh muscles strains are among the most common injuries in high school soccer for both males and females. Similar results have been reported among collegiate soccer players, specifically for hamstring strains. In collegiate soccer, males have a higher injury rate than women although they share common injury characteristics. Currently, no studies exist comparing the injury rate or injury characteristics of thigh muscle strains between sexes playing high school soccer. The objective of the study was to compare thigh muscle strain injury rates and injury event characteristics among sexes participating in high school soccer. High school soccer athletes who had a thigh muscle strain were involved in this study. Injury rates of thigh muscle strains were calculated between sexes. The occurrence of the following variables during a thigh muscle injury were compared between sexes: grade level, age, level of play, event type, time of practice, time of competition, basic injury mechanism, soccer activity, player position, field location, practice type, time of season. Males had a lower injury rate of thigh muscle strains during competition than females. (RR=0.66; 95% CI, 0.47, 0.93) No differences between sexes existed in the distribution of first-time or recurrent event characteristics. When combining sexes, recurrent strains (93%) occurred more frequently on the offensive side of the field than first-time strains (59%), P<0.0001. The majority of strains occurred among the varsity players (71%), during running activities (60%) and during practices (58%). Males were less likely to sustain a thigh muscle strain during competitions, but no other differences existed between sexes. The events surrounding all thigh muscle strains may be described with some common properties. Consideration of these characteristics may assist in the development of preventive and rehabilitative programs as well as direct future research on thigh muscle strains among high school soccer players.

#4 Locomotor and Heart Rate Responses of Floaters During Small-Sided Games in Elite Soccer Players: Effect of Pitch Size and Inclusion of Goal Keepers
Reference: Int J Sports Physiol Perform. 2017 Sep 27:1-13. doi: 10.1123/ijspp.2017-0340. [Epub ahead of print]
Authors: Lacome M, Simpson BM, Cholley Y, Buchheit M
Summary: The purpose was to (1) compare the locomotor and heart rate responses between floaters and regular players during both small and large small sided games (SSGs) and (2) examine whether the type of game (i.e., game simulation vs possession game) affects the magnitude of the difference between floaters and regular players. Data were collected in 41 players belonging to an elite French football team during three consecutive seasons (2014-2017). 5-Hz GPS were used to collect all training data, with the Athletic Data Innovation analyser (v5.4.1.514, Sydney, Australia) used to derive total distance (m), high-speed distance (> 14.4 km.h-1, m) and external mechanical load (MechL, a.u). All SSGs included exclusively one floater, and were divided into two main categories, according to the participation of goal-keepers (GK) (game simulation, GS) or not (possession games, PO) and then further divided into small and large (>100 m2/player) SSGs based on the area per player ratio. Locomotor activity and mechanical load performed were likely-to-most likely lower (moderate to large magnitude) in floaters compared with regular players, while differences in HR responses were unclear to possibly higher (small) in floaters. The magnitude of the difference in locomotor activity and MechL between floaters and regular players was substantially greater during GS compared with PO. Compared with regular players, floaters present decreased external load (both locomotor and MechL) despite unclear to possibly slightly higher HR responses during SSGs. Moreover, the responses of floaters compared with regular players are not consistent across different sizes of SSGs, with greater differences during GS than PO.

#5 Successful return to play following adductor longus proximal tendon rupture in professional soccer without re-injury at 12 months: A case report
Reference: J Back Musculoskelet Rehabil. 2017 Sep 8. doi: 10.3233/BMR-170857. [Epub ahead of print]
Authors: Gozubuyuk OB, Moen MH, Akman M, Ipseftel I, Karakuzu A
Summary: Treatment of total ruptures of adductor longus is challenging in professional sports. Time for return to pre-injury level as well as re-injury rates are of concern and surgical and conservative treatment approaches are debated; yet no consensus approach described for professional athletes. We present a case of a professional soccer player who experienced a rupture in his left adductor longus proximal tendon during a game and was treated conservatively. This case was followed-up during clinical assessment, imaging and strength testing until and after return to play. Primary outcome measure was the return to standard play condition at his pre-injury level without any functional deficits, measured by isokinetic testing. Second outcome measure was the recurrence. No recurrence was observed during the first year of follow-up. Total ruptures are very challenging for both the physician and the player to make a quick decision due to minimal or lack of pain. Functional outcomes are almost identical although operative treatments need longer time to return to play. This case report adds another example to the literature of a successful return to play after non-operative treatment of adductor longus rupture at elite level soccer.

