Fascicle Behavior and Muscle Activity of The Biceps Femoris Long Head during Running at Increasing Speeds.

Hamstring strain injuries (HSIs) are prevalent in sports involving high-speed running and most of the HSIs are biceps femoris long head (BFlh) injuries. The primary cause for HSIs during high-speed running remains controversial due to the lack of in vivo measurement of the BFlh muscle behavior during running. Therefore, the purpose of this study was to quantify the muscle-tendon unit (MTU) and fascicle behavior of BFlh during running. Seven college male sprinters (22.14 ± 1.8 years; 177.7 ± 2.5 cm; 70.57 ± 5.1 kg; personal bests in 100m: 11.1 ± 0.2 s) were tested on a motorized treadmill instrumented with two force plate for running at 4, 5, 6m/s. The ground reaction force (GRF), 3D lower limb kinematics, EMG, and ultrasound images of biceps femoris long head (BFlh) in the middle region were recorded simultaneously. BFlh fascicles undergo little length change (about 1 cm) in the late swing phase during running at three submaximal speeds. BFlh fascicle lengthening accounted for about 30% of MTU length change during the late swing phase. BFlh was most active during the late swing and early stance phases, ranging from 83%MVC at a running speed of 4 m/s to 116%MVC at 6 m/s. Muscle fascicles in the middle region of BFlh undergo relatively little lengthening relative to the MTU in the late swing phase during running in comparison to results from simulation studies. These results suggest that there is a decoupling between the fascicle in the middle region and MTU length changes during the late swing phase of running.

Effects of Muscle Architecture on Eccentric Exercise Induced Muscle Damage Responses.

There is a need to investigate the role of muscle architecture on muscle damage responses induced by exercise. The aim of this study was to determine the effect of muscle architecture and muscle length on eccentric exercise-induced muscle damage responses. Eccentric exercise-induced muscle damage was performed randomly to the elbow flexor (EF), knee extensor (KE), and knee flexor (KF) muscle groups with two week intervals in 12 sedentary male subjects. Before and after each eccentric exercise (immediately after, on the 1st, 2nd, 3rd, and 7th days) range of motion, delayed onset muscle soreness, creatine kinase activity, myoglobin concentration and isometric peak torque in short and long muscle positions were evaluated. Furthermore, muscle volume and pennation angle of each muscle group was evaluated before initiating the eccentric exercise protocol. Pennation angle and muscle volume was significantly higher and the workload per unit muscle volume was significantly lower in the KE muscles compared with the KF and EF muscles (p < 0.01). EF muscles showed significantly higher pain levels at post-exercise days 1 and 3 compared with the KE (p < 0.01-0.001) and KF (p < 0.01) muscles. The deficits in range of motion were higher in the EF muscles compared to the KE and KF muscles immediately after (day 0, p < 0.01), day 1 (p < 0.05-0.01), and day 3 (p < 0.05) evaluations. The EF muscles represented significantly greater increases in CK and Mb levels at day 1, 3, and 7 than the KE muscles (p < 0.05-0.01). The CK and Mb levels were also significantly higher in the KF muscles compared with the KE muscles (p < 0.05, p < 0.01 respectively). The KF and EF muscles represented higher isometric peak torque deficits in all the post-exercise evaluations at muscle short position (p < 0.05-0.001) compared with the KE muscle after eccentric exercise. Isometric peak torque deficits in muscle lengthened position was significantly higher in EF in all the post-exercise evaluations compared with the KE muscle (p < 0.05-0.01). According to the results of this study it can be concluded that muscle structural differences may be one of the responsible factors for the different muscle damage responses following eccentric exercise in various muscle groups.

Modeling the effect of static stretching and strengthening exercise in lengthened position on balance in low back pain subject with shortened hamstring: a randomized controlled clinical trial.

