Injuries and illnesses among competitive Norwegian rhythmic gymnasts during preseason: a prospective cohort study of prevalence, incidence and risk factors.

OBJECTIVES: Rhythmic gymnastics is an Olympic sport that demands high training volume from early age. We investigated the extent of, and risk factors for, injuries among competitive Norwegian rhythmic gymnasts. METHODS: One hundred and seven of 133 (80.5%) female rhythmic gymnasts (mean age: 14.5 years (SD 1.6), mean body mass index: 18.9 (SD 2.2)) participated. All gymnasts completed a baseline questionnaire and the 'Triad-Specific Self-Report Questionnaire'. Injuries, illnesses and training hours were recorded prospectively for 15 weeks during preseason using the 'Oslo Sports Trauma Research Center Questionnaire on Health Problems' (OSTRC-H2). RESULTS: Response rate to OSTRC-H2 was 97%. Mean overuse and acute injury prevalence were 37% (95% CI: 36% to 39%) and 5% (95% CI: 4% to 6%), respectively. Incidence was 4.2 overuse injuries (95% CI: 3.6 to 4.9) and 1.0 acute injuries (95% CI: 0.5 to 1.6) per gymnast per year. Overuse injuries in knees, lower back and hip/groin represented the greatest burdens. Previous injury increased the odds of injury (OR 30.38, (95% CI: 5.04 to 183.25)), while increased age (OR 0.61 per year, (95% CI: 0.39 to 0.97)) and presence of menarche (OR: 0.20, (95% CI: 0.06 to 0.71)) reduced the odds of all injuries and substantial injuries, respectively. CONCLUSIONS: Overuse injuries were common among Norwegian rhythmic gymnasts. Younger gymnasts had higher all-injury risk. Gymnasts who were not menstruating had higher substantial injury risk. Injury prevention interventions should start at an early age and focus on preventing knee, lower back and hip/groin injuries.

Studies on Practical Applications of Safe-Fall Control Strategies for Lower Limb Exoskeletons.

Lower limb exoskeletons (LLEs) are susceptible to falls, and users are at risk of head and/or hip injuries. To address concerns regarding the safety of LLE users, optimization techniques were used to study safe-fall control strategies. Simulation results of these studies showed promising performance that leads to head impact avoidance and mitigation of hip impact velocity. The motivation for the current research was to extend the application of previously developed optimization techniques to study more realistic human-LLE fall conditions. We examined a range of feasible fall durations for the human-LLE model and found the optimal fall duration for which the user's safety is maximized. Next, we used a range of coefficients of friction to examine fall strategies on different ground surface conditions. We found that the effectiveness of a safe-fall strategy is higher when falling on less slippery surfaces compared to more slippery ones. The simulation results were implemented in a half-scale physical model of a three-link inverted pendulum, which represented a human-LLE model. Results of our experiments verified that the optimal safe-fall strategy could be implemented in a mechanical test setup. The hip linear velocity at impact was found to have similar values in both the experimental (2.04 m/s) and simulation results (2.09 m/s). Further studies should be conducted with appropriate software and hardware platforms to successfully implement safe-fall strategies in an actual LLE.

A Decade of Hip Injuries in National Collegiate Athletic Association Football Players: An Epidemiologic Study Using National Collegiate Athletic Association Surveillance Data.

CONTEXT: The complex, high-energy nature of football puts players at risk for hip injuries. OBJECTIVE: To analyze National Collegiate Athletic Association (NCAA) Injury Surveillance Program data for men's football hip injuries from 2004-2005 through 2013-2014. DESIGN: Descriptive epidemiologic study. SETTING: National Collegiate Athletic Association football teams. PATIENTS OR OTHER PARTICIPANTS: Data on collegiate football players was provided by the NCAA Injury Surveillance System from 2004-2005 through 2013-2014. MAIN OUTCOME MEASURE(S): The incidence, risk factors, rates, and distribution of hip injuries over the 10-year period from 2004-2005 through 2013-2014 were determined. Rates and distribution of injuries were analyzed by injury type, time loss, event type, time of season, recurrence, mechanism of injury, player position, and if surgery was required. Injury rate ratios were calculated to compare rates between event types and by time of season. RESULTS: A total of 1618 hip injuries occurred during 3 121 380 athlete-exposures (AEs), resulting in an overall hip injury rate of 5.18 per 10 000 AEs. Adductor strains (38.63%) were the most common type, followed by hip-flexor strains (28.55%) and hip contusions (18.23%). Players were 3.56 (95% confidence interval [CI] = 3.19, 3.98) times more likely to sustain a hip injury during competitions compared with practices. They were 2.37 (95% CI = 2.15, 2.62) and 3.56 (95% CI = 2.49, 5.08) times more likely to sustain a hip injury during the preseason than in-season or the postseason, respectively. CONCLUSIONS: During the 10-year period, NCAA football players sustained higher rates of hip injuries during competitions and the preseason. The majority were noncontact injuries, resulted in time loss of less than 6 days, and did not require surgery. The injuries varied with player position and occurred most often to defensive backs. Muscle strains were the most frequent group of hip injuries, while adductor strains, hip-flexor strains, and hip contusions were the most common injury types.