#6 Is strength-training frequency a key factor to develop performance adaptations in young elite soccer players?
Reference: Eur J Sport Sci. 2017 Sep 24:1-11. doi: 10.1080/17461391.2017.1378372. [Epub ahead of print]
Authors: Otero-Esquina C, de Hoyo Lora M, Gonzalo-Skok O, Dominguez-Cobo S, Sanchez H
Summary: The aim of this study was to analyse the effects of a combined strength-training programme (full-back squat, YoYoTM leg curl, plyometrics and sled towing exercises) on performance in elite young soccer players and to examine the effects when this training programme was performed one or two days per week. Thirty-six male soccer players (U-17 to U-19) were recruited and assigned to experimental groups (EXP1: 1 s w-1; EXP2: 2 s w-1) or a control group (CON). Performance was assessed through a countermovement jump (CMJ) test (relative peak power [CMJPP] and CMJ height [CMJH]), a 20-m linear sprint test with split-times at 10-m, and a change of direction test (V-cut test) 1 week before starting the training programme and also 1 week after performing such training programme. Within-group analysis showed substantial improvements in CMJ variables (ES: 0.39-0.81) and COD (ES: 0.70 and 0.76) in EXP1 and EXP2, while EXP2 also showed substantial enhancements in all linear sprinting tests (ES: 0.43-0.52). Between-group analysis showed substantially greater improvements in CMJ variables (ES: 0.39-0.68) in experimental groups in comparison to CON. Furthermore, EXP2 achieved a substantial better performance in 20-m (ES: 0.48-0.64) than EXP1 and CON. Finally, EXP2 also showed greater enhancements in 10-m (ES: 0.50) and V-cut test (ES: 0.52) than EXP1. In conclusion, the combined strength-training programme improved jumping ability, independently of training frequency, though the achievement of two sessions per week also enhanced sprinting abilities (linear and COD) in young soccer players.

#7 Neuromuscular responses and physiological patterns during a soccer simulation protocol. Artificial turf versus natural grass
Reference: J Sports Med Phys Fitness. 2017 Sep 22. doi: 10.23736/S0022-4707.17.07768-4. [Epub ahead of print]
Authors: Lopez-Fernandez J, Garcia-Unanue J, Sanchez-Sanchez J, Leon M, Hernando E, Gallardo L
Summary: Latest studies suggest similar performance of soccer players either on artificial turf (AT) or natural grass (NG). However, it is not clear if their muscular and physiological responses are also similar on both surfaces. This research aims to assess the influence of game surface on physiological patterns and neuromuscular responses of soccer players during a soccer simulation protocol (SSP) that incorporates repeated sprints and nonlinear actions at maximum speed. Sixteen amateur soccer players completed three bouts of the SSP on both AT and NG. The mechanical behaviour of both surfaces was recorded and the order was randomly established for each player. The physiological responses were measured during the SSP. A contra-movement jump and a tensiomyography analysis of the rectus femurs (RF) and biceps femoris (BF) were assessed right before and right after the SSP. Both surfaces presented different mechanical properties. No differences among either surfaces or bouts were found for heart rate (HR) peak and HR mean (p >0.05). While the half-relaxation time of the RF on NG decreased after the SSP (right-leg:-44.430 ms; p = 0.049; left-leg: -52.131 ms; p = 0.008), the sustain time of the BF decreased after the SSP on AT (right-leg: +64.868 ms; p = 0.007; left-leg: +87.564 ms; p<0.001). No differences between surfaces were found for the contra-movement jump. The mechanical behaviour of both surfaces does not differ enough to cause different physiological and neuromuscular responses. Playing on AT should cause similar neuromuscular responses to NG.

