Semitendinosus Research Articles

The Influence of Shoe and Cleat Type on Lower Extremity Muscle Activation in Youth Baseball Pitchers

Background: Baseball pitching is a dynamic movement where the lower extremities generate and sequentially transfer energy to the upper extremities to maximize ball velocity. The need for lower body muscular strength to produce adequate push-off and landing forces has been documented; however, the influence footwear and surface inclination has on muscle activation remains unknown. Objectives: Determine how pitching in molded cleats and turf shoes from a pitching mound and flat ground affects stride-leg muscle activation in youth baseball pitchers while determining percent activation during each pitching phase. Methods: Cross – sectional study analyzing mean muscle activity and percent activation of the vastus medialis, semitendinosus, tibialis anterior, and medial gastrocnemius on the stride-leg of 11 youth baseball pitchers when pitching fastballs. Results: Footwear did not significantly alter vastus medialis or semitendinosus muscle activation (P 0.05). The turf shoe x pitching mound interaction elicited significantly (P 0.05) greater mean muscle activity in the medial gastrocnemius and tibialis anterior from stride foot contact to maximum glenohumeral internal rotation. Molded cleats produced greater activation levels in the tibialis anterior on flat ground from stride foot contact (0.374 ± 0.176 mV) to ball release (0.469 ± 0.150 mV). Conclusion: Findings suggest footwear significantly alters the activity level of the ankle stabilizing musculature. Youth baseball pitchers and coaches should be cognizant of what footwear is worn on a pitching surface. Maximal activation of the tibialis anterior and medial gastrocnemius can ensure the stride leg is adequately stabilized to absorb the momentum generated by trail leg.

In Hamstring Muscles of Patients With Knee Osteoarthritis an Increased Ultrasound Shear Modulus Indicates a Permanently Elevated Muscle Tonus.

BackgroundSome patients with knee osteoarthritis (KOA) show pain, stiffness and limited flexion and extension at the back of the knee, leading to dysfunction and affecting life. This may be related to changes in the biomechanical properties of skeletal muscles. Shear wave elastography (SWE) can detect these changes by measuring muscle shear modulus.AimsTo investigate hamstring muscle shear modulus of healthy people and patients was studied using SWE method, and the correlation analysis between the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score of patients’ subjective feeling and shear modulus of objective quantification was conducted.MethodsThe hamstring shear modulus was measured by SWE in 50 patients and 50 healthy individuals. Pearson correlation coefficient was used to evaluate the correlation between hamstring stiffness and shear modulus in patients.ResultsThe hamstring shear modulus were significantly higher in the KOA group [the semimembranosus (SM) 15.23 ± 7.23, the semitendinosus (ST) 15.94 ± 5.40, the biceps femoris long tendinitis (BFL) 14.21 ± 6.55] than in the control group (the SM 10.95 ± 2.41, the ST 11.25 ± 2.23, the BFL 9.98 ± 2.81) (p = 0.000, p = 0.000, p = 0.001). The hamstring shear modulus in the KOA group was moderately positively correlated with pain, shear modulus, and physical function score.ConclusionPreliminary results show that the shear modulus of the hamstring of KOA patients is higher than that of healthy people, the WOMAC score and the shear modulus of patients are moderately correlated. These preliminary results show that ultrasonic shear wave elastography measurement of shear modulus may be enough to sensitive, can detect these effects, more targeted in order to assist the doctor’s diagnosis and treatment.

Effects of ankle position during the Nordic Hamstring exercise on range of motion, heel contact force and hamstring muscle activation

ABSTRACT One of the main benefits of the Nordic Hamstring Exercise (NHE) is that it can be performed without the need of any extra material. However, numerous technical execution variables such as the ankle and pelvis position can influence the performance. The primary aims of this study were to investigate the effects of ankle position (i.e., plantar or dorsal flexion) on Nordic Hamstring Break Point (NHBP), repetition time and heel contact force. A secondary aim was to investigate differences in biceps femoris long head and semitendinosus muscle activation. Male professional field hockey players (n = 12) volunteered for the study. Paired t-tests were used to analyse the effect of ankle position on muscle NHBP, eccentric peak torque and repetition time. Ankle dorsal flexion resulted in a higher NHBP (p = 0.002, effect size [ES] = 1.48 [0.57 to 2.38]), repetition time (p = 0.004, ES = 0.98 [0.24 to 1.72]) and both absolute and relative heel contact force (p = 0.028, ES = 0.67 [0.01 to 1.34], p = 0.017, ES = 0.76 [0.07 to 1.44], respectively) compared to plantar flexion. Muscle activation was not significant different. This study showed a higher NHBP, absolute and relative heel contact force and repetition time with a dorsal flexed ankle vs. a plantar flexed ankle in the NHE, without changes in hamstrings muscle activation.