Hip and Core Muscle Injuries in Soccer.

Soccer is the most popular sport in the world and has the fourth highest number of sports injuries. Hip and groin injuries account for 14% of soccer injuries and can be difficult to recognize and treat as they often require a high level of suspicion and advanced imaging. Groin pain can be separated into 3 categories: (1) defined clinical entities for groin pain (adductor-related, iliopsoas-related, inguinal-related [sports hernias/athletic pubalgia], and pubic-related groin pain), (2) hip-related groin pain (hip morphologic abnormalities, labral tears, and chondral injuries), and (3) other causes of groin pain. Conservative approaches are typically the first line of treatment, but operative intervention has been reported to result in higher rates of return to sport in athletes with hip-related and inguinal-related groin pain injuries. In patients with concurrent hip-related and inguinal-related groin pain, the failure to recognize the relationship and treat both conditions may result in lower rates of return to sport. Preseason screening programs can identify high-risk athletes, who may benefit from a targeted prevention program. Further study on exercise therapy, early surgical intervention, and potential biologic intervention are needed to determine the most effective methods of preventing groin injuries in athletes.

Hip and Groin Injuries Among Collegiate Male Soccer Players: The 10-Year Epidemiology, Incidence, and Prevention.

The physical and demanding style of play in soccer places these athletes at an elevated risk for hip and groin injuries. Several studies have examined hip and groin injuries in professional and youth soccer in European countries, but few have involved American counterparts. Hip injury data were analyzed retrospectively from the National Collegiate Athletic Association Injury Surveillance Program for the 2004 to 2014 academic years for collegiate men's soccer. This study found that hip and groin injuries among collegiate male soccer players were most often new injuries (87.8%; n=527) that were noncontact in nature (77.3%; n=464) and resulted in time loss of less than 7 days (67.5%; n=405). Hip injuries were significantly more likely during the pre-season (5.72 per 1000 athlete exposures) relative to in-season (injury proportion ratio, 1.64; 95% confidence interval, 1.39-1.94) and post-season (injury proportion ratio, 1.69; 95% confidence interval, 1.18-2.41). Further, they were more likely in competition relative to practice (injury proportion ratio, 2.33; 95% confidence interval, 1.98-2.74). The most common injuries were adductor strains (46.5%; n=279) followed by hip flexor strains (27.3%; n=164) and hip contusions (10.8%; n=65). Among these injuries, adductor (73.1%; n=204) and hip flexor (59.8%; n=98) strains were more commonly noncontact related and occurred in practice, whereas hip contusions were due to contact and during competition. The study of the complex and lingering nature of hip and groin injuries in soccer players is critical because these injuries not only are prevalent but also have multifactorial risks associated with coexisting pathologies that make them difficult to prevent and treat effectively. [Orthopedics. 2018; 41(6):e831-e836.].

Effect of Hip-Focused Injury Prevention Training for Anterior Cruciate Ligament Injury Reduction in Female Basketball Players: A 12-Year Prospective Intervention Study.

