Latest research in football - week 27 -2015

#1 Soccer-Related Injuries in Children and Adults Aged 5 to 49 Years in US Emergency Departments From 2000 to 2012
Reference: Sports Health. 2015 Jul;7(4):366-70. doi: 10.1177/1941738115579854.
Authors: Esquivel AO, Bruder A, Ratkowiak K, Lemos SE
Summary: An increase in soccer-related injuries occurred in the United States between 2000 and 2012; however, most studies of soccer-related injuries have only examined the pediatric population and not adults. We hypothesized that the number of soccer injuries is increasing in both the pediatric and adult populations. There are differences in injury types and counts when comparing male and female players within various age groups. This retrospective analysis surveyed the US Consumer Product Safety Commission's National Electronic Injury Surveillance System (NEISS) database from 2000 to 2012 for soccer-related injuries in children and adults aged 5 to 49 years. From 2000 to 2012, there were an estimated 2,472,066 soccer-related injuries among 5- to 49-year-olds; 629,994 (25.5%) in adults (aged 20-49 years). The overall estimated pediatric injury count increased significantly over the time period (R (2) = 0.764, P < 0.001). In the 20- to 49-year age range, there was also a significant increase in the estimated number of injuries over the 13-year period, from 41,292 injuries in 2000 to 55,743 in 2012 (R (2) = 0.719, P < 0.001). The estimated injury counts for male players were significantly higher than female players in any given year for all age groups (P < 0.001). Girls aged 5 to 19 years were more likely to have lower extremity injuries than boys (odds ratio [OR], 1.256; 95% CI, 1.214-1.299; P < 0.001). The most common injuries reported were strain/sprains (33.3%), fractures (23.7%), and contusions and abrasions (17.4%) within the 5- to 49-year age category. In both sexes, strains and sprains were significantly lower among 5- to 19-year-olds in comparison with 20- to 49-year-olds (OR, 0.740; 95% CI, 0.714-0.766; P < 0.001). There are age- and sex-related differences in estimated injury count, body part injured, type of injury, and hospital admissions for soccer. Also, estimated injury count increased over the 2000 to 2012 time period.


#2 Impaired Femoral Vascular Compliance and Endothelial Dysfunction in 30 Healthy Male Soccer Players: Competitive Sports and Local Detrimental Effects
Reference: Sports Health. 2015 Jul;7(4):335-40. doi: 10.1177/1941738115577931.
Authors: Cioni G, Berni A, Gensini GF, Abbate R, Boddi M
Summary: Despite beneficial effects of physical activity on cardiovascular risk, discordant data on elite athletes (high atherosclerotic damage in activity comprising strenuous exertion) and retired sportsmen are reported in the literature. We hypothesize that long-lasting daily physical activity could affect the morphology and function of the carotid and femoral vessel walls differently, as assessed in elite male athletes aged 20 to 30 years compared with age- and sex-matched healthy controls. Retrospective case-control study. Sixty male subjects (30 athletes and 30 controls) underwent medical examination for ankle brachial index, augmentation index (AIX) and AIX corrected for heart rate (AIXr), peripheral arterial tonometry (PAT), and intima media thickness and pulse wave velocity assay at common carotid (carotid-intima media thickness [c-IMT], carotid-pulse wave velocity [c-PWv]) and femoral arteries (femoral-intima media thickness [f-IMT], femoral-pulse wave velocity [f-PWv]) assessed by ultrasonography using Doppler ultrasound. Athletes showed a significantly lower heart rate (HR) at rest and a better lipid profile than controls. In athletes, c-PWv (5.87 ± 0.80 vs 6.62 ± 1.02 m/s, P = 0.001) and f-PWv (8.96 ± 1.29 vs 7.89 ± 1.39, P = 0.002) were, respectively, significantly lower and higher than values found in controls; accordingly, carotid AIX (4.03 ± 6.21 vs 7.81 ± 5.21, P = 0.003) and femoral AIX (8.56 ± 10.21 vs 6.09 ± 7.95, P = 0.042) were lower and higher than control values, even after correction for heart rate (P = 0.03). On the other hand, IMT values were significantly higher in controls than in athletes (c-IMT, P < 0.0001; f-IMT, P < 0.0001). A positive significant correlation between HR and c-IMT and f-IMT (r = 0.527, P < 0.001 and r = 0.539, P < 0.0001, respectively) and between HR and c-PWv (r = 0.410, P = 0.01) was found when controls and athletes were considered as a whole group. Soccer players showed lower PAT values in comparison with controls (P = 0.002). Elite sports positively affect c-IMT, f-IMT, and carotid PWv and AIX but not femoral PWv, AIX, AIXr, or PAT. Physical activity affects vascular beds in elite athletes differentially, depending on the rate of superior or inferior limb involvement in different sports. In soccer players, physical activity has a protective effect on carotid and femoral vessel walls but worsens femoral arterial and endothelial function. These findings highlight how different results can be shown on carotid and femoral districts, when these vascular districts are differently stressed during sport activity.