Wavelet analysis reveals differential lower limb muscle activity patterns long after anterior cruciate ligament reconstruction

The purpose of this study was to test whether differences in muscle activity patterns between anterior cruciate ligament-reconstructed patients (ACLR) and healthy controls could be detected 10 to 15 years post-surgery using a machine learning classification approach. Eleven ACLR subjects and 12 healthy controls were recruited from an ongoing prospective randomized clinical trial. Surface electromyography (EMG) signals were recorded from gastrocnemius medialis and lateralis, tibialis anterior, vastus medialis, rectus femoris, biceps femoris, and semitendinosus muscles. Muscle activity was analyzed using wavelet analysis and examined within four sub-phases of the hop test, as well as an average of the task as a whole. K-nearest neighbor machine learning combined with a leave-one-out validation was used to classify the muscle activity patterns as either ACLR or Control. When muscle activity was averaged across the whole hop task, activity patterns for all muscles except the tibialis anterior were identified as being different between the study cohorts. ACLR patients demonstrated continuous muscle activities that spanned take-off, airborne, and landing hop phases versus healthy controls who displayed timed and regulated islets of muscle activities specific to each hop phase. The most striking features were 25–50% greater relative quadriceps intensity and approximately 66% diminished biceps femoris intensity in ACLR patients. The current findings are in contrast to previous work using conventional co-contraction and muscle activation onset EMG measures of the same dataset, underscoring the sensitivity and potential of the wavelet approach coupled with machine learning to reveal meaningful adaptation strategies in this at-risk population.

Sex differences in semitendinosus muscle fiber-type composition.

Sex differences in muscle fiber-type composition have been documented in several muscle groups while the hamstring muscle fiber-type composition has been poorly characterized. This study aimed to compare the semitendinosus muscle composition between men and women. Biopsy samples were obtained from the semitendinosus muscle of twelve men and twelve women during an anterior cruciate ligament reconstruction. SDH and ATPase activities as well as the size and the proportion of muscle fibers expressing myosin heavy chain (MyHC) isoforms were used to compare muscle composition between men and women. The proportion of SDH-positive muscle fibers was significantly lower (37.4±11.2% vs. 49.3±10.6%, p<0.05), and the percentage of fast muscle fibers (i.e., based on ATPase activity) was significantly higher (65.8±10.1% vs. 54.8±8.3%, p<0.05) in men versus women. Likewise, men muscles exhibited a lower percentage of the area that was occupied by MyHC-I labeling (35.6±10.1% vs. 48.7±8.9%; p<0.05) and a higher percentage of the area that was occupied by MyHC-IIA (38.3±6.7% vs. 32.5±6.5%; p<0.05) and MyHC-IIX labeling (26.1±9.6% vs. 18.8±8.5%; p=0.06) as compared with women muscles. The cross-sectional area of MyHC-I, MyHC-IIA, and MyHC-IIX muscle fibers was 31%, 43%, and 50% larger in men as compared with women, respectively. We identified sex differences in semitendinosus muscle composition as illustrated by a faster phenotype and larger muscle size in men as compared with women. This sexual dimorphism might have functional consequences.

Characterization of Alternative Splicing Events in Porcine Skeletal Muscles with Different Intramuscular Fat Contents.

