Latest research in football - week 10 - 2015

As previous literature updates, we have performed a PubCrawler search looking for football articles in NCBI Medline (PubMed) and GenBank databases.

Following studies were retrieved for this week:


#1 Return to Sport Following Surgery for a Complicated Tibia and Fibula Fracture in a Collegiate Women's Soccer Player with a Low Level of Kinesiophobia
Reference: Int J Sports Phys Ther. 2015 Feb;10(1):95-103.
Authos: Feigenbaum LA, Baraga M, Kaplan LD, Roach KE, Calpino KM, Dorsey K, Martorelli C, Sagarduy B, King LA, Scavo VA
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Summary: Much attention has been solely paid to physical outcome measures for return to sport after injury in the past. However, current research shows that the psychological component of these injuries can be more predictive of return to sport than physical outcome measures. The purpose of this case report is to describe the successful return to sport following surgery of a complicated tibia and fibula fracture of a Division I collegiate women's soccer player with a low level of kinesiophobia. A 22-year-old female sustained a closed traumatic mid-shaft fracture of her tibia and fibula. During a high velocity play she sustained a direct blow while colliding with an opposing player's cleats. As a result of the play, her distal tibia was displaced 908 to the rest of her leg. She underwent a closed reduction and tibial internal fixation with an intramedullary rod. Outcome scores were tracked using the IKDC and TSK-11. The IKDC measures symptoms, function, and sport activity related to knee injuries. The TSK-11 measures fear of movement and re-injury, which was important to assess during this case due to the gruesome nature of the injury. At 4 months, the subject became symptomatic over the fibula and was diagnosed with a fibular nonunion fracture. This was unexpected due to the low incidence of and usual asymptomatic nature of fibular nonunion fractures, which required an additional surgery. TSK-11 scores ranged from 19-20 throughout, signifying low levels of kinesiophobia. IKDC scores improved from 8.05 to 60.92. The subject ultimately signed a professional soccer contract. The rehabilitation of this subject was complex due to her low levels of kinesiophobia, self-guided overtraining, and the potential role they may have had in her fibular nonunion fracture. This case study demonstrates a successful outcome despite a unique injury presentation, multiple surgeries, and low levels of kinesiophobia. While a low level of kinesiophobia can be detrimental to rehabilitation compliance, it may have benefited her in the long-term.

#2 Effect of different recovery durations between bouts in 3-a-side games on youth soccer players' physiological responses and technical activities
Reference: J Sports Med Phys Fitness. 2015 Feb 20. [Epub ahead of print]
Authors: Köklü Y, Alemdaroğlu U, Delall A, Wong DP
Summary: The aim of this study was to investigate the effects of the length of recovery durations between bouts in 4x4min 3--a--side small--sided games (SSG) on time--motion analysis, technical actions and physiological responses of players. Twelve young soccer players participated in 4 different 3--a--side games in which the recovery durations between bouts were different (R1: 1min, R2: 2min, R3: 3min, and R4: 4min). Heart rate (HR), total distance covered in different speed zones, and technical performance were monitored during all SSGs, whereas the rating of perceived exertion (RPE, CR--10) and venous blood lactate were determined at the end of the last bout of each SSG. Results showed that SSGs--R1 induced higher %HRreserve and lower successful passes (vs. R3 and R4 conditions, p<0.05), lower total passes (vs. R4 conditions, p<0.05), and greater distance covered in walking zone (0-6.9 km.h --1) (vs. other 3 conditions, p<0.05). In addition, during the SSG--R3 players covered greater distances in high--intensity running zone (>18 km.h --1) , performed more tackles (vs. R1 condition, p<0.05) and had more ball contacts (vs. R1 and R2 conditions, p<0.05). According to these results, it is thought that R1 and R2 are suitable for inducing higher physiological responses, while R3 and R4 are more appropriate for training aim to improve technical skills in 4x4min 3--a--side SSGs among young soccer players. These findings provide evidence for coaches to justify the selection of recovery duration between bouts in 3--a--side SSGs among young soccer players.

#3 Home advantage in soccer - A matter of expectations, goal setting and tactical decisions of coaches?
Reference: J Sports Sci. 2015 Mar 6:1-10. [Epub ahead of print]
Authors: Staufenbiel K, Lobinger B, Strauss B
Summary: In soccer, home teams win about 67% of decided games. The causes for this home advantage are still unresolved. There is a shortage of research on the psychological states of actors involved. In this study, we examined soccer coaches' expectations, goal setting and tactical decisions in relation to game location. Soccer coaches (N = 297) with different expertise levels participated in an experimental, online management game and were randomly assigned to one of two groups, "home game (HG)" or "away game." Participants received information on the game for which they were asked to make decisions in multiple points. The only differing information between groups was game location. Regardless of expertise, HG coaches had higher expectations to win, set more challenging goals and decided for more offensive and courageous playing tactics. Possible consequences of these findings concerning home advantage in soccer are discussed.