#8 Variability of GPS-derived running performance during official matches in elite professional soccer players
Reference: J Sports Med Phys Fitness. 2017 Sep 22. doi: 10.23736/S0022-4707.17.07500-4. [Epub ahead of print]
Authors: Al Haddad H, Mendez-Villanueva A, Torreno N, Munguia-Izquierdo D, Suarez-Arrones L
Summary: The aim of this study was to assess the match-to-match variability obtained using GPS devices, collected during official games in professional soccer players. GPS-derived data from nineteen elite soccer players were collected over two consecutive seasons. Time-motion data for players with more than five full-match were analyzed (n=202). Total distance covered (TD), TD >13-18 km/h, TD >18-21 km/h, TD >21 km/h, number of acceleration >2.5-4 m.s-2 and >4 m.s-2 were calculated. The match-to-match variation in running activity was assessed by the typical error expressed as a coefficient of variation (CV,%) and the magnitude of the CV was calculated (effect size). When all players were pooled together, CVs ranged from 5% to 77% (first half) and from 5% to 90% (second half), for TD and number of acceleration >4 m.s-2, and the magnitude of the CVs were rated from small to moderate (effect size = 0.57-0.98). The CVs were likely to increase with running/acceleration intensity, and were likely to differ between playing positions (e.g., TD > 13-18 km/h 3.4% for second strikers vs 14.2% for strikers and 14.9% for wide-defenders vs 9.7% for wide-midfielders). Present findings indicate that variability in players' running performance is high in some variables and likely position-dependent. Such variability should be taken into account when using these variables to prescribe and/or monitor training intensity/load. GPS-derived match-to-match variability in official games' locomotor performance of professional soccer players is high in some variables, particularly for high-speed running, due to the complexity of match running performance and its most influential factors and reliability of the devices.

#9 Adding a post-training FIFA 11+ exercise program to the pre-training FIFA 11+ injury prevention program reduces injury rates among male amateur soccer players: a cluster-randomised trial
Reference: J Physiother. 2017 Sep 20. pii: S1836-9553(17)30102-9. doi: 10.1016/j.jphys.2017.08.004. [Epub ahead of print]
Authors: Al Attar WSA, Soomro N, Pappas E, Sinclair PJ, Sanders RH
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Summary: Does adding a post-training Fédération Internationale de Football Association (FIFA) 11+ exercise program to the pre-training FIFA 11+ injury prevention program reduce injury rates among male amateur soccer players? Twenty-one teams of male amateur soccer players aged 14 to 35 years were randomly assigned to the experimental group (n=10 teams, 160 players) or the control group (n=11 teams, 184 players). Both groups performed pre-training FIFA 11+ exercises for 20minutes. The experimental group also performed post-training FIFA 11+ exercises for 10minutes. The primary outcomes measures were incidence of overall injury, incidence of initial and recurrent injury, and injury severity. The secondary outcome measure was compliance to the experimental intervention (pre and post FIFA 11+ program) and the control intervention (pre FIFA 11+ program). During one season, 26 injuries (team mean=0.081 injuries/1000 exposure hours, SD=0.064) were reported in the experimental group, and 82 injuries were reported in the control group (team mean=0.324 injuries/1000hours, SD=0.084). Generalised Estimating Equations were applied with an intention-to-treat analysis. The pre and post FIFA 11+ program reduced the total number of injuries (χ2 (1)=11.549, p=0.001) and the incidence of initial injury (χ2 (2)=8.987, p=0.003) significantly more than the pre FIFA 11+ program alone. However, the odds of suffering a recurrent injury were not different between the two groups (χ2 (1)=2.350, p=0.125). Moreover, the severity level of injuries was not dependent upon whether or not the pre and post FIFA 11+ program was implemented (χ2 (1)=0.016, p=0.898). Implementation of the FIFA 11+ program pre-training and post-training reduced overall injury rates in male amateur soccer players more than the pre FIFA 11+ program alone.

#10 Symptoms of common mental disorders and related stressors in Danish professional football and handball
Reference: Eur J Sport Sci. 2017 Sep 29:1-7. doi: 10.1080/17461391.2017.1381768. [Epub ahead of print]
Authors: Kilic O, Aoki H, Haagensen R, Jensen C, Johnson U, Kerkhoffs GMMJ, Gouttebarge V
Summary: The aim of the study was twofold, namely (i) to determine the prevalence of symptoms of common mental disorders (CMDs) among current and retired professional football and handball players and (ii) to explore the relationship of psychosocial stressors with the outcome measures under study. A total of 1155 players were enrolled in an observational study based on a cross-sectional design. Questionnaires based on validated scales were set up and distributed among current and retired professional football and handball players by the Danish football and handball players' union. In professional football, the highest prevalence (4 weeks) of symptoms of CMDs was 18% and 19% for anxiety/depression among current and retired players, respectively. In professional handball, the highest prevalence (4 weeks) of symptoms of CMDs was 26% and 16% for anxiety/depression among current and retired players, respectively. For both the current and retired professional football and handball players, a higher number of severe injuries and recent adverse life events (LE) were related to the presence of symptoms of CMD. Players exposed to severe injuries and/or recent adverse LE were 20-50% times more likely to report symptoms of CMD. The results suggest that it is possible to recognize the population of professional athletes that are more likely to develop symptoms of CMD. This could create the opportunity to intervene preventively on athletes that suffered from severe injury and/or recent adverse LE that could lead to a faster and safer recovery and psychological readiness to return to play.

