Brain morphometry in former American football players: Findings from the DIAGNOSE CTE research project.

Exposure to repetitive head impacts (RHIs) in contact sports is associated with neurodegenerative disorders including chronic traumatic encephalopathy (CTE) which currently can be diagnosed only at postmortem. American football players are at higher risk of developing CTE given their exposure to RHIs. One promising approach for diagnosing CTE in vivo is to explore known neuropathological abnormalities at postmortem in living individuals using structural magnetic resonance imaging (MRI). MRI brain morphometry was evaluated in 170 male former American football players ages 45-74 years (n = 114 professional; n = 56 college) and 54 same-age unexposed asymptomatic male controls (n = 58 age range 45-74). Cortical thickness and volume of regions of interest were selected based on established CTE pathology findings and were assessed using FreeSurfer. Group differences and interactions with age and exposure factors were evaluated using a generalized least squares model. A separate logistic regression and independent multinomial model were performed to predict each Traumatic Encephalopathy Syndrome (TES) diagnosis core clinical features and provisional level of certainty for CTE pathology using brain regions of interest. Former college and professional American football players (combined) showed significant cortical thickness and/or volume reductions compared to unexposed asymptomatic controls in the hippocampus amygdala entorhinal cortex parahippocampal gyrus insula temporal pole and superior frontal gyrus. Post-hoc analyses identified group-level differences between former professional players and unexposed asymptomatic controls in the hippocampus amygdala entorhinal cortex parahippocampal gyrus insula and superior frontal gyrus. Former college players showed significant volume reductions in the hippocampus amygdala and superior frontal gyrus compared to the unexposed asymptomatic controls. We did not observe age-by-group interactions for brain morphometric measures. Interactions between morphometry and exposure measures were limited to a single significant positive association between the age of first exposure to organized tackle football and right insular volume. We found no significant relationship between brain morphometric measures and the TES diagnosis core clinical features and provisional level of certainty for CTE pathology outcomes. These findings suggest that MRI morphometrics detects abnormalities in individuals with a history of RHI exposure that resemble the anatomic distribution of pathological findings from postmortem CTE studies. The lack of findings associating MRI measures with exposure metrics (except for one significant relationship) or TES diagnosis and core clinical features suggests that brain morphometry must be complemented by other types of measures to characterize individuals with RHIs.

Characterizing Neurobehavioral Dysregulation Among Former American Football Players: Findings From the DIAGNOSE CTE Research Project.

OBJECTIVE: Neurobehavioral dysregulation (NBD), a core clinical feature of traumatic encephalopathy syndrome, encompasses neuropsychiatric symptoms reported among individuals with a history of repetitive head impact exposure, including contact sport athletes. The objective of this study was to examine the construct and subconstructs of NBD through a series of factor and cluster analyses. METHODS: Six clinician-scientists selected self-report questionnaire items relevant to NBD from seven available neuropsychiatric scales through a blinded voting process. These items were subjected to confirmatory factor analyses in a sample of 178 former college and professional American football players and 60 asymptomatic individuals without a history of repetitive head impact exposure. All participants were enrolled in the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy Research Project. Factor scores were generated on the basis of the optimal expert-informed model for NBD. Construct validity was assessed with neuropsychiatric scales not included in generation of the factor scores. Cluster analyses with NBD factor scores were used to examine symptom profiles. RESULTS: Factor analyses confirmed that NBD was composed of four subconstructs: explosivity, emotional dyscontrol, impulsivity, and affective lability. Cluster analyses indicated four distinct symptom profiles of NBD in this group of former football players: asymptomatic (N=80, 45%), short fuse (N=33, 19%), high affective lability (N=34, 19%), and high NBD (N=31, 17%). CONCLUSIONS: These findings characterize NBD as a multifaceted clinical construct with a heterogeneous presentation, providing a foundation for empirical work on the diagnostic criteria for traumatic encephalopathy syndrome and research on the neurobiological underpinnings of NBD.

