Latest research in football - week 30 - 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 The preventive effect of a soccer-specific ankle brace on acute lateral ankle sprains in girls amateur soccer players: study protocol of a cluster-randomised controlled trial
Reference: Inj Prev. 2017 Jul 27. pii: injuryprev-2017-042465. doi: 10.1136/injuryprev-2017-042465. [Epub ahead of print]
Authors: Thijs K, Huisstede B, Goedhart E, Backx F
Summary: Acute lateral ankle sprains are the single most often diagnosed injury in female soccer players and often result in an inability to play. This highlights the need for effective prevention strategies. Proprioceptive training and/or the use of an external support to decrease inversion of the ankle joint can prevent or reduce the number of acute lateral ankle sprains. The effectiveness of a soccer-specific ankle brace in reducing first-time and recurrent acute lateral ankle sprains has never been investigated in girl soccer players. If effective, ankle braces could be introduced into soccer. Girl amateur soccer players (aged 14-18 years) will be allocated to an intervention or control group. The intervention group will be instructed to wear soccer-specific ankle braces on both ankles during soccer training and matches; the control group will continue playing soccer as usual. Primary outcomes are the incidence and severity of acute lateral ankle sprains. Secondary outcomes are the prognostic value of generalised joint hypermobility and functional stability on the risk of acute lateral ankle sprains and compliance with the intervention. The findings from this study may provide evidence to support the use of a soccer-specific ankle brace to prevent lateral ankle sprains during soccer. We hypothesise that this brace will reduce the incidence of ankle sprains among young amateur girl soccer players by 50%. The prevention of such injuries will be beneficial to players, clubs and society.

#2 The use of metabolic power to assess physical demands in soccer: how does it differ from the traditional approach through speed running?
Reference: J Sports Med Phys Fitness. 2017 Jul 25. doi: 10.23736/S0022-4707.17.07563-6. [Epub ahead of print]
Authors: Martinez-Cabrera FI, Nunez-Sanchez FJ
Summary: Metabolic power and speed running are in the top-10-ranked variables used to quantify the physical demand in soccer matches or training practices. The purpose of this study were 1) to compare metabolic power (MP) and the traditional approach using speed running during soccer matches in absolute values and 2) in zones of intensity in function of the playing positions. Thirty-eight professional soccer players were analysed during 18 friendly matches from 4 preseasons (n=300) and divided into 5 groups of playing positions: central defender (CD) (n=64), wide defender (WD) (n=55), central midfielder (CM) (n=58), wide attacker (WA) (n=70) and attacker (AT) (n=53). The individual profiles to each playing positions were assessed using MP and speed running approaches. The magnitude of change was substantial when there was a ≥75% likelihood of the effect. The effect size was also calculated using a confidence interval of 90%. In absolute values, CMs and WAs had substantially greater values than did the other positions, with CMs having the highest values in both approaches and an identical relationship between the positions in both approaches. In categories of intensity, medium-low intensity displayed differences between the approaches; the physical demands of ATs and CDs were lower using the traditional approach but were higher than the other playing positions when assessed using MP. No differences were found at low, medium or high intensities. The MP and energy expenditure reported differences at medium-low intensity compared to the speed running traditional approach between playing positions. However, the other intensities did not report differences compared to the traditional approach in the different playing positions.

