Latest research in football - week 19 - 2016

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 Optimizing physical therapy for ankylosing spondylitis: a case study in a young football player
Reference: J Phys Ther Sci. 2016 Apr;28(4):1392-7. doi: 10.1589/jpts.28.1392. Epub 2016 Apr 28.
Authors: Tricás-Moreno JM, Lucha-López MO, Lucha-López AC, Salavera-Bordás C, Vidal-Peracho C
Download link:
Summary: Ankylosing spondylitis is prevalent in men. Modern and expert consensus documents include physical therapy among the strategies for the treatment of ankylosing spondylitis. This study aimed to describe the physical therapy approach in an athlete with ankylosing spondylitis. The patient, refractory to treatment with anti-inflammatory medication, showed pelvic and lumbar pain and joint, muscle, and functional disorders, which were treated with orthopedic joint mobilization, dry needling, exercise, and whole-body hyperthermia. After the treatment, pain relief, normal joint mobility, improved muscle function, and return to activities of daily living and competitive sporting activities were recorded. The literature provides evidence for the use of joint mobilization techniques; however, no previous studies have used the same techniques and methods. There is no previous evidence for the use of dry needling in this pathology. Exercise therapy has a higher level of evidence, and guidelines with scientific support were followed. This research confirms the effectiveness of hyperthermia for arthritis. The early stage of ankylosing spondylitis, and the young age, good overall condition, and cooperative attitude of the patient led to positive outcomes. In conclusion, a favorable response that promoted the remission of the disease was observed.

#2 The neurological, neuroimaging and neuropsychological effects of playing professional football: Results of the UK five-year follow-up study
Reference: Brain Inj. 2016 May 16:1-7. [Epub ahead of print]
Authors: Kemp S, Duff A, Hampson N
Summary: Whilst the scientific understanding of mild traumatic brain injury sequelae has advanced, the consequences of neurological insults sustained during football play in the form of multiple concussions and heading remains unclear. To the authors' knowledge, this is the first longitudinal prospective study to follow-up a group of footballers and controls over time. Thirty-two elite young professional footballers were recruited and 24 were identified at follow-up. Thirty-three controls were recruited and 17 identified at follow-up. Medical examination, MRI (brain) imaging and detailed neuropsychological data were collected on the footballers at baseline and 5-year follow-up. Medical examination and detailed neuropsychological data were collected on the controls at baseline and 5-year follow-up. All participants had normal neurological examination at both time points. At baseline, 37% of the footballers had sustained minor neurological insults. Between baseline and 5 years, 66% of the footballers had sustained minor neurological insults. No MRI (brain) abnormalities were identified among the footballers at either time point. Regarding the neuropsychology, there was a 6-point IQ difference between footballers and controls, with the footballers being low. Test-re-test analysis on a range of carefully selected neurocognitive tests revealed a picture of good stability in cognitive functioning over this 5-year period. These longitudinal prospective data indicate no significant neurological, structural brain imaging or neuropsychological change among a sample of young elite professional footballers over the first 5 years of their professional career.

#3 Angiotensin-converting enzyme (ACE-I/D) polymorphism frequency in Brazilian soccer players
Reference: Appl Physiol Nutr Metab. 2016 Feb 24:1-3. [Epub ahead of print]
Authors: Coelho DB, Pimenta E, Rosse IC, Veneroso C, Pussieldi G, Becker LK, Carvalho MR, Silami-Garcia E
Summary: This study aimed to analyze the angiotensin-converting enzyme (ACE-I/D) allelic and genotypic frequencies in Brazilian soccer players of different ages. The study group comprised 353 players from first-division clubs in the under (U)-14, U-15, U-17, U-20, and professional categories. The allelic and genotypic frequencies did not differ significantly in any of the categories between the group of players and the control group. This was the first study of ACE-I/D polymorphism in Brazilian soccer players.

#4 Cardiorespiratory Fitness and Body Composition of Soccer Referees; Do These Correlate With Proper Performance?
Reference: Asian J Sports Med. 2016 Mar 1;7(1):e29577. doi: 10.5812/asjsm.29577. eCollection 2016.
Authors: Mazaheri R, Halabchi F, Seif Barghi T, Mansournia MA
Download link:
Summary: The elite-level referee is exposed to similar physical demands to those placed on a midfield soccer player. They have an important responsibility to implement the rules of the game. So, good health and performance of soccer referees have a great importance. The purpose of this study was to assess the cardiorespiratory fitness and body composition of all 78 soccer referees officiating at the Iranian Premier League and determine the correlation between these parameters and performance. In a cross-sectional study, all referees selected for the competitions were enrolled. Participants underwent exercise stress test, pulmonary function test and body composition assessment. Then the weekly scores of each referee, assessed by qualified supervisors of national federation were obtained using the FIFA standard form throughout the season (34 weeks) and registered. Among 78 participants (including 32 center and 46 side referees), mean and standard deviation of age, body mass index, percent of body fat, VO2max and performance scores were 37 ± 3.8, 23.6 ± 2.1, 20.7 ± 3.9, 59.9 ± 7.1 and 85.8 ± 0.25, respectively. No significant correlation between referees' mean score and selected parameters were found. It seems that the acquired scores of top-class referees may be influenced by multiple factors other than the laboratory findings of cardiopulmonary fitness and body composition.