Meat quality is one of the most important economic traits in pig breeding and production. Intramuscular fat (IMF) is a major factor that improves meat quality. To better understand the alternative splicing (AS) events underlying meat quality, long-read isoform sequencing (Iso-seq) was used to identify differential (D)AS events between the longissimus thoracis (LT) and semitendinosus (ST), which differ in IMF content, together with short-read RNA-seq. Through Iso-seq analysis, we identified a total of 56,789 novel transcripts covering protein-coding genes, lncRNA, and fusion transcripts that were not previously annotated in pigs. We also identified 456,965 AS events, among which 3930 were DAS events, corresponding to 2364 unique genes. Through integrative analysis of Iso-seq and RNA-seq, we identified 1174 differentially expressed genes (DEGs), among which 122 were DAS genes, i.e., DE-DAS genes. There are 12 overlapped pathways between the top 20 DEGs and DE-DAS genes, as revealed by KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis, indicating that DE-DAS genes play important roles in the differential phenotype of LT and ST. Further analysis showed that upregulated DE-DAS genes are more important than downregulated ones in IMF deposition. Fatty acid degradation and the PPAR (peroxisome proliferator-activated receptor) signaling pathway were found to be the most important pathways regulating the differential fat deposition of the two muscles. The results update the existing porcine genome annotations and provide data for the in-depth exploration of the mechanisms underlying meat quality and IMF deposition.

Knee Flexor Eccentric Strength, Hamstring Muscle Volume and Sprinting in Elite Professional Soccer Players with a Prior Strained Hamstring.

Simple SummaryGiven the link between a prior hamstring injury and the increased risk of suffering a subsequent injury in professional soccer, an understanding of the features displayed by previously injured players is important. The aim of the present study was to investigate if players with a history of hamstring injury exhibit bilateral deficits in knee flexor eccentric strength, hamstring muscle volume, and sprinting performance. The eccentric knee flexor strength was greater in the previously injured limbs compared to both the contralateral uninjured limbs in the previously injured group and the uninjured limbs in the previously uninjured players. Previously injured limbs showed possibly larger short heads of the biceps femoris and likely semitendinosus muscle volumes. Sprinting performances in the 5-m were possibly worse in players with a history of hamstring muscle strain injury compared to the previously uninjured players.The aim was to determine if players with a prior hamstring strain injury (HSI) exhibit bilateral deficits in knee flexor eccentric strength and hamstring muscle volume and differences in sprinting performance compared with players without a history of HSIs. Forty-six male professional soccer players participated in this study. Eccentric knee flexor strength, hamstring muscle volume (MRI), and a 20-m running sprint test (5- and 10-m split time) were assessed at the start of the preseason. Eccentric knee strength of the previously injured limbs of injured players was greater (ES: 1.18–1.36) than the uninjured limbs in uninjured players. Previously injured limbs showed possibly larger biceps femoris short heads (BFSh) and likely semitendinosus (ST) muscle volumes than the contralateral uninjured limbs among the injured players (ES: 0.36) and the limbs of the uninjured players (ES: 0.56), respectively. Players who had experienced a previous HSI were possibly slower in the 5-m (small ES: 0.46), while unclear differences were found in both the 10-m and 20-m times. Players with a prior HSI displayed greater eccentric knee flexor strength, possibly relatively hypertrophied ST and BFSh muscles, and possibly reduced 5-m sprinting performances than previously uninjured players. This can have implication for the design of secondary hamstring muscle injury prevention strategies.

Анатомические особенности ахиллова сухожилия у кошки домашней

The article presents the morphological and functional characteristics of the muscles that form the Achilles tendon in felines. The studies were carried out at the Department of Anatomy and Histology of Animals. Professor A. F. Klimov Moscow State Academy of Veterinary Medicine and Biotechnology – MBA named after K. I. Skryabin. The objects of research were 10 outbred cats aged from 1 to 6 years, kept at home, without pronounced signs of pathology of the musculoskeletal system. When studying the structural and functional features of the Achilles tendon, a comprehensive methodological approach was used, including classical and fine anatomical preparation under the control of a binocular loupe, followed by a description of the identified structures, biomechanical modeling with an analysis of the stato-locomotor act. It has been established that in a cat, the domestic muscular apparatus, which forms the Achilles tendon, has general patterns of anatomical structure, characteristic of representatives of other taxonomic categories. At the same time, we have identified species-specific anatomical features characteristic of Feliadae representatives. So the biceps femoris in the form of a powerful muscle layer located on the latero-caudal surface of the femur is represented by the union of a wide cranial and narrow caudal heads. Both heads with their initial tendon are fixed on the ischial tuberosity and, following distally, differentiate into three terminal branches: knee, tibia and calcaneus, while the calcaneal branch is woven into the Achilles tendon. The calcaneal branches of the biceps, semitendinosus and triceps muscles, as well as the superficial flexor of the fingers, take part in the structural design of the Achilles tendon. The identified specific anatomical features of the muscular system that form the Achilles tendon in a domestic cat are expressed in the specific fixation of the heads of the biceps femoris muscle, the structural design of the semitendinosus and triceps muscles of the leg.