BACKGROUND: Hamstring shortening may have negative impacts on function and biomechanics of knee and hip joints and lumbo-pelvic rhythm. Many interventions are believed to correct hamstring to its normal length. There are several reports of impairment in postural control of patients with low back pain. The purpose of this study was to compare the effect of stretching exercise and strengthening exercise in lengthened position of the hamstring muscle on improving the dynamic balance of the person in patients with chronic low back pain with short hamstring muscles. METHODS: Forty-five patients with hamstring shortening who referred to physiotherapy clinic of Kermanshah university of Medical Sciences, Kermanshah, Iran were randomly allocated to the three groups; static stretching (n = 15), strengthening exercise in lengthened hamstring position (n = 15) and control (n = 15). All groups received conventional physiotherapy for low back pain and the two intervention groups received stretching exercise and strengthening exercise in lengthened position programs as well. All groups performed three treatment sessions for a week, a total of 12 sessions. For balance assessment, Y-Balance test was performed for each participant in three reach directions. To determine the important and significant variables, all variables entered a model (Generalized Estimation Equations method). RESULTS: The results indicate that based on GEE model, by controlling other variables, participants of static stretching exercise showed more improvement in balance than control group (ß = 9.58, p-value = 0.014). Also, balance status showed significant improvement in the end of study compared to baseline of the study (ß = 7.71, P-value< 0.001). In addition, the balance in three reach directions improved significantly and the greatest balance improvement was in the anterior reach direction (ß ranged over = 6.16 to 11.59) and the height of patients affected their balance (ß = 0.28, P-value = 0.034). CONCLUSIONS: Group (type of intervention), phase of intervention, reach direction of test (anterior, posteromedial and posterolateral) and height of participants were associated with balance performance. Static stretching exercise was more effective than muscle strengthening exercise in lengthened position for improving dynamic balance in low back pain patients with hamstring tightness. TRIAL REGISTRATION: Iranian Registry of Clinical Trials (I RCT201507258035n2 ). Registered 16th September 2015.

Comparison of Protonics™ Knee Brace With Sport Cord on Knee Pain and Function in Patients With Patellofemoral Pain Syndrome: A Randomized Controlled Trial.

CONTEXT: Protonics™ knee brace has been suggested as an intervention for patients with patellofemoral pain syndrome. However, the effectiveness of this knee brace compared with traditional conservative methods knee rehabilitation is lacking. OBJECTIVE: To compare the effect of Protonics™ knee brace versus sport cord on knee pain and function in patients with patellofemoral pain syndrome. DESIGN: Randomized controlled trial. SETTING: Loma Linda University. PARTICIPANTS: There were 41 subjects with patellofemoral pain with a mean age of 28.8 (5.0) years and body mass index of 25.6 (4.7) kg/m2 participated in the study. INTERVENTION: Subjects were randomized to 1 of 2 treatment groups, the Protonics™ knee brace (n = 21) or the sport cord (n = 20) to complete a series of resistance exercises over the course of 4 weeks. MAIN OUTCOME MEASURES: Both groups were evaluated according to the following clinical outcomes: anterior pelvic tilt, hip internal/external rotation, and iliotibial band flexibility. The following functional outcomes were also assessed: Global Rating of Change Scale, the Kujala score, the Numeric Pain Rating Scale, and the lateral step-down test. RESULTS: Both groups showed significant improvement in the outcome measures. However, the Protonics™ knee brace was more effective than the sport cord for the Global Rating of Change Scale over time (immediate 1.0 [2.1] vs post 2 wk 3.0 [2.2] vs 4 wk 4.6 [2.3] in the Protonics™ brace compared with 0.0 [2.1] vs 1.3 [2.2] vs 3.0 [2.3] in the sport cord, P < .01), suggesting greater satisfaction. CONCLUSIONS: Both study groups had significant improvements in the clinical and functional symptoms of patellofemoral pain. The Protonics™ knee brace group was significantly more satisfied with their outcome. However, the sport cord may be a more feasible and cost-effective method that yields similar results in patients with patellofemoral pain syndrome.

Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship.

The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength was measured in 20 healthy people at four knee joint angles (90°, 70°, 50°, 30°) before and after stretching. One leg received SS, the contralateral received CRS. Both stretching techniques resulted in significant strength loss, which was most apparent at short muscle lengths [SS: P = 0.025; stretching × angle P < 0.001; 11.7% at 90° P < 0.01; 5.6% at 70° nonsignificant (ns); 1.3% at 50° ns; -3.7% at 30° ns. CRS: P < 0.001; stretching × angle P < 0.001; 17.7% at 90°, 13.4% at 70°, 11.4% at 50°, all P < 0.01, 4.3% at 30° ns]. The overall stretch-induced strength loss was greater (P = 0.015) after CRS (11.7%) vs SS (3.7%). The muscle length effect on strength loss was not different between CRS and SS (stretching × angle × stretching technique P = 0.43). Contrary to the hypothesis, CRS did not result in a greater shift in the length-tension relationship, and in fact, resulted in greater overall strength loss compared with SS. These results support the use of SS for stretching the hamstrings.