#5 Individual heart rate variability responses to preseason training in high level female soccer players
Reference: J Strength Cond Res. 2016 May 23. [Epub ahead of print]
Authors: Flatt AA, Esco MR, Nakamura FY.
Summary: The purpose of this study was to track changes in training load (TL) and recovery status indicators throughout a 2-week preseason and to interpret the meaning of these changes on an individual basis among 8 Division-1 female soccer players. Weekly averages for heart rate variability (lnRMSSD), TL and psychometrics were compared with effect sizes (ES) and magnitude based inferences. Relationships were determined with Pearson correlations. Group analysis showed a very likely moderate decrease for total training load (TTL) (TTL week 1 = 1203 ± 198, TTL week 2 = 977 ± 288; proportion = 1/2/97, ES = -0.93) and a likely small increase in lnRMSSD (week 1 = 74.2 ± 11.1, week 2 = 78.1 ± 10.5; proportion = 81/14/5, ES = 0.35). Fatigue demonstrated a very likely small improvement (week 1 = 5.03 ± 1.09, week 2 = 5.51 ± 1.00; proportion = 95/4/1; ES = 0.45) while the other psychometrics did not substantially change. A very large correlation was found between changes in TL and lnRMSSD (r = -0.85) while large correlations were found between lnRMSSD and perceived fatigue (r = 0.56) and soreness (r = 0.54). Individual analysis suggests that 2 subjects may benefit from decreased TL, 2 subjects may benefit from increased TL and 4 subjects may require no intervention based on their psychometric and lnRMSSD responses to the TL. Individual weekly changes in lnRMSSD varied among subjects and related strongly with individual changes in TL. Training intervention based on lnRMSSD and wellness responses may be useful for preventing the accumulation of fatigue in female soccer players.

#6 The effects of a single whole body cryotherapy exposure on physiological, performance and perceptual responses of professional academy soccer players following repeated sprint exercise
Reference: J Strength Cond Res. 2016 May 21. [Epub ahead of print]
Authors: Russell M, Birch J, Love T, Cook CJ, Bracken RM, Taylor T, Swift E, Cockburn E, Finn C, Cunningham D, Wilson L, Kilduff LP.
Summary: In professional youth soccer players, the physiological, performance and perceptual effects of a single whole body cryotherapy (WBC) session performed shortly after repeated sprint exercise were investigated. In a randomized, counter-balanced and crossover design, 14 habituated English Premier League academy soccer players performed 15 x 30 m sprints (each followed by a 10 m forced deceleration) on two occasions. Within 20 min of exercise cessation, players entered a WBC chamber (Cryo: 30 s at -60°C, 120 s at -135°C) or remained seated (Con) indoors in temperate conditions (∼25°C). Blood and saliva samples, peak power output (countermovement jump) and perceptual indices of recovery and soreness were assessed pre-exercise and immediately, 2 h and 24 h post-exercise. When compared to Con, a greater testosterone response was observed at 2 h (+32.5 ± 32.3 pg[BULLET OPERATOR]ml, +21%) and 24 h (+50.4 ± 48.9 pg[BULLET OPERATOR]ml, +28%) post-exercise (both P=0.002) in Cryo (trial x treatment interaction: P=0.001). No between trial differences were observed for other salivary (cortisol and testosterone/cortisol ratio), blood (lactate and Creatine Kinase), performance (peak power output) or perceptual (recovery or soreness) markers (all trial x treatment interactions: P>0.05); all of which were influenced by exercise (time effects: all P<0.05). A single session of WBC performed within 20 min of repeated sprint exercise elevated testosterone concentrations for 24 h but did not affect any other performance, physiological or perceptual measurements taken. While unclear, WBC may be efficacious for professional soccer players during congested fixture periods.