#3 Impaired Femoral Vascular Compliance and Endothelial Dysfunction in 30 Healthy Male Soccer Players: Competitive Sports and Local Detrimental Effects
Reference: Sports Health. 2015 Jul;7(4):335-40. doi: 10.1177/1941738115577931.
Authors: Cioni G, Berni A, Gensini GF, Abbate R, Boddi M
Summary: Despite beneficial effects of physical activity on cardiovascular risk, discordant data on elite athletes (high atherosclerotic damage in activity comprising strenuous exertion) and retired sportsmen are reported in the literature. We hypothesize that long-lasting daily physical activity could affect the morphology and function of the carotid and femoral vessel walls differently, as assessed in elite male athletes aged 20 to 30 years compared with age- and sex-matched healthy controls. Sixty male subjects (30 athletes and 30 controls) underwent medical examination for ankle brachial index, augmentation index (AIX) and AIX corrected for heart rate (AIXr), peripheral arterial tonometry (PAT), and intima media thickness and pulse wave velocity assay at common carotid (carotid-intima media thickness [c-IMT], carotid-pulse wave velocity [c-PWv]) and femoral arteries (femoral-intima media thickness [f-IMT], femoral-pulse wave velocity [f-PWv]) assessed by ultrasonography using Doppler ultrasound. Athletes showed a significantly lower heart rate (HR) at rest and a better lipid profile than controls. In athletes, c-PWv (5.87 ± 0.80 vs 6.62 ± 1.02 m/s, P = 0.001) and f-PWv (8.96 ± 1.29 vs 7.89 ± 1.39, P = 0.002) were, respectively, significantly lower and higher than values found in controls; accordingly, carotid AIX (4.03 ± 6.21 vs 7.81 ± 5.21, P = 0.003) and femoral AIX (8.56 ± 10.21 vs 6.09 ± 7.95, P = 0.042) were lower and higher than control values, even after correction for heart rate (P = 0.03). On the other hand, IMT values were significantly higher in controls than in athletes (c-IMT, P < 0.0001; f-IMT, P < 0.0001). A positive significant correlation between HR and c-IMT and f-IMT (r = 0.527, P < 0.001 and r = 0.539, P < 0.0001, respectively) and between HR and c-PWv (r = 0.410, P = 0.01) was found when controls and athletes were considered as a whole group. Soccer players showed lower PAT values in comparison with controls (P = 0.002). Elite sports positively affect c-IMT, f-IMT, and carotid PWv and AIX but not femoral PWv, AIX, AIXr, or PAT. Physical activity affects vascular beds in elite athletes differentially, depending on the rate of superior or inferior limb involvement in different sports. In soccer players, physical activity has a protective effect on carotid and femoral vessel walls but worsens femoral arterial and endothelial function. These findings highlight how different results can be shown on carotid and femoral districts, when these vascular districts are differently stressed during sport activity.


#4 Physical performance and markers of muscle damage following sports specific sprints in male collegiate soccer players: repeated bout effect
Reference: J Sports Med Phys Fitness. 2015 Jul 1. [Epub ahead of print]
Authors: Verma S, Moiz JA, Shareef MY, Husain ME
Summary: This is the first study to examine the repeated bout effect (RBE) on physical performance parameters in an athletic population. Protocols used by previous studies to induce muscle injury and assess performance following injury, are dissimilar from those utilized by physically trained individuals or are impractical in relation to athletic performance. The present study uses a sport specific protocol to study the effects of exercise induced muscle damage (EIMD) on physical performance to provide a more systematic analysis of the extent of muscle injury. Thirty two male collegiate soccer players were randomly assigned into either a repeated bout group (n=16) or control group (n=16). The repeated bout group performed 2 bouts of sports-specific sprints separated by 14 days. The control group performed a single bout of the same sprint protocol. Maximum voluntary isometric contraction for quadriceps (MVCQ) and hamstrings (MVCH), knee range of motion (ROM), thigh circumference, muscle soreness, plasma creatine kinase (CK) and lactate dehydrogenase (LDH), in addition to physical performance parameters- speed, agility and power were measured before, 24, 48 and 72 hours following the sprinting bouts. MVCQ, MVCH, ROM, thigh circumference, CK, LDH and agility showed significant Group X Time interaction (p < 0.05), suggesting lesser decrements and better recovery profile for the repeated bout group. Muscle soreness showed a main effect for group (p < 0.001). The physical performance parameters (speed, agility and power) are less affected by EIMD as compared to other markers and therefore did not demonstrate RBE.