Changes in the central nervous system in football players: an MRI study.

BACKGROUND: Football (soccer) is the world's most popular team sport. PURPOSE: To comprehensively examine the brain in football (soccer) players, with the use of magnetic resonance imaging (MRI) techniques. MATERIAL AND METHODS: The study involved 65 football players and 62 controls. The MR examinations were performed using MR 1.5-T system (Optima MR 360; GE Medical Systems). The examinations were carried out in the 3D Bravo, CUBE, FSEpropeller, and diffusion-weighted imaging (DWI) sequences. The 1HMRS signal was obtained from the volume of interest in the frontal and occipital lobes on both sides. RESULTS: The present study, based on structural MRI, shows some changes in the brains of the group of football players. The findings show asymmetry of the ventricular system in four football players, arachnoid cysts in the parieto-occipital region, and pineal cysts. NAA/Cr concentration in the right frontal lobe was lower in the football players than in the controls, and the Glx/Cr concentration in the right occipital lobe was higher. The apparent diffusion coefficient value is lower in football players in the occipital lobes. CONCLUSION: Playing football can cause measurable changes in the brain, known to occur in patients diagnosed with traumatic brain injury. The present findings fill the gap in the literature by contributing evidence showing that playing football may lead to changes in the brain, without clinical symptoms of concussion.

Prevalence of hip femoroacetabular impingement deformities in high-level (La Liga) male professional football players.

BACKGROUND: Femoroacetabular impingement (FAI) is considered one of the main causes of hip osteoarthritis in young adults, especially in athletes. In recent years, morphological changes in FAI in the hip have been linked to early and intense sports participation, but studying top-level athlete samples is not easy. This paper presents the prevalence of FAI radiological markers in 120 active white male professional football players in the Spanish First Division League (La Liga) and compares the morphological changes with those of a control group of healthy individuals without significant sport activity. METHODS: The precontract medical evaluation hip X-rays of 120 white male professional football players from four different First Division Spanish football teams were prospectively filed and retrospectively reviewed by a dedicated skeletal radiologist. The footballers' hip X-rays were compared with those of a control group of 80 healthy individuals (age-sex matched) without significant sport activity (obtained from routine work medical checks). RESULTS: The femoral head-neck deformity associated with the Cam type of femoroacetabular impingement was observed in 61.6% of professional football players and only in 11.6% of the control group (p <0.01). The presence of "herniation pit" (11.6%) and os acetabuli (13.3%) also reached statistical significance in the professional football players group. In the other analyzed parameters, no statistically significant differences between the groups were observed. CONCLUSIONS: White professional top-level football players have an increased incidence of abnormal lateral epiphyseal extension ("pistol grip deformity"), os acetabuli and herniation pits.

Effect of the FIFA 11+ injury prevention program in collegiate female football players over three consecutive seasons.

This study aimed to investigate the preventive effects of the FIFA 11+ for one-season and over three consecutive seasons on the injury incidence rates in collegiate female football players in terms of duration of intervention. A total of 763 collegiate female football players from seven teams belonging to Kanto University Women Football Association Division 1 in 2013-2015 seasons were included in the study. At the start of the study, 235 players were assigned to a FIFA 11+ intervention group (four teams, 115 players) and a control group (three teams, 120 players). The intervention period was set to three seasons, and the players were followed up during this period. The one-season effect of the FIFA 11+ was investigated after each season. The effect of continuous intervention was verified in 66 and 62 players from the intervention and control groups who continued the study for all three seasons, respectively. The one-season intervention showed significantly lower total, ankle, knee, sprain, ligament injury, noncontact, moderate and severe injury incidence rates in the intervention group in each season. Regarding the continuous intervention, compared with the first season, the injury incidence rates in lower extremity, ankle, and sprain, decreased in the intervention group by 66.0%, 79.8%, and 82.2%, respectively, in the second season, and by 82.6%, 94.6%, and 93.4%, respectively, in the third season, indicating the persistent effect of the FIFA 11+. In conclusion, the FIFA 11+ is an effective program for lower extremity injury prevention in collegiate female football players, and preventive effects persist with continuation of the program.

