المؤلفون: Hernández-Stender, C. L., Molina-Rueda, F., Cuesta-Gómez, A., Alguacil-Diego, I. M.

المصدر: Sports Biomechanics; Jul2024, Vol. 23 Issue 7, p949-960, 12p

مصطلحات موضوعية: LEG physiology, HAMSTRING muscle physiology, SKELETAL muscle physiology, CALF muscle physiology, BIOMECHANICS, LONG-distance running, TASK performance, RUNNING, DIAGNOSIS, GAIT in humans, GLUTEAL muscles, ELECTROMYOGRAPHY, RECTUS femoris muscles, SPRINTING, MUSCLE contraction

مستخلص: Running is one of the most popular sport practices in the world. However, to our knowledge, none of the previous research about the characteristics of outdoor running makes a distinction between the different modalities of runners. Sixty-five healthy runners classified in sprinters, middle distance and long-distance runners performed five series of 100 metres on the synthetic outdoor track at competition pace. Muscle activity of lower limb muscles at initial contact and toe-off, involving the gluteus medius (GMED), gluteus maximus (GMAX), biceps femoris (BF), rectus femoris (RF), tiabilis anterior (TA) and medial gastrocnemius (MGAS), and spatiotemporal parameters were analysed. Sprinters showed high percentages of muscle activity at initial contact, in particular, the TA activity was the highest. The RF activity was significantly the lowest activity registered. At toe-off, sprinters showed the highest activity in all muscles analysed. Middle-distance runners had the highest activity of GMAX, BF and MGAS during the initial contact. In long-distance runners, the GMED and RF activity during the initial contact is highlighted, showing the highest activity of this phase. Different patterns of lower limb muscle activity and spatiotemporal parameters exist depending on the modality of the runner. [ABSTRACT FROM AUTHOR]

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المؤلفون: Sheikhalizade, Hamed, Imani, Fariborz, Jafarnezhadgero, AmirAli, Brouj, Sara Imani

المصدر: Physical Treatments: Specific Physical Therapy Journal; Spring2024, Vol. 14 Issue 2, p1-8, 8p

مصطلحات موضوعية: LEG physiology, QUADRICEPS muscle physiology, HAMSTRING muscle physiology, SKELETAL muscle physiology, CALF muscle physiology, SAND, BIOMECHANICS, ANTERIOR cruciate ligament surgery, EXERCISE therapy, STATISTICAL sampling, TREATMENT effectiveness, RANDOMIZED controlled trials, TIBIALIS anterior, FOOT abnormalities, WALKING, ELECTROMYOGRAPHY, GLUTEAL muscles, ANALYSIS of variance, RECTUS femoris muscles, DATA analysis software, PRONATION, EVALUATION, REHABILITATION

مستخلص: Purpose: This study investigates the effects of exercises on sand on the frequency content of the lower limb muscles in individuals with anterior cruciate ligament reconstruction and pronated feet during walking. Methods: This was a semi-experimental and laboratory-type study. The study samples included 28 male students with pronated feet and anterior... [ABSTRACT FROM AUTHOR]

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المؤلفون: Hou, Zongchen, Shen, Wei, Fong, Daniel T. P., Winter, Samantha L.

المصدر: Scandinavian Journal of Medicine & Science in Sports; Feb2024, Vol. 34 Issue 2, p1-9, 9p

مصطلحات موضوعية: LEG physiology, STATISTICAL power analysis, STATISTICS, ANALYSIS of variance, RECTUS femoris muscles, ANKLE joint, JOINT instability, CHRONIC diseases, PERONEAL nerve, ANTHROPOMETRY, SPRAINS, ANKLE injuries, TIBIALIS anterior, GLUTEAL muscles, HAMSTRING muscle, CALF muscles, DESCRIPTIVE statistics, RESEARCH funding, JUMPING, ELECTROMYOGRAPHY, DATA analysis, DATA analysis software, KINEMATICS, DISEASE complications

