Agreement between isokinetic eccentric hamstring strength, Nordic hamstring strength and Nordic break-point angle in a sample of trained and healthy individuals.

Different eccentric strength assessments are used to identifying the risk of hamstring injury in athletes. However, there is scarce information to determine the association between Nordic-based measurements and the gold standard measurement of eccentric hamstring strength in an isokinetic dynamometer. To investigate the relationship of different measures of eccentric hamstring strength (break-point angle and eccentric strength during Nordic exercise) with eccentric hamstring peak torque measured with an isokinetic dynamometer. Forty-six participants volunteered to participate in this study. Eccentric peak force in the Smart-Nordic System and break-point angle measured as trunk lowering at >20°/s and >150°/s2 during the Nordic exercise via high-frequency video-analysis were compared to eccentric hamstring peak torque in an isokinetic dynamometer set to produce knee extension at 30°/s. There was a moderate association between peak eccentric strength with the Smart-Nordic and isokinetic eccentric hamstring peak torque (r = -0.65, p < 0.001, 95%CI = [-0.76-(-0.50)]). The association between Nordic break-point angle measured at 20°/s (r = 0.49, p < 0.001, 95%CI = [0.30-0.64]) and at 150°/s2 (r = 0.52, p < 0.001, 95%CI = [0.33-0.66]) presented statistically significant but lower associations with isokinetic eccentric hamstring peak torque. All Nordic-based measurements presented acceptable associations with the gold standard isokinetic eccentric hamstring peak torque. However, peak eccentric force measured on the Smart-Nordic device had a better agreement with eccentric peak torque measured with an isokinetic dynamometer than the video-based measurements.Highlights Peak eccentric force measured on the isometric strain-gauges device had a better agreement with eccentric hamstring peak torque measured with an isokinetic dynamometer than the break-point angle.The Nordic-based measurements are an alternative cost-effective method to assess eccentric muscle strength and weakness when the access to isokinetic dynamometry is not feasible.Caution should be taken with certain variables such as participants body mass, hip position and movement speed when interpreting the results of Nordic-based measurements.

Adductor squeeze test and groin injuries in elite football players: A prospective study.

OBJECTIVE: To examining the relationship between hip adductor strength and groin injury incidence during the competitive season of professional football teams. DESIGN: Prospective Cohort study. SETTING: Controlled laboratory environment. PARTICIPANTS: Seventy-one players volunteered to participate. MAIN OUTCOME MEASURES: In the pre-season, maximal hip adductor strength was measured by means of the isometric adductor squeeze test. Hip adductor strength, normalized by body mass, was compared between players who suffered a groin injury (n = 18) vs uninjured players (n = 53). Risk ratios (RR) were used to evaluate the likelihood of players to suffer this type of injury. RESULTS: Most of the reported groin injuries occurred during competitive matches (5.5 per 1000 match hours). Maximal isometric hip adductor strength was lower in the groin-injured group compared with their uninjured counterparts (429.8 ±â€¯100 vs 564 ±â€¯58.7 N, d = -1.58 and 5.40 ±â€¯1.27 vs 7.71 ±â€¯0.89 N/kg, d = -1.88, respectively). Results revealed that values of maximal isometric adductor strength lower than 465.33 N increased the probability to suffer a groin injury by 72%. Furthermore, values of force relative to body mass lower than 6.971 N/kg increased the probability to suffer a groin injury by 83%. CONCLUSION: The assessment of Hip adductor strength, in addition to other measurements, might help practitioners to determine the probability of suffering an overuse groin injuries in elite football players.

Comparison of hip extension and rotation ranges of motion in young elite tennis players with and without history of low back pain.

BACKGROUND: Although low back pain (LBP) is known to be multi-factorial, certain studies have suggested that a deficit in hip extension and rotation range of motion (ROM) may be associated with LBP in athletes. OBJETIVE: The purpose of this study was to compare hip extension and rotation ROMs in elite tennis players with and without a history of LBP. METHODS: Forty-two male and 22 female young elite tennis players completed this study. Participants were divided into two groups: (1) 32 with history of LBP and (2) 32 without history of LBP. Descriptive measures of passive hip extension and rotation ROMs of the dominant and non-dominant limbs were taken. Active hip rotation ROMs were also assessed. Magnitude-based inferences on differences between groups and legs were made by standardizing differences. RESULTS: The inter-group statistical analysis reported no significant differences (p> 0.05; trivial effect with a probability higher than 95%; d⩽ 0.4) in any ROM measure analyzed. Further, neither LBP group nor control group reported significant bilateral or side-to-side differences (p> 0.05; trivial effect with a probability higher than 99%; d< 0.3) between legs regarding hip extension and rotation ROM measures. CONCLUSION: No relationship between hip extension and rotation ROM and history of LBP was found.

A COMPARATIVE STUDY OF PASSIVE SHOULDER ROTATION RANGE OF MOTION, ISOMETRIC ROTATION STRENGTH AND SERVE SPEED BETWEEN ELITE TENNIS PLAYERS WITH AND WITHOUT HISTORY OF SHOULDER PAIN.

