Long Head Of Biceps Femoris Muscle Research Articles

Smaller Biceps Femoris Aponeurosis Size in Legs with a History of Hamstring Strain Injury.

Biceps femoris long head (BFLH) aponeurosis size was compared between legs with and without prior hamstring strain injury (HSI) using two approaches: within-group (injured vs. uninjured legs of previous unilateral HSI athletes) and between-group (previously injured legs of HSI athletes vs. legs of No Prior HSI athletes). MRI scans were performed on currently healthy, competitive male athletes with Prior HSI history (n=23;≥1 verified BFLH injury; including a sub-group with unilateral HSI history; most recent HSI 1.6±1.2 years ago) and pair-matched athletes with No Prior HSI history (n=23). Anonymized axial images were manually segmented to quantify BFLH aponeurosis and muscle size. Prior unilateral HSI athletes' BFLH aponeurosis maximum width, aponeurosis area, and aponeurosis:muscle area ratio were 14.0-19.6% smaller in previously injured vs. contralateral uninjured legs (paired t-test, 0.008≤P≤0.044). BFLH aponeurosis maximum width and area were also 9.4-16.5% smaller in previously injured legs (n=28) from Prior HSI athletes vs. legs (n=46) of No Prior HSI athletes (unpaired t-test, 0.001≤P≤0.044). BFLH aponeurosis size was smaller in legs with prior HSI vs. those without prior HSI. These findings suggest BFLH aponeurosis size, especially maximum width, could be a potential cause or consequence of HSI, with prospective evidence needed to support or refute these possibilities.

Individual and region-specific hamstring muscles use during a novel Flywheel Russian belt Deadlift exercise

BackgroundDespite the implementation of specific exercises to reduce hamstrings strain injuries (HSI) risk, the incidence has remained unchanged over the past 30 years. Therefore, the purpose of the study was to analyze hamstrings muscle activation induced by a novel Flywheel Russian belt Deadlift (FRD) exercise, together with individual muscle-, region- and limb-specific differences. MethodsThe activation of hamstring muscles before and immediately after a 10 × 10 FRD training session was assessed by the T2 shift technique through functional magnetic resonance imaging, in one international-level filed hockey male player. The individual use of the biceps femoris long head (BFLH) and short head (BFSH), semitendinosus (ST), and semimembranosus (SM) were analyzed, together with the region-specific activation for each muscle. ResultsT2 values significantly increased immediately after exercise in all regions of the hamstring muscles in both dominant and non-dominant lower limb. However, the SM muscle showed a lesser activation, compared to BFLH, BFSH and ST muscles [F(3,106) = 9.557, p < 0.001]. Overall, the most activated muscle by the FRD training session was the biceps femoris (short head +13.8 %, long head, +12.7 %), followed by the ST (+11.3 %), and lastly the SM (+6.9 %). ConclusionThe novel FRD exercise triggers a homogeneous and consistent activation of hamstring muscles. Particularly, the lateral positioning muscles (i.e., BFLH and BFSH) were more activated than the medial positioning muscles (i.e., ST and SM). Therefore, the FRD exercise could enhance training programs to strengthen and activate the hamstring muscles, and specifically, the BFLH, in order to reduce HSI risk.

Acute fatigue-induced alterations in hamstring muscle properties after repeated Nordic hamstring exercises.

This study aimed to investigate the impact of the Nordic hamstring exercises (NHE) on acute fatigue-induced alterations in the mechanical and morphological properties of hamstring muscles. The second aim was to define the blood flow and perfusion after NHE in recreational active volunteers. Twenty-two individuals volunteered to participate in the study. This study investigated fatigue outcomes: rate of perceived exertion (RPE) scale and average force generated during NHE; mechanical properties (stiffness); morphological properties (thickness, pennation angle, and fascicle length), and vascularity index (VI) of the semitendinosus (ST) and biceps femoris long head (BFLH) at baseline, immediately post-exercise and 1-h post-exercise. The NHE fatigue procedure consisted of six bouts of five repetitions. The results showed an increase in thickness and pennation angle of BFLH and ST immediately post-exercise and a decrease in thickness and pennation angle of BFLH and ST 1-h post-exercise. While the fascicle length of BFLH and ST decreased immediately post-exercise and increased 1-h post-exercise. The VI for two muscles increased immediately post-exercise and after 1-h post-exercise. Moreover, we found a relationship between RPE and average force, that is, as RPE increased during NHE, average force decreased. In conclusion, eccentric NHE exercises significantly and acutely affect BFLH and ST. The NHE fatigue protocol significantly affected the mechanical and morphological properties of BFLH and ST muscles, changing their thickness, fascicle length, pennation angle, and VI.

