Latest research in football - week 35 - 2013

Latest research in football

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 Superior compliance with a neuromuscular training programme is associated with fewer ACL injuries and fewer acute knee injuries in female adolescent football players: secondary analysis of an RCT

Authors: Hägglund M, Atroshi I, Wagner P, Waldén M.
Reference: Br J Sports Med. 2013 Aug 20. doi: 10.1136/bjsports-2013-092644. [Epub ahead of print]
Summary: The purpose was to evaluate team and player compliance with an NMT programme in adolescent female football and to study the association between compliance and acute knee injury rates. A prospective cohort study was based on a cluster randomised controlled trial on players aged 12-17 years with 184 intervention teams (2471 players) and 157 control teams (2085 players). Exposure and acute time loss knee injuries were recorded. Team and player compliance was recorded by the coaches on a player attendance form. The intervention group was divided into tertiles of compliance. Injury rates were compared by calculating rate ratios (RRs) and 95% CIs using exact Poisson tests with the low-compliance tertile as reference. Seasonal compliance trends were analysed using linear regression. Players in the high-compliance tertile had an 88% reduction in the anterior cruciate ligament (ACL) injury rate (RR 0.12, 95% CI 0.01 to 0.85), whereas the rate in the control group players was not significantly different from those in the low-compliance tertile (RR 0.77, 95% CI 0.27 to 2.21). A significant deterioration occurred in team (b=-3.0% per month, 95% CI -5.2 to -0.8) and player (b=-5.0% per month, 95% CI -7.1 to -2.9) compliance over the season. Players with high compliance with the NMT programme had significantly reduced ACL injury rate compared with players with low compliance. Significant deterioration in team and player compliance occurred over the season.

#2 Alcohol consumption and sport: a cross-sectional study of alcohol management practices associated with at-risk alcohol consumption at community football clubs
Authors: Kingsland M, Wolfenden L, Rowland BC, Gillham KE, Kennedy VJ, Ramsden RL, Colbran RW, Weir S, Wiggers JH.
Reference: BMC Public Health. 2013 Aug 16;13(1):762. doi: 10.1186/1471-2458-13-762.
Summary: Excessive alcohol consumption is responsible for considerable harm from chronic disease and injury. Within most developed countries, members of sporting clubs participate in at-risk alcohol consumption at levels above that of communities generally. There has been limited research investigating the predictors of at-risk alcohol consumption in sporting settings, particularly at the non-elite level. The purpose of this study was to examine the association between the alcohol management practices and characteristics of community football clubs and at-risk alcohol consumption by club members. A cross sectional survey of community football club management representatives and members was conducted. Logistic regression analysis (adjusting for clustering by club) was used to determine the association between the alcohol management practices (including alcohol management policy, alcohol-related sponsorship, availability of low- and non-alcoholic drinks, and alcohol-related promotions, awards and prizes) and characteristics (football code, size and location) of sporting clubs and at-risk alcohol consumption by club members. Members of clubs that served alcohol to intoxicated people [OR: 2.23 (95% CI: 1.26-3.93)], conducted 'happy hour' promotions [OR: 2.84 (95% CI: 1.84-4.38)] or provided alcohol-only awards and prizes [OR: 1.80 (95% CI: 1.16-2.80)] were at significantly greater odds of consuming alcohol at risky levels than members of clubs that did not have such alcohol management practices. At-risk alcohol consumption was also more likely among members of clubs with less than 150 players compared with larger clubs [OR:1.45 (95% CI: 1.02-2.05)] and amongst members of particular football codes. The findings of this study suggest a need and opportunity for the implementation of alcohol harm reduction strategies targeting specific alcohol management practices at community football clubs.

#3 Concentric and eccentric strength of trunk muscles in osteitis pubis soccer players
Authors: Sayed Mohammad W, Ragaa Abdelraouf O, Abdel-Aziem AA.
Reference: J Back Musculoskelet Rehabil. 2013 Aug 20. [Epub ahead of print]
Summary: Osteitis pubis refers to a painful, inflammatory condition involving the pubic bones, pubic symphysis, and adjacent structures. So, the aims of the study were to evaluate the strength of trunk muscles of soccer players suffering from osteitis pubis, and to compare the agonist/antagonist ratio of trunk muscles in osteitis pubis athletes with that of healthy athletes. Twenty-five soccer male athletes with osteitis pubis, and 25 healthy soccer athletes. Peak torque/body weight (PT/BW) was recorded from trunk muscles during isokinetic concentric and eccentric contraction modes at a speed of 120°/s for healthy and osteitis pubis soccer players. There was a significant decrease in concentric contraction of back muscles in osteitis pubis group (p=0.01). A significant decrease in eccentric contraction of abdominal muscles was also recorded in osteitis pubis group (p=0.008). Concentric abdominal/back muscles ratio was significantly higher in osteitis pubis group (p=0.016), with no significant difference in eccentric abdominal/back muscles ratio between both groups (p>0.05). Osteitis pubis group displayed concentric weakness of back muscle and eccentric weakness of abdominal muscles that lead to disturbance of the normal concentric abdominal/back ratio.