#3 The relationship between movement speed and duration during soccer matches
Reference: PLoS One. 2017 Jul 25;12(7):e0181781. doi: 10.1371/journal.pone.0181781. eCollection 2017.
Authors: Roecker K, Mahler H, Heyde C, Roll M, Gollhofer A
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Summary: The relationship between the time duration of movement (t(dur)) and related maximum possible power output has been studied and modeled under many conditions. Inspired by the so-called power profiles known for discontinuous endurance sports like cycling, and the critical power concept of Monod and Scherrer, the aim of this study was to evaluate the numerical characteristics of the function between maximum horizontal movement velocity (HSpeed) and t(dur) in soccer. To evaluate this relationship, GPS data from 38 healthy soccer players and 82 game participations (≥30 min active playtime) were used to select maximum HSpeed for 21 distinct t(dur) values (between 0.3 s and 2,700 s) based on moving medians with an incremental t(dur) window-size. As a result, the relationship between HSpeed and Log(t(dur)) appeared reproducibly as a sigmoidal decay function, and could be fitted to a five-parameter equation with upper and lower asymptotes, and an inflection point, power and decrease rate. Thus, the first three parameters described individual characteristics if evaluated using mixed-model analysis. This study shows for the first time the general numerical relationship between t(dur) and HSpeed in soccer games. In contrast to former descriptions that have evaluated speed against power, HSpeed against t(dur) always yields a sigmoidal shape with a new upper asymptote. The evaluated curve fit potentially describes the maximum moving speed of individual players during the game, and allows for concise interpretations of the functional state of team sports athletes.

#4 Relevance of whole body virabtion exercise in sport: A short review with soccer, diver and combat sport
Reference: Afr J Tradit Complement Altern Med. 2017 Jul 7;14(4 Suppl):19-27. doi: 10.21010/ajtcam.v14i4S.3. eCollection 2017.
Authors: Morel DS, Dionello CDF, Moreira-Marconi E, Brandao-Sobrinho-Neto S, Paineiras-Domingos LL, Souza PL, Sa-Caputo DDC, Dias G, Figueiredo C, Carmo RCR, Paiva PC, Sousa-Goncalves CR, Kutter CR, Guedes-Aguiar EO, Cloak R, Bernardo-Filho M
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Summary: Whole body vibration exercise (WBVE) has been used as a safe and accessible exercise and important reviews have been published about the use of this exercise to manage diseases and to improve physical conditions of athletes The aim of this paper is to highlight the relevance of WBVE to soccer players, divers and combat athletes. This study was made through a systematic review of publications involving WBVE and the selected sports in two databases (Pubmed and PEDRo). It were identified 10 studies involving WBVE and sports (6 of soccer, 2 of diving and 2 of sport combat) with 156 subjects (80 soccer players, 32 divers and 44 combat athletes), with age from 17 to 44 years old. The use of WBVE has proven to be a safe and useful strategy to improve the physical conditions of players of different sports. These findings may have clinical relevance and should be considered as a strategy to be used to try improve the physical conditions of players.

#5 Benign paroxysmal positional vertigo (BPPV) diagnosis and treatment in an elite professional football (soccer) player
Reference: BMJ Case Rep. 2017 Jul 24;2017. pii: bcr-2017-220000. doi: 10.1136/bcr-2017-220000.
Authors: Burrows L, Price R
Summary: A 33-year-old male professional football player suffered from acute-onset dizziness following a lower limb soft tissue treatment in prone lying. Symptoms included spinning vertigo lasting for 30's, headache, visual vertigo and disorientation. Clinical examination of balance and vestibular systems confirmed a left posterior canalithiasis benign paroxysmal positional vertigo (BPPV) and excluded other central and peripheral causes of dizziness. Two cycles of a left Epley manoeuvre were performed. An Epley manoeuvre abolished the BPPV and negated the need for medication. The player was able to return to play without dizziness within 24 hours completely symptom free. BPPV can be successfully identified and treated in elite football players and they can see a return to training and games within 24 hours. There are no epidemiology studies for this group of elite athletes either male or female despite increased occupational risk factors.

#6 Opportunities and Benefits for Powerchair Users Through Power Soccer
Reference: Adapt Phys Activ Q. 2017 Jul;34(3):235-255. doi: 10.1123/apaq.2016-0022.
Authors: Jeffress MS, Brown WJ
Summary: Power soccer (or powerchair football), the first competitive team sport for users of motorized wheelchairs, is receiving increased attention among people with disabilities, healthcare professionals, and academics. The present study provides a qualitative analysis of the experiences of 34 American power soccer athletes. Participant observation and in-depth interviews with 11 female and 23 male athletes were conducted between 2007 and 2013. Results indicate that involvement in power soccer provides participants with an increased sense of empowerment, acquisition of social capital, and psychosocial benefits, including a deep satisfaction of the desire to participate in competitive sports and an opportunity to be independent. Implications of these findings for improving the quality of life of people with physical disabilities and for future research are discussed.