The anatomy of the motor branches of the sciatic nerve: an anatomical study with clinical implications.

BACKGROUND: The sciatic nerve gave the motor branches supply to: biceps femoris long and short head, semitendinosus, semimembranosus and adductor magnus muscles. The anatomy of these motor branches is highly variable. The aim of this study was to estimate the anatomy and morphometry of hamstring muscles innervation. MATERIALS AND METHODS: The motor branches of the sciatic nerve were dissected from both sides from 20 cadaveric specimens (9 left and 11 right) from the 11 cadavers (4 females and 7 males) at the Department of Anatomy, Jagiellonian University Medical College Cracow. RESULTS: The motor branches of the sciatic nerve length, distance from piriformis muscle and number of all branches that exist from tibial nerve and common fibular nerve were measured. In most cases common fibular nerve gave off one branch to the short head of biceps femoris, in most cases the proximal hamstring tendon was innervated only by the first trunk, the highest number of branches were innervating the semimembranosus and the long head of biceps femoris, the longest branches were coming to the semimembranosus and the shortest to the proximal hamstring tendon CONCLUSIONS: The present study shows that there are various innervation types of the posterior group of thigh muscles. Knowledge of possible innervation patterns could be of utmost value to operators performing surgeries on the posterior region of the thigh.

Comparison of Clinical Characteristics between Responders and Non-Responders to Hamstring Stretching in Individuals with Chronic Low Back Pain.

Background/Objectives: Hamstring muscle (HM) flexibility is frequently compromised in people with chronic low back pain (CLBP), contributing to disability and leading to a less favorable recovery. In a previous article, we presented the results of a study on the immediate effect of passive HM stretching on flexibility in 90 people with CLBP. There was considerable variability in the changes after stretching. The objective of this supplementary analysis was to compare the clinical characteristics of individuals who experienced a significant improvement in flexibility with those who did not. Methods: We fixed a threshold of 7° to indicate an improvement in passive Straight Leg Raise (SLR) angle and differentiate between 'Responders' and 'Non-responders' regarding passive HM stretching. Results: Only body mass index differed between groups; it was significantly smaller in Responders (p = 0.007). The majority of Non-responders experienced workplace accidents, but this was of marginal difference compared to Responders (p = 0.056). Conclusions: Further studies should consider a broader clinical analysis with a larger sample size to understand which factors influence the HM stretching response in CLBP patients.

Stress-strain relationship of individual hamstring muscles: A human cadaver study.

The incidence of hamstring muscle strain varies among muscles, suggesting that the mechanical stresses associated with elongation may differ among muscles. However, the passive mechanical properties of whole human muscles have rarely been directly measured and clarified. This study aimed to clarify the stress-strain relationship of the hamstring muscles using a soft-embalmed Thiel cadaver. The long heads of the biceps femoris (BFlh), semimembranosus (SM), and semitendinosus (ST) muscles were dissected from eight cadavers. The proximal and distal hamstring tendons were affixed to the mechanical testing machine. Slack length was defined as the muscle length at the initial loading point detected upon the application of a tensile load. Muscle length was measured using a tape measure, and the anatomical cross-sectional area (ACSA) of the muscle was measured at the proximal and distal sites using B-mode ultrasonography. In the loading protocol, the muscle was elongated from its slack length to a maximum of 8% strain at an average rate of 0.83 L0/s, and the amount of displacement and tensile load were measured for each muscle. Further, the strain (%, displacement/slack muscle length) and stress (kPa, tensile load/ACSA) were calculated to evaluate the mechanical properties. Two-way repeated-measures analysis of variance (ANOVA) was used to compare stress changes with increasing muscle strain. A significant interaction between the muscle and strain factors was observed with respect to stress. Post-hoc tests revealed higher stresses in the BFlh and SM than in ST after 3% strain (P < 0.01). However, no significant differences were observed between the BFlh and SM groups. At 8% strain, the BFlh, SM, and ST exhibited stresses of 63.7 ± 12.1, 53.7 ± 23.2, and 21.0 ± 11.9 kPa, respectively. The results indicate that the stress changes associated with muscle strain differed among muscles. In particular, the stress applied to the three muscles at the same strain was found to be higher in the BFlh and SM. Thus, these findings suggest that increased mechanical stress during elongation may contribute to the frequent occurrence of muscle strain in BFlh and SM.