BACKGROUND: Glenohumeral internal rotation deficit and external rotation strength have been associated with the development of shoulder pain in overhead athletes. OBJECTIVE: To examine the bilateral passive shoulder rotational range of motion (ROM), the isometric rotational strength and unilateral serve speed in elite tennis players with and without shoulder pain history (PH and NPH, respectively) and compare between dominant and non-dominant limbs and between groups. STUDY DESIGN: Cohort study. METHODS: Fifty-eight elite tennis players were distributed into the PH group (n = 20) and the NPH group (n = 38). Serve velocity, dominant and non-dominant passive shoulder external and internal rotation (ER and IR) ROM, total arc of motion (TAM: the sum of IR and ER ROM), ER and IR isometric strength, bilateral deficits and ER/IR strength ratio were measured in both groups. Questionnaires were administered in order to classify characteristics of shoulder pain. RESULTS: The dominant shoulder showed significantly reduced IR ROM and TAM, and increased ER ROM compared to the non-dominant shoulder in both groups. Isometric ER strength and ER/IR strength ratio were significantly lower in the dominant shoulder in the PH group when compared with the NPH group. No significant differences between groups were found for serve speed. CONCLUSION: These data show specific adaptations in the IR, TAM and ER ROM in the dominant shoulder in both groups. Isometric ER muscle weakness and ER/IR strength ratio deficit appear to be associated with history of shoulder injuries in elite tennis players. It would be advisable for clinicians to use the present information to design injury prevention programs. LEVEL OF EVIDENCE: 2.

Comparisons of hip strength and countermovement jump height in elite tennis players with and without acute history of groin injuries.

BACKGROUND: Despite the high groin-injury (GI) prevalence in tennis, no studies have assessed the extent to which intrinsic groin injury risk factors, such as hip muscle strength, have recovered in elite tennis players with a history of previous GI. OBJECTIVE: To investigate whether elite tennis players with a history of GI show differences in hip strength and jump height between injured and uninjured limbs and compared with dominant limb in tennis players without history of acute groin-injuries (NGI). DESIGN: Cohort study. PARTICIPANTS: Sixty-one tennis players completed this study: 17 in the GI group and 44 in the NGI. Isometric adductor and abductor hip strength were assessed with a handheld dynamometer, and unilateral counter-movement jump tests were performed on a contact mat connected to an Ergo tester. Paired t-tests were conducted to identify differences between injured and non-injured limbs in the GI group, and independent measures t-tests were conducted to compare between GI and NGI groups. RESULTS: Isometric adductor strength and adductor/abductor strength ratios were lower in the injured limb (16.4% and 20.1%, respectively) compared with uninjured side within the GI group, and lower than the dominant side in the NGI group. No significant differences were found for unilateral jump heights between sides in the GI, nor isometric abductor strength, when comparing GI to NGI groups. CONCLUSIONS: Isometric adductor weakness and adductor/abductor strength ratio deficits suggest that adductor muscle strength is not fully recovered in these athletes, potentially increasing their risk of a repeat groin injury.

Core stability: evaluación y criterios para su entrenamiento / / Core stability: avaliação e critérios para treinamento / Core stability: evaluation and training criteria

El objetivo de este trabajo fue revisar las características de los métodos utilizados para valorar la estabilidad de la zona central del cuerpo (core stability), así como las características más importantes de los programas de ejercicios de estabilización del tronco. Los resultados de la revisión indican que métodos biomecánicos, como la aplicación controlada de cargas o descargas súbitas, el paradigma del asiento inestable y la modelación matemática, han permitido analizar el efecto de numerosos factores sobre la estabilidad del raquis. Por otro lado, los test de campo utilizados habitualmente para valorar la core stability (test de condición muscular, test de equilibrio corporal en apoyo monopodal, test de control postural del raquis lumbar y la pelvis, etc.) presentan limitaciones importantes, principalmente debido a la falta de estudios sobre la validez de estas medidas. Finalmente, existe una gran cantidad de información en relación con la eficacia y la seguridad de los ejercicios de estabilización, pero carecemos de información suficiente sobre otras características de la carga de entrenamiento (AU)

The aim of this study was to review both the characteristics of the tests used to assess core stability and the most important features of trunk stabilization exercise programs. The results of this review suggest that biomechanical methods such as sudden and controlled trunk loading and unloading, unstable sitting paradigm and mathematical modeling, have allowed us to analyze the effect of several factors on spine stability. In addition, field tests commonly used to assess core stability (muscle condition tests, single leg stance balance tests, postural control of lumbar spine and pelvis tests, etc.) have important limitations, mainly due to the absence of studies on the validity of these measurements. Finally, there is a lot of information regarding the effectiveness and safety of the stabilization exercises, but we lack enough information on other training load characteristics (AU)

