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To record the time-loss injuries of female rink hockey players and describe the affected region, tissue, and onset of injury. Cross-sectional survey study. First (Ok Liga) and Second (Plata) division clubs. Participants: 280 player-seasons. Incidence of overall, training, and match injuries (number of injuries per 1000 h) from two seasons. A total of 229 injuries occurred in 56,438 h of exposure. The overall incidence was 4 injuries per 1000 h (4/1000 h), with a significantly higher rate of injuries during matches (15.2/1000 h) compared to training sessions (2.6/1000 h) (p < 0.001). Injuries affecting the lower limb were the most common (2.3/1000 h), followed by upper limb (1.2/1000 h), and head/trunk (0.6/1000 h). The tissue with the highest incidence of injury was the muscle/tendon (1.3/1000 h), followed by the ligament (0.8/1000 h). Around one in every three injuries (31%) affected either the thigh or hip/groin (73 injuries). The injury incidence in elite female rink hockey is moderate and occurs mainly during match sessions. Preventative measurements should be implemented in rink hockey with a special concern for injuries affecting the thigh, and hip/groin. • Injury incidence is moderate in female rink hockey. • One third of the injuries affect the thigh and hip/groin. • Most injuries were of moderate severity. [ABSTRACT FROM AUTHOR]

Hamstring strain injuries (HSI) are a common occurrence in athletics and complicated by high rates of reinjury. Evidence of remaining injury observed on magnetic resonance imaging (MRI) at the time of return to sport (RTS) may be associated with strength deficits and prognostic for reinjury, however, conventional imaging has failed to establish a relationship. Quantitative measure of muscle microstructure using diffusion tensor imaging (DTI) may hold potential for assessing a possible association between injury-related structural changes and clinical outcomes. The purpose of this study was to determine the association of RTS MRI-based quantitative measures, such as edema volume, muscle volume, and DTI metrics, with clinical outcomes (i.e., strength and reinjury) following HSI. Spearman's correlations and Firth logistic regressions were used to determine relationships in between-limb imaging measures and between-limb eccentric strength and reinjury status, respectively. Twenty injuries were observed, with four reinjuries. At the time of RTS, between-limb differences in eccentric hamstring strength were significantly associated with principal effective diffusivity eigenvalue λ 1 (r = -0.64, p = 0.003) and marginally associated with mean diffusivity (r = -0.46, p = 0.056). Significant relationships between other MRI-based measures of morphology and eccentric strength were not detected, as well as between any MRI-based measure and reinjury status. In conclusion, this preliminary evidence indicates DTI may track differences in hamstring muscle microstructure, not captured by conventional imaging at the whole muscle level, that relate to eccentric strength. [ABSTRACT FROM AUTHOR]

To investigate the effects of knee flexion angle on peak torque, rate of torque development (RTD) during isometric contraction and hamstring flexibility after hamstring strain injury (HSI). Cross-sectional. Controlled laboratory research. Fourteen male athletes with a history of HSI and 14 athletes without HSI (controls). Hamstring flexibility was evaluated using active knee extension test. Isometric knee flexion peak torque and RTD were determined at 30°, 60°, and 90° of knee flexion measured by an isokinetic dynamometer. Individuals with a history of HSI had statistically significant, moderate deficits in isometric peak torque at 30° of knee flexion (P = 0.037; effect size = 0.55) in the HSI limb than in the uninjured limb, but not at 60° and 90° of knee flexion. In the control group, no significant differences in isometric peak torque at any angle were found between limbs. No differences in peak RTD and flexibility were found between limbs in both groups. Isometric peak torque at 30° of knee flexion was lower in the injured limb than in the uninjured limb. Isometric strength deficits after HSI tended to be affected by lengthened hamstring angles. • Hamstring strain injury (HSI) affected isometric peak torque at different knee angles. • Isometric strength deficits after HSI were found at lengthened hamstring position. • Peak RTD and hamstring flexibility did not differ between limbs in the HSI group. [ABSTRACT FROM AUTHOR]