#4 Incidence and clinical presentation of groin injuries in sub-elite male soccer
Authors: Hölmich P, Thorborg K, Dehlendorff C, Krogsgaard K, Gluud C.
Reference: Br J Sports Med. 2013 Aug 16. doi: 10.1136/bjsports-2013-092627. [Epub ahead of print]
Summary: Groin injuries cause major problems in the football codes, as they are prevalent and lead to prolonged symptoms and high recurrence. The aim of the present study was to describe the occurrence and clinical presentation of groin injuries in a large cohort of sub-elite soccer players during a season. Physiotherapists allocated to each of the participating 44 soccer clubs recorded baseline characteristics and groin injuries sustained by a cohort of 998 sub-elite male soccer players during a full 10-month season. All players with groin injuries were examined using the clinical entity approach, which utilises standardised reproducible examination techniques to identify the injured anatomical structures. The exposure time and the injury time were also recorded. Injury time was analysed using multiple regression on the log of the injury times as the data were highly skewed. Effects are thus reported at relative injury time (RIT). Adductor-related groin injury was the most common entity found followed by iliopsoas-related and abdominal-related injuries. The dominant leg was significantly more often injured. Age and previous groin injury were significant risk factors for sustaining a groin injury. Groin injuries were generally located on the same side as previously reported groin injuries. Adductor-related injuries with no abdominal pain had significantly longer injury times compared to injuries with no adductor and no abdominal pain (RIT 2.28, 95% CI 1.22 to 4.25, p=0.0096). Having both adductor and abdominal pain also increased the injury time significantly when compared to injuries with no adductor and no abdominal pain (RIT=4.56, 95% CI 1.91 to 10.91, p=0.001). Adductor-related groin injury was the most common clinical presentation of groin injuries in male soccer players and the cause of long injury time, especially when combined with abdominal-related injury.

#5 Repeated Sprint and Change-of-Direction Abilities in Soccer Players: Effects of Age Group
Authors: Dellal A, Wong del P
Reference: J Strength Cond Res 27(9): 2504-2508, 2013 doi: 10.1519/JSC.0b013e31827f540c
Summary: The purpose of the present study was to compare the performance in repeated sprint ability (RSA) and repeated changes-of-direction (RCOD) among elite soccer players with different age categories. Forty-nine elite soccer players from the same club and from different age categories (Pro2: n = 8, U19: n = 18, U17: n = 13, and U15: n = 10) participated in this study. Each player was tested in both a RSA straight-line sprints (10 × 20 m with active recovery) and a RCOD test including four 100° COD at every 4 m (10 × 20 m with active recovery). The average time (AT), fastest time (FT), total time (TT), percentage of decrement score (%Dec), and RSA/RCOD index were recorded and calculated during all the RSA and RCOD tests. Results showed significant age group effects on RSA and RCOD parameters (p < 0.01) and RSA/RCOD index parameters (p < 0.01). Compared with other groups, U15 has significant (p < 0.05) higher values in RSA-AT, RSA-FT, RSA-TT, RCOD-AT, RCOD-FT, RCOD-TT, index-AT, index-FT, and index-TT. However, the trend of performance time and RSA/RCOD index was always similar (i.e., U15 > U17 > U19 > Pro2; Pro2 > U19 > U17 > U15) showing an age dependant for RSA and RCOD performance. The %Dec in RSA of U15 and U17 was significantly (p < 0.05) higher than U19 and Pro2, whereas the %Dec in RCOD of U15 was significantly (p < 0.05) higher than U19. In conclusion, the present study showed that the RSA and RCOD are age dependent, and therefore, coaches should plan a specific program differentiating the RSA and RCOD, while the individualized training could begin in U17.