Validity of Elastic Imaging Evaluation of Hamstring Muscles With Knee Contracture Using Ultrasound Shear Wave Elastography.

PURPOSE: This study used ultrasound shear wave elastography (SWE) to evaluate the mechanical properties of hamstring muscles from cadaveric specimens with knee flexion contractures. METHODS: Hamstring muscles for tensile testing were harvested from Thiel soft-embalmed cadavers with and without knee flexion contracture. Muscle specimens were mounted on a testing machine. The initial load detected when a tensile load was applied to the distal end was used as the slack length. The cross-sectional areas of the muscle at slack length were measured at the proximal and distal sites using B-mode ultrasonography. Subsequently, the muscle specimen was elongated from the slack length to 8% strain, with the shear modulus measured using SWE. Young's modulus (stress/strain) was calculated based on the displacement and tensile force obtained from the tensile test. RESULTS: Regression analysis showed a significant positive linear relationship between the Young's and shear moduli for all specimens at all the sites (P < 0.01 and coefficient of determination: 0.95-0.99). The Young's and average shear moduli at the proximal and distal sites were higher in all hamstring muscles with contractures than in those without contractures. CONCLUSIONS: SWE can be used to estimate Young's moduli of hamstring muscles with contractures. Muscle specimens with contractures exhibited higher resistance to elongation, thereby indicating that their mechanical properties differed from those of muscles without contractures.

CAN SENSORY DISTURBANCES DUE TO INJURY TO THE INFRAPATELLAR BRANCH OF THE SAPHENOUS NERVE BE PREVENTED BY AN OBLIQUE INCISION?

Objective: To evaluate the incidence of injuries to the infrapatellar branch of the saphenous nerve (IPBSN) after anterior cruciate ligament reconstruction (ACLR) with an oblique incision for hamstring graft harvesting. Methods: In total, 59 knees (from 57 patients) were evaluated in the follow-up of ACLR for six months. We drew a horizontal line parallel to the ground, passing through the most medial portion of the surgical incision and another, perpendicular to the first, starting at the tibial tuberosity (TT). We measured the length and angle of the cut, the distances from its most medial point to the perpendicular line, and from the TT to the horizontal line. Skin sensitivity was tested with a brush and the altered sensitivity area was measured. Patients were asked about difficulties in activities daily of living (ADL). Results: A total of 27 knees (45.7%) had sensory disorders, which persisted until the sixth postoperative month in 92.6% of them. The ADL were compromised in one knee (3.7%). No significant differences were found between the groups with and without changes in sensitivity regarding age, affected side, incision angle, or measured distances. The incision size was larger in the group without alteration in sensitivity. Conclusions: An oblique incision did not avoid IPBSN injuries. This condition rarely compromised the ADL. Level of Evidence II, Lesser Quality Prospective Study.

Objetivo: Avaliar a incidência de lesões do ramo infrapatelar do nervo safeno (RIPNS) na reconstrução do ligamento cruzado anterior (RLCA), com incisão oblíqua para a coleta do enxerto dos isquiotibiais. Métodos: 59 joelhos (57 pacientes) foram avaliados no pós-operatório da RCLA, por seis meses. Traçamos uma linha horizontal paralela ao solo, passando pela porção mais medial da incisão cirúrgica, e outra perpendicular à esta, iniciando na tuberosidade tibial (TT). Medimos o comprimento e a angulação do corte, as distâncias do ponto mais medial do corte à linha perpendicular e outra, da TT, à linha horizontal. A sensibilidade da pele foi testada com um pincel, e a área alterada foi mensurada. Os pacientes foram questionados sobre as dificuldades nas atividades diárias da vida (ADV). Resultados: 27 joelhos (45,7%) apresentaram distúrbios sensitivos, persistentes até o sexto mês pós-operatório em 92,6% deles. As ADV foram comprometidas em um joelho (3,7%). Não houve diferença significante entre os grupos com e sem alterações da sensibilidade, relativamente à idade, ao lado comprometido, ao ângulo da incisão ou às distâncias medidas. O tamanho da incisão foi maior no grupo sem alteração de sensibilidade. Conclusões: Uma incisão oblíqua não evitou lesões no RIPNS. Essa condição raramente comprometeu as ADV. Nível de Evidência II, Estudo Prospectivo de Menor Qualidade.

