Latest research in football - week 26 - 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 Computerized neuropsychological test performance of youth football players at different positions: A comparison of high and low contact players
Reference: Appl Neuropsychol Child. 2017 Feb 28:1-7. doi: 10.1080/21622965.2017.1290530. [Epub ahead of print]
Authors: Tsushima WT, Ahn HJ, Siu AM, Fukuyama T, Murata NM
Summary: The aim of this study was to examine the effects of head impact frequency on the neuropsychological test results of football players who participate in different positions on the team. Based on the biomechanical measures of head impact frequency reported in high school football, a High Contact group (n = 480) consisting of offensive and defensive linemen was compared with a Low Contact group (n = 640) comprised of receivers and defensive backs. The results revealed that the High Contact group obtained poorer performances on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) on three Composite scores (Verbal Memory, Visual Motor Speed, Impulse Control) and the Total Symptom score compared to the Low Contact group. The present study is the first, to date, to report differences in the neuropsychological test performances of athletes who participate in high and low contact football positions. The findings raise tentative concerns that youth football players exposed to repetitive head trauma, including subconcussive impacts, may be at risk for lowered neuropsychological functioning and increased symptoms.

#2 Effects of inspiratory muscle training in professional women football players: a randomized sham-controlled trial
Reference: J Sports Sci. 2017 Jun 16:1-10. doi: 10.1080/02640414.2017.1340659. [Epub ahead of print]
Authors: Archiza B, Andaku DK, Caruso FCR, Bonjorno JC Jr, Oliveira CR, Ricci PA, Amaral ACD, Mattiello SM, Libardi CA, Phillips SA, Arena R, Borghi-Silva A
Summary: This study was conducted to determine the effects of inspiratory muscle training (IMT) on respiratory and peripheral muscles oxygenation during a maximal exercise tolerance test and on repeated-sprint ability (RSA) performance in professional women football players. Eighteen athletes were randomly assigned to one of the following groups: SHAM (n = 8) or IMT (n = 10). After a maximal incremental exercise test, all participants performed (on a different day) a time-to-exhaustion (Tlim) test. Peripheral and respiratory muscles oxygenation by near-infrared spectroscopy, breath-by-breath ventilatory and metabolic variables, and blood lactate concentration were measured. The RSA test was performed on a grass field. After a 6 week intervention, all athletes were reevaluated. Both groups showed increases in inspiratory muscles strength, exercise tolerance and RSA performance, however only the IMT group presented lower deoxyhemoglobin and total hemoglobin blood concentrations on intercostal muscles concomitantly to an increased oxyhemoglobin and total hemoglobin blood concentrations on vastus lateralis muscle during Tlim. In conclusion, these results may indicate the potential role of IMT to attenuate inspiratory muscles metaboreflex and consequently improve oxygen and blood supply to limb muscles during high-intensity exercise, with a potential impact on inspiratory muscle strength, exercise tolerance and sprints performance in professional women football players.

#3 Effects of oxygen therapy on wall-motion score index in patients with ST elevation myocardial infarction-the randomized SOCCER trial
Reference: Echocardiography. 2017 Jun 29. doi: 10.1111/echo.13599. [Epub ahead of print]
Authors: Khoshnood A, Akbarzadeh M, Roijer A, Meurling C, Carlsson M, Bhiladvala P, Hoglund P, Sparv D, Todorova L, Mokhtari A, Erlinge D, Ekelund U
Summary: Although oxygen (O2 ) is routinely used in patients with acute myocardial infarction (AMI), it may have negative effects. In this substudy of the SOCCER trial, we aimed to evaluate the effects of O2 -treatment on myocardial function in patients with ST elevation myocardial infarction (STEMI). Normoxic (≥94%) STEMI patients were randomized in the ambulance to either supplemental O2 or room air until the end of the percutaneous coronary intervention (PCI). The patients underwent echocardiography on day 2-3 after the PCI and once again after 6 months. The study endpoints were wall-motion score index (WMSI) and left ventricular ejection fraction (LVEF). Forty-six patients in the O2 group and 41 in the air group were included in the analysis. The index echocardiography showed no significant differences between the groups in WMSI (1.32±0.27 for O2 group vs 1.28±0.28 for air group) or LVEF (47.0±8.5% vs 49.2±8.1%). Nor were there differences at 6 months in WMSI (1.16±0.25 vs 1.14±0.24) or LVEF (53.5±5.8% vs 53.5±6.9%). The present findings indicate no harm or benefit of supplemental O2 on myocardial function in STEMI patients. Our results support that it is safe to withhold supplemental O2 in normoxic STEMI patients.

