Latest research in football - week 40 - 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 A test of basic psychological needs theory in young soccer players: time-lagged design at the individual and team levels
Reference: Scand J Med Sci Sports. 2016 Sep 27. doi: 10.1111/sms.12778. [Epub ahead of print]
Authors: González L, Tomás I, Castillo I, Duda JL, Balaguer I
Summary: Within the framework of basic psychological needs theory (Deci & Ryan, 2000), multilevel structural equation modeling (MSEM) with a time-lagged design was used to test a mediation model examining the relationship between perceptions of coaches' interpersonal styles (autonomy supportive and controlling), athletes' basic psychological needs (satisfaction and thwarting), and indicators of well-being (subjective vitality) and ill-being (burnout), estimating separately between and within effects. The participants were 597 Spanish male soccer players aged between 11 and 14 years (M = 12.57, SD = 0.54) from 40 teams who completed a questionnaire package at two time points in a competitive season. Results revealed that at the individual level, athletes' perceptions of autonomy support positively predicted athletes' need satisfaction (autonomy, competence, and relatedness), whereas athletes' perceptions of controlling style positively predicted athletes' need thwarting (autonomy, competence, and relatedness). In turn, all three athletes' need satisfaction dimensions predicted athletes' subjective vitality and burnout (positively and negatively, respectively), whereas competence thwarting negatively predicted subjective vitality and competence and relatedness positively predicted burnout. At the team level, team perceptions of autonomy supportive style positively predicted team autonomy and relatedness satisfaction. Mediation effects only appeared at the individual level.

#2 Vertical and Horizontal Impact Force Comparison During Jump-Landings With and Without Rotation in NCAA Division 1 Male Soccer Players
Reference: J Strength Cond Res. 2016 Sep 22. [Epub ahead of print]
Authors: Harry JR, Barker LA, Mercer JA, Dufek JS
Summary: There is a wealth of research on impact force characteristics when landing from a jump. However, there are no data on impact forces during landing from a jump with an airborne rotation about the vertical axis. We examined impact force parameters in the vertical and horizontal axes during vertical jump (VJ) landings and vertical jump landings with a 180-degree rotation (VJR). Twenty-four Division 1 male soccer players performed three VJ and VJR landings on a dual-force platform system. Paired-samples t-tests (α=0.05) compared differences in the first (F1) and second (F2) peak vertical ground reaction forces, times to F1 (tF1), F2 (tF2), and the end of the impact phase, vertical impulse, and anterior-posterior and medial-lateral force couples. Effect sizes (ES; large >0.8) were computed to determine the magnitude of the differences. Lower jump height (41.60±4.03 cm, VJ landings; 39.40±4.05 cm, VJR landings; p=0.002; ES=0.39), greater F2 (55.71±11.95 N•kg-1, VJ; 68.16±14.82 N•kg-1; p<0.001; ES=0.94), faster tF2 (0.057±0.012 sec, VJ; 0.047±0.011 sec, VJR; p=0.001; ES=0.89), greater anterior-posterior (0.06±0.03 N•s•kg-1, VJ; 0.56±0.15 N•s•kg-1, VJR; p<0.001; ES=1.83) and medial-lateral force couples (0.29±0.11 N•s•kg-1, VJ; 0.56±0.14 N•s•kg-1, VJR; p<0.001; ES=1.46) occurred during VJR landings. No other differences were identified. This kinetic analysis determined that landing from a jump with 180-degree airborne rotation is different than landing from a jump without an airborne rotation. Male Division 1 soccer players could benefit from increasing the volume of VJR landings during training to address the differences in jump height and force parameters compared to VJ landings.

#3 Influence of physical maturity status on sprinting speed among youth soccer players
Reference: J Strength Cond Res. 2016 Sep 21. [Epub ahead of print]
Authors: McCunn R, Weston M, Hill JK, Johnston RD, Gibson NV
Summary: The relative age effect is well documented with the maturation-selection hypothesis the most common explanation; however, conflicting evidence exists. We observed the birth-date distribution within an elite junior soccer academy. The influence of physical maturity status on anthropometric variables and sprinting ability was also investigated. Annual fitness testing was conducted over an eight-year period with a total of 306 players (age: 12.5 ± 1.7 y [range: 9.7 - 16.6 y]; stature: 156.9 ± 12.9 cm; mass: 46.5 ± 12.5 kg) drawn from six age categories (under-11s to -17s) who attended the same Scottish Premiership club academy. Measurements included mass, stature, maturity offset and 0-15 m sprint. Odds ratios revealed a clear bias towards recruitment of players born in quartile one compared to quartile four. The overall effect (all squads combined) of birth quartile was very likely small for maturity offset (0.85 years; 90% confidence interval 0.44 years to 1.26 years) and stature (6.2 cm; 90% confidence interval 2.8 cm to 9.6 cm), and likely small for mass (5.1 kg; 90% confidence interval 1.7 kg to 8.4 kg). The magnitude of the relationship between maturity offset and 15 m sprinting speed ranged from trivial for under-11s (r = 0.01; 90% confidence interval -0.14 to 0.16) to very likely large for under-15s (r = -0.62; -0.71 to -0.51). Making decisions about which players to retain and release should not be based on sprinting ability around the under-14 and under-15 age categories since any inter-individual differences may be confounded by transient inequalities in maturity offset.