American Football
#1 Evaluating behavioral skills training to teach safe tackling skills to youth football players
Reference:  J Appl Behav Anal. 2017 Sep 20. doi: 10.1002/jaba.412. [Epub ahead of print]
Authors: Tai SSM, Miltenberger RG
Summary: With concussion rates on the rise for football players, there is a need for further research to increase skills and decrease injuries. Behavioral skills training is effective in teaching a wide variety of skills but has yet to be studied in the sports setting. We evaluated behavioral skills training to teach safer tackling techniques to six participants from a Pop Warner football team. Safer tackling techniques increased during practice and generalized to games for the two participants who had opportunities to tackle in games.

#2 Return to play after shoulder instability in National Football League athletes
Reference: J Shoulder Elbow Surg. 2017 Sep 20. pii: S1058-2746(17)30448-2. doi: 10.1016/j.jse.2017.07.027. [Epub ahead of print]
Authors: Okoroha KR, Taylor KA, Marshall NE, Keller RA, Fidai M, Mahan MC, Varma V, Moutzouros V
Summary: We hypothesized that National Football League (NFL) players sustaining a shoulder destabilizing injury could return to play (RTP) successfully at a high rate regardless of treatment type. We identified and evaluated 83 NFL players who sustained an in-season shoulder instability event while playing in the NFL. NFL RTP, incidence of surgery, time to RTP, recurrent instability events, seasons/games played after the injury, and demographic data were collected. Overall RTP was determined, and players who did and did not undergo operative repair were compared. Ninety-two percent of NFL players returned to NFL regular season play at a median of 0.0 weeks in those sustaining a shoulder subluxation and 3.0 weeks in those sustaining a dislocation who did not undergo surgical repair (P = .029). Players who underwent operative repair returned to play at a median of 39.3 weeks. Forty-seven percent of players had a recurrent instability event. For players who were able to RTP, those who underwent surgical repair (31%) had a lower recurrence rate (26% vs. 55%, P = .021) and longer interval between a recurrent instability event after RTP (14.7 vs. 2.5 weeks, P = .050). There is a high rate of RTP after shoulder instability events in NFL players. Players who sustain shoulder subluxations RTP faster but are more likely to experience recurrent instability than those with shoulder dislocations. Surgical stabilization of the shoulder after an instability event decreases the chances of a second instability event and affords a player a greater interval between the initial injury and a recurrent event.

#3 Concussion Nondisclosure During Professional Career Among a Cohort of Former National Football League Athletes
Reference: Am J Sports Med. 2017 Sep 1:363546517728264. doi: 10.1177/0363546517728264. [Epub ahead of print]
Authors: Kerr ZY, Register-Mihalik JK, Kay MC, DeFreese JD, Marshall SW, Guskiewicz KM
Summary: Despite a focus on the incidence and effects of concussion, nondisclosure of sports-related concussions among retired players from the National Football League (NFL) has yet to be examined. The purpose was to examine the prevalence of and factors associated with nondisclosure of sports-related concussions in former NFL athletes. A sample of 829 former NFL players completed a general health survey. This historical cohort included players who had played before World War II to 2001. Respondents retrospectively recalled sports-related concussions that they sustained during their professional careers and whether at least one of these sports-related concussions was not reported to medical staff. We computed the prevalence of nondisclosure among those recalling sport-related concussions during their professional careers. Multivariable binomial regression estimated adjusted prevalence ratios (PR) with 95% confidence intervals (CIs) controlling for race/ethnicity, number of years played, primary position played, professional career concussion history, and playing era. Playing era was categorized by whether the majority of a player's career was before or after a 1976 rule change to limit contact ("spearing"). Overall, 417 (50.3%) respondents reported they had sustained a concussion and did not inform medical staff at least once during their professional playing career. Nonwhite respondents had a higher prevalence of nondisclosure than white/non-Hispanic respondents (adjusted PR = 1.19; 95% CI, 1.02-1.38). An interaction between professional career concussion history and playing era was also found ( P = .08). Compared with those in the pre-spearing rule change group with 1 or 2 concussions, all other groups had larger prevalences of nondisclosure (increases ranging from 41% to 153% in multivariable models). Across concussion strata, nondisclosure prevalence was generally higher in the post-spearing rule change group than the pre-spearing rule change group, with the largest differences found among those with 1 or 2 concussions or those with 3 or 4 concussions. A large proportion of former NFL players in this historical cohort reported at least one instance of not disclosing sports-related concussions to medical staff. Future research on concussion nondisclosure needs to identify mechanisms to improve football players' intentions to disclose concussion-related symptoms to health care providers and to equip health care providers with more effective strategies for timely identification of concussion.