#4 Evidence of sub-optimal sleep in adolescent Middle Eastern academy soccer players which is exacerbated by sleep intermission proximal to dawn
Reference: Eur J Sport Sci. 2017 Jun 25:1-9. doi: 10.1080/17461391.2017.1341553. [Epub ahead of print]
Authors: Fowler PM, Paul DJ, Tomazoli G, Farooq A, Akenhead R, Taylor L
Summary: The purpose was to assess sleep patterns, quantity and quality in adolescent (16.2 ± 1.2 yr) Middle Eastern academy soccer players (n = 20) and the influence of an intermission upon these characteristics. On a 17-day training camp (located one time zone west of home) including three discrete matches, sleep was assessed pre- (PRE) and post-match (POST) via wrist actigraphy. Retrospective actigraphy analysis identified sleep characteristics, including if players experienced a sleep intermission (YES) or not (NO) proximal to dawn, and bedtime (hh:mm), get-up time (hh:mm), time in bed (h), sleep duration (h) and sleep efficiency (%). Within YES two bouts were identified (BOUT1 and BOUT2). No differences were seen between PRE and POST, nor between BOUT1 and BOUT2 (p > .05). Overall players did not meet National Sleep Foundation (NSF) guidelines (7:04 ± 1:16 h vs. recommended 8-10 h for 14-17 yr). Sleep duration was significantly reduced (∼ -13% or -1:06) in YES compared to NO (6:33 ± 1:05 vs. 7:29 ± 1:17, p < .01). Despite players in YES waking earlier due to an intermission, they did not compensate for this with a later wake time, rising significantly earlier compared to NO (09:40 ± 00:38 vs. 10:13 ± 00:40, p < .05). These players on average do not obtain sufficient sleep durations relative to NSF guidelines, with decrements increased by an intermission proximal to dawn. High inter- and intra-individual variance in the players sleep characteristics indicates the need for individualized sleep education strategies and interventions to promote appropriate sleep.

#5 Return to competition after an Achilles tendon rupture using both on and off the field load monitoring as guidance: A case report of a top-level soccer player
Reference: Phys Ther Sport. 2017 Apr 29. pii: S1466-853X(17)30187-6. doi: 10.1016/j.ptsp.2017.04.008. [Epub ahead of print]
Authors: Fanchini M, Impellizzeri FM, Silbernagel KG, Combi F, Benazzo F, Bizzini M
Summary: The purpose was to describe the Return to competition after Achilles Tendon rupture (ATR) in an elite soccer player. Return to sport (RTS) of a professional soccer player who suffered an ATR during a match. The RTS phase started 15 weeks after surgery and specific on-field activities were gradually introduced. Criteria used to monitor the transition through the different phases were strength and endurance of the calf muscle and ability to sustain specific on-field training loads (TL) monitored with Global Positioning System and heart-rate system. TLs were weekly compared to pre-injury values to evaluate recovery and to prescribe future sessions. A 39-year-old (height 178 cm, weight 75 kg) elite soccer defender player, playing in Italian Serie-A league. Days of absence were lower compared to a cohort presented in UEFA study (119 versus 161 ± 65 days, respectively). External-TL and Internal-TL were organized to gradually increase during RTS and resulted in higher values prior to return to competition compared to pre-injury values. Concentric plantar flexion peak torque increased till 9th months after surgery. Monitoring of the field activities allowed comparison with pre-injury values and provided a useful and functional criteria to pass return to team activity and competition.

#6 Head injuries in professional male football (soccer) over 13 years: 29% lower incidence rates after a rule change (red card)
Reference: Br J Sports Med. 2017 Jun 23. pii: bjsports-2016-097217. doi: 10.1136/bjsports-2016-097217. [Epub ahead of print]
Authors: Beaudouin F, Aus der Funten K, Troß T, Reinsberger C, Meyer T
Summary: Absolute numbers of head injuries in football (soccer) are considerable because of its high popularity and the large number of players. In 2006 a rule was changed to reduce head injuries. Players were given a red card (sent off) for intentional elbow-head contact. The purpse was to describe the head injury mechanism and examine the effect of the rule change. Based on continuously recorded data from the German football magazine "kicker", a database of all head injuries in the 1st German Male Bundesliga was generated comprising seasons 2000/01-2012/13. Injury mechanisms were analysed from video recordings. Injury incidence rates (IR) and 95% confidence intervals (95% CI) as well as incidence rate ratios (IRR) to assess differences before and after the rule change were calculated. 356 head injuries were recorded (IR 2.22, 95% CI 2.00 to 2.46 per 1000 match hours). Contact with another player caused most head injuries, more specifically because of head-head (34%) or elbow-head (17%) contacts. After the rule change, head injuries were reduced by 29% (IRR 0.71, 95% CI 0.57 to 0.86, p=0.002). Lacerations/abrasions declined by 42% (95% CI 0.39 to 0.85), concussions by 29% (95% CI 0.46 to 1.09), contusions by 18% (95% CI 0.43 to 1.55) and facial fractures by 16% (95% CI 0.55 to 1.28). This rule change appeared to reduce the risk of head injuries in men's professional football.