#4 Analysis of the predictive qualities of betting odds and FIFA World Ranking: evidence from the 2006, 2010 and 2014 Football World Cups
Reference: J Sports Sci. 2016 Aug 11:1-9. [Epub ahead of print]
Authors: Wunderlich F, Memmert D
Summary: The present study aims to investigate the ability of a new framework enabling to derive more detailed model-based predictions from ranking systems. These were compared to predictions from the bet market including data from the World Cups 2006, 2010, and 2014. The results revealed that the FIFA World Ranking has essentially improved its predictive qualities compared to the bet market since the mode of calculation was changed in 2006. While both predictors were useful to obtain accurate predictions in general, the world ranking was able to outperform the bet market significantly for the World Cup 2014 and when the data from the World Cups 2010 and 2014 were pooled. Our new framework can be extended in future research to more detailed prediction tasks (i.e., predicting the final scores of a match or the tournament progress of a team).

#5 The use and modification of injury prevention exercises by professional youth soccer teams
Reference: Scand J Med Sci Sports. 2016 Oct 7. doi: 10.1111/sms.12756. [Epub ahead of print]
Authors: O'Brien J, Young W, Finch CF
Summary: The efficacy of injury prevention exercise programs (IPEPs) for amateur youth soccer has been established, but little is known about their adaptability to other soccer populations. This study aimed to assess the use of individual injury prevention exercises by professional youth soccer teams, against the industry-standard, FIFA 11+ program. Four teams' chosen IPEPs were observed across one season and documented on a standardized form. The use of each FIFA 11+ exercise was coded as "performed", "performed modified" or "not performed". The proportion of the 160 observed sessions containing each individual exercise was calculated. Staff provided reasons for their use and modification of FIFA 11+ exercises. On average, individual FIFA 11+ exercises were conducted in original form in 12% of the sessions (range 0-33%), and in modified form in 28% of sessions (range 2-62%). The five most frequently observed exercises, in either original or modified form, were "bench" (72%), "squats" (69%), "running straight" (68%), "single-leg stance" (66%), and "sideways bench" (64%). Staff modified exercises to add variation, progression, and individualization, and to align with specific training formats and goals. Professional youth soccer teams often use injury prevention exercises similar to those in the FIFA 11+, but tailor them considerably to fit their implementation context.

#6 Relationship between daily training load and psychometric status of professional soccer players
Reference: Res Sports Med. 2016 Oct 7:1-8. [Epub ahead of print]
Authors: Moalla W, Fessi MS, Farhat F, Nouira S, Wong DP, Dupont G
Summary: We studied the relationship between daily training load (TL) experienced by professional soccer players and the Hooper questionnaire reflecting their perceived quality of sleep, fatigue, stress and delayed onset muscle soreness. During a 16-week training period, the rating of perceived exertion and duration were collected after each training session, and daily TL was calculated from 14 professional soccer players. The Hooper questionnaire was completed every day before the first training session and the Hooper's score (HS) was then calculated. The daily TL and HS were 379.9 ± 198.3 AU and 16.2 ± 5.1, respectively. Pearson correlation showed significant relationships (p < 0.01) between TL and perceived fatigue, muscle soreness, sleep and stress. Our findings revealed that the perceived sleep, stress, fatigue and muscle soreness are moderately related to the daily TL in professional soccer players. The Hooper questionnaire is both a simple and useful tool for monitoring perceived wellness and psychometric players' status of professional soccer players.