The Effect of Variations in Knee and Hip Angles on Electromyographic Activity of the Hamstrings and Related Muscles During the Nordic Hamstring Exercise.

Background: The benefit of performing the Nordic Hamstring Exercise (NHE) on an inclined board has been described, however, isometric hamstring activation in different knee and hip angles has not yet been thoroughly explored. Purpose: This study investigated the effect of variations in knee and hip angles during the isometric performance of the NHE on electromyographic activity of the hamstring muscles. Study design: Crossover study. Methods: Thirteen male volunteers performed isometric contractions during the NHE with the knee (30°, 50°, 60°) and the hip (0°, 30°, and 45°) in various angles of flexion on a leg support platform which was inclined at 30°. An electrical goniometer was used to monitor the knee and hip joint angles during 5-s isometric contractions. A multivariate analysis of variance with repeated measures was used to compare normalized electromyographic values of each muscle across different knee and hip angles, followed by pairwise comparisons. Results: The electromyographic activity of the biceps femoris, semitendinosus, and semimembranosus at a knee angle of 30° and hip angle of 0° were significantly higher than those observed with a knee angle of 50° and hip angle of 0°, or a knee angle of 60° and hip angle of 0° (p<0.05). The electromyographic activity of the semimembranosus at a knee angle of 60° and hip angle of 45° was significantly higher than values obtained with knee and hip angles of 60° and 0°, respectively (p<0.05). Conclusions: The results indicate that using a knee flexion of 30° and a hip flexion of 0°, while isometrically performing the NHE on a platform inclined at 30°, may optimize electromyographic activity of the hamstrings. Level of Evidence: 3.

Assessment of arthrogenic quadriceps muscle inhibition by physical examination in the supine position during isometric contraction is feasible as demonstrated by electromyography: a cross-sectional study.

BACKGROUND: Preventing severe arthrogenic muscle inhibition (AMI) after knee injury is critical for better prognosis. The novel Sonnery-Cottet classification of AMI enables the evaluation of AMI severity but requires validation. This study aimed to investigate the electromyography (EMG) patterns of leg muscles in the examination position from the classification during isometric contraction to confirm its validity. We hypothesised that the AMI pattern, which is characterised by quadriceps inhibition and hamstring hypercontraction, would be detectable in the supine position during isometric contraction. METHODS: Patients with meniscal or knee ligament injuries were enrolled between August 2023 and May 2024. Surface EMG was assessed during submaximal voluntary isometric contractions (sMVIC) at 0° extension in the supine position for the vastus medialis (VM) and vastus lateralis (VL) muscles and at 20° flexion in the prone position for the semitendinosus (ST) and biceps femoris (BF) muscles. Reference values for normalisation were obtained from the EMG activity during the gait of the uninjured leg. The Kruskal-Wallis test was used to compare the activation patterns of the muscle groups within the same leg, and the post-hoc tests were conducted using the Mann-Whitney U test and Bonferroni correction. RESULTS: Electromyographic data of 40 patients with knee injuries were analyzed. During sMVIC, the extensor and flexor muscles of the injured leg showed distinct behaviours (P < 0.001), whereas the uninjured side did not (P = 0.144). In the injured leg, the VM differed significantly from the ST (P = 0.018), and the VL differed significantly from the ST and BF (P = 0.001 and P = 0.026, respectively). However, there were no statistically significant differences within the extensor muscle groups (VM and VL, P = 0.487) or flexor muscle groups (ST and BF, P = 0.377). CONCLUSION: AMI was detectable in the examination position suggested by the Sonnery-Cottet classification. The flexor and extensor muscles of the injured leg exhibited distinct activation behaviours, with inhibition predominantly occurring in the quadriceps muscles, whereas the hamstrings showed excitation.

How different knee flexion angles influence the hip extensor in the prone position.

