Concept: College football
How much does a fumble affect the probability of winning an American football game? How balanced should your offense be in order to increase the probability of winning by 10%? These are questions for which the coaching staff of National Football League teams have a clear qualitative answer. Turnovers are costly; turn the ball over several times and you will certainly lose. Nevertheless, what does “several” mean? How “certain” is certainly? In this study, we collected play-by-play data from the past 7 NFL seasons, i.e., 2009-2015, and we build a descriptive model for the probability of winning a game. Despite the fact that our model incorporates simple box score statistics, such as total offensive yards, number of turnovers etc., its overall cross-validation accuracy is 84%. Furthermore, we combine this descriptive model with a statistical bootstrap module to build FPM (short for Football Prediction Matchup) for predicting future match-ups. The contribution of FPM is pertinent to its simplicity and transparency, which however does not sacrifice the system’s performance. In particular, our evaluations indicate that our prediction engine performs on par with the current state-of-the-art systems (e.g., ESPN’s FPI and Microsoft’s Cortana). The latter are typically proprietary but based on their components described publicly they are significantly more complicated than FPM. Moreover, their proprietary nature does not allow for a head-to-head comparison in terms of the core elements of the systems but it should be evident that the features incorporated in FPM are able to capture a large percentage of the observed variance in NFL games.
To test a helmetless-tackling behavioral intervention for reducing head impacts in National Collegiate Athletic Association Division I football players.
The acknowledgement of risks for traumatic brain injury in American football players has prompted studies for sideline concussion diagnosis and testing for neurological deficits. While concussions are recognized etiological factors for a spectrum of neurological sequelae, the consequences of sub-concussive events are unclear. We tested the hypothesis that blood-brain barrier disruption (BBBD) and the accompanying surge of the astrocytic protein S100B in blood may cause an immune response associated with production of auto-antibodies. We also wished to determine whether these events result in disrupted white matter on diffusion tensor imaging (DT) scans. Players from three college football teams were enrolled (total of 67 volunteers). None of the players experienced a concussion. Blood samples were collected before and after games (n = 57); the number of head hits in all players was monitored by movie review and post-game interviews. S100B serum levels and auto-antibodies against S100B were measured and correlated by direct and reverse immunoassays (n = 15 players; 5 games). A subset of players underwent DTI scans pre- and post-season and after a 6-month interval (n = 10). Cognitive and functional assessments were also performed. After a game, transient BBB damage measured by serum S100B was detected only in players experiencing the greatest number of sub-concussive head hits. Elevated levels of auto-antibodies against S100B were elevated only after repeated sub-concussive events characterized by BBBD. Serum levels of S100B auto-antibodies also predicted persistence of MRI-DTI abnormalities which in turn correlated with cognitive changes. Even in the absence of concussion, football players may experience repeated BBBD and serum surges of the potential auto-antigen S100B. The correlation of serum S100B, auto-antibodies and DTI changes support a link between repeated BBBD and future risk for cognitive changes.
Repetitive head impacts (RHI) refer to the cumulative exposure to concussive and subconcussive events. Although RHI is believed to increase risk for later-life neurological consequences (including chronic traumatic encephalopathy), quantitative analysis of this relationship has not yet been examined due to the lack of validated tools to quantify lifetime RHI exposure. The objectives of this study were: 1) to develop a metric to quantify cumulative RHI exposure from football, that we term the cumulative head impact index (CHII); 2) to use the CHII to examine the association between RHI exposure and long-term clinical outcomes; and (3) to evaluate its predictive properties relative to other exposure metrics (i.e., duration of play, age of first exposure, concussion history). Participants included 93 former high school and collegiate football players that completed objective cognitive and self-reported behavioral/mood tests as part of a larger ongoing longitudinal study. Using established cut-off scores, we transformed continuous outcomes into dichotomous variables (normal versus impaired). The CHII was computed for each participant and derived from a combination of self-reported athletic history (i.e., number of seasons, position(s), levels played), and impact frequencies reported in helmet accelerometer studies. A bivariate probit, instrumental variable model revealed a threshold dose-response relationship between the CHII and risk for later-life cognitive impairment (p<0.0019), self-reported executive dysfunction (p<0.0003), depression (p<0.0009), apathy (p<0.0040), and behavioral dysregulation (p<.0001). Ultimately, the CHII demonstrated greater predictive validity relative to other individual exposure metrics.