#4 Recovery of powerful kick biomechanics after intense running fatigue in male and female soccer players
Reference: Asian J Sports Med. 2014 Dec;5(4):e24013. doi: 10.5812/asjsm.24013. Epub 2014 Nov 10.
Authors: Katis A, Amiridis I, Kellis E, Lees A
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Summary: Fatigue seems to have a significant effect on soccer kick performance. However, the duration of these effects has not been previously investigated. The purpose of the present study was to investigate the duration of the acute effects of fatigue on soccer kick performance in males and females. Ten male (age: 26.3 ± 4.9 years, height: 178.1 ± 5.1 cm, mass: 81.3 ± 8.1 kg) and ten female (age: 24.4 ± 4.2 years, height: 169.7 ± 5.7 cm, mass: 61.8 ± 5.1 kg) amateur soccer players performed three instep kicks prior to and after running on a treadmill till exhaustion. Three-dimensional kinematics were collected pre- and post-fatigue. Analysis of variance indicated a statistically significant decline in ball speed during the first and the second trial after fatigue (P < 0.05), but recovered to pre-fatigue levels during the third post-fatigue kicking trial (P > 0.05). Similarly, maximum ankle, knee and hip linear velocity and ankle angular displacement were significantly lower during the first two trials (P < 0.05), but not during the third trial after fatigue (P > 0.05). Soccer kick parameters recovered to pre-fatigue levels approximately within a minute after the end of the protocol. These findings have a practical meaning for players who have to perform set piece kicks under fatigue conditions and for coaches who have to guide their players.

#5 Anthropometric and somatotype characteristics of young soccer players: differences among categories, sub-categories and playing position
Reference: J Strength Cond Res. 2015 Feb 14. [Epub ahead of print]
Authors: Perroni F, Vetrano M, Camolese G, Guidetti L, Baldari C
Summary: Considering that anthropometric parameters are important factors in the performance of the soccer players, the aim of this study was to explore the differences in anthropometric and somatotype characteristics of Italian Young Soccer Players. Weight, Height, Body Mass Index (BMI) and somatotype of 112 young soccer players, grouped in Giovanissimi "A" (14 yrs), "B" (13 yrs) and "C" (12 yrs), Allievi "B" (15 yrs) and "A" (16 yrs) and "Juniores" (>17 yrs), were evaluated. Statistical analysis tests were computed at p≤0.05 and an analysis of variance (ANOVA) for each somatotype was calculated to analyze the main effects and interactions of the factors: categories, sub-categories and playing position. Bonferroni's post hoc analysis was used to identify differences among means. Considering all subjects, we have found significant differences in categories, sub-categories and playing position between anthropometric values and a somatotype value of 2.8-3.8-2.9.Significant differences have found among Goalkeepers and the others playing position in endomorphy (p≤0.001) and with Defenders and Midfielders in ectomorphy (p<0.01) components, whereas no differences in mesomorphy. Analyzing the interaction between sub-categories and playing position factors, a significant effect was found only in endomorphy component (p= 0.05). The analysis of anthropometric characteristic of Italian young soccer players indicate that players have high muscularity value and low adiposity. This study showed the presence of somatotype differences for playing position within categories also in the youngest categories and sub-categories, in particular, in endomorphy component. Young soccer players should be trained with more appropriate and specific training-load to avoid the increased injury risk during adolescence.

#6 Reliability and Validity of Instrumented Soccer Equipment
Reference: J Appl Biomech. 2015 Mar 3. [Epub ahead of print]
Authors: Akins JS, Heebner NR, Lovalekar M, Sell TC.
Summary: Ankle ligament sprains are the most common injury in soccer. The high rate of these injuries demonstrates a need for novel data collection methodologies. Therefore, soccer shoes and shin guards were instrumented with inertial sensors to measure ankle joint kinematics in the field. The purpose of this study was to assess test-retest reliability and concurrent criterion validity of a kinematic assessment using the instrumented soccer equipment. Twelve soccer athletes performed athletic maneuvers in the laboratory and field during two sessions. In the laboratory, ankle joint kinematics were simultaneously measured with the instrumented equipment and a conventional motion analysis system. Reliability was assessed using ICC and validity was assessed using correlation coefficients and RMSE. While our design criteria of good test-retest reliability was not supported (ICC > 0.80), sagittal plane ICCs were mostly fair to good and similar to motion analysis results; and sagittal plane data were valid (r = 0.90-0.98, RMSE < 5°). Frontal and transverse plane data were not valid (r < 0.562; RMSE > 3°). Our results indicate that the instrumented soccer equipment can be used to measure sagittal plane ankle joint kinematics. Biomechanical studies support the utility of sagittal plane measures for lower extremity injury prevention.