[Purpose] The present study examined the effects of knee flexion angle on hip extensor muscle activity. [Subjects and Methods] Twenty healthy subjects maintained knee flexion angles of 0°, 30°, 60°, 90° and 110° in the prone position and performed maximal voluntary contraction in hip extension. Maximum torque in hip extension at the different angles was measured, and surface electromyogram activities of the gluteus maximus (GM), biceps femoris (BF) and semitendinosus (ST) were recorded and normalized by the maximum voluntary isometric contraction (MVIC). [Results] The maximum torque of the hip extensor showed significant decreases between 0°and 60°, 90° and 110° of knee flexion. The muscle activity of BF was significantly high at 0°, and GM showed a significantly higher activity than both BF and ST at 60°, 90°and 110° of knee flexion. [Conclusion] The maximum torque in hip extension and muscle activities of BF and ST were significantly high at 0° but they decreased at knee flexion angles of more than 60°. Therefore, we consider that more than 60° of knee joint flexion is required to increase GM activity, and to reduce the muscle activities of BF and ST.

Effectiveness of muscle strengthening exercises on the clinical outcomes of patients with knee osteoarthritis: A randomized four-arm controlled trial.

Background: Knee osteoarthritis (OA) is one of the major causes of dysfunction that reduces patients' quality of life. The aim of current study was to investigate the effectiveness of muscle strengthening exercises on the clinical outcomes of patients with knee OA. Methods: We conducted a single-blind clinical trial on 96 patients with mild to moderate knee osteoarthritis. Patients were randomly assigned to 4 groups with 24 patients and followed-up for 8 weeks. Quadriceps, hamstring and both hamstring and quadriceps strengthening exercises were received by the first (G1), second (G2) and third (G3) groups, respectively. The fourth group (G4) was the control group and did not receive any intervention. The main outcome variables were pain, physical function and morning stiffness. This study was retrospectively registered at irct.ir (Iranian Registry of Clinical Trials) with the code IRCT20220206053950N2, 2022-09-07. Results: Our findings demonstrated a significant impact of interventions on VAS score, pain, and stiffness (All, p < 0.001). Nonetheless, the effect of interventions was not significant for physical function (P = 0.78). After adjusting for the potential confounders, similar results were observed. Besides, the results of Dunnett post hoc test showed that either G1 or G3 had the most decrease in VAS and WOMAC-morning stiffness scores compared to G2 and G4. Conclusion: Based on the evidence from the present study, we can recommend a combination of quadriceps and hamstring strengthening exercises as the most effective intervention to reduce pain and morning stiffness in patients with OA.

Comparison of instrument-assisted soft tissue mobilization and proprioceptive neuromuscular stretching on hamstring flexibility in patients with knee osteoarthritis.

Background: The association between hamstring tightness and knee osteoarthritis (KOA) is significant because tight hamstrings can put more strain on the knee joint, reduce its range of motion, and cause compensatory movements that worsen the KOA. Objective: To compare the effects of instrument-assisted soft tissue mobilization (IASTM) and proprioceptive neuromuscular (PNF) on hamstring flexibility in patients with KOA. Methods: Data for the randomized controlled trial (NCT05110326) was collected from n = 60 participants randomly divided into group A received IASTM and group B received PNF stretching. In group A, the therapist made 30 strokes gentle strokes with the tool from the origin to the insertion while holding the plane at a 45-degree angle over the treatment area. In group B, PNF stretching was done with three repetitions and 10 seconds rest between each, after isometric contraction of the hamstring muscle using approximately 50% of their maximum strength, holding it for 8 seconds, and then releasing it. A 30-minute session was given to each patient three times per week and was given for 6 weeks. Outcome measures were the visual analog scale (VAS) for pain intensity, the active knee extension test (AKET) for hamstring flexibility, and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) for the health status of KOA patients. Results: The study found a significant interaction (p < 0.001) between interventions and time across several measurements. After 6 weeks, both interventions resulted in significant improvements (p < 0.001) across all dependent variables, with group A (IASTM) showing more significant improvement in hamstring flexibility, pain reduction, and health status (p < 0.001) compared to group B (PNF). Conclusions: Both the IASTM technique and PNF stretching resulted in increased hamstring flexibility, decreased pain, and enhanced general health. The IASTM technique, however, showed potential benefits over PNF stretching in terms of flexibility, pain relief, and public health enhancement. Physical therapists and manual therapists may prioritize the usage of the IASTM technique for patients who want to make significant changes in these areas.