#5 A Narrative Review of the Physical Demands and Injury Incidence in American Football: Application of Current Knowledge and Practices in Workload Management
Reference: Sports Med. 2017 Sep 25. doi: 10.1007/s40279-017-0783-2. [Epub ahead of print]
Authors: Edwards T, Spiteri T, Piggott B, Haff GG, Joyce C
Summary: The sport of American football (AmF) exposes athletes to high-velocity movements and frequent collisions during competition and training, placing them at risk of contact and non-contact injury. Due to the combative nature of the game, the majority of injuries are caused by player contact; however, a significant number are also non-contact soft-tissue injuries. The literature suggests that this mechanism of injury can be prevented through workload monitoring and management. The recent introduction of microtechnology into AmF allows practitioners and coaches to quantify the external workload of training and competition to further understand the demands of the sport. Significant workload differences exist between positions during training and competition; coupling this with large differences in anthropometric and physical characteristics between and within positions suggests that the training response and physiological adaptations will be highly individual. Effective athlete monitoring and management allows practitioners and coaches to identify how athletes are coping with the prescribed training load and, subsequently, if they are prepared for competition. Several evidence-based principles exist that can be adapted and applied to AmF and could decrease the risk of injury and optimise athletic performance.

#6 The Epidemiology of Overuse Conditions in Youth Football and High School Football Players
Reference: J Athl Train. 2017 Sep 26. doi: 10.4085/1062-6050-52.10.04. [Epub ahead of print]
Authors: Morris K, Simon J, Grooms DR, Starkey C, Dompier TP, Kerr ZY
Summary: High-intensity sport training at the youth level has led to increased concern for overuse conditions. Few researchers have examined overuse conditions in youth sports. The purpose was to examine the rates, risks, and distributions of overuse conditions between youth and high school football. The Youth Football Safety Study (YFSS) investigated youth football athletes from age 5 to 14 years. The National Athletic Treatment, Injury and Outcomes Network (NATION) focused on high school football athletes 14 to 18 years old. The YFSS data consisted of 210 team-seasons, and the NATION data consisted of 138 team-seasons. Athletic trainers collected football injury and exposure data during the 2012 and 2013 seasons. Injury rates, risks, and distributions were calculated, with injury rate ratios, risk ratios, and injury proportion ratios with 95% confidence intervals (CIs) comparing high school and youth football players. The YFSS reported 1488 injuries, of which 53 (3.6%) were overuse conditions. The NATION reported 12 013 injuries, of which 339 (2.8%) were overuse conditions. The overuse condition rate did not differ between high school and youth football (3.93 versus 3.72/10 000 athlete exposures; injury rate ratio = 1.06; 95% CI = 0.79, 1.41). However, the 1-season risk of overuse condition was higher in high school than in youth football players (2.66% versus 1.05%; risk ratio = 2.53; 95% CI = 1.84, 3.47). Compared with high school football players, youth football players had greater proportions of overuse conditions that were nontime loss (ie, <24 hours participation-restriction time; 83.0% versus 67.0%; injury proportion ratio = 1.24; 95% CI = 1.07, 1.43) and affecting the lower extremity (92.5% versus 62.5%; injury proportion ratio = 1.48; 95% CI = 1.32, 1.65). Overuse conditions may not present a primary concern in youth and high school football players. However, differences existed between the 2 levels of competition. Although additional research on the incidence of overuse conditions across all youth and high school sports is needed, these findings may highlight the need for programming that is specific to competition level.