#7 The relationship between somatotype and stress hormone levels in young soccer players
Reference: J Sports Med Phys Fitness. 2015 Mar 3. [Epub ahead of print]
Authors: Handziska E, Handziski Z, Gjorgoski I, Dalip M
Summary: The relationship between somatotype and cortisol and adrenocorticotropic (ACTH) hormone concentrations at rest or after exercise in adolescent soccer players at different time points throughout a soccer season is not understood. Therefore, t he aim of this study was to examine the relationship between somatotype and cortisol and ACTH concectrations at rest and after exercise in adolescent soccer players at different time points during a soccer season. During the first 4 months of the soccer season, 47 soccer players (between 15--17 years of age) were tested at three different time points including at baseline, after 6 weeks, and at the end of 4 months. Testing included anaerobic threshold (AnT, km/h) and maximal speed of running (Max, km/h) were measured with Conconi protocol on treadmill. Before and after a maximal exercise test, plasma levels of cortisol (ug/dl) and ACTH (pg/ml) were assessed by chemiluminometry enzyme amplificated method. Heath--Carter anthropometric somatotype model was used to determine 13 elements of somatotype. Descriptive statistics and multiple regression were used for statistical analysis (p<0.05). Body composition and AnT were not significantly different between each time point of testing. The mesomorph-ectomorph (N=21), balanced mesomorph (N=8) and balanced ectomorph (N=7) were the most frequent somatotypes. There were significant decrements of cortisol plasma levels (at rest 33.4%;; after test 27.46%), with insignificant changes of ACTH plasma levels, after 6 weeks of preparation phase and after finishing of half season, at rest and after maximal treadmill test. There were significant correlation between ACTH levels at rest (R=0.44; p<0.01) and some somatotypes (mesomorph endomorph, central and balanced endomorph) and ACTH levels after maximal exercise test (R=0.36; p<0.05) and balanced ectomorph and endomorph mesomorph. There were significant correlation between cortisol levels after maximal exercise test at the beginning of training process (R=0.59; p<0.01) and some somatotypes (mesomorph ectomorph, mesomorph endomorph, balanced endomorph and endomorph mesomorph) and after the finishing of training process (R=0.62; p<0.01) and some somatotypes (central, balanced ectomorph and mesomorph ectomorph). The significant decreases of cortisol plasma levels during soccer training process could indicate a stagnation of training process, accordingly with insignificant changes of AnT. The significant correlations of some somatotypes with stress hormonal responses could only suggest that the somatotype characteristics of young soccer players could be of interest in process of selection and planning of soccer training process with an essential need for more studies.

#8 Relative Match Intensities at High Altitude in Highly-Trained Young Soccer Players (ISA3600)
Reference: J Sports Sci Med. 2015 Mar 1;14(1):98-102. eCollection 2015.
Authors: Buchheit M, Hammond K, Bourdon PC, Simpson BM, Garvican-Lewis LA, Schmidt WF, Gore CJ, Aughey RJ
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Summary: The purpose of the study was to compare relative match intensities of sea-level versus high-altitude native soccer players during a 2-week camp at 3600 m, data from 7 sea-level (Australian U17 National team, AUS) and 6 high-altitude (a Bolivian U18 team, BOL) native soccer players were analysed. Two matches were played at sea-level and three at 3600 m on Days 1, 6 and 13. The Yo-Yo Intermittent recovery test (vYo-YoIR1) was performed at sea-level, and on Days 3 and 10. Match activity profiles were measured via 10-Hz GPS. Distance covered >14.4 km.h(-1) (D>14.4 km·h(-1)) and >80% of vYo-YoIR1 (D>80%vYo-YoIR1) were examined. Upon arrival at altitude, there was a greater decrement in vYo-YoIR1 (Cohen's d +1.0, 90%CL ± 0.8) and D>14.4 km·h(-1) (+0.5 ± 0.8) in AUS. D>14.4 km.h(-1) was similarly reduced relative to vYo-YoIR1 in both groups, so that D>80%vYo-YoIR1 remained similarly unchanged (-0.1 ± 0.8). Throughout the altitude sojourn, vYo-YoIR1 and D>14.4 km·h(-1) increased in parallel in AUS, so that D>80%vYo-YoIR1 remained stable in AUS (+6.0%/match, 90%CL ± 6.7); conversely D>80%vYo-YoIR1 decreased largely in BOL (-12.2%/match ± 6.2). In sea-level natives competing at high-altitude, changes in match running performance likely follow those in high-intensity running performance. Bolivian data confirm that increases in 'fitness' do not necessarily translate into greater match running performance, but rather in reduced relative exercise intensity. Key pointsWhen playing at high-altitude, players may alter their activities during matches in relation to their transient maximal physical capacities, possibly to maintain a 'tolerable' relative exercise intensity.While there is no doubt that running performance per se in not the main determinant of match outcomes (Carling, 2013), fitness levels influence relative match intensity (Buchheit et al., 2012, Mendez-Villanueva et al., 2013), which in-turn may impact on decision making and skill performance (Rampinini et al., 2008).In the context of high-altitude competitions, it is therefore recommended to arrive early enough (i.e., ~2 weeks) to allow (at least partial) acclimatisation, and in turn, allow sea-level native players to regulate their running activities in relation to both actual game demands and relative match intensity.