BACKGROUND: Programs to prevent anterior cruciate ligament (ACL) injuries in female basketball players are scarce. Also, ACL injury prevention training that focuses on hip joint function has not been reported. PURPOSE: To determine the effectiveness of a hip-focused ACL injury prevention program in female basketball players. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A prospective intervention study was conducted for 12 years. Incidence rates of ACL injuries were collected in the first 4 years (observation period) from college female basketball players. After the observation period, a hip-focused ACL injury prevention program was implemented for 8 years (intervention period). A total of 309 players (mean ± SD age, 19.6 ± 1.2 years; height, 163.7 ± 5.6 cm; weight, 59.1 ± 5.1 kg; body mass index, 22.0 ± 1.4) were tracked in the observation period and compared with 448 players (age, 19.6 ± 1.1 years; height, 162.6 ± 5.8 cm; weight, 58.0 ± 5.7 kg; body mass index, 21.9 ± 1.5) who participated in the intervention period. Athlete-exposures (AEs), ACL numbers and mechanisms of injury (MOIs), relative risk (RR), absolute risk reduction (ARR), numbers needed to treat (NNT), and compliance were analyzed. RESULTS: There were 16 ACL injuries (13 noncontact MOIs) in the 4-year observation period, whereas 9 ACL injuries (8 noncontact MOIs) were recorded in the 8-year intervention period. The overall ACL injury incidence was 0.25/1000 AEs in the 4-year observation period compared with 0.10/1000 AEs in the 8-year intervention period, respectively. Compared with the 4-year observation period, significant RR reduction was observed (0.38; 95% CI, 0.17-0.87; P = .017) with ARR and NNT of 0.032 (95% CI, 0.027-0.037) and 31.6 (95% CI, 27.1-37.7), respectively, in the 8-year intervention period. The noncontact ACL injury incidence was 0.21 per 1000 AEs during the 4-year observation period compared with 0.08/1000 AEs in the 8-year intervention period, which also showed significant RR reduction (0.37; 95% CI, 0.15-0.92; P = .026), with ARR and NNT of 0.024 (95% CI, 0.020-0.029) and 41.3 (95% CI, 34.6-51.3), respectively. The mean compliance rate during the intervention periods (8 years) was 89%. CONCLUSION: A hip-focused injury prevention program demonstrated significant reduction in the incidence of ACL injury in female collegiate basketball players.

Reduced severity of lumbo-pelvic-hip injuries in professional Rugby Union players following tailored preventative programmes.

OBJECTIVES: The aim of this study was to tailor lumbo-pelvic-hip (LPH) injury reduction programmes in professional rugby union players based on screening data and examine its effectiveness. DESIGN: Prospective case controlled study. METHODS: Twenty-eight professional rugby union players were screened pre- and immediately post- the YO-YO intermittent recovery level 1 test using six hip and groin strength tests (adductor squeeze at 0°, 60° and 90°, prone hip extension, abductor, adductor hand held dynamometry). The changes in hip and groin measures, were analysed using hierarchical cluster analysis. Three clusters emerged and a tailored LPH injury reduction programme was administered for each cluster. In addition, 22 players who were not involved in the initial testing received a generic LPH injury reduction programme and were used as the control. Seasonal information for LPH injury incidence, severity and prevalence were compared to the previous season. RESULTS: The same number of injuries were observed when the prospective injury surveillance data was compared to the previous season, however a reduced injury severity (936days vs 468days), average severity (78±126days vs 42±37days) and prevalence (21% vs 19%) were found. Moreover, LPH injury severity for players who were prescribed a tailored injury reduction programme (209days) were 50days less than players given a generic LPH injury reduction programme (259days). CONCLUSIONS: Our preliminary observations support the effectiveness of grouping players and tailoring intervention based on common group characteristics in reducing the severity of LPH injuries in professional Rugby Union.

Programas de bipedestación para la prevención de la displasia de cadera en niños con síndrome de Down / Standing programs to prevent hip dysplasia in children with Down's syndrome

Objetivo: Valorar cómo influye el uso de los programas de bipedestación en la prevención de la displasia de cadera en una cohorte de niños con síndrome de Down. Material y métodos: Se realizó un estudio retrospectivo a lo largo de 11 años a 76 niños con síndrome de Down que asistieron al Centro de Desarrollo Infantil y Atención Temprana de la Asociación para Personas con Síndrome Down de Murcia. El 21% de los niños (16) presentaban inestabilidad de cadera y el 17% (13) de ellos usaron un programa de bipedestación durante 10 meses de media. Resultados: Ninguno de los niños que usaron el programa de bipedestación desarrollaron displasia de cadera. Conclusiones: Los programas de bipedestación pueden ser eficaces en la prevención de la displasia de cadera en niños con trisomía 21

Objective: To assess the influence of the use of standing programs to prevent hip dysplasia in a cohort of children with Down's syndrome. Material and methods: An 11-year retrospective study of 76 children with Down's syndrome attending the Centre for Child Development and Early Intervention of the Associaton for People with Down's Syndrome in Murcia. Unstable hips were found in 21% (16) of children, and 17% (13) of them used a standing program for an average of 10 months. Results: None of the children that used the standing program developed hip dysplasia. Conclusions: Standing programs may be effective in preventing hip dysplasia in children with trisomy 21