Effects of the COVID-19 confinement period on hip strength, flexibility and muscle injury rate in professional soccer players.

OBJECTIVES: This study aimed to examine the effects of COVID-19 confinement on hamstring eccentric strength, hip adduction-abduction strength, and posterior chain flexibility in professional male soccer players. We also aimed to investigate whether muscle strength and flexibility would change when the players returned to play after COVID-19 confinement. METHODS: Thirty professional male soccer (Age; 24.9 ± 4.8 yrs, BMI; 22.7 ± 1.4 kg/m2) players participated in this study. Hamstring eccentric strength, hip abduction-adduction strength and posterior chain flexibility (PCF) were measured before (time 1) and after the home confinement period (time 2) and after return to play (time 3). Repeated measures of ANOVA was used for statistical analysis. RESULTS: PCF decreased from time 1 to time 2 (p = 0.005) but it increased from time 2 to time 3 (p = 0.03). Hamstring eccentric strength decreased from time 1 to time 2 for both dominant (p = 0.002) and non-dominant (p = 0.04) limbs and no difference was observed between time 2 and time 3 (p > 0.05). Hip abductor and adductor strength did not change between time 1 and time 2 (p > 0.05) but they increased from time 2 and time 3 in the dominant limb (p < 0.05). Five players (16%) had muscle injuries including hamstrings and adductors when they returned to play. CONCLUSION: This study showed that 8-week COVID-19 confinement had an adverse effect on hamstring eccentric strength and PCF and 3 players had hamstring muscle injuries when they returned to play. Therefore, soccer players can be at risk of hamstring muscle injuries due to long-term detraining. Hip abductor and adductor strength seem not to be negatively affected by 8-week COVID-19 confinement. However, 2 players had adductor strain when they returned to play.

Comparison Between the Effects of Transfer Energy Capacitive and Resistive Therapy and Therapeutic Ultrasound on Hamstring Muscle Shortness in Male Athletes: A Single-Blind Randomized Controlled Trial.

BACKGROUND: Transfer energy capacitive and resistive (TECAR) therapy (TT) is a newly developed deep heating therapy that can generate heat within tissues through high-frequency wave stimulation. Compared to conventional physiotherapy methods, the application of TT especially in sports rehabilitation is becoming more popular. This study aimed to investigate the comparative effect of TT and therapeutic ultrasound (US) on hamstring muscle shortness. Additionally, the effects of TT with static stretching (SS) were compared with US combined with SS. MATERIALS AND METHODS: Totally, 39 male athletes with hamstring shortness were randomly assigned into three groups: A, B, and C. Group A received 15 minutes of TT plus SS, while Group B received 15 minutes of US with SS, and Group C only performed SS. Hamstring flexibility was measured by active knee extension (AKE), passive knee extension (PKE), and the sit and Reach (SR) tests before the intervention, and following the first, and third treatment sessions. RESULTS: The range of motion of the AKE and PKE, and displacement range in the SR test improved significantly after the first and third sessions in all three groups (P0.0001). The improvement of the three flexibility indices in the TT group was greater than in the other two groups. CONCLUSION: The present study showed that TT could increase the flexibility of hamstring muscles more than US therapy. However, TT in combination with SS had a similar effect to SS alone.

The influence of menstrual cycle on the efficiency of stretching.

BACKGROUND: Muscle stretching has been practiced by people for thousands of years. Its effectiveness is well-proven, but the diversity of the obtained results should prompt a search for causative factors. One of the possible explanations can be hormonal fluctuations, which occur during the menstrual cycle. OBJECTIVES: To assess the influence of menstrual cycle on the efficiency of static stretching of hamstrings with special reference to changes in their length. MATERIAL AND METHODS: A total of 534 young women were recruited for the study, but after applying the inclusion criteria, only 48 of them have been accepted. The inclusion criteria for the study comprised a reduced length of the hamstring muscles and a regular menstrual cycle. The whole study included a twofold examination of hamstring length before and after the stretching (3 × 45 s), performed by a physiotherapist. All the measurements were carried out 3 times in individual phases of the menstrual cycle. RESULTS: Statistically significant influence of static stretching upon the length of hamstring muscle was revealed. A change in the passive knee extension (PKE) test was 13.34% (standard deviation (SD) = 10.97), and in active knee extension (AKE) test it was 8.46% (SD = 9.26). Hamstrings length demonstrated no differences in various phases of the menstrual cycle. CONCLUSIONS: Static stretching is an effective tool for the improvement of the length of the hamstring muscle in young women. However, the effectiveness of stretching in healthy women is not influenced by the menstrual cycle phases.

