Hamstring injuries remain prevalent across a number of professional sports. In football, the incidence has even increased by 4% per year at the Champions League level over the last decade. The role ...of muscle strength or strength ratios and their association with risk of hamstring injury remain restricted by small sample sizes and inconclusive results.
The purpose of this study is to identify risk factors for hamstring injury in professional football players in an adequately powered, prospective cohort study. Using both established (isokinetic) and novel (eccentric hamstring test device) measures of muscle strength, we aimed to investigate the relationship between these strength characteristics over the entire range of motion with risk of hamstring injury.
All teams (n=18) eligible to compete in the premier football league in Qatar underwent a comprehensive strength assessment during their annual periodic health evaluation at Aspetar Orthopaedic and Sports Medicine Hospital in Doha, Qatar. Variables included isokinetic strength, Nordic hamstring exercise strength and dynamic hamstring: quadriceps ratios.
Of the 413 players included (68.2% of all league players), 66 suffered a hamstring injury over the two seasons. Only isokinetic quadriceps concentric at 300°/s (adjusted for bodyweight) was associated with risk of hamstring injury when considered categorically. Age, body mass and playing position were also associated with risk of hamstring injury. None of the other 23 strength variables examined were found to be associated with hamstring injury.
The clinical value of isolated strength testing is limited, and its use in musculoskeletal screening to predict future hamstring injury is unfounded.
The incidence and recurrence of hamstrings injuries are very high in sports, posing elevated performance and financial-related costs. Attempts to identify the risk factors involved in predicting ...vulnerability to hamstrings injury is important for designing exercise-based programs that aim to mitigate the rate and severity of hamstrings injuries and improve rehabilitation strategies. However, research has shown that non-modifiable risk factors may play a greater role than modifiable risk factors. Recognizing non-modifiable risk factors and understanding their implications will afford the prescription of better suited exercise programs, i.e., that are more respectful of the individual characteristics. In a nutshell, non-modifiable risk factors can still be acted upon, even if indirectly. In this context, an underexplored topic is how intra and inter- individual anatomic and physiologic variations in hamstrings (e.g., muscle bellies, fiber types, tendon length, aponeurosis width, attachment sites, sex- and age-related differences) concur to alter hamstrings injuries risk. Some anatomic and physiologic variations may be modifiable through exercise interventions (e.g., cross-sectional area), while others may not (e.g., supernumerary muscle bellies). This apparent dichotomy may hide a greater complexity, i.e., there may be risk factors that are partially modifiable. Therefore, we explored the available information on the anatomic variations of the hamstrings, providing a deeper insight into the individual risk factors for hamstrings injuries and contributing with better knowledge and potential applications toward a more individualized exercise prescription.
Quadriceps strength deficits are known for patients with knee osteoarthritis (OA), whereas findings on hamstrings are less clear. The Adaptive Force (AF) as a special neuromuscular function has never ...been investigated in OA before. The maximal adaptive holding capacity (max. isometric AF; AFiso
) has been considered to be especially vulnerable to disruptive stimuli (e.g., nociception). It was hypothesized that affected limbs of OA patients would show clear deficits in AFiso
.
AF parameters and the maximal voluntary isometric contraction (MVIC) of hamstrings were assessed bilaterally comparing 20 patients with knee OA (ART) vs. controls (CON). AF was measured by a pneumatically driven device. Participants were instructed to maintain a static position despite an increasing load of the device. After reaching AFiso
, the hamstrings merged into eccentric action whereby the force increased further to the maximum (AF
). MVIC was recorded before and after AF trials. Mixed ANOVA was used to identify differences between and within ART and CON (comparing 1st and 2nd measured sides).
AFiso
and the torque development per degree of yielding were significantly lower only for the more affected side of ART vs. CON (p ≤ 0.001). The percentage difference of AFiso
amounted to - 40%. For the less affected side it was - 24% (p = 0.219). MVIC and AF
were significantly lower for ART vs. CON for both sides (p ≤ 0.001). Differences of MVIC between ART vs. CON amounted to - 27% for the more, and - 30% for the less affected side; for AF
it was - 34% and - 32%, respectively.
The results suggest that strength deficits of hamstrings are present in patients with knee OA possibly attributable to nociception, generally lower physical activity/relief of lower extremities or fear-avoidance. However, the more affected side of OA patients seems to show further specific impairments regarding neuromuscular control reflected by the significantly reduced adaptive holding capacity and torque development during adaptive eccentric action. It is assumed that those parameters could reflect possible inhibitory nociceptive effects more sensitive than maximal strengths as MVIC and AF
. Their role should be further investigated to get more specific insights into these aspects of neuromuscular control in OA patients. The approach is relevant for diagnostics also in terms of severity and prevention.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Purpose: The purpose of this study was to bring to the attention of orthopedic surgeon community of our new technique of quadruple hamstrings graft in neglected Achilles tendon rupture. Materials and ...Methods: In this technique article we present results of treatment of 3 cases with neglected painful chronic Achilles tendon rupture with no palpable gap using our new surgical technique. Our method uses semitendinosus and gracilis tendon as autograft which are passes through 2 bone tunnels in calcaneum and tied over a button. Results: At least after 1 year each patient was satisfied with result of our treatment. Patients were able to stand on their forefoot without pain. There was no infection or other complications. Conclusions: Our results show that new surgical technique may be use in similar cases and should be evaluated with better analytical studies.
