Prevalence of Hamstring Strain Injury Risk Factors in Professional and Under-20 Male Football (Soccer) Players.

CONTEXT: Hamstring strain injury (HSI) is the most prevalent injury in football (soccer), and a few intrinsic factors have been associated with higher injury rates. OBJECTIVE: To describe the prevalence of the main intrinsic risk factors for HSI in professional and under-20 football players. DESIGN: Cross-sectional study. SETTING: Physiotherapy laboratory, Federal University of Health Sciences of Porto Alegre (Brazil). PARTICIPANTS: A total of 101 football players (52 professional and 49 under-20 players). INTERVENTION: An evidence-based testing protocol for screening HSI risk factors. MAIN OUTCOME MEASURES: Anamnesis, ultrasonography of the hamstrings, passive straight-leg raise test, Functional Movement Screen, and isokinetic dynamometry were performed. Eleven HSI risk factors for each leg were assessed, besides the player's age as a systemic risk factor. Reports were delivered to the coaching staff. RESULTS: Professionals had greater prevalence of HSI history compared with under-20 players (40% vs 18%). No between-group differences were found for the other screening tests. Altogether, 30% of players had already sustained at least one HSI; 58% had a history of injuries in adjacent regions; 49% had short biceps femoris fascicles; 66% and 21% had poor passive and active flexibility, respectively; 42% and 29% had deficits in functional movements and core stability, respectively; 7% and 26% presented bilateral imbalance for hamstring concentric and eccentric strength, respectively; 87% and 94% obtained low values for hamstring-to-quadriceps conventional and functional ratios, respectively. Two-thirds of players had 3 to 5 risk factors per leg. None of the players was fully free of HSI risk factors. CONCLUSION: Most football players present multiple risk factors for sustaining an HSI. Hamstring weakness is the most prevalent risk factor, but the teams should also be aware of deficits in flexibility, core stability, functional movements, and hamstring fascicle length.

Effects of low-level laser therapy applied before or after plyometric exercise on muscle damage markers: randomized, double-blind, placebo-controlled trial.

Promising effects of phototherapy on markers of exercise-induced muscle damage has been already demonstrated in constant load or isokinetic protocols. However, its effects on more functional situations, such as plyometric exercises, and when is the best moment to apply this treatment (pre- or post-exercise) remain unclear. Therefore, the purpose of this study was to investigate the effect of low-level laser therapy (LLLT) before or after plyometric exercise on quadriceps muscle damage markers. A randomized, double-blinded, placebo-controlled trial was conducted with 24 healthy men, 12 at pre-exercise treatment group and 12 at post-exercise treatment group. Placebo and LLLT (810 nm, 200 mW per diode, 6 J per diode, 240 J per leg) were randomly applied on right/left knee extensor muscles of each volunteer before/after a plyometric exercise protocol. Muscular echo intensity (ultrasonography images), soreness (visual analogue scale - VAS), and strength impairment (maximal voluntary contraction - MVC) were assessed at baseline, 24, 48, and 72 h post-exercise. Legs treated with LLLT before or after exercise presented significantly smaller increments of echo intensity (values up to 1 %) compared to placebo treatments (increased up to ∼7 %). No significant treatment effect was found for VAS and MVC, although a trend toward better results on LLLT legs have been found for VAS (mean values up to 30 % lesser than placebo leg). In conclusion, LLLT applied before or after plyometric exercise reduces the muscle echo intensity response and possibly attenuates the muscle soreness. However, these positive results were not observed on strength impairment.

ACCURACY OF THE FUNCTIONAL MOVEMENT SCREEN (FMSTM) ACTIVE STRAIGHT LEG RAISE TEST TO EVALUATE HAMSTRING FLEXIBILITY IN SOCCER PLAYERS.

BACKGROUND: Poor flexibility is considered a risk factor for the hamstring strain injury, and the active straight leg raise (ASLR) test proposed as a part of the Functional Movement Screen™ (FMS™) has been used to assess athletes hamstring flexibility. However, the accuracy of this screening test remains undescribed. PURPOSE: To examine the accuracy of the FMS™ ASLR test for assessment of hamstring flexibility in soccer players. STUDY DESIGN: Cross-sectional study. METHODS: One-hundred and one male soccer players (age, 21 ± 3 years; height, 179 ± 7 cm; weight, 75 ± 9 kg) were bilaterally evaluated. All players performed a gold standard test for hamstring flexibility evaluation: the passive straight leg raise (PSLR) test measured using a gravitational inclinometer. All players also performed the ASLR test and were scored using the criteria proposed by the FMS™. RESULTS: Of the 202 lower limbs evaluated, 17.82% scored a 1 on the ASLR [mean passive flexibility: 80.44 ± 14.69 ° (55 °-110 °)], 50.99% scored a 2 on the ASLR [mean passive flexibility = 84.60 ± 10.59 ° (56 °-115 °)], and 31.18% scored a 3 on the ASLR [mean passive flexibility = 92.32 ± 11.53 ° (70 °-120 °)]. Limbs with FMS™ score of 3 presented significantly higher values for passive flexibility than limbs with scores of 1 and 2 (p < 0.05), but there was no significant difference between limbs with scores of 1 and 2 (p > 0.05). CONCLUSION: The score obtained in the FMS™ ASLR test does not satisfactorily stratify the level of hamstring flexibility in soccer players. LEVEL OF EVIDENCE: 3a.