#7 Characteristics and Outcomes of Arthroscopic Femoroacetabular Impingement Surgery in the National Football League
Reference: Am J Sports Med. 2017 Sep 1:363546517729163. doi: 10.1177/0363546517729163. [Epub ahead of print]
Authors: Nwachukwu BU, Bedi A, Premkumar A, Draovitch P, Kelly BT
Summary: Previous studies have reported that hip abnormalities may account for 10% of injuries in professional football players. The effect of femoroacetabular impingement (FAI) and arthroscopic FAI surgery in National Football League (NFL) athletes has not been well studied. The purpose was to investigate the effect of arthroscopic FAI surgery on return to play (RTP) and RTP performance in NFL players. NFL athletes undergoing arthroscopic FAI surgery at a single institution between 2006 and 2014 were identified. Medical records were reviewed for demographic, clinical, and operative variables. RTP and RTP performance were assessed based on a review of publicly available NFL player statistics. RTP and RTP performance data included time to RTP; games played before and after the injury; yearly total yards and touchdowns for offensive players; and yearly total tackles, sacks, and interceptions for defensive players. The offensive power rating (OPR = [total yards/10] + [total touchdowns × 6]) and defensive power rating (DPR = total tackles + [total sacks × 2] + [total interceptions × 2]) were calculated. Paired t tests comparing preinjury and postinjury seasons were performed. A matched cohort of NFL players was created to compare trends for OPR, DPR, and career longevity. Forty-eight hips in 40 NFL players (mean age, 25.6 years) with symptomatic FAI were included; 8 players underwent staged bilateral hip arthroscopic procedures. The majority of players were offensive (n = 24; 60.0%), with offensive lineman (n = 11; 27.5%) being the most common of all positions. Of the 48 included hips, all had labral tears, and 41 (85.4%) underwent labral repair. Forty-two of the 48 hips (87.5%) underwent cam decompression, and 10 (20.8%) underwent rim decompression. Of the 40 included players, 37 (92.5%) achieved RTP to professional competition after their hip arthroscopic surgery at a mean of 6.0 months. Before the injury, included patients played in a mean of 11.0 games compared with 9.5 games in their postoperative season ( P = .26). The mean OPR and DPR demonstrated a nonsignificant decline in the postoperative season (preinjury OPR, 40.2; postinjury OPR, 32.3; P = .34) (preinjury DPR, 49.6; postinjury DPR, 36.4; P = .10). A similar decline in the OPR and DPR across seasons was observed in the control group. NFL athletes played, on average, 3.3 ± 1.5 seasons after undergoing hip arthroscopic surgery; this was not significantly different from the controls (2.5 ± 1.5 seasons; P = .47). There was no significant difference in mean annual salaries based on contracts negotiated before the injury and the first negotiated contract after surgery ($3.3 million vs $3.6 million, respectively; P = .58). There was a very high rate of RTP in the NFL after arthroscopic FAI surgery; this rate is higher than what has been previously reported for other orthopaedic procedures in NFL athletes. Additionally, these NFL athletes achieved RTP at a faster time frame (6 months) than previously reported for other procedures. These findings have important implications for counseling elite football players about the expected outcome of arthroscopic FAI surgery.

#8 Daily Fantasy Football and Self-Reported Problem Behavior in the United States
Reference: J Gambl Stud. 2017 Sep 26. doi: 10.1007/s10899-017-9720-4. [Epub ahead of print]
Authors: Dwyer B, Shapiro SL, Drayer J
Summary: Traditional, season-long fantasy sport participation has grown considerably since the late 1990s, and in an attempt to capitalize on this growing demand, daily fantasy sports (DFS) providers have created a new game where money changes hands instantly. This change has led some legal commentators and state agencies to believe the game is a form of Internet gambling similar to online poker, blackjack, and sports wagering, and thus, it requires increased regulation or even prohibition. Little is known, however, about the gambling behavior associated with DFS participation. Thus, the purpose of the current study was to examine problem gambling severity in conjunction with DFS participant motives, perceptions, and consumption behavior. Over 500 DFS participants were surveyed, and the results suggest DFS participants behave similarly with participants in other forms of gambling activities. In addition, the findings suggest additional consumer protections may be needed to prevent further problem behavior such as chasing.