The Effect of Using Brace in Three Different Knee Flexion Angles on Frequency of Muscular Activity During Running in People With Genu Varus

Background and Aims Genu valgus malalignment is associated with altered lower limb muscular activities during running. The study aimed to evaluate the effect of using a brace in three different knee flexion angles on the frequency of muscular activity during running in people with genu varus. Methods The statistical sample of this study consisted of 30 soccer students. Fifteen persons with genu varus and 15 healthy persons were selected to participate in this study. The electrical activity of the muscles, including medial gastrocnemius, tibialis anterior, vastus medialis, rectus femoris, vastus lateralis, biceps femoris, and semitendinosus, were recorded by electromyography system during running with four brace conditions (without a brace, knee brace at 15˚, 30˚, and 60˚ knee flexion). Results The results showed that the main effect of “brace” on the frequency spectrum of the biceps femoris during the loading phase was increased statistically. During the loading phase, the most significant median frequency of the biceps femoris was running with a brace with 30˚ knee flexion. The main effect of “brace” on the frequency spectrum of semitendinosus during the push-off phase was statistically significant. The lowest value of semitendinosus muscle was during running with a brace with 15˚ knee flexion. Conclusion The most significant effect of a knee flexor brace is on the frequency content of biceps femoris and semitendinosus muscles with a mount at 30˚ knee flexion. This may be due to the passive support role of the brace and possibly could prevent biceps femoris and semitendinosus injuries.

Functional Outcome of Anterior Cruciate Ligament Reconstruction by Tibial Attachment Preserving versus Sacrificing Hamstring Graft Technique- A Prospective Interventional Study

Introduction: Anterior Cruciate Ligament (ACL) is a stout, short intra-articular, extra synovial structure. For a knee with the deficiency of ACL, the ligament reconstruction using an autograft, either a free bone patellar tendon bone graft or a Semi Tendinosus and Gracilis (STG) tendon free hamstring graft, is the most common surgical treatment. Tibial fixation region of the graft is presumed to be a delicate point in arthroscopic ACL reconstruction. There, can be a chance of graft pull out from the tibial tunnel before actual healing of the graft– tunnel can occur. To avoid this problem, the technique of tibial attachment preserved hamstring graft can be used instead of free hamstring graft. Aim: To evaluate and compare the functional outcome of patients who underwent ACL reconstruction with either a free hamstring graft or by tibial attachment preserving hamstring graft. Materials and Methods: A prospective interventional study was conducted in the Department of Orthopaedics, Swami Rama Himalayan University Hospital, Dehradun, Uttarakhand, India, over a period of one year (July 2019-July 2020). A total 52 patients were included and they were divided into two groups. Group A (tibial attachment preserving hamstring graft) and Group B (tibial attachment sacrificing hamstring graft) with each group comprised 26 patients. Patients were assessed with Lysholm score at 6, 12 and 24 weeks of follow-up. For determining the statistical difference between the two groups Independent Student’s t-test was used, whereas for more than two groups Analysis of Variance (ANOVA) test was used and a p-value &lt;0.05 was considered to be significant. Results: The mean age of patients in group A was 30.73±10.02 years whereas in group B it was 29.54±9.84 years. For group A, mean Lysholm score at 6 weeks was 73.23±8.37, at 12 week score was 86.85±5.93 and at 24 week score was 95.58±4.91. For group B, mean Lysholm score at 6 weeks was 74.15±5.82, at 12 weeks score was 87.46±5.95 and at 24 weeks score was 96.92±3.61. Post-hoc analysis showed that there was a significant difference in mean Lysholm score {between preoperative and other time points (p&lt;0.001, respectively)} for both the groups but there was no significant difference in Lysholm score at 6 weeks (p=0.646), 12 weeks (p=0.710) and 24 weeks (p=0.265) when compared between the two groups. Conclusion: ACL reconstruction using hamstring autograft with preserved tibial insertion resulted in no statistically significant difference in functional outcome as compared with free autograft.