Blood and Salivary Cortisol Variations in Athletes in Relation to Cardiopulmonary Exercise Testing.

Background and Objectives: Cortisol is a valuable marker for assessing the body's response to any form of stress. We conducted this study in order to evaluate the variations of salivary and serum cortisol levels in professional football players in relation to cardiopulmonary exercise testing (CPET) and their significance in potentially evaluating overtraining in athletes. Also, the question of whether salivary cortisol determination could fully substitute serum sampling was addressed. Materials and Methods: A total of 19 male professional football players were evaluated by measuring serum cortisol levels at rest (T0) and immediately after a CPET (T1) and salivary cortisol levels at rest (T0), 10 min after a CPET (T2), and 30 min after a CPET (T3). Results: T0 serum cortisol showed a statistically significant correlation with the oxygen uptake at the anaerobic threshold divided by the body weight (VO2-AT/weight), as did the T2 salivary cortisol with the maximum oxygen uptake at the anaerobic threshold (VO2-AT) and VO2-AT/weight. T0 salivary cortisol was significantly correlated with the subjects' height and the predicted O2 pulse. Conclusions: While some correlations were discovered, they are insufficient to recommend cortisol as a routine biomarker in athletes' evaluation. However, significant correlations were established between salivary and serum determinations, meaning that the non-invasive procedure could substitute venous blood sampling.

Effect of Position Specific Physiotherapy Training on performance of Indian football players: A Randomized Control Trial.

This study evaluated the effect of Position-Specific Physiotherapy Training on Agility, Speed endurance, and Balance in Indian Football Players. Around 70 football players were approached of which 48 gave consent to participate, and further 30 players sufficing inclusion criteria were recruited. They were divided into three groups, Forwards (Group A, n = 10), Defenders (Group B, n = 10), and Control (Group C, n = 10), according to their On-field Position. These participants underwent Position Specific Physiotherapy Training for 4 weeks. Significant improvement was noted in the Agility of Group A (p ≤ 0.001) and Group B (p ≤ 0.001) as compared to Group C (p = 0.071). Speed Endurance improved for Group A (p ≤0.001) and Group B (p ≤ 0.001) as compared to Group C (p = 0.111). Fatigue Index of Group A (p ≤ 0.001) and Group B (p ≤ 0.001) improved significantly as compared to Group C (p = 0.383). The Balance of Group A (p = 0.0063) and Group B (p = 0.0019) improved significantly as compared to Group C (p = 0.0632). Position-Specific Physiotherapy Training was found to be effective in improving Agility, Speed endurance, and Balance ability of the Indian Football Players.

History of ankle sprain affect the star excursion balance test among youth football players.

BACKGROUND: The relationship between the results of the Star Excursion Balance Test (SEBT) and lateral ankle sprain (LAS) among youth football players was investigated. METHODS: The dominant leg and history of LASs were asked from 33 male youth football players. The SEBT in the anterior, posterolateral, and posteromedial directions were measured for both limbs. The relationship between the history of LAS and reach difference over 4 cm between the dominant and nondominant legs in each direction was statistically analyzed. RESULTS: The number of players with the history of LAS, whose dominant/nondominant reach difference was over 4 cm in the anterior direction, was significantly higher to that in players without a history of LAS in both the dominant (94% vs. 63%, p = 0.02) and nondominant (100% vs. 25%, p = 0.02) legs. CONCLUSION: Youth football players with a history of LAS showed reach deficit in the anterior direction in the SEBT.

Quantitative assessment of the effect of acute anaerobic exercise on macular perfusion via swept-source optical coherence tomography angiography in young football players.