The semitendinosus muscle contains distinct proximal and distal compartments arranged anatomically in series but separated by a tendinous inscription, with each compartment innervated by separate ...nerve branches. Although extensively investigated in other mammals, compartment-specific mechanical properties within the human semitendinosus have scarcely been assessed in vivo. Experimental data obtained during muscle-tendon unit stretching (e.g., slack angle) can also be used to validate and/or improve musculoskeletal model estimates of semitendinosus muscle force. The purpose of this study was to investigate the passive stretching response of proximal and distal human semitendinosus compartments to distal (knee) joint extension. Using two-dimensional shear-wave elastography, we bilaterally obtained shear moduli of both semitendinosus compartments from 14 prone-positioned individuals at 10 knee flexion angles from 90° to 0° (full extension) at 10° intervals. Passive muscle mechanical characteristics (slack angle, slack shear modulus, and the slope of the increase in shear modulus) were determined for each semitendinosus compartment by fitting a piecewise exponential model to the shear modulus-joint angle data. We found no differences between compartments or legs for slack angle, slack shear modulus, or the slope of the increase in shear modulus. We also found that the experimentally determined slack angle occurred at ∼15°-80° higher knee flexion angles compared with estimates from two commonly used musculoskeletal models, depending on participant and model used. Overall, these findings demonstrate that passive shear modulus-joint angle curves do not differ between proximal and distal human semitendinosus compartments and provide experimental data to improve semitendinosus force estimates derived from musculoskeletal models.
We conducted an elastography-based investigation of the passive stretching response of the proximal and distal compartments of the human semitendinosus muscle and found no difference in shear modulus-joint angle curves between compartments. We also found that common musculoskeletal models tend to misestimate semitendinosus slack angle, most likely due to typical model assumptions. These results provide an important step toward a better understanding of semitendinosus passive muscle mechanics and improving computational estimates of muscle force.
This paper addresses if and how a periodic health examination to screen for risk factors for injury can be used to mitigate injury risk. The key question asked is whether it is possible to use ...screening tests to identify who is at risk for a sports injury-in order to address the deficit through a targeted intervention programme. The paper demonstrates that to validate a screening test to predict and prevent sports injuries, at least 3 steps are needed. First, a strong relationship needs to be demonstrated in prospective studies between a marker from a screening test and injury risk (step 1). Second, the test properties need to be examined in relevant populations, using appropriate statistical tools (step 2). Unfortunately, there is currently no example of a screening test for sports injuries with adequate test properties. Given the nature of potential screening tests (where test performance is usually measured on a continuous scale from low to high), substantial overlap is to be expected between players with high and low risk of injury. Therefore, although there are a number of tests demonstrating a statistically significant association with injury risk, and therefore help the understanding of causative factors, such tests are unlikely to be able to predict injury with sufficient accuracy. The final step needed is to document that an intervention programme targeting athletes identified as being at high risk through a screening programme is more beneficial than the same intervention programme given to all athletes (step 3). To date, there is no intervention study providing support for screening for injury risk.
Nordic exercises are considered gold standard and indicated for increasing eccentric strength and injury prevention, however, their application should be focused on various sports disciplines, so the ...objective of this study was to analyze the effects of training on flexibility. of soccer, basketball, athletics, cycling, taekwondo and sport climbing athletes. For this purpose, 60 athletes who met the inclusion criteria were analyzed, with an age of 19±1.8, divided between the control group (31) and the experimental group (29); same that were evaluated in initial and final form with the test of Sit and Reach. A training that included the Nordic exercises was applied for 7 weeks in the experimental group and the control group continued with their established training, later they were evaluated after the mentioned time.
The results obtained show the usefulness of this training to increase flexibility, since a significant increase (P=<0.05) was evi-denced in the experimental group between the initial and final evaluation, unlike the control group ( P=>0.05), however, in climbing and athletics, significant differences (P=<0.05) were obtained after training with Nordic exercises. From these data, it was possible to show that the training allows an increase in flexibility in the trainees, so it is recommended to include them in sports training and treatments where the purpose is to increase this physical capacity, especially in sports such as athletics and climbing where there are demands for range of motion to carry out the sporting gesture.