Riesgo de cesárea secundaria tras versión externa / Risk of secondary caesarean section after external version

A partir de los resultados obtenidos en el presente estudio y de los resultados obtenidos en estudios anteriores, se puede concluir que los factores que influyen en el éxito del parto vaginal tras una versión externa exitosa son los mismos que actúan sobre las presentaciones cefálicas primarias. Se necesitarían más estudios para determinar si la versión externa previene la luxación de cadera, y si la utilización de óxido nitroso puede ser de utilidad en el control de las molestias originadas por la maniobra y si mejora la tasa de éxitos (AU)

From the results obtained in the present study and from the results obtained in previous studies, it can be concluded that the factors that influence the success of vaginal delivery after successful external version are the same ones that act on primary cephalic presentations. More studies would be needed to determine whether external version prevents hip dislocation and whether the use of nitrous oxide may be useful in controlling the discomfort caused by the maneuver and if the rate of success improves (AU)

Influence of different safety shoes on gait and plantar pressure: a standardized examination of workers in the automotive industry.

OBJECTIVE: Working conditions, such as walking and standing on hard surfaces, can increase the development of musculoskeletal complaints. At the interface between flooring and musculoskeletal system, safety shoes may play an important role in the well-being of employees. The aim of this study was to evaluate the effects of different safety shoes on gait and plantar pressure distributions on industrial flooring. METHODS: Twenty automotive workers were individually fitted out with three different pairs of safety shoes ( "normal" shoes, cushioned shoes, and midfoot bearing shoes). They walked at a given speed of 1.5 m/s. The CUELA measuring system and shoe insoles were used for gait analysis and plantar pressure measurements, respectively. Statistical analysis was conducted by ANOVA analysis for repeated measures. RESULTS: Walking with cushioned safety shoes or a midfoot bearing safety shoe led to a significant decrease of the average trunk inclination (p<0.005). Furthermore, the average hip flexion angle decreased for cushioned shoes as well as midfoot bearing shoes (p<0.002). The range of motion of the knee joint increased for cushioned shoes. As expected, plantar pressure distributions varied significantly between cushioned or midfoot bearing shoes and shoes without ergonomic components. CONCLUSION: The overall function of safety shoes is the avoidance of injury in case of an industrial accident, but in addition, safety shoes could be a long-term preventive instrument for maintaining health of the employees' musculoskeletal system, as they are able to affect gait parameters. Further research needs to focus on safety shoes in working situations.

The Hip in Ice Hockey: A Current Concepts Review.

Ice hockey is a fast, physical sport with unique associated biomechanical demands often placing the hip in forced and repetitive supraphysiological ranges of motion. Ice hockey players commonly endure and are sidelined by nebulous groin injury or hip pain. Underlying causes can be chronic or acute and extra-articular, intra-articular, or "hip-mimicking." This article serves to review common hip-related injuries in ice hockey. For each, we define the particular condition; comment on risk factors and preventive strategies; discuss key historical, physical examination, and imaging findings; and finally, suggest nonoperative and/or operative treatment plans.

Assessment of Compensated Turnout Characteristics and their Relationship to Injuries in University Level Modern Dancers.

Dancers may compensate alignment at the spine, hip, knees, ankles, and feet to achieve a greater turnout than is available at the hip alone. Such compensations are believed to lead to many of the musculoskeletal injuries experienced by dancers, especially overuse injuries. The aim of this study was to explore the relationship between compensated turnout and injury of the lower extremities and low back. Twenty-two university level modern dancers age 19 to 23 participated. Measurements were taken of active hip external rotation (AHER) prone and functional turnout (FTO) in first position. The difference between FTO and AHER was designated as compensated turnout (CTO). A questionnaire was conducted to gather information about dancers' injuries within the past 2 years. A total of 17 participants (77%) reported experiencing at least one injury in the 24 month period. All dancers compensated turnout. Results revealed a large variability in CTO among participants, ranging from 3° to 72°. Statistical analysis showed a significant relationship (r = 0.45, N = 22, p = 0.04) between CTO and the number of injuries experienced, especially as related to low back pain (r = 0.50, N = 22, p = 0.02). Students with no injury had a CTO mean of 26°, while those with two or more injuries had a CTO mean of 43°. Results contribute to previous studies that have examined the effects of CTO in ballet dancers and further indicate that compensatory patterns of turnout may increase the risk of experiencing more than one injury in university level modern dancers.