Effect of Weekly Training Frequency With the Nordic Hamstring Exercise on Muscle-Strain Risk Factors in Football Players: A Randomized Trial.

To examine the differences between performing Nordic hamstring exercises once or twice a week on hamstring eccentric strength and other muscle-strain risk factors in high-level football players. In this randomized trial, 32 football players (18-23 y old) completed an 8-week Nordic hamstring exercise training program in 1 of 2 experimental groups: group 1 (once a week; n = 15) and group 2 (twice a week; n = 17). Knee-flexor/extensor peak torques and biceps femoris long-head muscle architecture were assessed through isokinetic dynamometry and ultrasonography, respectively, before and after the training programs. Analysis of covariance, effect sizes (ESs), and t tests for percentage change were used to assess the effect of the 2 interventions on the outcome measures. Group 2 demonstrated higher hamstring concentric peak torque than group 1 posttraining (155-164 vs 149-158N·m; P = .043; ES = 0.27), although there was also a statistical trend for higher hamstring eccentric peak torque (212-234 vs 198-221N·m; P = .098; ES = 0.37), hamstring-to-quadriceps conventional ratio (0.56-0.59 vs 0.54-0.57; P = .089; ES = 0.31), and hamstring-to-quadriceps functional ratio (0.76-0.84 vs 0.71-0.79; P = .076; ES = 0.50). No between-groups differences were found for muscle thickness (P = .864; ES = 0.12), pennation angle (P = .289; ES = 0.18), fascicle length (P = .406; ES = 0.03), and quadriceps concentric peak torque (P = .340; ES = 0.02). Only the Nordic hamstring exercise training program performed twice a week strengthened the hamstrings of high-level football players, while similar changes in muscle architecture occurred with both once- and twice-weekly sessions.

Biceps femoris long head muscle fascicle length does not differ between sexes

ABSTRACT Hamstring strain injury (HSI) rates are higher for males vs. females. This cross-sectional study investigated if inherent differences in biceps femoris long head (BFLH) fascicle length (Lf) exist between recreationally active males and females (i.e., individuals without specific training practice history). Twenty-four young healthy participants (12 males; 12 females) had their BFLH muscle architecture (Lf, pennation angle [θp], and muscle thickness [MT]) measured using B-mode ultrasonography. Eccentric and isometric knee flexion strength were also assessed. BFLH Lf did not differ between sexes when expressed in absolute terms (males, 81.5 ± 14.7 mm; females, 73.6 ± 15.9 mm, P = 0.220, effect size (ES) = 0.52) or relative to femur length (0.140 ≤ P ≤ 0.220, ES = 0.63). Similarly, BFLH θp did not differ between sexes (P = 0.650) but BFLH MT was 18.9% larger for males vs. females (P = 0.024, ES = 0.99). Isometric and eccentric knee flexion strength was greater for males vs. females in absolute terms ([both] P < 0.001, 2.00 ≤ ES ≤ 2.27) and relative to body mass ([both] P < 0.001, 1.93 ≤ ES ≤ 2.13). In conclusion, factors other than BFLH Lf seem likely to be implicated in higher male vs. female HSI rates.