THE FUNCTIONAL MOVEMENT SCREEN (FMS™) IN ELITE YOUNG SOCCER PLAYERS BETWEEN 14 AND 20 YEARS: COMPOSITE SCORE, INDIVIDUAL-TEST SCORES AND ASYMMETRIES.

BACKGROUND: The Functional Movement Screen (FMS™) is a widely used seven-test battery used by practitioners working in sport medicine. The FMS™ composite score (sum of seven tests) in soccer athletes from different competitive levels has been well explored in literature, but the specific movement deficits presented by young high competitive level players remains unclear. PURPOSE: The aim of the present study was to provide a detailed description of the performance of elite young soccer players (age 14-20 years) on the FMS™ testing battery. STUDY DESIGN: Cross-sectional observational study. METHODS: One-hundred and three young soccer players (14-20 years) from a premier league club were assessed by two experienced raters using the FMS™ testing battery. FMS™ composite score, individual-test scores and asymmetries were considered for analysis, and comparisons between age categories were performed. RESULTS: FMS™ composite scores ranged from 9 to 16 points (median=13 points). 82% of the athletes had a composite score ≤14 points, and 91% were classified into the "Fail" group (score 0 or 1 in at least one test). Almost half of athletes (48%) had poor performance (i.e., individual score < 2) in "deep squat" test. Most of athletes in the younger categories (under-15 and under-16) had poor performance in the "trunk stability push-up" test (70%) and in the "rotary stability" test (74%). Asymmetry in at least one of five unilateral FMS™ tests was found in 65% of athletes. CONCLUSION: High-performance young soccer players have important functional deficits, especially in tasks involving deep squat and trunk stability, as well as high prevalence of asymmetry between right and left body side. LEVEL OF EVIDENCE: 3a.

Isokinetic Performance of Knee Flexor and Extensor Muscles in American Football Players from Brazil / Desempenho Isocinético de Flexores e Extensores de Joelho em Jogadores de Futebol Americano do Brasil

Abstract The isokinetic performance of thigh muscles has been related to athletic performance and risk for non-contact injuries, such as anterior cruciate ligament ruptures and hamstring strains. Although isokinetic profile of American football players from United States (USA) is widely described, there is a lack of studies comprising players acting outside the USA. The primary objective of this study was to describe the isokinetic performance of thigh muscles in elite American football players in Brazil. Secondarily, we aimed to compare the playing positions and compare the Brazilian players with high-level athletes from USA. Knee extensor (KE) and flexor (KF) muscles of 72 Brazilian players were assessed through isokinetic tests at 60°∙s-1. KE concentric peak torque was 276±56 N∙m, while KF had concentric and eccentric peak torques of 151±37 N∙m and 220±40 N∙m, respectively. Offensive linemen players presented greater peak torque values than defensive lineman, halfbacks, and wide receivers (all comparisons are provided in the article). Brazilian players had lower scores than USA athletes for KE and KF peak torque values. In addition, a conventional torque ratio (concentric/concentric) lower than 0.6 was found in 76-83% of athletes, and a functional ratio (eccentric/eccentric) below to 1.0 in 94%. Bilateral asymmetry greater than 10% was verified in 26% and 43% of athletes for KE and KF muscles, respectively. Elite players in Brazil present high incidence of strength imbalance in thigh muscles, and they are below USA players in relation to torque production capacity of KE and KF muscles.

Resumo O desempenho isocinético dos músculos da coxa são associados com o desempenho atlético e com o risco de lesões sem contato físico. Apesar do perfil isocinético dos jogadores de futebol americano que atuam nos Estados Unidos (EUA) ser amplamente pesquisado, poucos são os estudos com atletas fora dos EUA. O objetivo primário desse estudo era descrever o desempenho isocinético dos atletas de futebol americano no Brasil. Além disso, buscamos comparar as posições de jogo e comparar os de elite brasileiros e americanos. Os músculos extensores (EXT) e flexores (FLE) de joelho de 72 jogadores brasileiros foram avaliados por testes isocinéticos a 60°∙s-1. O pico de torque concêntrico de EXT foi de 276±56 N∙m, enquanto os FLE tiveram pico de torque concêntrico e excêntrico de 151±37 N∙m e 220±40 N∙m, respectivamente. Jogadores de linha ofensiva apresentaram os maiores picos de torque (todas as comparações constam no artigo). Os jogadores brasileiros apresentaram valores inferiores aos atletas dos EUA para o pico de torque de EXT e FLE. Além disso, uma razão convencional (concêntrico/concêntrico) menor que 0,6 foi observada em 76-83% dos atletas, e uma razão funcional (excêntrico/concêntrico) abaixo de 1,0 foi encontrada em 94% dos atletas. Assimetrias bilaterais superiores a 10% foram verificadas em 26% e 43% dos atletas para EXT e FLE, respectivamente. Os jogadores de elite no Brasil apresentam alta incidência de desequilíbrios de força nos músculos da coxa e estão abaixo dos jogadores norte-americanos em relação à capacidade de produção de torque de EXT e FLE de joelho.