Gait Analysis of a Subject with Total Hip Arthroplasty

Introduction: gait analysis of a subject with total hip replacement is described. Objective: instrumental gait analysis of a subject 12 years after the total hip arthroplasty. Materials and Methods: in a movement analysis laboratory, locomotion studies were carried out at freely chosen walking speed by a 64-year-old subject, obtaining kinematic, kinetic and surface electromyographic data in time and space. All measurements were assessments by applying walking protocols on a straight surface of 8 m long. Results: abnormal slight activations of semitendinosus and tibialis anterior muscles, of the left limb, were observed throughout the gait cycle, no spatiotemporal parameters far from normal values were detected. Conclusions: it was possible to obtain an exhaustive analysis of the parameters associated with the gait of a subject after 12 years of total hip arthroplasty.

Influence of biofeedback training time on muscle torque and knee excursion following semitendinosus release in spastic quadriplegic children with cerebral palsy: A randomized controlled trial

Background. Medial hamstring shortening represents a serious common complication in children suffering from spastic quadriplegic cerebral palsy. Objective. The purpose of the study was to examine the efficacy of biofeedback training timing following tendon release in spastic quadriplegic cerebral palsied children. Design. a prospective, single-blind, randomized controlled trial. Setting: several hospitals across Giza and Cairo, where children were operated. Methods. Thirty spastic quadriplegic cerebral palsied children of both genders, with their ages ranged from 7 to 9 years (x ̅ = 8.2 ± 0.86 yr.) were randomly assigned into two equal groups (A and B). The control group (A) was trained using electromyographic biofeedback daily for two weeks after removal of plaster cast, in addition to an hour/ day of a designed physical therapy program, while the study group (B) was trained by electromyographic biofeedback during the immobilization period and for two weeks after removal of the cast along with the same physical therapy program as the group (A). The knee extensors’ peak torque and knee excursion angle were measured immediately and two weeks following cast removal by MERAC isokinetic system and electro-goniometer, respectively. Results. The findings exhibited a significant increase (P &lt; 0.05) in the peak torque of knee extensors and an increase in knee excursion in the group (B) immediately and after two weeks of the cast removal when compared with the results of the group (A) after the same period. Conclusion. Applying electromyographic biofeedback training at the two-week immobilization period resulted in a strengthening of the quadriceps and maintaining the obtained range of knee extension following semitendinosus muscle release in spastic quadriplegic children with cerebral palsy.

Comparison of thigh muscle activations in single leg exercises: bench squat, step-up, airborne lunge

Background and Study Aim. Single leg exercises have some advantages in terms of time, practice and energy costs. However, the activation values that occur in different single leg exercises can be used for training planning. The aim of this research was to examine the thigh muscle activation values during three different single leg exercises.&#x0D; Materials and Methods. Ten healthy male volunteers who were students of the faculty of sports sciences participated in the study. In the study, the EMG ampilitude values of the vastus medialis (VM), vastus lateralis (VL), semitendinosus (SEM) and biceps femoris (BF) muscles were examined during Step-up, Bench Squat and Airborne Lunge exercises. At the same time, Quadriceps (VM+VL): Hamstring (SEM+BF) ratios were determined.&#x0D; Results. Significant differences were detected in all thigh muscles in the ascent and descent phases (p&lt;0.05). While the greatest activation for the quadriceps group was seen in the airborne lunge, the greatest activation for the hamstring group was detected in the bench squat. A statistically significant difference was found in terms of exercise practices in the quadriceps: hamstring (Q:H) ratio (F(2,18)=12.282, p=.003). It was seen that the most balanced exercise was bench squat (Q:H=2.55), and the most unbalanced exercise (agonist dominant) was airborne lunge (Q:H=5.51).&#x0D; Conclusions. The findings show that the exercises examined can be selected depending on the purpose of the training. While bench squats can be preferred for more balanced co-activation the airborne lunge can be preferred for dominant knee extensors.

In vivo assessment of the passive stretching response of the bicompartmental human semitendinosus muscle using shear-wave elastography.