Effect of concentric and eccentric hamstring training on sprint recovery, strength and muscle architecture in inexperienced athletes

ObjectivesTo investigate whether five-weeks of concentric (CON) or eccentric (ECC) hamstring strength training have different effects on recovery from sprint running, eccentric strength and architecture of the biceps femoris long head (BFLH). DesignCohort study. MethodsThirty males (age, 22.8±4.1y; height, 180.1±6.4cm; weight, 85.2±14.6kg) were allocated into either a CON or ECC group, both performing nine sessions of resistance training. Prior to and immediately after the five-week intervention, each participant’s BFLH fascicle length (FL), pennation angle (PA), muscle thickness (MT), peak isometric KF torque and Nordic eccentric strength were assessed. Post-intervention, participants performed two timed sprint sessions (10×80m) 48h apart. Blood samples and passive KF torques were collected before, immediately after, 24h and 48h after the first sprint session. ResultsAfter five-weeks of strength-training, fascicles lengthened in the ECC (p<0.001; d=2.0) and shortened in the CON group (p<0.001; d=0.92), while PA decreased for the ECC (p=0.001; d=0.52) and increased in the CON group (p<0.001; d=1.69). Nordic eccentric strength improved in both ECC (p<0.001; d=1.49) and CON (p<0.001; d=0.95) groups. No between-group differences were observed in peak isometric strength (p=0.480), passive KF torques (p=0.807), sprint performance decrements between sprint sessions (p=0.317) and creatine kinase (p=0.818). ConclusionsDespite inducing significant differences in BFLH muscle architecture, there were no significant between group differences in sprint performance decrements across two sprint sessions.

Progressive Workload Periodization Maximizes Effects of Nordic Hamstring Exercise on Muscle Injury Risk Factors.

Severo-Silveira, L, Dornelles, MP, Lima-e-Silva, FX, Marchiori, CL, Medeiros, TM, Pappas, E, and Baroni, BM. Progressive workload periodization maximizes effects of Nordic hamstring exercise on muscle injury risk factors. J Strength Cond Res 35(4): 1006-1013, 2021-This study aimed to investigate the effect of 2 different Nordic hamstring exercise (NHE) training programs (constant workload vs. progressive workload) on multiple risk factors for hamstring strain injury in high competitive level athletes. Twenty-one premier league rugby union players (∼26 years) were randomized into 1 of 2 experimental groups and completed an 8-week NHE training program: constant training group (CTG) or progressive training group (PTG). Knee flexor/extensor strength and biceps femoris long head (BFLH) muscle architecture were assessed through isokinetic dynamometry and ultrasonography, respectively, before and after the training programs. Increased hamstring concentric (Δ = 8%, p = 0.004, d = 0.42) and eccentric (Δ = 7%, p = 0.041, d = 0.39) peak torques, as well as H:Q conventional (Δ = 7%, p = 0.015, d = 0.54) and functional (Δ = 6%, p = 0.026, d = 0.62) ratios were observed in the follow-up compared with baseline for the PTG group only. Nordic hamstring exercise training significantly increased BFLH muscle thickness (CTG: Δ = 7%, p = 0.001, d = 0.60; PTG: Δ = 7%, p < 0.001, d = 0.54) and fascicle length (CTG: Δ = 8%, p < 0.001, d = 0.29; PTG: Δ = 10%, p < 0.001, d = 0.35) in both groups. Training adaptations on hamstring peak torque (concentric and eccentric) and H:Q ratio (conventional and functional) "likely favor" PTG, whereas changes in BFLH fascicle length "possibly favor" PTG. In conclusion, only PTG enhanced hamstring strength; both NHE training programs increased BFLH muscle thickness and fascicle length, but progressive training generated greater changes on fascicle length than constant training. Medical/coaching staff should be aware that NHE with adequate training periodization with workload progression to maximize its benefits.

Acute hamstring injury in football players: Association between anatomical location and extent of injury-A large single-center MRI report.