O objetivo desse trabalho foi revisar as características dos métodos utilizados para avaliar a estabilidade da zona central do corpo ("core estability"), assim como as características mais importantes dos programas de exercícios de estabilização do tronco. Os resultados da revisão indicam que métodos biomecânicos como a aplicação controlada de cargas ou descargas súbitas, o paradigma do assento estável e a modelação matemática, tem permitido analisar o efeito de numerosos fatores sobre a estabilidade da coluna. Por outro lado, os testes de campo utilizados habitualmente para avaliar a estabilidade do core (teste de condição muscular, teste de equilíbrio corporal em apoio monopodal, teste de controle postural da coluna lombar e da pelve, etc.) apresentam limitações importantes, principalmente devido a falta de estudos sobre a validade dessas medidas. Finalmente, existe uma grande quantidade de informação em relação à eficácia e à segurança dos exercícios de estabilização, mas carecemos de informação suficiente sobre outras características da carga de treinamento

Core stability. Concepto y aportaciones al entrenamiento y la prevención de lesiones / / «Core stability». Conceito e contribuições no treinamento e a prevenção de lesões / «Core stability». Concept and contributions to training and injury prevention

En este trabajo presentamos una revisión de la literatura científica sobre la estabilidad de la zona central del cuerpo (core stability) con el objeto de clarificar el significado de este concepto y su relación con el rendimiento y las lesiones deportivas. Los resultados de la revisión indican que el uso del término core stability es ambiguo, existiendo una gran confusión terminológica tanto en la literatura científica como en el ámbito profesional. Diversos estudios biomecánicos y epidemiológicos sugieren que el déficit en el control neuromuscular de la core stability está relacionado con el síndrome de dolor lumbar y lesiones de los miembros inferiores. Sin embargo, a pesar de que los ejercicios de core stability son elementos habituales dentro de los programas de entrenamiento deportivo, no existen evidencias suficientes para establecer una relación clara entre la práctica de estos ejercicios y la mejora del rendimiento en el deporte (AU)

In this work we present a scientific literature review on core stability with the aim of clarifying the meaning of this concept and its relation with sport performance and injury. The results of this review show that the use of the term core stability is ambiguous, as there is a great terminological confusion in both scientific literature and professional fields. Several biomechanical and epidemiological studies suggest that the neuromuscular control deficit of core stability is related to low back pain and lower limb injuries. Nevertheless, despite the fact that core stability exercises are key elements in sport training programs,there isnot enoughevidence to establisha clear relationbetweenthe practice ofthese exercises and the improvement in sport performance (AU)

Neste trabalho apresentamos uma revisão da literatura científica sobre a estabilidade da zona central do corpo (core stability), com o objetivo de esclarecer o significado do conceito e sua relação com o rendimento e lesões desportivas. Os resultados desta revisão indicam que o uso do termo core stability é ambíguo, existindo uma grande confusão terminológica tanto na literatura científica como no âmbito profissional. Diversos estudos biomecânicos e epidemiológicos sugerem que o déficit no controle neuromuscular da core stability está relacionado com a síndrome da dor lombar e lesões dos membros inferiores. No entanto, apesar dos exercícios de core stability serem elementos habituais dentro dos programas de treinamento desportivo, não existem evidências suficientes para estabelecer uma relação clara entre a prática dos exercícios e a melhora do rendimento no esporte (AU)

Mitos y realidades en la tendinopatía rotuliana del deportista. Abordaje desde la evidencia científica / Myths and realities in patellar tendinopathy in the athlete. Scientific evidence based approach

ObjetivoEn este artículo de revisión se pretende contrastar algunos tópicos establecidos sobre la tendinopatía rotuliana del deportista con la evidencia científica actual.Estrategias y selección de estudiosSe ha realizado una búsqueda bibliográfica de los trabajos publicados sobre la patología en la última década (1998–2008) en las siguientes bases de datos: MedLine, Embase, PEDro, ISI Web of Science, Ibecs e IME. Se seleccionaron aquellos trabajos cuyos títulos contenían términos relacionados con aspectos de tratamiento quirúrgico, ejercicio excéntrico o fisiopatología de la tendinosis rotuliana.ConclusionesTras el análisis de esta información se puede afirmar que el ejercicio excéntrico es una de las terapias no invasivas de elección, aunque existe una falta de acuerdo sobre la metodología de su aplicación; se puede afirmar que tras la evaluación de los resultados con el tratamiento quirúrgico éstos son muy heterogéneos; por último, se puede afirmar que existe todavía desconocimiento acerca de los mecanismos por los que el tendón comienza a padecer procesos degenerativos y de los cambios que este hecho conlleva, lo cual genera a su vez mayores expectativas de investigación(AU)

ObjectiveThis article has aimed to compare some established topics on patellar tendinopathy in the athlete with current scientific evidence.Strategies and study selectionA bibliographical search was established to find articles on patellar tendinopathy published in the last decade (1998–2008) within the following data bases: MedLine, Embase, PEDro, ISI Web of Science, Ibecs and IME. Those works whose titles included terms related with aspects of surgical treatment, eccentric exercise, or physiopathology of patellar tendinosis were selected.ConclusionsAfter close analysis of this information, it can be stated that eccentric exercise is one of the important non-invasive form of therapy of choice. However, there is lack of agreement on its methodology application which is found to be very heterogeneous after the evaluation of the results following surgical treatment. Finally, knowledge is still lacking about the mechanisms leading to the onset of a degenerative process of the tendon and of the resulting changes, which generates higher expectations for research(AU)