#6 Muscle Lesions and Inflammation in Futsal Players According to Their Tactical Positions
Authors: de Moura N, Borges LS, Santos VC, Joel GB, Bartolon JR, Hirabara SM, Cury/Boaventura MF, Pithon-Curi TC, Curi R, Hatanaka E
Reference: J Strength Cond Res 27(9): 2612–2618, 2013
Summary: Muscle lesions and inflammation in futsal players according to their tactical positions—A futsal player's performance depends on his technical and tactical skills but may be improved by a less harmful inflammatory profile that is better adjusted to his tactical position in the game. Thus, the purpose of this study was to characterize muscle lesion and inflammation in futsal players according to their positions in an official match. The participants in this study were 5 goalkeepers (23 ± 1.2 years old, body mass = 74 ± 2.5 kg, height = 178 ± 3.2 cm, body fat = 13 ± 2%, V[Combining Dot Above]O2max = 40 ± 2 ml·kg−1), 8 defenders (21 ± 1 years, body mass = 69 ± 2 kg, height = 174 ± 1 cm, body fat = 10 ± 2%, V[Combining Dot Above]O2max 42 ± 1 ml·kg−1), 8 wingers (22 ± 1 years, body mass = 68 ± 2 kg, height = 169 ± 3 cm, body fat = 11 ± 2%, V[Combining Dot Above]O2max = 48 ± 1 ml·kg−1), and 8 pivots (25 ± 2 years, body mass 71 ± 2 kg, height 173 ± 2 cm, body fat 10 ± 2%, V[Combining Dot Above]O2max 46 ± 2 ml·kg−1). Blood samples were collected from the participants before and immediately after a match. Muscle damage was detected based on CK and lactate dehydrogenase (LDH) activity. The inflammatory status was evaluated by determining C-reactive protein and cytokines (TNF-α, interleukin [IL]-1β, IL-6, IL-10, and IL-1ra). Goalkeepers showed higher LDH and IL-6 than players occupying other tactical positions, leading to the conclusion that the tactical position of futsal goalkeeper causes more inflammation and muscle damage than other positions. Moreover, this position is usually occupied by athletes with higher body mass and percentage of body fat and lower V[Combining Dot Above]O2max than players in the other positions.

#7 Performance and muscle architecture comparisons between starters and nonstarters in National Collegiate Athletic Association Division I women's soccer
Authors: Jajtner, AR, Hoffman, JR, Scanlon, TC, Wells, AJ, Townsend, JR, Beyer, KS, Mangine, GT, McCormack, WP, Bohner, JD, Fragala, MS, and Stout, JR.
Reference: J Strength Cond Res 27(9): 2355–2365, 2013
Summary: This study compared performance and muscle architecture (MA) changes in starters (S) and nonstarters (NS) during a National Collegiate Athletic Association Division I women's soccer season. Twenty-eight women (19.9 ± 1.1 years; 1.71 ± 0.08 m; 64.7 ± 6.4 kg) were monitored for vertical jump power (VJP), repeated line drills (LDs), 3-dimensional multiple object tracking (3D-MOT), and reaction time (RT) at preseason, midseason, and postseason. Muscle architecture changes using ultrasonography were assessed at preseason and postseason. Comparisons between S (n = 11; 70.0 ± 14.6 min per game) and NS (n = 17; 8.4 ± 8.0 min per game) were performed to make magnitude-based inferences. No differences were seen in VJP during the season in either group. Starters were more likely (81.1%) to decrease LD time than NS, with no differences in fatigue rate. Starters and NS improved 3D-MOT (1.14 ± 0.41 to 1.55 ± 0.43) and RT (0.37 ± 0.05 to 0.34 ± 0.33 seconds), with no differences between groups. Rectus femoris (RF) echo intensity improved (65.57 ± 1.50 to 61.26 ± 1.59) in both groups, with no interactions observed. Cross-sectional area (20.84 ± 3.58 to 21.46 ± 3.66 cm2) increased and pennation angle (PANG) (12.58 ± 2.56 to 11.78 ± 2.03°) decreased for both groups in the vastus lateralis (VL). Muscle architecture comparisons between groups revealed S likely decreased VL muscle thickness (MT) and PANG (81.6 and 79.4%, respectively) and possibly decreased RF MT and PANG (65.7 and 59.4%, respectively) when compared with NS. Results indicate that VJP and LD fatigue rate are not changed during a competitive season, but S become faster than NS. Three-dimensional multiple object tracking and RT improve regardless of playing time. Changes in MA indicate that practices alone provide sufficient stimulus for improving muscle quality during the competitive season.

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