To describe in detail the anatomic distribution of acute hamstring injuries in football players, and to assess the relationship between location and extent of edema and tears, all based on findings from MRI. Retrospective observational study. We included 275 consecutive male football players who had sustained acute hamstring injuries and had positive findings on MRI. For each subject, lesions were recorded at specific locations of the hamstring muscles, which were divided into proximal or distal: free tendon, myotendinous junction, muscle belly, and myofascial junction locations. For each lesion, we assessed the largest cross-sectional area of edema and/or tears. We calculated the prevalence of injuries by location. The relationships between locations and extent of edema and tears were assessed using a one-sample t-test, with significance set at p<0.05. The long head of biceps femoris (LHBF) was most commonly affected (56.5%). Overall, injuries were most common in the myotendinous junction and in proximal locations. The proximal myotendinous junction was associated with a greater extent of edema in the LHBF and semitendinosus (ST) muscles (p<0.05). Proximal locations in the LHBF had larger edema than distal locations (p<0.05). Distal locations in the ST muscle had larger tears than proximal locations (p<0.05). The proximal myotendinous junction (LHBF and ST muscles) and proximal locations (LHBF muscle) are more commonly affected and are associated with a greater extent of edema in acute hamstring muscle injury. Distal locations (ST muscle), however, seem to be more commonly associated with larger tears.

Accuracy assessment of CKC high-density surface EMG decomposition in biceps femoris muscle

The aim of this study was to assess the accuracy of the convolution kernel compensation (CKC) method in decomposing high-density surface EMG (HDsEMG) signals from the pennate biceps femoris long-head muscle. Although the CKC method has already been thoroughly assessed in parallel-fibered muscles, there are several factors that could hinder its performance in pennate muscles. Namely, HDsEMG signals from pennate and parallel-fibered muscles differ considerably in terms of the number of detectable motor units (MUs) and the spatial distribution of the motor-unit action potentials (MUAPs). In this study, monopolar surface EMG signals were recorded from five normal subjects during low-force voluntary isometric contractions using a 92-channel electrode grid with 8 mm inter-electrode distances. Intramuscular EMG (iEMG) signals were recorded concurrently using monopolar needles. The HDsEMG and iEMG signals were independently decomposed into MUAP trains, and the iEMG results were verified using a rigorous a posteriori statistical analysis. HDsEMG decomposition identified from 2 to 30 MUAP trains per contraction. 3 ± 2 of these trains were also reliably detected by iEMG decomposition. The measured CKC decomposition accuracy of these common trains over a selected 10 s interval was 91.5 ± 5.8%. The other trains were not assessed. The significant factors that affected CKC decomposition accuracy were the number of HDsEMG channels that were free of technical artifact and the distinguishability of the MUAPs in the HDsEMG signal (P < 0.05). These results show that the CKC method reliably identifies at least a subset of MUAP trains in HDsEMG signals from low force contractions in pennate muscles.

The effects of aponeurosis geometry on strain injury susceptibility explored with a 3D muscle model

In the musculoskeletal system, some muscles are injured more frequently than others. For example, the biceps femoris longhead (BFLH) is the most commonly injured hamstring muscle. It is thought that acute injuries result from large strains within the muscle tissue, but the mechanism behind this type of strain injury is still poorly understood. The purpose of this study was to build computational models to analyze the stretch distributions within the BFLH muscle and to explore the effects of aponeurosis geometry on the magnitude and location of peak stretches within the model. We created a three-dimensional finite element (FE) model of the BFLH based on magnetic resonance (MR) images. We also created a series of simplified models with a similar geometry to the MR-based model. We analyzed the stretches predicted by the MR-based model during lengthening contractions to determine the region of peak local fiber stretch. The peak along-fiber stretch was 1.64 and was located adjacent to the proximal myotendinous junction (MTJ). In contrast, the average along-fiber stretch across all the muscle tissue was 0.95. By analyzing the simple models, we found that varying the dimensions of the aponeuroses (width, length, and thickness) had a substantial impact on the location and magnitude of peak stretches within the muscle. Specifically, the difference in widths between the proximal and distal aponeurosis in the BFLH contributed most to the location and magnitude of peak stretch, as decreasing the proximal aponeurosis width by 80% increased peak average stretches along the proximal MTJ by greater than 60% while slightly decreasing stretches along the distal MTJ. These results suggest that the aponeurosis morphology of the BFLH plays a significant role in determining stretch distributions throughout the muscle. Furthermore, this study introduces the new hypothesis that aponeurosis widths may be important in determining muscle injury susceptibility.