#7 Dietary Intake, Body Composition and Nutrition Knowledge of Australian Football and Soccer Players: Implications for Sports Nutrition Professionals in Practice
Reference: Int J Sport Nutr Exerc Metab. 2016 Oct 6:1-21. [Epub ahead of print]
Authors: Devlin BL, Leveritt MD, Kingsley M, Belski R
Summary: Sports nutrition professionals aim to influence nutrition knowledge, dietary intake and body composition to improve athletic performance. Understanding the interrelationships between these factors and how they vary across sports has the potential to facilitate better-informed and targeted sports nutrition practice. This observational study assessed body composition (DXA), dietary intake (multiple-pass 24-hour recall) and nutrition knowledge (two previously validated tools) of elite and sub-elite male players involved in two team-based sports; Australian football (AF) and soccer. Differences in, and relationships between, nutrition knowledge, dietary intake and body composition between elite AF, sub-elite AF and elite soccer players were assessed. A total of 66 (23 ± 4 years, 82.0 ± 9.2 kg, 184.7 ± 7.7 cm) players participated. Areas of weaknesses in nutrition knowledge are evident (57% mean score obtained) yet nutrition knowledge was not different between elite and sub-elite AF and soccer players (58%, 57% and 56%, respectively, p > 0.05). Dietary intake was not consistent with recommendations in some areas; carbohydrate intake was lower (4.6 ± 1.5 g/kg/day, 4.5 ± 1.2 g/kg/day and 2.9 ± 1.1 g/kg/day for elite and sub-elite AF and elite soccer players, respectively) and protein intake was higher (3.4 ± 1.1 g/kg/day, 2.1 ± 0.7 g/kg/day and 1.9 ± 0.5 g/kg/day for elite and sub-elite AF and elite soccer players, respectively) than recommendations. Nutrition knowledge was positively correlated with fat-free soft tissue mass (n = 66; r2 = 0.051, p = 0.039). This insight into known modifiable factors may assist sports nutrition professionals to be more specific and targeted in their approach to supporting players to achieve enhanced performance.

#8 Traditional Periodization versus Optimum Training Load Applied to Soccer Players: Effects on Neuromuscular Abilities
Reference: Int J Sports Med. 2016 Oct 5. [Epub ahead of print]
Authors: Loturco I, Nakamura FY, Kobal R, Gil S, Pivetti B, Pereira LA, Roschel H
Summary: It is unknown whether traditional periodization of strength-power training involving accumulation, transformation and realization blocks is superior to other simpler and more practical training schemes. The purpose of this study was thus to investigate changes in strength/power/speed characteristics of elite soccer players in response to either classic strength-power periodization (TSP) or optimum power load (OPL). 23 professional soccer players were randomly assigned to TSP or OPL for 6 weeks in-season regular training (3 times per week). TSP involved half squats or jump squats, depending on the respective training block, while OPL involved only jump squats at the optimum power load. Results revealed that both groups presented similar significant (P<0.05) improvements in squat one repetition maximum, squat and countermovement jump heights and change of direction speed. In addition, although both groups reported significant increases in sprinting speed (P<0.05); delta change scores demonstrated a superior effect of OPL to improve 10- and 20-m speed. Similarly, OPL presented greater delta change in mean propulsive power in the jump squat. Therefore, training continuously at the optimum power zone resulted in superior performance improvements compared to training under classic strength-power periodization.

#9 Continued Sex-Differences in the Rate and Severity of Knee Injuries among Collegiate Soccer Players: The NCAA Injury Surveillance System, 2004-2009
Reference: Int J Sports Med. 2016 Oct 5. [Epub ahead of print]
Authors: Fulstone D, Chandran A, Barron M, DiPietro L
Summary: We extend previous analyses and examined sex-differences in the rate and severity of knee injuries among collegiate soccer players between 2004 and 2009. Data from the National Collegiate Athletic Association Injury Surveillance System (NCAA ISS) were used to calculate injury incidence density (ID) per 1 000 athletic exposures (AE). Multivariable regression modeling then tested the relation between sex and knee injury incidence and severity among all injured soccer players, while controlling for contact, setting, and division level, as well as for the interactions among these variables. The rate of knee injuries was 1.19 per 1 000 AEs in women and 0.91 per 1 000 AEs in men (RR=1.31, 95% Wald CI=[1.16, 1.47]). In the multivariable modeling, women continued to experience significantly higher odds of knee injury compared with men (aOR=1.44, 95% CI=[1.27,1.63]). Also, the adjusted odds of a knee injury that resulted in surgery remained higher in women compared with men (aOR=1.61 (1.00, 2.58), as well as the amount of time lost from participation (beta=0.129; p=0.05). Given the prominence of soccer play in the United States, continued efforts to evaluate and improve knee injury prevention practices and policies may be especially important for female players.