AIM: To evaluate the effect of acute anaerobic exercise on macular perfusion measured by swept-source optical coherence tomography angiography (SS-OCTA) in young football players. MATERIALS AND METHODS: Football players with ages between 18 and 20 years were included into the study. After a detailed ophthalmological examination, physiological parameters including height (cm), body weight (kg), body fat percentage (%), systemic blood pressure (BP) (mmHg), hematocrit values (%), oxygen saturation pO2 (%) and heart rate (bpm) were recorded. Intraocular pressure (IOP) (mmHg) and SS-OCTA using DRI OCT Triton (Topcon, Tokyo, Japan) were measured immediately before and after Wingate test. RESULTS: Out of 20, 16 participants completed the study. All participants were males with a mean age of 18.12 ± .34 years. Systolic BP, hematocrit and heart rate increased, while pO2 and IOP decreased remarkably after Wingate test (p < .01). After anaerobic exercise, there was an increase in mean FAZ area in superficial capillary plexus (FAZs) which was not significant (p = .13), while decrease in FAZ area in deep capillary plexus (FAZd) (mm2) was remarkable (p = .04). No changes were observed in mean vessel density (VD) (%) in superficial capillary plexus (VDs), deep capillary plexus (VDd), choriocapillaris (VDcc), central macular thickness (CMT) (µm) and subfoveal choroidal thickness (SFCT) (µm) after Wingate test (p > .05). FAZd and some of the VD parameters showed a significant correlation with BP (p < .05). CONCLUSION: Acute anaerobic exercise seems not to alter either mean VD in retina and choroid or CMT and SFCT. Among OCTA parameters, only FAZd decreased remarkably.

Mri and ultrasound criteria for the diagnosis of a sports hernia in football players.

OBJECTIVE: The aim of the study is to specify diagnostic MRI and ultrasound criteria for a sports hernia in order to verify its diagnosis in football players. PATIENTS AND METHODS: Materials and methods: The study included 50 professional and amateur football players aged 15 to 34 from 2016 to 2019. The criteria for inclusion in the study were: the presence of groin pain in football players, which prevented them from continuing to actively participate in sports activities. RESULTS: Results: The findings of the study revealed that during MRI the two factors, which had the strongest influence, were "increased MR signal intensity on PDfs observed from the structures of the inguinal canal" and "increased MR signal intensity on PDfs observed from bone marrow of superior ramus of the pubic bone". During ultrasound of the inguinal area, the main criterion for a sports hernia diagnosis was "increased size of the inguinal canal". The verification of the diagnosis was carried out on the basis of the presence of a protrusion in the posterior wall of the inguinal canal. For a sports hernia diagnosis the MRI sensitivity is 91.67% (95% CI 77.5 - 98.2), specificity -78.57% (95% CI 49.2 - 95.3) and the sensitivity of ultrasound is 88.89% (95% CI 73.9 - 96.9), the specificity - 50% (95% CI 23.0 - 77). CONCLUSION: Conclusions: The combination of MRI and ultrasound makes it possible to accurately detect the presence of a sports hernia in the football player. Based on the findings of our study, we formulated MRI and ultrasound criteria for a sports hernia diagnosis.

Side-to-side asymmetry in lower limb strength and hamstring-quadriceps strength ratio among collegiate American football players.

[Purpose] The present study aimed to investigate the lower limbs injury risk factors that are based on conventional Hamstring to Quadriceps ratio and limb asymmetry index in varsity American football players. [Participants and Methods] Twenty-six varsity American football players aged 19-27 years and with 2.31 ± 1.29 years of American football experience from Dogu Akdeniz University volunteered to undergo measurements of average peak torque for isokinetic flexion and extension of dominant limb and non-dominant limb at 60°·s-1 and 300°·s-1. Hamstring to Quadriceps ratio and limb asymmetry index were also calculated for Hamstring and Quadriceps muscles. [Results] Statistical analysis revealed that dominant Quadriceps is stronger than non-dominant Quadriceps at 60°·s-1 speed. No statistical difference was found between dominant and non-dominant Hamstring peak torque at 60°·s-1 . Hamstring to Quadriceps ratio determined as normal both for 60°·s-1 and 300°·s-1according to the currently reported cut off value (H:Q ratio >60). Hamstring and Quadriceps limb asymmetry index also determined as normal (cut off value for LSI 10%) at 60°·s-1. However, for both Hamstring and Quadriceps, side- to- side strength asymmetry at 300°·s-1 was observed. [Conclusion] To prevent possible lower limb injury and to increase performance, varsity American football players who are actively training and competing might consider taking strength asymmetry into account to tailor their strength training program accordingly.