Influence of Altered Knee Angle on Electromyographic Activity of Hamstring Muscles Between Nordic Hamstring Exercise and Nordic Hamstring Exercise with Incline Slope Lower Leg Board.

Background: Previous studies have shown that performing the Nordic hamstring exercise (NHE) with different board slope angles can affect hamstring activation. However, changes in muscle length with different board slopes can alter joint angles leading to the moment arm (MA) at the knee changing during the NHE. Purpose: This study aimed to investigate the influence of changing muscle length on hamstring electromyographic activity during an isometric NHE, while maintaining an equal moment arm. Study Design: A crossover study design. Methods: Sixteen male volunteers performed two types of conventional NHE, one with knees on the floor (NHE) and one with the legs placed upon an incline slope of a lower leg board (NHEB). To compare between the conventional and inclined NHE, the moment arm at the knee was calculated to be equal by an examiner holding the lower legs at points marked at 77% and 94% of the length of the lower leg. The four sub-groups comprised of: 1) NHE-77%, 2) NHE-94%, 3) NHEB-77%, and 4) NHEB-94%. The hamstring EMG activity was measured at the biceps femoris long head (BFlh) and at the semitendinosus (ST) and related compensatory muscles. The RMS data were normalized as a percentage of the maximum isometric values (normalized EMG [nEMG]). Significant main effects findings were followed up with Tukey's post-hoc test using SPSS software and statistical significance was set at the p < 0.05 level. Results: The BFlh EMG activity values for NHE-77% were significantly higher than those for NHE-94% (p= 0.036) and NHEB-77% (p < 0.001), respectively, while ST during NHE-77% was significantly higher only in NHEB-77% (p < 0.001). In addition, NHEB-94% was significantly greater than NHEB-77% for both BFlh (p < 0.001) and ST (p < 0.001). Conclusion: These results indicate that hamstring electromyographic activity is decreased when the hamstring muscle is lengthened during the Nordic hamstring exercise. Level of Evidence: 3.

Outcomes following surgical management of proximal hamstring tendon avulsions : a systematic review and meta-analysis.

AIMS: Avulsion of the proximal hamstring tendon origin can result in significant functional impairment, with surgical re-attachment of the tendons becoming an increasingly recognized treatment. The aim of this study was to assess the outcomes of surgical management of proximal hamstring tendon avulsions, and to compare the results between acute and chronic repairs, as well as between partial and complete injuries. METHODS: PubMed, CINAHL, SPORTdiscuss, Cochrane Library, EMBASE, and Web of Science were searched. Studies were screened and quality assessed. RESULTS: In all, 35 studies (1,530 surgically-repaired hamstrings) were included. Mean age at time of repair was 44.7 years (12 to 78). A total of 846 tears were acute, and 684 were chronic, with 520 tears being defined as partial, and 916 as complete. Overall, 92.6% of patients were satisfied with the outcome of their surgery. Mean Lower Extremity Functional Score was 74.7, and was significantly higher in the partial injury group. Mean postoperative hamstring strength was 87.0% of the uninjured limb, and was higher in the partial group. The return to sport (RTS) rate was 84.5%, averaging at a return of 6.5 months. RTS was quicker in the acute group. Re-rupture rate was 1.2% overall, and was lower in the acute group. Sciatic nerve dysfunction rate was 3.5% overall, and lower in the acute group (p < 0.05 in all cases). CONCLUSION: Surgical treatment results in high satisfaction rates, with good functional outcomes, restoration of muscle strength, and RTS. Partial injuries could expect a higher functional outcome and muscle strength return. Acute repairs result in a quicker RTS with a reduced rate of re-rupture and sciatic nerve dysfunction. Cite this article: Bone Jt Open 2022;3(5):415-422.