#10 A Comparison of Body Segment Inertial Parameter Estimation Methods and Joint Moment and Power Calculations During a Drop Vertical Jump in Collegiate Female Soccer Players
Reference: J Appl Biomech. 2016 Oct 5:1-15. [Epub ahead of print]
Authors: Arena SL, McLaughlin K, Nguyen AD, Smoliga JM, Ford KR
Summary: Athletic individuals may differ in body segment inertial parameter (BSIP) estimates due to differences in body composition, and this may influence calculation of joint kinetics. The purposes of this study were to 1) compare BSIPs predicted by the method introduced by de Leva1 with DXA-derived BSIPs in collegiate female soccer players, and 2) examine the effects of these BSIPs estimation methods on joint moment and power calculations during a drop vertical jump (DVJ). Twenty female NCAA Division 1 soccer players were recruited. BSIPs of the shank and thigh (mass, COM location, and radius of gyration) were determined using de Leva's method and analysis of whole-body DXA scans. These estimates were used to determine peak knee joint moments and power during the DVJ. Compared to DXA, de Leva's method located the COM more distally in the shank (p = 0.008) and more proximally in the thigh (p < 0.001), and the radius of gyration of the thigh to be further from the thigh COM (p < 0.001). All knee joint moment and power measures were similar between methods. These findings suggest that BSIP estimation may vary between methods, but the impact on joint moment calculations during a dynamic task is negligible.

#11 Effectiveness of community-based football compared to usual care in men with prostate cancer: Protocol for a randomised, controlled, parallel group, multicenter superiority trial (The FC Prostate Community Trial)
Reference: BMC Cancer. 2016 Oct 3;16(1):767.
Authors: Bjerre E, Bruun DM, Tolver A, Brasso K, Krustrup P, Johansen C, Christensen R, Rørth M, Midtgaard J
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Summary: Prostate cancer is the most common non-cutaneous malignancy in men. Today most patients may expect to live years following the diagnosis and may thus experience significant morbidity due to disease progression and treatment toxicity. In order to address some of these problems exercise has been suggested and previously studies have shown improvements of disease specific quality of life and a reduction in treatment-related toxicity. Cohort studies with long term follow up have suggested that physical activity is associated with improved survival in prostate cancer patients. Previously one randomised controlled trial has examined the efficacy of football in prostate cancer patients undergoing androgen deprivation therapy to usual care and reported positive effects on lean body mass and bone markers. Against this background, we wish to examine the effectiveness of community-based football for men diagnosed with prostate cancer. Using a randomised controlled parallel group, multicenter, superiority trial design, two hundred prostate cancer patients will be recruited and randomised (1:1) to either community-based football one hour twice weekly or to a control group. The intervention period will be six months. The primary outcome is quality of life assessed after 12 weeks based on the change from baseline in the Functional Assessment of Cancer Therapy-Prostate questionnaire. Secondary outcomes are change from baseline to six months in quality of life, lean body mass, fat mass, whole body and regional bone markers, as well as physical activity and functional capacity at 12 weeks and six months. Safety outcome variables will be falls resulting in seeking medical assessment and fractures during the six-month period. Football is viewed as a case for non-professional, supervised community-based team sport for promoting long-term physical activity in men diagnosed with prostate cancer. This randomised trial will provide data on effectiveness and safety for men with prostate cancer when football training is delivered in local football clubs.

#12 Comparison of Two Different Modes of Active Recovery on Muscles Performance after Fatiguing Exercise in Mountain Canoeist and Football Players
Reference: PLoS One. 2016 Oct 5;11(10):e0164216. doi: 10.1371/journal.pone.0164216. eCollection 2016.
Authors: Mika A, Oleksy Ł, Kielnar R, Wodka-Natkaniec E, Twardowska M, Kamiński K, Małek Z
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Summary: The aim of this study is to assess if the application of different methods of active recovery (working the same or different muscle groups from those which were active during fatiguing exercise) results in significant differences in muscle performance and if the efficiency of the active recovery method is dependent upon the specific sport activity (training loads). Thirteen mountain canoeists and twelve football players participated in this study. Measurements of the bioelectrical activity, torque, work and power of the vastus lateralis oblique, vastus medialis oblique, and rectus femoris muscles were performed during isokinetic tests at a velocity of 90°/s. Active legs recovery in both groups was effective in reducing fatigue from evaluated muscles, where a significant decrease in fatigue index was observed. The muscles peak torque, work and power parameters did not change significantly after both modes of active recovery, but in both groups significant decrease was seen after passive recovery. We suggest that 20 minutes of post-exercise active recovery involving the same muscles that were active during the fatiguing exercise is more effective in fatigue recovery than active exercise using the muscles that were not involved in the exercise. Active arm exercises were less effective in both groups which indicates a lack of a relationship between the different training regimens and the part of the body which is principally used during training.


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