#7 Physical performance and environmental conditions: 2014 World Soccer Cup and 2016 Summer Olympics in Brazil
Reference: Temperature (Austin). 2015 Oct 29;2(4):439-40. doi: 10.1080/23328940.2015.1106637.
Authors: Veneroso CE, Ramos GP, Mendes TT, Silami-Garcia E
Download link:
Summary: This editorial is for the special issue "Temperature sciences in Brazil" of the journal Temperature. It focuses on the physical performance and environmental conditions during the 2014 World Cup and the coming 2016 Summer Olympics. It emphasizes that a hot and humid environment imposes a great challenge to the human thermoregulation system, can lead to performance decrements, and increases the risk of developing hyperthermia. Adequate hydration, acclimatization, and body cooling strategies are effective interventions to minimize the risks associated with exercise in the heat.

#8 Kinetic Post-match Fatigue in Professional and Youth Soccer Players During the Competitive Period
Reference: Asian J Sports Med. 2016 Mar 7;7(1):e28267. doi: 10.5812/asjsm.28267. eCollection 2016.
Authors: Djaoui L, Diaz-Cidoncha Garcia J, Hautier C, Dellal A
Download link:
Summary: No previous research has analysed kinetic fatigue of elite adult players and elite youth players during the competitive period. The aim of the present study was to analyse kinetic post-match fatigue in professional and youth soccer players during the competitive period. Resting heart rate (HRrest), post-effort recovery heart rate (HRrecovery), rate of perceived exertion fatigue (RPEf), muscle soreness and blood samples with creatine kinase (CK) and resting lactate (La) from nine professional soccer players were measured immediately before, 24 hour and 48 hour after two official French first league matches (Ligue 1) whereas RPEf, HRrest, and 20m speed performance (speed-20 m) were measured in ten U-17 elite players immediately before, 24 hour and 48h after a friendly match. For professionals, a soccer match elevated all physiological markers during the next 24 hours (P < 0.05); only HRrecovery remained significantly different 48 hours after the match (P < 0.05) whereas there was no variation of HRrest, RPEf, and speed-20m, which were elevated until 24h and got back to reference values 48 hours after the match (P < 0.05) for the U17 players. Comparing the two groups, HRrest results remained lower all the time for professionals, and RPEf was lower for U-17, 24 hours after the match (P < 0.05). Independent of their level, professional soccer players, need 48 hours to recover after an official match. Professionals gain more fatigue than young players after a match, but recover as fast. Thus, they recover more efficiently especially due to a better physical condition and fitness training. It is expected that the results showed in the study help elite soccer and fitness coaches to manage the training load of the team according to the match.

#9 Agility and change of direction in soccer: differences according to the player ages
Reference: J Sports Med Phys Fitness. 2016 May 24. [Epub ahead of print]
Authors: Fiorilli G, Mitrotasios M, Iuliano E, Pistone EM, Aquino G, Calcagno G, DI Cagno A.
Summary: The goal of this study was to compare the Changes of Direction Speed (CODS) and Reactive Agility (RA) in soccer players of different ages, in order to optimise the best training of these skills. One hundred eighty-seven players, divided into bi-annual age-groups, U12, U14, U16 and U18, performed two tests: Y-Agility Test, carried out in planned and reactive mode (Y-PLAN and Y-REAC) and Illinois for Change Of Direction Test (ICODT). Difference between Y-REAC minus Y-PLAN represents the index of reactivity (REAC-INDEX). MANOVA showed significant differences among groups (F3,182=14.591; p<0.01; η2p =0.244). Y-PLAN showed significant differences only between U12 and the other groups (p<0.01). ICODT results were significantly different between the groups U12 and U14 and the other groups (p<0.01). Significant Pearson's correlations between Y-TEST and ICODT, for the three categories of young players (0.398 p<0.05; 0.615 p<0.01; 0.608 p<0.01 respectively), were found, whereas no significant correlation was found in U18 group. The best performance of Y-PLAN and ICODT, through age, depends on physical skill level, whereas the best RA results depend on technique and experience that help the players to use anticipatory skill. The high correlations between CODS and RA performances, differently than adult athletes, suggest that an effective work program for young players may include RA and CODS training at the same time.

#10 Anterior Cruciate Ligament Ganglion Cyst Treated Under Computed Tomography-Guided Aspiration in a Professional Soccer Player
Reference: Orthop J Sports Med. 2016 May 3;4(5):2325967116644585. doi: 10.1177/2325967116644585. eCollection 2016.
Authors: Sonnery-Cottet B, Guimarães TM, Daggett M, Pic JB, Kajetanek C, de Padua VB, Carrillon Y, Thaunat M
Download link:

#11 Team Commitment as a Mediator Between Self-Esteem and Team Climate as Perceived by Korean Youth Soccer Players
Reference: Percept Mot Skills. 2016 May 19. pii: 0031512516649345. [Epub ahead of print]
Authors: Jung M, Kang S, Kwon S
Download link:
Summary: This study examined whether team commitment mediates the relationship between self-esteem and perceived team climate in Korean youth soccer players. A total of 366 youth soccer players from the Korea football association participated in this study. Self-esteem and team commitment were found to significantly and positively affect perceived team climate; team commitment more strongly affected perceived team climate. Regarding structural relationships, self-esteem's direct effect on perceived team climate was not significant; however, self-esteem's indirect effect through team commitment was significant. Team commitment therefore mediated the relationship between self-esteem and perceived team climate. Metric invariance was supported for groups categorized by grade and key player, confirming that the model could be applied to various groups.