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.NEW & NOTEWORTHY 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.

Hamstring branches of the sciatic nerve as donors for neurotization of the superior gluteal nerve: A cadaveric feasibility study.

Although superior gluteal nerve (SGN) injury can have significant morbidity, to date, surgical strategies for its repair are scant in the literature. Specifically, neurotization options have not been explored. To address this deficiency in the literature, the current cadaveric feasibility study was performed. Via a transgluteal approach on 16 cadaveric sides, the proximal sciatic nerve and the entrance of the SGN into the gluteus medius and minimus were identified. Additionally, branches from the sciatic nerve to the hamstring muscles were traced proximally to confirm their position in relation to the sciatic nerve as a whole. These branches were cut at the level of the ischial tuberosity and teased away from the sciatic nerve proximally to the greater sciatic foramen and transferred superolateral to the SGN. The diameter of each nerve branch was measured as well as its available length for reaching the SGN. All branches of the sciatic nerve to the hamstring muscles arose from the anteromedial part of the nerve. The mean diameters of the branches to the semimembranosus, semitendinosus, and biceps femoris muscles were 2.1, 1.9, and 1.5 mm, respectively. The mean diameter of the SGN was 3.1 mm and the mean distance from this entrance point to the ischial spine was 7.2cm. The mean length of the donor nerve was 8.5cm. Based on our study, use of a tibial-innervated hamstring branch as a donor for nerve transfer to the SGN is feasible.

Profiling of open chromatin in developing pig (Sus scrofa) muscle to identify regulatory regions.

There is very little information about how the genome is regulated in domestic pigs (Sus scrofa). This lack of knowledge hinders efforts to define and predict the effects of genetic variants in pig breeding programs. To address this knowledge gap, we need to identify regulatory sequences in the pig genome starting with regions of open chromatin. We used the “Improved Protocol for the Assay for Transposase-Accessible Chromatin (Omni-ATAC-Seq)” to identify putative regulatory regions in flash-frozen semitendinosus muscle from 24 male piglets. We collected samples from the smallest-, average-, and largest-sized male piglets from each litter through five developmental time points. Of the 4661 ATAC-Seq peaks identified that represent regions of open chromatin, >50% were within 1 kb of known transcription start sites. Differential read count analysis revealed 377 ATAC-Seq defined genomic regions where chromatin accessibility differed significantly across developmental time points. We found regions of open chromatin associated with downregulation of genes involved in muscle development that were present in small-sized fetal piglets but absent in large-sized fetal piglets at day 90 of gestation. The dataset that we have generated provides a resource for studies of genome regulation in pigs and contributes valuable functional annotation information to filter genetic variants for use in genomic selection in pig breeding programs.

Characteristics of Pork Muscles Cooked to Varying End-Point Temperatures.

M. biceps femoris (BF), m. semimembranosus (SM) and m. semitendinosus (ST) from fresh pork ham were evaluated for characteristics of quality after cooking to an internal endpoint temperature of 62 °C or 73 °C. Fresh ham muscles from the left side (N = 68) were cut into 2.54 cm thick chops and allocated to cooking loss, Warner–Bratzler shear force (WBSF), pH and instrumental cooked color analysis. Cooking losses were greater (p < 0.0001) for SM and chops cooked to an internal temperature of 73 °C (p < 0.0001), whereas WBSF did not differ (p = 0.2509) among the three muscles, but was greater (p < 0.0001) in chops cooked to 73 °C. Fresh muscle’s pH was greater (p < 0.05) in ST than BF or SM. Lastly, the interactive effect (p < 0.05) of muscle × endpoint temperature for ST chops cooked to 73 °C was lighter (L*), but, when cooked to 62 °C, they were more red (a*), more yellow (b*) and incurred less color change from red to brown than BF or SM. The current results suggest it is plausible for BF, SM and ST to be considered for alternative uses instead of traditional value-added manufacturing.