Nutrition Status of Young Elite Female German Football Players.

PURPOSE: To investigate energy intake, energy expenditure, and the nutritional status of young female elite football players using 7-day food and activity records and blood parameters. METHODS: A total of 56 female elite football players [14.8 (0.7) y] completed the requested food and activity protocols. Misreporting was assessed by the ratio of energy intake to energy expenditure. The food records were analyzed concerning energy and macronutrient and micronutrient intakes, and energy expenditure was calculated using predictive equations. Hematological data and 25-hydroxyvitamin D serum concentrations were determined. RESULTS: Mean energy intake was 2262 (368) kcal/d [40.5 (7.0) kcal/kg/d] and estimated EE averaged 2403 (195) kcal/d. Fifty-three percent of the players exhibited an energy availability <30 kcal/kg lean body mass; 31% of the athletes consumed <5 g/kg carbohydrates and 34% consumed <1.2 g/kg proteins. A large proportion of players (%) had intakes below the recommended daily allowance of folate (75%), vitamin D (100%), iron (69%), and calcium (59%). Ferritin and 25-hydroxyvitamin D serum levels were below the recommendations of 59% and 38%, respectively. CONCLUSIONS: A remarkable number of players failed to meet the energy balance and the recommended carbohydrate and protein intakes. Low iron and 25-hydroxyvitamin D serum levels were observed showing a suboptimal nutrition status of some young female football players. As a consequence, strategies have to be developed for a better information and application of sport nutrition practice among young female football players.

Effect of lifelong football training on the expression of muscle molecular markers involved in healthy longevity.

PURPOSE: We investigated whether lifelong football training affects the expression of healthy longevity-related muscle molecular markers. METHODS: Biopsies were collected from the vastus lateralis muscle of 10 lifelong football-trained men (68.2 ± 3.0 years) and of 10 active untrained healthy men (66.7 ± 1.3 years). Gene and protein expression was measured by RTqPCR on RNA and by western blotting on protein extracts from muscle biopsies, respectively. RESULTS: The expression of AMPKα1/α2, NAMPT, TFAM and PGC1α, which are markers of oxidative metabolism, and MyHC ß isoform expression was higher in the muscle of football-trained men vs untrained men. Also citrate synthase activity was higher in trained than in untrained men (109.3 ± 9.2 vs 75.1 ± 9.2 mU/mg). These findings were associated with a healthier body composition in trained than in untrained men [body weight: 78.2 ± 6.5 vs 91.2 ± 11.2 kg; body mass index BMI: 24.4 ± 1.6 vs 28.8 ± 4.0 kg m-2; fat%: 22.6 ± 8.0 vs 31.4 ± 5.0%)] and with a higher maximal oxygen uptake (VO2max: 34.7 ± 3.8 vs 27.3 ± 4.0 ml/min/kg). Also the expression of proteins involved in DNA repair and in senescence suppression (Erk1/2, Akt and FoxM1) was higher in trained than in untrained men. At BMI- and age-adjusted multiple linear regression analysis, fat percentage was independently associated with Akt protein expression, and VO2max was independently associated with TFAM mRNA and with Erk1/2 protein expression. CONCLUSIONS: Lifelong football training increases the expression of key markers involved in muscle oxidative metabolism, and in the DNA repair and senescence suppression pathways, thus providing the molecular basis for healthy longevity.