Los ejercicios nórdicos son considerados estándar de oro e indicados para el aumento de la fuerza excéntrica y la prevención de lesiones, sin embargo, su aplicación debe estar enfocada a diversas disciplinas deportivas, por lo que el objetivo de este estudio fue analizar los efectos del entrenamiento sobre la flexibilidad. de deportistas de fútbol, baloncesto, atletismo, ciclismo, taekwondo y escalada deportiva. Para ello, se analizaron 60 deportistas que cumplieron con los criterios de inclusión, con una edad de 19±1,8, divididos entre el grupo control (31) y el grupo experimental (29); mismos que fueron evaluados en forma inicial y final con el test de Sit and Reach. Se aplicó un entrenamiento que incluía los ejercicios nórdicos durante 7 semanas en el grupo experimental y el grupo control continuó con su entrenamiento establecido, posteriormente fueron evaluados pasado el tiempo mencionado.
Los resultados obtenidos muestran la utilidad de este entrenamiento para aumentar la flexibilidad, ya que se evidenció un aumento significativo (P=<0,05) en el grupo experimental entre la evaluación inicial y final, a diferencia del grupo control (P=>0,05), sin embargo , en escalada y atletismo se obtuvieron diferencias significativas (P=<0,05) tras el entrenamiento con ejercicios nórdicos. A partir de estos datos se pudo evidenciar que el entrenamiento permite un aumento de la flexibilidad en los practicantes, por lo que se recomienda incluirlos en entrenamientos y tratamientos deportivos donde la finalidad sea aumentar esta capacidad física, especialmente en deportes como el atletismo y escalada donde hay demandas de amplitud de movimiento para llevar a cabo el gesto deportivo.
•Gait outcomes are better following primary vs. repeat hamstring lengthening (HSL).•Hamstrings are short and/or slow in primary and repeat HSL before and after surgery.•Recurrent crouch is likely ...caused by factors other than hamstring dysfunction.
Hamstring lengthening surgery (HSL) is often performed to correct crouch gait in patients with cerebral palsy (CP). However, crouch can recur over time, and repeat HSL may be ineffective. One possible reason is that the hamstrings in repeat HSL patients are neither short nor lengthening slowly and would therefore not benefit from HSL.
This study aimed to determine whether the hamstrings are short and/or slow preoperatively only in patients with primary, and not repeat, HSL.
We compared pre- and postoperative dynamic semimembranosus muscle-tendon lengths for children with CP who had primary (N = 15) or repeat (N = 8) HSL to a group of control participants (N = 10). Outcome measures were compared between visits (pre- vs. postoperative) and groups (control, primary HSL, repeat HSL) using mixed model analysis.
Preoperatively, hamstrings were shorter and slower than normal on average in both HSL groups (p < 0.001); all but 3 limbs (primary 26/28, repeat 13/14) had hamstrings that were shorter and/or slower than controls by more than two standard deviations. Postoperative improvements were observed in the primary HSL group for popliteal angle, initial contact knee flexion, minimum stance knee flexion, and dynamic hamstring length (p ≤ 0.001). The repeat HSL group improved only in dynamic hamstring length (p = 0.004) and worsened in passive knee extension (p = 0.01) and minimum hip flexion in stance (p = 0.04). Hamstrings in both surgical groups on average remained shorter and slower than controls postoperatively (p ≤ 0.001).
The fact that repeat HSL is less effective in improving knee motion is not due to a lack of short or slow hamstrings preoperatively. However, in recurrent crouch, short or slow hamstrings do not usually indicate hamstring dysfunction, and correction of other deformities such as rotational malalignment, fixed knee flexion contractures, patella alta, weak calf muscles, and/or loose heelcords should be considered rather than repeat HSL.
Limited studies have compared the muscle activity of the medial and lateral hamstrings as knee flexors with tibial internal and external rotation and hip extensors with hip internal and external ...rotation. In particular, hamstring activity during hip extension with hip rotation has rarely been investigated.
This study aimed to compare the muscle activity of the medial and lateral hamstrings as knee flexors and hip extensors and to compare the activity of these muscles according to tibial rotation during isometric knee flexion and hip rotation during isometric hip extension.
A total of 23 healthy adults participated in the study. The electromyographic (EMG) activity of the hamstrings was measured during maximal isometric knee flexion and maximal isometric hip extension. In addition, tibial rotation was applied actively during maximal isometric knee flexion, whereas hip rotation was applied actively during maximal isometric hip extension.
EMG activity during maximal isometric knee flexion with tibial internal and external rotation was significantly higher than that during maximal isometric hip extension with hip internal and external rotation, respectively. For EMG activity according to tibial and hip rotation, there was no significant difference between tibial internal and external rotation during maximal isometric knee flexion, whereas there was a significant difference between hip internal and external rotation during maximal isometric hip extension.
Hamstring activity was higher for knee flexors than for hip extensors. However, hip rotation during maximal isometric hip extension is an effective intervention for selective muscle activation of the medial and lateral hamstrings.
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