#7 Oxidative stress and antioxidant biomarker responses after a moderate-intensity soccer training session
Reference: Res Sports Med. 2017 Jun 28:1-11. doi: 10.1080/15438627.2017.1345738. [Epub ahead of print]
Authors: Mello R, Mello R, Gomes D, Paz GA, Nasser I, Miranda H, Salerno VP
Summary: The present study investigated the effects of a moderate-intensity soccer training session on the production of reactive oxygen species (ROS) and the antioxidant capacity in athletes along with the biomarkers creatine kinase and transaminases for lesions in muscle and liver cells. Twenty-two male soccer players participated in this study. Blood samples were collected 5 min before and after a moderate-intensity game simulation. The results showed a decrease in the concentration of reduced glutathione (GSH) from an elevation in the production of ROS that maintained the redox homeostasis. Although the session promoted an elevated energy demand, observed by an increase in lactate and glucose levels, damage to muscle and/or liver cells was only suggested by a significant elevation in the levels of alanine transaminase (ALT). Of the two biomarkers analysed, the results suggest that measurements of the ALT levels could be adopted as a method to monitor recovery in athletes.

#8 Daily Distribution of Macronutrient Intakes of Professional Soccer Players From the English Premier League
Reference: Int J Sport Nutr Exerc Metab. 2017 Jun 28:1-18. doi: 10.1123/ijsnem.2016-0265. [Epub ahead of print]
Authors: Anderson L, Naughton RJ, Close GL, Di Michele R, Morgans R, Drust B, Morton JP
Summary: The daily distribution of macronutrient intake can modulate aspects of training adaptations, performance and recovery. We therefore assessed the daily distribution of macronutrient intake (as assessed using food diaries supported by the remote food photographic method and 24 h recalls) of professional soccer players (n=6) of the English Premier League during a 7-day period consisting of two match days and five training days. On match days, average carbohydrate (CHO) content of the pre-match (<1.5 body mass) and post-match (1 body mass) meals (in recovery from an evening kick-off) were similar (P>0.05) though such intakes were lower than contemporary guidelines considered optimal for pre-match CHO intake and post-match recovery. On training days, we observed a skewed and hierarchical approach (P<0.05 for all comparisons) to protein feeding such that dinner (0.8>lunch (0.6>breakfast (0.3>evening snacks (0.1 We conclude players may benefit from consuming greater amounts of CHO in both the pre-match and post-match meals so as to increase CHO availability and maximize rates of muscle glycogen re-synthesis, respectively. Furthermore, attention should also be given to ensuring even daily distribution of protein intake so as to potentially promote components of training adaptation.

#9 A Review Of Field-Based Assessments Of Neuromuscular Control And Their Utility In Male Youth Soccer Players
Reference: J Strength Cond Res. 2017 Jun 22. doi: 10.1519/JSC.0000000000002069. [Epub ahead of print]
Authors: Read PJ, Oliver JL, De Ste Croix MBA, Myer GD, Lloyd RS
Summary: Lower extremity injuries in male youth soccer are common and equate to a substantial time-loss from training and competitions during the course of a season. Extended periods of absence will impact player involvement in skill and physical development activities, as well as participation in competitive match play. Neuromuscular risk factors for lower extremity injury in male youth soccer players can be categorized into quadriceps dominance; leg dominance; ligament dominance; trunk dominance and reduced dynamic stability. Valid screening methods to identify risk factors that are practically viable are needed for youth athletes who may be at a greater risk of injury in soccer. While field-based tests of neuromuscular control provide a reliable option for the assessment of injury risk in adults and females, less data are available in male youth soccer players and further research is required to examine their ability to predict injury risk. This article provides a review of the current literature pertaining to field-based screening tests and critically appraises their suitability for use with male youth soccer players. Currently the only method that has been validated in male youth soccer players is the landing error scoring system. Asymmetrical anterior reach measured during the Y-Balance test may also be considered due to its strong predictive ability in male youth basketball players; however, further research is required to fully support its use with soccer players.

#10 Evaluation Of The Official Match External Load In Soccer Players With Cerebral Palsy
Reference: J Strength Cond Res. 2017 Jun 22. doi: 10.1519/JSC.0000000000002085. [Epub ahead of print]
Authors: Yanci J, Castillo D, Iturricastillo A, Reina R
Summary: The aims of this study were to analyze the official match external loads (i.e. total distance [TD], distance covered at different speeds, accelerations, decelerations, player load [PL], peak metabolic power [PMP] and changes of direction [CODs]) of football players with cerebral palsy (CP), and to determine the external loads according to playing time (i.e. < 20 min, 20-40 min and > 40 min). The external load of thirty-one international football players with CP (23.0 ± 6.6 years; 69.1 ± 9.0 kg; 174.8 ± 7.3 cm) was analyzed during a World Championship Qualification Tournament (n = 8 matches, 58 individual observations). Results showed that the football players with CP, covered less distance at high intensity running and sprinting, performing a smaller number of moderate and high intensity accelerations and decelerations, had a lower PL and made fewer CODs in official matches compared to conventional football players as reported in other studies. The number of minutes played by the players (i.e. < 20 min, 20-40 min and > 40 min) could significantly influence the players' match external load (ES = 0.3-5.5, small to extremely large). The impairments presented by football players with CP affect players' match external loads, especially in short-term high-intensity neuromuscular actions.

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