MRI detection of soleus muscle injuries in professional football players.

OBJECTIVES: To describe magnetic resonance imaging (MRI) characteristics of soleus muscle injuries in symptomatic professional football players stratified according to both the Munich consensus statement and the British Athletics Muscle Injury Classification (BAMIC), and to investigate the association between specific MRI features and the "return to play" (RTP). MATERIALS AND METHODS: Professional football players with an episode of acute posterior calf pain and impaired function, subsequent to sports activity, underwent ultrasound followed by MRI examination reviewed by two different radiologists with more than 10 years of experience in the musculoskeletal system. MRI features and RTP outcome were evaluated for all types of injuries. RESULTS: During a 36-month period, a total of 20 professional football players were evaluated. According to the Munich consensus, 11 were type 3A, 8 were type 3B, and 1 was type 4, whereas according to the BAMIC, 11 lesions were considered grade 1, 4 grade 2, 4 grade 3, and 1 grade 4. RTP data were available for all patients (mean 3.3 ± 1.6 weeks). Both the Munich consensus and the BAMIC correlated with RTP (Spearman correlation = 0.982 and p < 0.0001 and 0.886 and p < 0.0001 respectively). Extension of edema was an independent prognostic factor for RTP in two different models of multivariate regression analysis (p = 0.044 model A; p = 0.031 model B). CONCLUSIONS: The Munich consensus and BAMIC grading systems are useful tools for defining the patient's prognosis and proper rehabilitation time after injury. The MRI feature that we should carefully look for is the extension of edema, as it seems to significantly affect the RTP.

Effect of a Ten-week Sensorimotor Exercise Program on the Side-to-Side LAM Asymmetry of Adolescent Football Players: A Randomized Control Trial.

In this study we, evaluated the effects of a 10-week sensorimotor exercise program on the thickness and side-to-side asymmetry of the lateral abdominal muscles in adolescent soccer players. From among 120 initially recruited participants, we included 90 athletes (aged 10-17 years old) in our final analysis. Healthy athletes who met our inclusion criteria were randomly divided into comparative experimental and control groups. Sensorimotor exercises were conducted twice weekly for 10-weeks in the experimental group, and the control group received no intervention. We took ultrasound measurements when participants were in supine and standing rest positions. In the supine position, the experimental group (a) reduced the asymmetry of the internal oblique (IO) muscle by 0.4 mm (MD: 0.7; 95% CI 0.6-1.1); (b) increased the thickness of the external oblique (EO) muscle on the right by 0.7 mm (MD: 0.2; 95% CI 0.1-0.6) and on the left by 0.9 mm (MD: 0.2, 95% CI 0.2-0.7); and (c) increased the muscle on the IO right by 0.8 mm (MD: 0.3; 95% CI 0.2-0.9) and on the, left by 1.2 mm (MD: 0.4 95% CI 0.3-1.1). In a standing position the experimental group increased the thickness of the EO on the right by 1.5 mm (MD: 0.6; 95% CI 0.03-1.2) and on the left by 2.1 mm (MD: 0.6; 95% CI 0.1-1.3) and increased the IO on the right by 1.2 mm (MD: 0.7; 95% CI 0.2-1.7) and on the left by 1.1 mm (MD: 0.9; 95%CI 0.1-2.0). Thus, this 10-week program of additional sensorimotor exercises reduced the (side-to-side) asymmetry of the internal oblique muscle and increased the thickness of the EO and IO muscles in young football players.

[Characterization of injuries among elite football players during a sports season in Burkina Faso: the 2019-2020 sports season]. / Caractérisation des blessures sur une saison sportive chez des footballeurs d'élite au Burkina Faso: cas de la saison 2019-2020.

