Latest research in football - week 35 - 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 The Relationship between Common Anthropometric Measurements and Isokinetic Strength in Men's College Soccer Team
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):668. doi: 10.1249/01.mss.0000487004.11907.df.
Authors: Felton SD, Burkett PA, Cordova ML
Download link: http://journals.lww.com/acsm-msse/Citation/2016/05001/The_Relationship_between_Common_Anthropometric.1998.aspx

#2 Impact Of "Extra-time" On Performance And Physiological Responses To Simulated Soccer Match-play
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):667-8. doi: 10.1249/01.mss.0000487003.73788.9b.
Authors: Harper LD, Parker P, Hunter R, Goodall S, Thomas K, Howatson G, West DJ, Stevenson E, Russell M
Download link: http://journals.lww.com/acsm-msse/Citation/2016/05001/Impact_Of__Extra_time__On_Performance_And.1997.aspx

#3 Effect of Rest Time in Sprint Training in Young Soccer Players
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):667. doi: 10.1249/01.mss.0000487002.73788.d2.
Authors: Mazza JC, Festa RR, Groppo C, Ruffo L, Maggiolo L, Mangione P, Cosolito P, Grossi G
Download link: pdfs.journals.lww.com/acsm-msse/2016/05001/Effect_of_Rest_Time_in_Sprint_Training_in_Young.1996.pdf?token=method|ExpireAbsolute;source|Journals;ttl|1473662175881;payload|mY8D3u1TCCsNvP5E421JYK6N6XICDamxByyYpaNzk7FKjTaa1Yz22MivkHZqjGP4kdS2v0J76WGAnHACH69s21Csk0OpQi3YbjEMdSoz2UhVybFqQxA7lKwSUlA502zQZr96TQRwhVlocEp/sJ586aVbcBFlltKNKo+tbuMfL73hiPqJliudqs17cHeLcLbV/CqjlP3IO0jGHlHQtJWcICDdAyGJMnpi6RlbEJaRheGeh5z5uvqz3FLHgPKVXJzdKVgAgQT2Xde+Z+1EdY8MswkChdn/oaKSHzz572m32Mw=;hash|Gfd6z8EorUqOWYeIZiomlw==

#4 A Test Battery to Identify Elite Talent Among Youth International Soccer Players
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):667. doi: 10.1249/01.mss.0000487001.66165.2c.
Authors: O'Reilly J, Wong SH
Download link: pdfs.journals.lww.com/acsm-msse/2016/05001/A_Test_Battery_to_Identify_Elite_Talent_Among.1995.pdf?token=method|ExpireAbsolute;source|Journals;ttl|1473662274047;payload|mY8D3u1TCCsNvP5E421JYK6N6XICDamxByyYpaNzk7FKjTaa1Yz22MivkHZqjGP4kdS2v0J76WGAnHACH69s21Csk0OpQi3YbjEMdSoz2UhVybFqQxA7lKwSUlA502zQZr96TQRwhVlocEp/sJ586aVbcBFlltKNKo+tbuMfL73hiPqJliudqs17cHeLcLbV/CqjlP3IO0jGHlHQtJWcICDdAyGJMnpi6RlbEJaRheGeh5z5uvqz3FLHgPKVXJzdKVgAgQT2Xde+Z+1EdY8Ms85MawwtfLsaNSRiFaGpRss=;hash|YULjbeWuycURfTbumRYilg==

#5 Neuromuscular Fatigue In Response To 120 Minutes Of Soccer-specific Exercise
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):666-7. doi: 10.1249/01.mss.0000487000.89035.ed.
Authors: Goodall S, Thomas K, Hunter R, Parker P, Woolley G, Harper L, Stevenson E, West D, Russell M, Howatson G.
Download link: pdfs.journals.lww.com/acsm-msse/2016/05001/Neuromuscular_Fatigue_In_Response_To_120_Minutes.1994.pdf?token=method|ExpireAbsolute;source|Journals;ttl|1473662305533;payload|mY8D3u1TCCsNvP5E421JYK6N6XICDamxByyYpaNzk7FKjTaa1Yz22MivkHZqjGP4kdS2v0J76WGAnHACH69s21Csk0OpQi3YbjEMdSoz2UhVybFqQxA7lKwSUlA502zQZr96TQRwhVlocEp/sJ586aVbcBFlltKNKo+tbuMfL73hiPqJliudqs17cHeLcLbV/CqjlP3IO0jGHlHQtJWcICDdAyGJMnpi6RlbEJaRheGeh5z5uvqz3FLHgPKVXJzdKVgAgQT2Xde+Z+1EdY8Ms2OZ4KCUVnrCUJS+OcgcOy4=;hash|rvqqClLzDRr+NZ8rR7VpuQ==