#9 Effects of Thai massage on physical fitness in soccer players
Reference: J Phys Ther Sci. 2015 Feb;27(2):505-8. doi: 10.1589/jpts.27.505. Epub 2015 Feb 17.
Authors: Hongsuwan C, Eungpinichpong W, Chatchawan U, Yamauchi J
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Summary: The aim of this study was to determine the effects of Thai massage on physical fitness in soccer players. Thirty-four soccer players were randomly assigned to receive either rest (the control group) or three 30-minute sessions of Thai massage over a period of 10 days. Seven physical fitness tests consisting of sit and reach, hand grip strength, 40 yards technical agility, 50-meter sprint, sit-ups, push-ups, and VO2, max were measured before and after Thai massage or rest. [Results] All the physical fitness tests were significantly improved after a single session of Thai massage, whereas only the sit and reach, and the sit-ups tests were improved in the control group. Thai massage could provide an improvement in physical performance in soccer players.

#10 The Yo-Yo intermittent recovery test level 1 is reliable in young high-level soccer players
Reference: Biol Sport. 2015 Mar;32(1):65-70. doi: 10.5604/20831862.1127284. Epub 2014 Nov 3.
Authors: Deprez D1, Fransen J1, Lenoir M1, Philippaerts R1, Vaeyens R1.
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Summary: The aim of the study was to investigate test reliability of the Yo-Yo intermittent recovery test level 1 (YYIR1) in 36 high-level youth soccer players, aged between 13 and 18 years. Players were divided into three age groups (U15, U17 and U19) and completed three YYIR1 in three consecutive weeks. Pairwise comparisons were used to investigate test reliability (for distances and heart rate responses) using technical error (TE), coefficient of variation (CV), intra-class correlation (ICC) and limits of agreement (LOA) with Bland-Altman plots. The mean YYIR1 distances for the U15, U17 and U19 groups were 2024 ± 470 m, 2404 ± 347 m and 2547 ± 337 m, respectively. The results revealed that the TEs varied between 74 and 172 m, CVs between 3.0 and 7.5%, and ICCs between 0.87 and 0.95 across all age groups for the YYIR1 distance. For heart rate responses, the TEs varied between 1 and 6 bpm, CVs between 0.7 and 4.8%, and ICCs between 0.73 and 0.97. The small ratio LOA revealed that any two YYIR1 performances in one week will not differ by more than 9 to 28% due to measurement error. In summary, the YYIR1 performance and the physiological responses have proven to be highly reliable in a sample of Belgian high-level youth soccer players, aged between 13 and 18 years. The demonstrated high level of intermittent endurance capacity in all age groups may be used for comparison of other prospective young soccer players.

#11 Sport-specific trunk muscle profiles in soccer players of different skill levels
Reference: Arch Orthop Trauma Surg. 2015 Mar 1. [Epub ahead of print]
Authors: Krutsch W, Weishaupt P, Zeman F, Loibl M, Neumann C, Nerlich M, Angele P.
Summary: Physical fitness and trunk stability are essential factors for successful soccer competition. We investigated the impact of soccer exposure on the trunk muscle profile of players of different skill levels. Professional and amateur soccer players were examined for trunk flexibility and maximum isometric muscle strength in the midseason period 2011. 24 professional soccer players who had not participated in any specific trunk muscle training programmes had significantly higher isometric trunk muscle strength in the sagittal plane (Ext: p = 0.003, Flex: p = 0.014), the frontal plane (Lat. right: p = 0.001, left: p = 0.003) and the transverse plane (Rotation right and left: p < 0.001) than 83 amateur soccer players. Professional players also had higher trunk flexibility in the sagittal plane (Flex: p = 0.001) and the transverse plane (Rotation right: p = 0.02, left: p = 0.002) than amateur players. The side of the dominant kicking leg had no influence on muscle strength and flexibility of the trunk. Trunk flexibility and stability as necessary factors for avoiding physical overstress and injuries are differently trained in player of different soccer skill levels.

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