Introduction: injuries are a major undesirable event in sportsmen's career and prevention depends on their characteristics. The aim of this study was to determine the characteristics of injuries suffered by elite footballers in Burkina Faso during the 2019-2020 sports season. Methods: we conducted a cross-sectional study among 160 players who were administered a questionnaire. Proportion and χ2 tests were used to calculate frequencies and determine associated factors, respectively. Results: a total of 157 injuries were recorded in 143 players (89.4%). Muscle injuries (45.85%) and sprains (30.6%) were common. The majority of injuries (52%) were of medium severity. The thigh (30%), ankle (26.5%) and knee (18%) were the most affected areas. The frequency of injuries was higher after physical contact than without physical contact with another player (69.5% versus 30.5; p = 0.009), during matches than during training (82% versus 28%; p = 0.003) and during the return leg than the first leg of the championship (58.5% versus 41.5%; p = 0.02). Conclusion: the frequency of injuries suffered by footballers during the 2019-2020 season was high. These injuries were mostly muscular and tendinous, and the lower limbs were mostly affected. They were associated with physical contact, matches and the return phase of the championship. To be effective, preventive measures should take these characteristics into account.

A new injury prevention program 'FUNBALL' improves cognitive performance of young football (soccer) players: A cluster randomized controlled trial.

The youth football injury prevention program 'FUNBALL' contains exercises requiring high cognitive demands, which are performed concurrently to the training of the respective motor task. This study evaluates whether the program increases cognitive performances of young football players. 1253 football players (aged 13-19 years old) were randomly assigned to either a control (CON) or an intervention (INT) group. The INT group performed the 'FUNBALL' program at least twice per week in their training sessions for one season (9 months). The CON group continued their training routine. From the total sample, the cognitive performance of 304 players (n=135 CON; n=169 INT) was assessed at the beginning and the end of the season using the Cogstate® Brief Battery, with the following subtests: One Back test (accuracy), Two Back test (accuracy), One Card Learning test (accuracy), Chase Test (correct moves per second), Set Shifting (accuracy), Identification test (speed), Detection test (speed), Groton Maze Learning Test (accuracy), and Groton Maze Learning Test Delayed Recall (accuracy). A multivariate analysis of variance (MANOVA) on the cognitive performance improvements from pre- to posttest showed that the INT group improved their performances more strongly than the CON group for all cognitive tests, namely for working memory, visual learning, visual motor control, attention, psychomotor function, memory, and executive function. The present study indicates that the exercise-based injury prevention program 'FUNBALL' may improve the cognitive performance of young football players. Future research should include an active control group, and should investigate whether the improvement in cognition also has beneficial effects on in-game performance. TRIAL REGISTRATION NUMBER: AsPredicted (https://aspredicted.org/2kb3b.pdf).

Development of novel calibration model(s) to predict whole-body density in professional football players.

INTRODUCTION: Questions continue to be raised about the validity that is in existence to estimate Db, in professional male footballer players. METHODS: Phase 1: n = 28 anthropometric variables were used on n = 206 footballers, using regression analyses to determine standard error of estimate and R2. A cut-off correlation coefficient set at r = 0.950 and 90% R2. Phase 2: all variables (z-scores, x- = 0.0, SD = ±1.0) to help reduce heteroscedasticity, ß, r, t, significance of t and P-values were calculated. Phase 3: a forced stepwise-backwards regression analysis approach with nine predictors which met the acceptance criteria (r = 0.950, R2 = 90% and ß weights) was used to develop a 'best fit' and a 'practical' calibration model. Phase 4: cross-validation of the two newly developed calibration method using LoA. RESULTS: The 'best fit' model SEM (0.115 g ml-1), the highest R2 (6.6%) (P ≤ 0.005), whereas the 'practical' calibration model SEM (0.115 g ml-1), R2 (4.7%) (P ≤ 0.005) with r values = 0.271 and 0.596 and R2 (%) coefficients = 0.3526 for the 'best fit' and 'practical' calibration models, respectively (P = 0.01). CONCLUSIONS: The two calibration models supported an ecologically and statistically valid contribution and can provide sound judgements about professional footballers' body composition.