#6 Heart Rate Variability And Autonomic Activity In A Nonfunctional Overreached Professional Soccer Player
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):666. doi: 10.1249/01.mss.0000486999.81412.ea.
Authors: Vilamitjana JJ, Lentini NA, Verde PE, Perez MF Jr
Download link: pdfs.journals.lww.com/acsm-msse/2016/05001/Heart_Rate_Variability_And_Autonomic_Activity_In_A.1993.pdf?token=method|ExpireAbsolute;source|Journals;ttl|1473662338577;payload|mY8D3u1TCCsNvP5E421JYK6N6XICDamxByyYpaNzk7FKjTaa1Yz22MivkHZqjGP4kdS2v0J76WGAnHACH69s21Csk0OpQi3YbjEMdSoz2UhVybFqQxA7lKwSUlA502zQZr96TQRwhVlocEp/sJ586aVbcBFlltKNKo+tbuMfL73hiPqJliudqs17cHeLcLbV/CqjlP3IO0jGHlHQtJWcICDdAyGJMnpi6RlbEJaRheGeh5z5uvqz3FLHgPKVXJzdKVgAgQT2Xde+Z+1EdY8MswDKIXv1XX+D8a0O/tpP4aI=;hash|x0d/3gotaPn4NNzMHdpOnw==

#7 Changes in Performance, HRV, and Inflammation Following an Individualized Soccer Specific Training Program
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):666. doi: 10.1249/01.mss.0000486998.81412.a3.
Authors: Berry NT, Cone JR, Ritsche K, Wideman L
Download link: pdfs.journals.lww.com/acsm-msse/2016/05001/Changes_in_Performance,_HRV,_and_Inflammation.1992.pdf?token=method|ExpireAbsolute;source|Journals;ttl|1473662383616;payload|mY8D3u1TCCsNvP5E421JYK6N6XICDamxByyYpaNzk7FKjTaa1Yz22MivkHZqjGP4kdS2v0J76WGAnHACH69s21Csk0OpQi3YbjEMdSoz2UhVybFqQxA7lKwSUlA502zQZr96TQRwhVlocEp/sJ586aVbcBFlltKNKo+tbuMfL73hiPqJliudqs17cHeLcLbV/CqjlP3IO0jGHlHQtJWcICDdAyGJMnpi6RlbEJaRheGeh5z5uvqz3FLHgPKVXJzdKVgAgQT2Xde+Z+1EdY8Ms/vhfWL9H7EYHV3epZAq7ok=;hash|8cSBxbIxJJbV7qf+jmnoaw==

#8 Effects of Training on ACL Volume in Female Intercollegiate Soccer Athletes
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):492. doi: 10.1249/01.mss.0000486479.39854.47.
Authors: Kim G, Mele B, Myrick K, Feinn R, Gonzales R, Garbalosa JC
Download link: pdfs.journals.lww.com/acsm-msse/2016/05001/Effects_of_Training_on_ACL_Volume_in_Female.1473.pdf?token=method|ExpireAbsolute;source|Journals;ttl|1473662421730;payload|mY8D3u1TCCsNvP5E421JYK6N6XICDamxByyYpaNzk7FKjTaa1Yz22MivkHZqjGP4kdS2v0J76WGAnHACH69s21Csk0OpQi3YbjEMdSoz2UhVybFqQxA7lKwSUlA502zQZr96TQRwhVlocEp/sJ586aVbcBFlltKNKo+tbuMfL73hiPqJliudqs17cHeLcLbV/CqjlP3IO0jGHlHQtJWcICDdAyGJMnpi6RlbEJaRheGeh5z5uvqz3FLHgPKVXJzdKVgAgQT2Xde+Z+1EdY8Ms0GJeiIi2dY0FfJJ0T5fXrE=;hash|RAKYQidJC4AeVRw1VdhoeA==