#5 Knowledge, attitudes and behaviours on doping and supplements in young football players in Italy
Reference: Public Health. 2015 Jun 25. pii: S0033-3506(15)00206-1. doi: 10.1016/j.puhe.2015.05.008. [Epub ahead of print]
Authors: Giraldi G, Unim B, Masala D, Miccoli S, La Torre G
Study highlights: This study investigates knowledge, attitudes and behaviours of young amateur players about doping (growth hormone, anabolic steroids) and the use of nutritional supplements (amino acids, creatine) in sport. Amateur football players, residing in three Italian regions (Campania, Lazio, Sardegna), were randomly selected from the list of qualified schools of the FIGC (Italian Football Federation) and interviewed. We found that up to 6.5% of males consider personal use of substances to enhance sport performance and, a gap in knowledge about their side-effects, especially for anabolic steroids. The present study provides additional information regarding the importance of the intention to use doping agents among young amateur players. The coach, the team manager and the general practitioner should be a referential figure for young athletes.


#6 The colour of a football outfit affects visibility and team success
Reference: J Sports Sci. 2015 Jul 3:1-7. [Epub ahead of print]
Authors: Olde Rikkert J, Haes V, Barsingerhorn AD, Theelen T, Olde Rikkert MG.
Summary: We investigated the impact of the colour of football outfits on localising football players and on the results of football matches. Two studies were conducted: an experimental study examining the effects of outfit colour on the assessment of the positions of computer-animated football players in a video set-up (study 1) and a retrospective study on professional football clubs' performances dependent on their outfit colours (study 2). The studies were conducted with 18 human volunteers aged 15-18 years (study 1) and league results from 10 professional European football teams over 17 years (1995-2013) (study 2). We analysed the number of correct assessments of the positions of virtual football players with different outfit colours (study 1) and analysed the relationship between match results and outfits' colours (study 2). Study 1 showed that the position of players wearing white outfits was better assessed in 5.2% of the trials compared to players wearing green outfits (P = 0.007). Study 2 showed that Manchester City conceded less goals against in away games in highly visible kits (r = 0.62; P = 0.024), while Newcastle United conceded less goals and won more points while playing in kits associated with low visibility (r = 0.63; P = 0.007; r = 0.50; P = 0.040, respectively). We conclude that the colour of football outfits affects evaluations of football players' positions on the field, with white tricots resulting in the best location assessment. The outfit colour may indirectly influence football match results, warranting more attention to the home and away shirts by team managers and football scientists.


#7 Why the Heart is like an Orchestra and the Uterus is like a Soccer Crowd
Reference: Am J Obstet Gynecol. 2015 Jun 23. pii: S0002-9378(15)00653-5. doi: 10.1016/j.ajog.2015.06.040. [Epub ahead of print]
Authors: Smith R, Imtiaz M, Banney D, Paul JW, Young RC
Summary: The human uterus has no pacemaker or motor innervation, yet develops rhythmic, powerful contractions that increase intrauterine pressure to dilate the cervix and force the fetus through the pelvis. To achieve the synchronous contractions required for labor, the muscle cells of the uterus act as independent oscillators that become increasingly coupled by gap junctions towards the end of pregnancy. The oscillations are facilitated by changes in resting membrane potential that occur as pregnancy progresses. Reductions of potassium channels in the myocyte membranes in late pregnancy prolong myocyte action potentials, further facilitating transmission of signals and recruitment of neighbouring myocytes. Late in pregnancy prostaglandin production increases leading to increased myocyte excitability. Also late in pregnancy myocyte actin polymerises allowing actin-myosin interactions that generate force, following myocyte depolarization, calcium entry and activation of myosin kinase. Labor occurs as a consequence of the combination of increased myocyte to myocyte connectivity, increased depolarisations that last longer and activated intracellular contractile machinery. During labor the synchronous contractions of muscle cells raise intrauterine pressure to dilate the cervix in a process distinct from peristalsis. The synchronous contractions occur in progressively larger region of the uterine wall. As the size of the region increases with increasing connectivity, the contraction of that larger area leads to an increase in intrauterine pressure. The resulting increased wall tension causes myocyte depolarisation in other parts of the uterus, generating widespread synchronous activity and increased force as more linked regions are recruited into the contraction. The emergent behavior of the uterus has parallels in the behavior of crowds at soccer matches that sing together without a conductor. This contrasts with the behavior of the heart where sequential contractions are regulated by a pacemaker in a similar way to the actions of a conductor and an orchestra.