Expanding pedestrian injury risk to the body region level: how to model passive safety systems in pedestrian injury risk functions.

OBJECTIVE: Assessment of the effectiveness of advanced driver assistance systems (ADAS) plays a crucial role in accident research. A common way to evaluate the effectiveness of new systems is to determine the potentials for injury severity reduction. Because injury risk functions describe the probability of an injury of a given severity conditional on a technical accident severity (closing speed, delta V, barrier equivalent speed, etc.), they are predestined for such evaluations. METHODS: Recent work has stated an approach on how to model the pedestrian injury risk in pedestrian-to-passenger car accidents as a family of functions. This approach gave explicit and easily interpretable formulae for the injury risk conditional on the closing speed of the car. These results are extended to injury risk functions for pedestrian body regions. Starting with a double-checked German In-depth Accident Study (GIDAS) pedestrian-to-car accident data set (N = 444) and a functional-anatomical definition of the body regions, investigations on the influence of specific body regions on the overall injury severity will be presented. As the measure of injury severity, the ISSx, a rescaled version of the well-known Injury Severity Score (ISS), was used. Though traditional ISS is computed by summation of the squares of the 3 most severe injured body regions, ISSx is computed by the summation of the exponentials of the Abbreviated Injury Scale (AIS) severities of the 3 most severely injured body regions. The exponentials used are scaled to fit the ISS range of values between 0 and 75. RESULTS: Three body regions (head/face/neck, thorax, hip/legs) clearly dominated abdominal and upper extremity injuries; that is, the latter 2 body regions had no influence at all on the overall injury risk over the range of technical accident severities. Thus, the ISSx is well described by use of the injury codes from the same body regions for any pedestrian injury severity. As a mathematical consequence, the ISSx becomes explicitly decomposable into the 3 body regions and so are the risk functions as body region-specific risk functions. The risk functions for each body region are stated explicitly for different injury severity levels and compared to the real-world accident data. CONCLUSIONS: The body region-specific risk functions can then be used to model the effect of improved passive safety systems. These modified body region-specific injury risk functions are aggregated to a new pedestrian injury risk function. Passive safety systems can therefore be modeled in injury risk functions for the first time. A short example on how the results can be used for assessing the effectiveness of new driver assistance systems concludes the article.

Can turnout measurements be used to predict physiotherapist-reported injury rates in dancers?

BACKGROUND: Research has suggested that dancers may be more at risk of injury when they excessively utilise non-hip components of turnout to compensate for deficits in hip external rotation when trying to achieve maximal total turnout. However, recently different measures of turnout have been cited in the literature as well as suggestions for derived variables to account for shortfalls in particular components of turnout. This study aimed to assess whether measurements of turnout can predict the number of injuries (0 or 1 injury, or 2+ injuries) over a 10-month period. METHODS: At the beginning of the academic year, 47 female, full-time, contemporary dance students (mean age 19.9 ± 2.51 yrs; height 1.65 ± 0.05 cm; weight 56.23 ± 6.51 kg) were screened as part of a biannual screening process. Measurements, summed of both legs, were obtained for passive hip external rotation (pER), total passive turnout (TPT), and total active turnout (TAT). From these, three further variables were derived: compensated turnout, muscular turnout, and active ER lag. At the end of 10 months, the dancers' physiotherapist-reported and self-reported injuries were obtained. RESULTS: Binary regression analyses for the six turnout variables identified compensated and muscular values as having significant positive effects. For every 1% increase in compensated and muscular values, there was a corresponding 9% or 8.4% increase in the odds that the dancer would sustain 2 or more injuries compared to 0 or 1 injury. CONCLUSION: Screening compensated and muscular values may be useful to address shortfalls to prevent injuries in the future.

How to prevent cut-out and cut-through in biaxial proximal femoral nails: is there anything beyond lag screw positioning and tip-apex distance?

PURPOSE: Hip perforation is a major complication in proximal femoral nailing. For biaxial nails, knowledge of their biomechanics is limited. Besides re-evaluation of accepted risk factors like the tip-apex distance (TAD), we analysed the influence of anti-rotational pin length. METHODS: We compared 22 hip perforation cases to 50 randomly chosen controls. TAD, lag-screw position, angle between lag-screw and femoral neck axis, lag-screw gliding capacity, displacement and anti-rotational pin length were investigated. RESULTS: Hip perforation was associated with a higher angle of deviation between lag-screw and femoral neck axis (p = 0.001), a lower telescoping capacity of the lag screw (p = 0.02), and higher TAD (p = 0.048). If the anti-rotational pin exceeded a line connecting the tip of the nail and the lag screw (NS line), hip perforation incidence was increased (p = 0.009). Inadequate pin length resulted in an odds ratio of 10.8 for hip perforation (p = 0.001). CONCLUSIONS: In biaxial nails anti-rotational element positioning is underestimated, however, crucial.