#9 Cardiac Systolic And Diastolic Function During Incremental Exercise In Highly-trained Youth Soccer Players
Reference: Med Sci Sports Exerc. 2016 May;48(5 Suppl 1):479. doi: 10.1249/01.mss.0000486440.58987.51.
Authors: Unnithan V, Rowland T, George K, Oxborough D
Download link: pdfs.journals.lww.com/acsm-msse/2016/05001/Cardiac_Systolic_And_Diastolic_Function_During.1434.pdf?token=method|ExpireAbsolute;source|Journals;ttl|1473662458182;payload|mY8D3u1TCCsNvP5E421JYK6N6XICDamxByyYpaNzk7FKjTaa1Yz22MivkHZqjGP4kdS2v0J76WGAnHACH69s21Csk0OpQi3YbjEMdSoz2UhVybFqQxA7lKwSUlA502zQZr96TQRwhVlocEp/sJ586aVbcBFlltKNKo+tbuMfL73hiPqJliudqs17cHeLcLbV/CqjlP3IO0jGHlHQtJWcICDdAyGJMnpi6RlbEJaRheGeh5z5uvqz3FLHgPKVXJzdKVgAgQT2Xde+Z+1EdY8Mswpz/9YwNuOG4m30Q/BcWv0=;hash|4v4vd+BLy2ZpJbZZgBUKfg==

#10 MRI-Based Regional Muscle Use during Hamstring Strengthening Exercises in Elite Soccer Players
Reference: PLoS One. 2016 Sep 1;11(9):e0161356. doi: 10.1371/journal.pone.0161356. eCollection 2016.
Authors: Mendez-Villanueva A, Suarez-Arrones L, Rodas G, Fernandez-Gonzalo R, Tesch P, Linnehan R, Kreider R, Di Salvo V
Download link: http://journals.plos.org/plosone/article/asset?id=10.1371/journal.pone.0161356.PDF
Summary: The present study examined site-specific hamstring muscles use with functional magnetic resonance imaging (MRI) in elite soccer players during strength training. Thirty-six players were randomized into four groups, each performing either Nordic hamstring, flywheel leg-curl, Russian belt or the hip-extension conic-pulley exercise. The transverse relaxation time (T2) shift from pre- to post-MRI were calculated for the biceps femoris long (BFl) and short (BFs) heads, semitendinosus (ST) and semimembranosus (SM) muscles at proximal, middle and distal areas of the muscle length. T2 values increased substantially after flywheel leg-curl in all regions of the BFl (from 9±8 to 16±8%), BFs (41±6-71±11%), and ST (60±1-69±7%). Nordic hamstring induced a substantial T2 increase in all regions of the BFs (13±8-16±5%) and ST (15±7-17±5%). T2 values after the Russian belt deadlift substantially increased in all regions of the BFl (6±4-7±5%), ST (8±3-11±2%), SM (6±4-10±4%), and proximal and distal regions of BFs (6±6-8±5%). T2 values substantially increased after hip-extension conic-pulley only in proximal and middle regions of BFl (11±5-7±5%) and ST (7±3-12±4%). The relevance of such MRI-based inter- and intra-muscle use in designing more effective resistance training for improving hamstring function and preventing hamstring injuries in elite soccer players should be explored with more mechanistic studies.

#11 No Relationship Between Hamstring Flexibility and Hamstring Injuries in Male Amateur Soccer Players: A Prospective Study
Reference: Am J Sports Med. 2016 Aug 31. pii: 0363546516664162. [Epub ahead of print]
Authors: van Doormaal MC, van der Horst N, Backx FJ, Smits DW, Huisstede BM
Summary: In soccer, although hamstring flexibility is thought to play a major role in preventing hamstring injuries, the relationship between hamstring flexibility and hamstring injuries remains unclear. The purpose of the study was to investigate the relationship between hamstring flexibility and hamstring injuries in male amateur soccer players. This study included 450 male first-class amateur soccer players (mean age, 24.5 years). Hamstring flexibility was measured by performing the sit-and-reach test (SRT). The relationship between hamstring flexibility and the occurrence of hamstring injuries in the following year, while adjusting for the possible confounding effects of age and previous hamstring injuries, was determined with a multivariate logistic regression analysis. Of the 450 soccer players, 21.8% reported a hamstring injury in the previous year. The mean (±SD) baseline score for the SRT was 21.2 ± 9.2 cm. During the 1-year follow-up period, 23 participants (5.1%) suffered a hamstring injury. In the multivariate analysis, while adjusting for age and previous injuries, no significant relationship was found between hamstring flexibility and hamstring injuries (P = .493). In this group of soccer players, hamstring flexibility (measured with the SRT) was not related to hamstring injuries. Age and previous hamstring injuries as possible confounders did not appear to influence this relationship. Other etiological factors need to be examined to further elucidate the mechanism of hamstring injuries.