مستخلص: Ankle inversion orientation and peroneal activation insufficiency may contribute to lateral ankle sprains during landing in chronic ankle instability (CAI); however, how anticipation alters these factors is neglected. This study aimed to assess the impact of anticipation on joint orientation and muscle activity during landing in individuals with CAI. Fifteen participants with CAI and 15 healthy participants (control) were recruited to perform single‐leg landings after bilateral countermovement jumps when the landing limb was specified before (planned) or after (unplanned) take‐off. Joint angle (hip, knee, and ankle) and electromyography (gluteus medius, rectus femoris, biceps femoris, gastrocnemius lateral head, tibialis anterior, and peroneal longus) were collected and analyzed with 2 (groups) × 2 (conditions) statistical parametric mapping ANOVA. In the unplanned condition, the CAI group demonstrated a less plantarflexed (maximum difference [MD] = 9.5°, p = 0.047) and more inverted ankle joint (MD = 4.1°, p < 0.001) before ground contact, along with lower peroneal activity at ground contact compared to the control group (MD = 28.9% of peak activation, p < 0.001). No significant differences between groups were observed in the planned condition. In conclusion, anticipation may mask jump landing deficits in people with CAI, including inverted ankle orientation and reduced peroneus longus activity pre‐ and post‐landing, which were observed exclusively in unplanned landings. Clinicians and researchers need to recognize the impact of anticipation on apparent landing deficits and consider the implications for injury prevention and rehabilitation strategies. [ABSTRACT FROM AUTHOR]

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المؤلفون: Albano, Domenico, Viglino, Umberto, Messina, Carmelo, Fusco, Stefano, Gitto, Salvatore, Lacelli, Francesca, Sconfienza, Luca Maria

المصدر: British Journal of Radiology; Jan2024, Vol. 97 Issue 1153, p267-273, 7p

مصطلحات موضوعية: SHOULDER, TENDINITIS, PATELLAR tendon, IRRIGATION (Medicine), ROTATOR cuff, GLUTEAL muscles, RECTUS femoris muscles

مستخلص: Objectives To investigate the efficacy and safety of ultrasound-guided percutaneous irrigation of calcific tendinopathy (US-PICT) applied out of the shoulder, comparing its effectiveness to US-PICT of the rotator cuff. Methods Patients subjected to US-PICT for extra-shoulder calcific tendinitis (Case Group) were compared to those subjected to US-PICT of the rotator cuff (Control Group). We had pre-procedure Visual Analogue Scale (VAS) pain score, 1- and 3-month VAS of patients of the Case Group, pre-procedure and 3-month VAS of patients of the Control Group. Results The Case Group consisted of 41 patients (27 women; mean age: 45 ± 9years): 26 gluteus medius, 5 patellar tendon, 3 rectus femoris, 2 gluteus maximus, 2 common extensor tendon, 1 extensor carpi radialis longus, 1 pes anserinus, and 1 peroneus longus. The Control Group included 41 patients (27 women; mean age: 47 ± 11 years). The mean pre-procedure VAS of the Case Group was 8.8 ± 0.7 with a significant (P  < .001) drop at 1 month (4.5 ± 0.6) and 3 months (3.6 ± 0.6). The mean pre-procedure VAS of the Control Group was 8 ± 1.4 and dropped to 3.1 ± 1.6 after 3 months (P  < .001). Post-treatment VAS at 3 months was not significantly different between two Groups (P  = 0.134). Similarly, the decrease of VAS from baseline to 3 months was not significantly different between the two Groups (P  = 0.264). Conclusions US-PICT is a safe and effective procedure that can be used out of the shoulder. Advances in knowledge This study demonstrated the safety and effectiveness of US-PICT as a valuable therapeutic option for extra-shoulder calcific tendinitis, with similar clinical outcome to the same procedure performed in the rotator cuff. The technique must be adapted in some deeply located calcifications by means of the use of different needles and by thoroughly planning the access point for the procedure. [ABSTRACT FROM AUTHOR]

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المؤلفون: Hora, Martin, Struška, Michal, Matějovská, Zuzana, Kubový, Petr, Sládek, Vladimír

المصدر: American Journal of Biological Anthropology; Jan2024, Vol. 183 Issue 1, p79-91, 13p

مصطلحات موضوعية: POSTURAL muscles, ELECTROMYOGRAPHY, HUMAN mechanics, GLUTEAL muscles, BICEPS femoris, RECTUS femoris muscles, SHORT stature