Investigation of the safety effects of knee bolster air bag deployment in similar real-world crash comparisons.

OBJECTIVE: The lower extremity is the most frequently injured body region and knee-thigh-hip (KTH) injuries account for half of these injuries. Knee bolster air bags (KBABs) have been incorporated in some vehicles to serve as an additional restraint for the occupant's knees and reduce KTH injuries. To investigate the safety benefits of KBABs, similar frontal crashes with opposing KBAB deployment were selected from the Crash Injury Research and Engineering Network (CIREN) database. METHODS: An 8-point similarity scoring algorithm was used to quantify crash and occupant similarity and select case comparisons. A total of 183 cases without a KBAB were scored for similarity to 9 KBAB cases. These similarity scores were used to select 31 final case comparisons. The effect of KBAB deployment on occupant injury patterns was investigated with a particular focus on KTH injuries. RESULTS: Over half of the occupants exposed to a KBAB sustained no KTH injuries and a reduction in femur fractures was observed in KBAB occupants (P = .036). However, increases in proximal tibia/fibula and foot/ankle fractures were observed in KBAB occupants (P = .022 and .002, respectively). Mildly significant decreases in pelvic fractures and Abbreviated Injury Scale (AIS) 2+ head injuries were observed in the KBAB occupants, supporting the notion that KBABs reduce forward occupant excursion (P = .094 and .055, respectively). Investigation of each case comparison yielded further insight into the reasons for injury pattern differences between cases with opposing KBAB deployment. In addition to KBAB deployment status, differences in occupant factors (age, height, and weight) and crash factors (delta V and belt use) between the cases for a particular comparison could explain variation in injury patterns. CONCLUSIONS: The current study presents a preliminary in-depth qualitative and quantitative assessment of KBAB safety benefits. However, further investigation is recommended to provide conclusive evidence of KBAB effectiveness.

Influence of hip-flexion angle on hamstrings isokinetic activity in sprinters.

CONTEXT: Hamstrings strains are common and debilitating injuries in many sports. Most hamstrings exercises are performed at an inadequately low hip-flexion angle because this angle surpasses 70° at the end of the sprinting leg's swing phase, when most injuries occur. OBJECTIVE: To evaluate the influence of various hip-flexion angles on peak torques of knee flexors in isometric, concentric, and eccentric contractions and on the hamstrings-to-quadriceps ratio. DESIGN: Descriptive laboratory study. SETTING: Research laboratory. PATIENTS AND OTHER PARTICIPANTS: Ten national-level sprinters (5 men, 5 women; age = 21.2 ± 3.6 years, height = 175 ± 6 cm, mass = 63.8 ± 9.9 kg). INTERVENTION(S): For each hip position (0°, 30°, 60°, and 90° of flexion), participants used the right leg to perform (1) 5 seconds of maximal isometric hamstrings contraction at 45° of knee flexion, (2) 5 maximal concentric knee flexion-extensions at 60° per second, (3) 5 maximal eccentric knee flexion-extensions at 60° per second, and (4) 5 maximal eccentric knee flexionextensions at 150° per second. MAIN OUTCOME MEASURE(S): Hamstrings and quadriceps peak torque, hamstrings-to-quadriceps ratio, lateral and medial hamstrings root mean square. RESULTS: We found no difference in quadriceps peak torque for any condition across all hip-flexion angles, whereas hamstrings peak torque was lower at 0° of hip flexion than at any other angle (P < .001) and greater at 90° of hip flexion than at 30° and 60° (P < .05), especially in eccentric conditions. As hip flexion increased, the hamstrings-to-quadriceps ratio increased. No difference in lateral or medial hamstrings root mean square was found for any condition across all hip-flexion angles (P > .05). CONCLUSIONS: Hip-flexion angle influenced hamstrings peak torque in all muscular contraction types; as hip flexion increased, hamstrings peak torque increased. Researchers should investigate further whether an eccentric resistance training program at sprint-specific hip-flexion angles (70° to 80°) could help prevent hamstrings injuries in sprinters. Moreover, hamstrings-to-quadriceps ratio assessment should be standardized at 80° of hip flexion.