Vitamin D Deficiency in Professional Football Players during Competitive Season of Italian First Division (Serie A).

BACKGROUND: Data in the literature have demonstrated the crucial role that vitamin D plays in the human organism, and recent studies also emphasize this essential role of vitamin D in athletes. Indeed, vitamin D acts on the skeletal muscles and plays a fundamental role in numerous physiological processes involved in immune function. Many factors such as sun exposure, skin tone, body mass index and chronic illness affect vitamin D levels. The aim of the study is to evaluate vitamin D levels in professional football players in Italy and investigate the variations in vitamin D values in footballers who train at different latitudes. METHODS: The study performed is a retrospective observational study analyzing 25-OH vitamin D values in professional football players of the Italian First Division (Serie A). Two teams during the competitive season were selected: team A (latitude of 41° N in southern Italy) and team B (latitude of 45° N in northern Italy). Three time periods were identified and were classified as follows: the first quarter (May, June, July, and August), the second quarter (September, October, November, and December) and the third quarter (January, February, March, and April). The purpose of this was to study the average values of vitamin D during the year corresponding to different levels of sunlight exposure. Each athlete was subjected to at least one sampling during the three quarters of the competitive season. RESULTS: Both vitamin D insufficiency (10.1%) and overt deficiency (1.93%) were found in Italian Serie A players. Insufficient vitamin D values are between 20 ng/mL and 29 ng/mL and overt deficiency values <20 ng/mL. At the same time, the data demonstrated a significant variation in vitamin D values depending on the period of the competitive season and the latitude of the cities of the two teams. In detail, there was no significant difference in the first quarter, while there was a significant increase in vitamin D values in team B in the second and third quarter, at p < 0.01 and p < 0.05, respectively. CONCLUSIONS: Latitude and seasons have a significant impact on vitamin D levels. Therefore, it is essential to measure vitamin D in professional football players, especially during the spring and winter months, so as to monitor changes in levels in relation to the season and latitude and evaluate any supplements. Further studies should be performed to evaluate the relationship between vitamin D deficiency and football players' athletic performance.

Relationship between Countermovement Jump and Sprint Performance in Professional Football Players.

Objectives: The aim of this study was to assess the relationship between the countermovement jump (CMJ) and sprint performance of professional football players, and to determine which strength and speed elements assessed by the CMJ translate into effective running. Methods: The research sample comprised 87 male professional football players (age 23.7 ± 4.20 years; body mass 82.33 ± 6.56 kg; body height 1.86 ± 0.05 m) who performed the CMJ on a dual-force platform, as well as the 30 m sprint test. The time and velocity of the run were recorded by photocells at 0, 5, 10, and 30 m of the distance. Results: No significant differences were noted in the time or velocity of the sprint over the initial 5 m between the groups of football players with a higher and lower braking rate of force development (RFD) in the CMJ (p > 0.05). However, at subsequent intervals (5-10 m and 10-30 m), players with a higher braking RFD achieved significantly better time and velocity than those with a lower RFD. Significant correlations in the group with a lower braking RFD between the CMJ and sprint variables occurred in the propulsion phase of the CMJ and most of them were in the first interval (0-5 m). In the group with a higher braking RFD, significant relationships were visible in both the propulsion (concentric) and braking (eccentric) phases of the CMJ, mainly during the second and third intervals of the sprint test. Conclusions: The noted observations may suggest that the relationship between strength and running performance is more complex than previously indicated, and that higher strength in the CMJ does not fully correlate with better sprinting. Therefore, it has been hypothesized that training aimed at generally increasing strength may not always be fully beneficial for running performance in football players and hence specific training guidelines are suggested for targeted strengthening of the required muscle performance characteristics. This may possibly contribute to reducing the unnecessary muscle overload during both training and matches, thereby preventing sports-related injuries.