#12 Injuries, Matches Missed and the Influence of Minimum Medical Standards in the A-League Professional Football: A 5-Year Prospective Study
Reference: Asian J Sports Med. 2016 Mar 1;7(1):e31385. doi: 10.5812/asjsm.31385. eCollection 2016.
Authors: Gouttebarge V, Hughes Schwab BA, Vivian A, M M J Kerkhoffs G
Download link:
Summary: Epidemiological data on the occurrence of time-loss injuries over several A-League seasons remains lacking, while the effect of the mandatory implementation of 'Minimum Medical Standards' as a part of the collective bargaining agreement (CBA) needs to be explored. The objective of this study was to explore the 5 year evolution of hamstring, groin, knee, ankle and total time-loss injuries among professional footballers in the A-League; to evaluate the consequences of these time-loss injuries in terms of total matches missed and costs incurred; and to explore whether the mandatory implementation of 'Minimum Medical Standards' in the A-League had led to a decrease in the occurrence of total time-loss injuries and total matches missed. An observational prospective study has been carried out since 2008. Data were collected weekly during the seasons 2008 - 2009 to 2012 - 2013 through official match previews/reviews, official media releases, official websites and/or self-reports by players. Total and specific (hamstring, groin, knee and ankle) numbers of time-loss injuries and matches missed were obtained for each season and the related financial costs calculated. The total number of time-loss injuries and matches missed rose from 129 and 506 respectively in 2008 - 2009 to 202 and 1110 in 2010 - 2011. Following the introduction of 'Minimum Medical Standards', both categories decreased (significantly for matches missed). These time-loss injuries and matches missed led to high costs of up to AUD$ 37,317,029.29 (2012 - 2013 season). The same trend was found for knee injuries, while hamstring and ankle injuries remained almost the same. However, time-loss due to groin injuries increased despite the introduction of "Minimum Medical Standards". The introduction of "Minimum Medical Standards" in the A-League had a favorable effect on the number of total, hamstring, knee and ankle injuries and on the number of matches missed due to these injuries, but not on the number of groin injuries. The costs related to time-loss injuries and related matches missed remained high.

#13 A Prospective Analysis of the Injury Incidence of Young Male Professional Football Players on Artificial Turf
Reference: Asian J Sports Med. 2016 Mar 5;7(1):e28425. doi: 10.5812/asjsm.28425. eCollection 2016.
Authors: Bianco A, Spedicato M, Petrucci M, Messina G, Thomas E, Nese Sahin F, Paoli A, Palma A
Download link:
Summary: The effects of synthetic surfaces on the risk of injuries is still debated in literature and the majority of published data seems to be contradictory. For such reasons the understanding of injury incidence on such surfaces, especially in youth sport, is fundamental for injury prevention. The aim of this study was to prospectively report the epidemiology of injuries in young football players, playing on artificial turfs, during a one sports season. 80 young male football players (age 16.1 ± 3.7 years; height 174 ± 6.6 cm; weight 64.2 ± 6.3 kg) were enrolled in a prospective cohort study. The participants were then divided in two groups; the first included players age ranging from 17 to 19 (OP) whereas the second included players age ranging from 13 to 16 (YP). Injury incidence was recorded prospectively, according to the consensus statement for soccer. A total of 107 injuries (35 from the OP and 72 from the YP) were recorded during an exposure time of 83.760 hours (incidence 1.28/1000 per player hours); 22 during matches (incidence 2.84/1000 per player hours, 20.5%) and 85 during training (incidence 1.15/1000 per player hours, 79.5%). Thigh and groin were the most common injury locations (33.6% and 21.5%, respectively) while muscle injuries such as contractures and strains were the most common injury typologies (68.23%). No statistical differences between groups were displayed, except for the rate of severe injuries during matches, with the OP displaying slightly higher rates compared to the YP. Severe injuries accounted for 10.28% of the total injuries reported. The average time lost due to injuries was 14 days. Re-injuries accounted for 4.67% of all injuries sustained during the season. In professional youth soccer injury rates are reasonably low. Muscle injuries are the most common type of injuries while groin and thigh the most common locations. Artificial turf pitches don't seem to contribute to injury incidence in young football players.

The Training Manager -