- Journal of strength and conditioning research / National Strength & Conditioning Association
- Published over 8 years ago
The aim of this study was to determine the changes in anthropomorphism and performance over a four year eligibility career of American football players. A total of 92 offensive and defensive linemen and 64 skill (wide receivers and defensive backs) player observations were included in the analysis. Data from pre-season testing over a seven year period were compiled, sorted and analyzed by players' year in school. Assessments of strength included 1RM bench press, squat, power clean and a 225 lb. maximum repetition muscle endurance test. Power and speed measures included the vertical jump (VJ) and 40 yd (36.6m) sprint. All strength measures improved significantly (p<0.05) over the years of training. Skill players demonstrated a significant increase in power (W) between years 1 and 2, but at no other time. Linemen did not demonstrate significant changes in VJ. Speed did not change significantly for either group over the four years of training. These data provide a theoretically predictable four-year rate of change in anthropometric, strength and power variables for Division I football players. By having a longitudinal assessment of expected physical improvement it may be possible for strength training personnel to determine those who may need additional attention in an area in order to more closely improve as expected. Additionally, it is suggested that elite athletes may possess genetically superior attributes and therefore, when selecting athletes particular attention should be paid to the selection of those who have previously demonstrated superior speed and power.
Graft survivorship, reinjury rates, and career length are poorly understood after anterior cruciate ligament (ACL) reconstruction in the elite collegiate athlete. The purpose of this study was to examine the outcomes of ACL reconstruction in a National Collegiate Athletic Association (NCAA) Division I athlete cohort.
Injuries are inherent to the sport of American football and often require operative management. Outcomes have been reported for certain surgical procedures in professional athletes in the National Football League (NFL), but there is little information comparing the career effect of these procedures.
OBJECT This study directly compares the number and severity of subconcussive head impacts sustained during helmet-only practices, shell practices, full-pad practices, and competitive games in a National Collegiate Athletic Association (NCAA) Division I-A football team. The goal of the study was to determine whether subconcussive head impact in collegiate athletes varies with practice type, which is currently unregulated by the NCAA. METHODS Over an entire season, a cohort of 20 collegiate football players wore impact-sensing mastoid patches that measured the linear and rotational acceleration of all head impacts during a total of 890 athletic exposures. Data were analyzed to compare the number of head impacts, head impact burden, and average impact severity during helmet-only, shell, and full-pad practices, and games. RESULTS Helmet-only, shell, and full-pad practices and games all significantly differed from each other (p ≤ 0.05) in the mean number of impacts for each event, with the number of impacts being greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. The cumulative distributions for both linear and rotational acceleration differed between all event types (p < 0.01), with the acceleration distribution being similarly greatest for games, then full-pad practices, then shell practices, and then helmet-only practices. For both linear and rotational acceleration, helmet-only practices had a lower average impact severity when compared with other event types (p < 0.001). However, the average impact severity did not differ between any comparisons of shell and full-pad practices, and games. CONCLUSIONS Helmet-only, shell, and full-pad practices, and games result in distinct head impact profiles per event, with each succeeding event type receiving more impacts than the one before. Both the number of head impacts and cumulative impact burden during practice are categorically less than in games. In practice events, the number and cumulative burden of head impacts per event increases with the amount of equipment worn. The average severity of individual impacts is relatively consistent across event types, with the exception of helmet-only practices. The number of hits experienced during each event type is the main driver of event type differences in impact burden per athletic exposure, rather than the average severity of impacts that occur during the event. These findings suggest that regulation of practice equipment could be a fair and effective way to substantially reduce subconcussive head impact in thousands of collegiate football players.
This study intended to determine if an acute bout of soccer heading alters postural control and pronounced self-reported symptoms of cerebral concussion. Collegiate soccer players were randomly assigned to one of 2 groups. Each participant completed a baseline postural control assessment prior to heading. Participants either simulated (control group; CG) or performed (experimental group; EG) 10 headers at 11.2 m/s in 10 min. The postural assessment was repeated post heading at hrs 1, 24, and 48. The postural control parameter assessed was the root mean square (RMS) of the center of mass (COM). COM RMS were calculated for the anterior-posterior (AP) and medial-lateral (ML) time series. Compared to the CG, for the AP and ML time series COM RMS values were significantly higher in the EG at hr 24 (p <0.05). An acute bout of heading results in quantifiable alterations in postural control that are detectable 24 h post heading and dissipate within an additional 24 h. The significant findings may be due to the dynamic postural control assessment that incorporated robust discordant environmental conditions.
To our knowledge, little research has examined concussion across the youth/adolescent spectrum and even less has examined concussion-related outcomes (ie, symptoms and return to play).