#9 Lifetime Prevalence of Injuries in Incoming Division I Collegiate Football Players
Reference: Phys Sportsmed. 2017 Sep 27. doi: 10.1080/00913847.2017.1386068. [Epub ahead of print]
Authors: Sarac N, Haynes W, Pedroza A, Kaeding C, Borchers J
Summary: The purpose of this study is to determine the lifetime prevalence of past injuries in incoming first year football players in a Division 1 college football team. Pre-participation questionnaires from 605 first-year football players over 20 years (1996-2015) were examined to determine the prevalence of concussions, stingers, fractures, and musculoskeletal surgeries sustained before playing at the collegiate level. Players were grouped by position: wide receiver and defensive back (WR/DB), offensive and defensive linemen (OL/DL), all other positions (OP), and unknown (UKN). Prevalence of injuries by year and position was compared using Pearson's χ2 Test (p<0.05). The reported lifetime prevalence is as follows: concussion (21%), stinger (23%), musculoskeletal surgery (23%), and fracture (44%). There were no significant differences in lifetime prevalence of concussions (p=0.49), stingers (p=0.31), fractures (p=0.60), or musculoskeletal surgeries (p=0.97) based on position. There were also no significant differences in the lifetime prevalence of concussions (p=0.14), musculoskeletal surgeries (p=0.50), or fractures (p=0.59) based on year. However, there was a significant difference in the lifetime prevalence of stingers based on year (p<0.001). There was an expectation to observe an increase in injury prevalence by entering year, but this was not seen. A decrease in stingers was actually observed, but there was no significant difference among any other injury recorded. These results do not support the perception that football injuries are on the rise. Under reporting is a significant concern as players may fear disqualification or that they are evaluated by the coaching staff based on their medical history. More research is needed to confirm lifetime injury prevalence and evaluate differences over time among football players.

#10 Distal Fibula Fractures in National Football League Athletes
Reference: Orthop J Sports Med. 2017 Sep 8;5(9):2325967117726515. doi: 10.1177/2325967117726515. eCollection 2017 Sep.
Authors: Werner BC, Mack C, Franke K, Barnes RP, Warren RF, Rodeo SA
Summary: Despite the frequency of distal fibula fractures in elite athletes and the significant potential impact on the athletes' season and future careers, little data exist characterizing the epidemiology of these injuries or, more importantly, return to competition. The purpose was to (1) evaluate the incidence of acute distal fibula fractures in National Football League (NFL) athletes, including isolated distal fibula and combined ankle fracture patterns; (2) analyze distal fibula fracture rates in NFL athletes by position, type of play, and contact type; (3) determine the rates of distal fibula fracture surgery in NFL athletes; and (4) report the days missed due to distal fibula fractures in NFL athletes. A retrospective review of distal fibula fractures reported to the NFL from 2000 to 2014 was performed using the NFL Injury Surveillance System. All distal fibula fractures were included, along with isolated and combined fracture patterns. Stress fractures and proximal fibula fractures were excluded. Epidemiological data and rates of surgery were determined. Return to sport was calculated and stratified by injury pattern and management. Overall, 237 distal fibula fractures in NFL athletes from 2000 to 2014 were included; 197 (83%) were isolated distal fibula fractures. A mean of 16 distal fibula fractures occurred each year (median, 16 per year). Fractures occurred most frequently on running (38%) and passing (24%) plays, but the frequency was next highest on kickoffs (16%), despite the relative infrequency of kickoffs during the average game compared with other play types. Surgery was reported for more than half of all distal fibula fractures (n = 128, 54%). Overall, patients who underwent surgery missed significantly more days (mean, 123.8 days) than players who did not undergo surgery (mean, 75.3 days) (P < .001). Players with isolated distal fibula fractures had significantly fewer days missed (mean, 93.6 days) compared with those with combined patterns (mean, 132.3 days) (P = .0004). Fibula fractures affect a number of NFL athletes and result in significant time missed from competition. Further research is required to determine the optimal management of fibula fractures in NFL athletes. In this study, time to return to play depended on both the fracture pattern and whether surgery was required and ranged from 72 to 145 days.

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