#7 Biomechanical differences in female basketball and soccer players during multi-directional jump landings
Reference: J Strength Cond Res. 2017 Jul 14. doi: 10.1519/JSC.0000000000001785. [Epub ahead of print]
Authors: Taylor JB, Ford KR, Schmitz RJ, Ross SE, Ackerman TA, Shultz SJ.
Summary: Anterior cruciate ligament injury prevention programs are less successful in basketball than soccer and may be due to distinct movement strategies that these athletes develop from sport-specific training. The purpose of this study was to identify biomechanical differences between female basketball and soccer players during multi-directional jump landings. Lower extremity biomechanics of eighty-nine female athletes who played competitive basketball (n=40) or soccer (n=49) at the middle- or high-school level were analyzed with three-dimensional motion analysis during a drop vertical jump (DVJ), double- (SAG-DL) and single-leg forward jump (SAG-SL), and double- (FRONT-DL) and single-leg (FRONT-SL) lateral jump. Basketball players landed with less hip and/or knee excursion during all tasks (p<.05) except for the SAG-SL task, where basketball players landed with greater peak hip flexion angles (p=.04). The FRONT-SL task elicited the most distinct sport-specific differences, including decreased hip adduction (p<.001) angles, increased hip internal rotation (p=.003), and increased relative knee external rotation (p=.001) excursions in basketball players. Additionally, the FRONT-SL task elicited greater forces in knee abduction (p=.003) and lesser forces in hip adduction (p=.001) and knee external rotation (p<.001) in basketball players. Joint energetics were different during the FRONT-DL task, as basketball players exhibited less sagittal plane energy absorption at the hip (p<.001), and greater hip (p<.001) and knee (p=.001) joint stiffness. Sport-specific movement strategies were identified during all jump landing tasks, such that soccer players exhibited a more protective landing strategy than basketball players, justifying future efforts toward sport-specific ACL injury prevention programs.

#8 Somatotype And Body Composition In Young Soccer Players According To The Playing Position And Sport Success
Reference: J Strength Cond Res. 2017 Jul 17. doi: 10.1519/JSC.0000000000002125. [Epub ahead of print]
Authors: Cardenas-Fernandez V, Chinchilla-Minguet JL, Castillo-Rodriguez A
Summary: Soccer players undergo an evolution in their body composition throughout the growth and passage through the different base stages, that is, childhood, puberty and adolescence. The aim of this study was to analyze the morphology and body composition of U14, U16, and U19 soccer players, taking into account in addition, their sport success endorsed through the regularity participation and their relation with the different playing positions occupied during competition (goalkeeper, external defender, central defender, midfielder and forward/extreme). For that, a total of 174 male young soccer players were evaluated anthropometrically. Dominant somatotype of the players was, according to their playing position: meso-endomorphic in goalkeepers, central for external defenders, balanced ectomorph in central defenders, balanced mesomorph in the case of midfielders, and meso-ectomorph in forwards/extremes. Taking into account that sport performance is directly mediated by the body composition of athletes, the differences found suggest a marked specialization between the goalkeepers and forwards, establishing significant differences between them. Further studies would be needed to evaluate the influence of individual maturation development versus sports training on the conformation of a certain anthropometric profile of a soccer player and its relation with the different playing positions occupied on the pitch during the game.