Hamstring strain injuries (HSI) are a common occurrence in athletics and complicated by limited prognostic indicators and high rates of reinjury. Assessment of injury characteristics at the time of injury (TOI) may be used to manage athlete expectations for time to return to sport (RTS) and mitigate reinjury risk. Magnetic resonance imaging (MRI) is routinely used in soft tissue injury management, but its prognostic value for HSI is widely debated. Recent advancements in musculoskeletal MRI, such as diffusion tensor imaging (DTI), have allowed for quantitative measures of muscle microstructure assessment. The purpose of this study was to determine the association of TOI MRI-based measures, including the British Athletic Muscle Injury Classification (BAMIC) system, edema volume, and DTI metrics, with time to RTS and reinjury incidence. Negative binomial regressions and generalized estimating equations were used to determine relationships between imaging measures and time to RTS and reinjury, respectively. Twenty-six index injuries were observed, with five recorded reinjuries. A significant association was not detected between BAMIC score and edema volume at TOI with days to RTS (p- values ≥ 0.15) or reinjury (p- values ≥ 0.13). Similarly, a significant association between DTI metrics and days to RTS was not detected (p- values ≥ 0.11). Although diffusivity metrics are expected to increase following injury, decreased values were observed in those who reinjured (mean diffusivity, p = 0.016; radial diffusivity, p = 0.02; principal effective diffusivity eigenvalues, p- values = 0.007–0.057). Additional work to further understand the directional relationship observed between DTI metrics and reinjury status and the influence of external factors is warranted. [ABSTRACT FROM AUTHOR]

Objectives To evaluate strength and flexibility measures pre- and post- Australian Football (AF) competition to determine their potential utility as secondary prevention measures. Design Cohort study. Setting Semi-professional AF club. Participants Ten male AF athletes (mean ± SD; age, 21.3 ± 2.2 years; height, 186.1 ± 6.3 cm; weight, 83.5 ± 8.6 kg). Main Outcome Measures Maximal unilateral isometric knee flexion strength performed in 45 degrees of hip flexion and 30 degrees of knee flexion, flexibility measures of hip and knee extension and ankle dorsiflexion. All outcome measures were evaluated pre-match to determine baseline measurements and repeated acutely post-match and at 26, 50 and 74 h following. Comparisons were made between baseline measures and all other time points. Results Knee flexion strength was significantly reduced at a group level acutely (−122.8N, 95%CI −156.2 to −89.4, p  = 0.000) and at 26 h (−89.6N, 95%CI −122.9 to −56.2, p  = 0.000) following competition. Hamstring flexibility was significantly reduced at all time periods following competition (all p  < 0.05), however these values were not clinically meaningful. Conclusions Knowledge that unilateral isometric knee flexion strength returns to pre-competition levels by 50 h following match-play in AF athletes is valuable for planning recovery time frames and may inform implementation of secondary prevention strategies. [ABSTRACT FROM AUTHOR]

Hamstring strain injuries are common in sprint-based activities and multifactorial. One of the main risk factors is the deficit of hamstring eccentric strength, which is not easily assessed in field conditions. Therefore, a new ergometer named "Hamtech" has been developed to accurately and practically assess hamstring force output. The aim of this study was to test the reproducibility of this novel ergometer during maximal isometric and eccentric contractions. Thirteen soccer players (age: 20.7 ± 1.6 years; stature: 178.1 ± 4.9 cm; body mass: 72.1 ± 6.3 kg) were recruited. After two familiarization sessions, hamstring force production was recorded during maximal isometric and eccentric contractions using the Hamtech. The coefficients of variations and intra-class correlations coefficients were used to quantify reproducibility. This ergometer allows reproducible measurements of unilateral (isometric + eccentric) and bilateral (eccentric) peak force. However, the reproducibility was moderate to good (unilateral) and poor (bilateral) for the knee angle at the eccentric peak force. A good reproducibility was observed for the rate of force development at 200-ms during maximal isometric contractions. The Hamtech offers a simple and reproducible solution to measure hamstring force production during isometric and eccentric contractions. The use of unilateral hamstring muscles at long muscular length might provide a valuable alternative to the classical bilateral condition to assess the hamstring force production. [ABSTRACT FROM AUTHOR]

Hamstring strain rehabilitation programs with an eccentric bias are effective but have a low adherence rate. Post-stretch isometric (PS-ISO) contractions which incorporate a highly controlled eccentric contraction followed by an isometric contraction resulting in elevated torque during following stretch, compared with isometric contractions at the same joint angle. This study measured torque, activation and musculotendinous unit behaviour of the hamstrings during PS-ISO contractions of maximal and submaximal levels using two stretch amplitudes. Ten male participants (24.6 years ± 2.22 years) completed maximal and submaximal baseline isometric contractions at 90°, 120° and 150° knee flexion and PS-ISO contractions of maximal and submaximal intensity initiated at 90° and 120° incorporating active stretch of 30° and 60° at 60°·s-1. Torque and muscle activation of the knee flexors were simultaneously recorded. Musculotendinous unit behaviour of the biceps femoris long head was recorded via ultrasound during all PS-ISO contractions. Compared with baseline, torque was 8% and 39% greater in the maximal and submaximal PS-ISO conditions respectively with no change in muscle activation. The biceps femoris long head muscle lengthened during all PS-ISO contractions. PS-ISO contractions may be beneficial where the effects of highly controlled eccentric contractions and elevated isometric torque are desired, such as hamstring rehabilitation. [ABSTRACT FROM AUTHOR]