#12 Dynamic balance is impaired after a match in young elite soccer players
Reference: Phys Ther Sport. 2016 May 21;22:11-15. doi: 10.1016/j.ptsp.2016.05.008. [Epub ahead of print]
Authors: Pau M, Mereu F, Melis M, Leban B, Corona F, Ibba G
Summary: The aim of this study is to assess the effect of actual match effort on dynamic balance abilities in young elite soccer players. Seventeen Under 15 male players who compete at national level participated in the study. Their dynamic balance was assessed by having them jump starting with both feet on the ground in a standing position and land on one foot only. Their vertical time to stabilization (vTTS) and postural sway were calculated before and after 35 min of an unofficial match. Postural sway was assessed on the basis of center-of-pressure (COP) trajectories. Parameters considered were sway area, COP displacements in the antero-posterior (AP) and medio-lateral (ML) directions and COP path length. After the match, a significant increase in vTTS (p = 0.007) COP path length (p = 0.001) and COP displacements in ML (p < 0.001) was observed. Such effects involve both non-dominant (vTTS, path length) and dominant limb (COP displacements). The physical effort associated with the match induces significant impairments of players' dynamic balance abilities. On the basis of such findings, coaches might consider integrating training sessions with specific balance exercises as well as performing injury-prevention routines even when players are fatigued, to better adapt them to match conditions.

#13 Changes of the psychophysical state and feeling of wellness of professional soccer players during pre-season and in-season periods
Reference: Res Sports Med. 2016 Aug 30:1-12. [Epub ahead of print]
Authors: Fessi MS, Nouira S, Dellal A, Owen A, Elloumi M, Moalla W
Summary: Perceived changes due to training monotony, strain, sleep, stress, fatigue, muscle soreness and the influence of specific training sessions on the affective valence were explored in professional soccer players. Seventeen players completed the Hooper questionnaire, the ratings of perceived exertion and feeling scale (FS) every training/match day before and during the soccer season. Higher players' training loads were recorded during pre-season when compared with in-season period (2558.1 ± 262.4 vs. 1642.8 ± 169.3 a.u., p < 0.01; respectively). The ratings of sleep, stress, fatigue and muscle soreness in pre-season were higher than those observed during in-season (p < 0.01) whereas the feeling score was lower (p < 0.01). Furthermore, training sessions, including technical/tactical work, induced an improved feeling score but linked with a lower training load when compared with sessions focus on physical emphasis (p < 0.01). Pre-season period of training induces a significantly more strenuous and exhausting demands on professional soccer players compared with the in-season period at the elite level.

#14 Relationship Between Internal Load Indicators And Changes On Intermittent Performance After The Preseason In Professional Soccer Players
Reference: J Strength Cond Res. 2016 Aug 22. [Epub ahead of print]
Authors: Campos-Vazquez MA, Toscano-Bendala FJ, Mora-Ferrera JC, Suarez-Arrones L.
Summary: The aim of this study was to examine the effects of accumulated internal training load during the preseason (4 weeks) on changes in the intermittent performance, in a professional soccer team. Twelve professionals soccer players (Mean±SD age 27.7±4.3 years; height: 177.1±6.2 cm; body mass: 73.1±5.2 kg; % body fat (Faulkner): 10.2±1.2) belonging to a Spanish second division team (2013-2014) participated in this study. The 30-15 intermittent fitness test was performed before and after the preseason, and the speed for the last period completed by each player was recorded (VIFT). During the preseason, the team alternated practice of training sessions (TRNs) with friendly matches (FMs). Session rating of perceived exertion (sRPE), heart rate (HR) and HR reserve were analized every TRN and FM in order to calculate internal training load (ITL: sRPE-TL, Edward's-TL and Edward's-TLres). The players' VIFT substantially increased after the preseason period (20.1±0.8 vs. 21.1±0.8 km·h; Effect Size [ES]=1.15±0.25; almost certainly). The average value of sRPE throughout FMs was substantially greater than the value of the TRNs (7.4±0.9 vs. 5.25±0.2; ES=2.31±2.45; almost certainly). sRPE-TL, practice volume and sum of RPE during the preseason were positively and largely correlated (r=0.70-0.75) with changes on intermittent performance. No relationships were found between HR-derived measures of exercise load and changes on intermittent fitness. The present results suggest that practice volume and subjective measures of TL, related better than HR-based TL methods to changes on intermittent performance after the preseason, in professional soccer players.

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