#9 A Pilot Study of the Effect of Outsole Hardness on Lower Limb Kinematics and Kinetics during Soccer Related Movements
Reference: J Hum Kinet. 2017 Jun 22;57:17-27. doi: 10.1515/hukin-2017-0043. eCollection 2017 Jun.
Authors: Sun D, Mei Q, Baker JS, Jia X, Gu Y
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Summary: The purpose of this study was to investigate the effect of different outsole hardness of turf cleats shoes on the lower limb kinematics and kinetics of soccer players playing on artificial turf. The participants were required to complete tasks of straight running and 45° left sidestep cutting movements, respectively, at the speed of 4.5 ± 0.2 m/s on artificial turf. They were asked to randomly select turf cleats shoes with a soft outsole (SO), medium hardness outsole (MO) and hard outsole (HO). During the stance phase of straight running, peak pressure and force-time integral in medial forefoot (MFF) of players wearing cleats shoes with MO were significantly higher than those wearing cleats shoes with SO. During the stance phase of a 45° cutting maneuver, players wearing cleats shoes with SO showed significantly higher peak knee flexion and abduction angles than the HO group. Players wearing cleats shoes with SO also showed higher ankle dorsiflexion and inversion angles compared with those wearing cleats shoes with HO. The vertical average loading rate (VALR) as well as peak pressure and force-time integral in the heel (H) and lateral forefoot (LFF) regions of players wearing cleats shoes with HO were significantly higher than those wearing shoes with SO. On the contrary, peak pressure and force-time integral of players wearing shoes with SO were significantly higher than those wearing shoes with HO in MFF. A higher vertical loading rate and plantar pressure of some areas may increase the potential risk of metatarsal stress fractures and plantar fasciitis. Therefore, this finding about turf cleats shoes could give some theoretic support for the design of turf cleats shoes and material optimization in the future.

#10 Cardiopulmonary Performance During Maximal Exercise in Soccer Players with Alterations in Renal Function
Reference: J Hum Kinet. 2017 Jun 22;57:107-115. doi: 10.1515/hukin-2017-0052. eCollection 2017 Jun.
Summary: Morales AP, Sampaio-Jorge F, da Cruz Rangel LF, de Souza Menezes J, Leite TC, Ribeiro BG
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Summary: The aim of this study was to evaluate the curves of cardiorespiratory variables during cardiopulmonary exercise testing (CPET) in soccer players who had acute alterations in the glomerular filtration rate (GFR) after performing the pre-season training protocol. Sixteen male professional soccer players (25 ± 3 years; 179 ± 2 cm; and 77 ± 6 kg) were evaluated for oxygen uptake (VO2), heart rate (HR) and pulse relative oxygen (relative O2 Pulse) curves with intervals corresponding to 10% of the total duration of CPET. Athletes were grouped according to the GFR and classified as decreased GFR (dGFR; n = 8) and normal GFR (nGFR; n = 8). Athletes from the dGFR group exhibited lower VO2 values (p < 0.05) when 90% (dGFR 49.8 ± 4.0 vs. nGFR 54.4 ± 6.1 ml·kg-1·min-1) and 100% (dGFR 52.6 ± 4.1 vs. nGFR 57.4 ± 5.9 ml·kg-1·min-1) of the test was complete; HR high values (p < 0.05) when 90% (dGFR 183.7 ± 5.1 vs. nGFR 176.6 ± 4.8 bpm-1) and 100% (dGFR 188.1 ± 5.0 vs. nGFR 180.8 ± 4.8 bpm-1) of the test was complete; and lower relative O2 Pulse values (p < 0.05) when 70% (dGFR 25.6 ± 8.4 vs. nGFR 27.9 ± 9.7 ml·beat-1·kg-1), 80% (dGFR 26.6 ± 8.8 vs. nGFR 29.1 ± 10.0 ml·beat-1·kg-1), 90% (dGFR 27.1 ± 9.0 vs. nGFR 30.8 ± 10.6 ml·beat-1·kg-1) and 100% (dGFR 28 ± 9.2 vs. nGFR 31.8 ± 10.9 ml·beat-1·kg-1) of the test was complete. A correlation was found (r = -0.66, R2 = 0.44, p = 0.00) between lower VO2 peak and elevated levels of urinary protein excretion. In conclusion, soccer players with reduced kidney function after performing the pre-season training protocol also presented alterations in cardiopulmonary variables. We suggest that monitoring of renal function may be used to identify less conditioned soccer players.

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