Сравнительное определение механической прочности моделей трансплантатов из половины сухожилия длинной малоберцовой мышцы и сухожилия полусухожильной мышцы (экспериментальное исследование)

Purpose To perform the comparative assessment of the mechanical strength of models of semitendinosus and peroneus longus tendon grafts prepared using the GraftLink technique. Materials and methods Tendon material was collected on the base of the Irkutsk Regional Bureau of Forensic Medicine. The main stage of the mechanical strength study of graft models was carried out at the National Research Irkutsk State Technical University, the Department of Strength of Materials, using universal tension testing desk-standing machine Shimadzu AGS-10kNXD. The mechanical strength of graft models of tendon of the semitendinosus and peroneal longus muscles, prepared by a known method (GraftLink technique) was defined. Statistical data processing was carried out using the statistical software Statistica for Windows 10.0 (StatSoft Inc., USA; license holder is the Irkutsk Scientific Center of Surgery and Traumatology). We used a nonparametric method for defining the statistical significance of differences, i.e. the Mann-Whitney test. Differences in the compared groups were considered statistically significant in p &lt; 0.01. Results The mechanical strength of the graft harvested from the semitendinosus muscle tendon according to the known technique averaged out at 351.8 ± 133.0 N, and the mechanical strength of the graft from the half of the peroneus longus tendon, prepared in a known manner, averaged out at 632.4 ± 193.7 N. Statistically significant differences were revealed (p &lt;0.01). Discussion Our study is the only one that shows the results of studying the mechanical strength of allografts prepared by two different techniques. In addition, we identified two phases of the graft rupture, when the free end of the graft being the weakest site of the graft ruptures during the first phase Conclusion The rupture of the graft from the half tendon of the peroneus longus muscle, prepared using the GraftLink technique, occurred at a force of 632.4 ± 193.7 N, which is 1.8 times more than the graft from the semitendinosus muscle prepared using the GraftLink technique.

Proprioceptive postural control strategies differ among non-injured athletes

Postural control during complex tasks requires adequate sensory integration and somaesthetic reweighting: suboptimal postural strategies can lead to injury. We assessed the ability of healthy athletes to reweight somaesthetic signals during postural perturbations on different surfaces. Thirty-five young (16 ± 1 years), healthy, elite handball players participated in this cross-sectional study. Proprioceptive reweighting was evaluated via vibration of the triceps surae and lumbar muscles on firm and foam surfaces. Postural variables and the electromyographic activity of the gluteus medius (GM), semitendinosus (ST) and fibularis longus (FL) were recorded during the PRE (10 s), VIBRATION (20 s) and POST (20 s) periods. Ankle proprioception was predominantly used on the firm compared to foam support. However, two opposing behaviours were observed: a “rigid” strategy in which reliance on ankle proprioception increased on the foam, and a “plastic” strategy that involved a proximal shift of proprioceptive reliance (p < 0.001). The plastic strategy was associated with a more effective recovery of balance after vibration cessation (p < 0.05). ST activation was higher during POST in the rigid strategy and did not return to the PRE level (p < 0.05) whereas it did in the plastic strategy. Proprioceptive strategies for postural control are highly variable and future studies should evaluate their contribution to injury.

Effect of knee joint angle on individual hamstrings morphology quantified using free-hand 3D ultrasonography

Exercise responses and injury rates differ between individual hamstrings and this may be linked with their morphology. The aim of this study was to compare muscle length and tendon dimensions between the individual hamstrings at two knee joint angles using free hand three-dimensional ultrasound (3D US). Muscle-tendon length and distal tendon cross-sectional area (CSA), volume, length and echogenicity of biceps femoris long (BFlh) and short (BFsh) head, semimembranosus (SM) and semitendinosus (ST) of 16 individuals were measured using free-hand 3D US at 0° (full extension) and 45° of knee flexion. ST showed the greatest length than all muscles and BFsh the lowest (p < 0.05). No difference was observed between SM and BFlh length (p > 0.05). Of the four muscles, ST tendon was longer, with less volume and CSA but greater echogenicity than the other tendons. In contrast, SM and BFlh showed shorter tendons and lower echogenicity but a greater volume and CSA than ST (p < 0.05). Muscle and tendon lengthened from 45° to 0° knee flexion angle (p < 0.05) but this change was not statistically different between individual hamstrings (p > 0.05). Freehand 3D US indicated that hamstring muscle length and distal tendon dimensions differ between individual hamstrings. All muscles and tendons lengthened as the knee was extended but this change was similar for all individual hamstrings.