مستخلص: Objectives: Muscle activity during crouched walking has been previously studied in the context of the evolution of hominin bipedalism and human movement disorders. However, crouched walking could also be used in approach hunting where postural height (actual height of the body from the ground to the top of the head during locomotion) is the limiting factor. Here, we aim to analyze the relationship between relative postural height (%stature), kinematics, and muscle activity during crouched walking. Materials and Methods: Adult males (n = 19) walked with extended limbs and at three degrees of crouch while their 3D motion capture kinematics and lower limb muscle electromyography were recorded. We measured activation of tibialis anterior, soleus, gastrocnemius medialis, gastrocnemius lateralis, vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus. We analyzed the effects of postural height on kinematics and muscle activation using linear mixed effects model. Results: Flexion angles, individual muscle activation (except for medial gastrocnemius), and total muscle activation were negatively related to relative postural height, that is, were greater at more crouched postures. Relative postural height had a stronger effect on the activation of the thigh and gluteal muscles compared to shank muscles. Discussion: General increase in lower limb muscle activation at lower postural heights suggests a negative relationship between relative postural height and fatigue, and may indicate a possible mechanism by which short stature could benefit the hunter in approach hunting. Greater activation of thigh and gluteal muscles relative to shank muscles may help to identify crouched walking in past human populations. [ABSTRACT FROM AUTHOR]

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المؤلفون: Goodman, William W., Helms, Eric, Graham, David F.

المصدر: Journal of Strength & Conditioning Research; Oct2023, Vol. 37 Issue 10, p1947-1954, 8p

مصطلحات موضوعية: SKELETAL muscle physiology, CALF muscle physiology, HAMSTRING muscle physiology, QUADRICEPS muscle physiology, RESISTANCE training, RECTUS femoris muscles, POSTURAL balance, PHYSIOLOGICAL effects of acceleration, TIBIALIS anterior, BODY movement, GLUTEAL muscles, POSTURE, DESCRIPTIVE statistics, BIOMECHANICS, KINEMATICS

مستخلص: The squat is used to enhance performance and rehabilitate the lower body. However, muscle forces and how muscles accelerate the center of mass (CoM) are not well understood. The purpose was to determine how lower extremity muscles contribute to the vertical acceleration of the CoM when squatting to parallel using 85% one-repetition maximum. Thirteen female subjects performed squats in a randomized fashion. Musculoskeletal modeling was used to obtain muscle forces and muscle-induced accelerations. The vasti, soleus, and gluteus maximus generated the largest upward accelerations of the CoM, whereas the muscles that produced the largest downward acceleration about the CoM were the hamstrings, iliopsoas, adductors, and tibialis anterior. Our findings indicate that a muscle's function is task and posture specific. That is, muscle function depends on both joint position and how an individual is interacting with the environment. [ABSTRACT FROM AUTHOR]

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العنوان البديل: Simulated analysis of influence of walking step length on lower limb muscle strength in the elderly. (English)

المؤلفون: 宋翠荣, 陈童真, 刘美晓, 张海峰

المصدر: Chinese Journal of Tissue Engineering Research / Zhongguo Zuzhi Gongcheng Yanjiu; 8/8/2023, Vol. 27 Issue 22, p3486-3491, 6p

مصطلحات موضوعية: PSOAS muscles, MUSCLE strength, RECTUS femoris muscles, GROUND reaction forces (Biomechanics), SKELETAL muscle, GLUTEAL muscles, STRENGTH training, MOTION capture (Human mechanics)

الملخص (بالإنجليزية): BACKGROUND: Aging is becoming increasingly serious. The elderly with skeletal muscle degeneration do not tolerate high intensity exercise, and are easy to fall, resulting in disability or death. How to improve the lower limb muscle strength of the elderly has become a hot research issue. OBJECTIVE: To provide guidance for daily activities through analyzing the influence of walking step length on lower limb muscle strength of the elderly (> 60 years old), and exploring the appropriate walking style. METHODS: Thirty healthy male elderly subjects aged 65-75 years old were randomly selected and their morphological parameters were measured. The skeletal muscle model was established by importing the simulation software Opensim 4.0. Vicon 2.3 three-dimensional motion capture system was used to record the movement track of the subjects’ normal step and large step walking in real time, and the plantar three-dimensional force platform was used to record the ground reaction force on the plantar during walking. The motion data of the subjects were imported into Opensim 4.0 software to establish the movement model, and the dynamic simulation was carried out. The effectiveness of the method was verified by the data of plantar dynamometer. Muscle strength changes of ilium, rectus femoris, psoas major, gluteus maximus, gluteus medius, biceps femoris, adductor magnus and medial femoral muscle were analyzed during walking with different step lengths in the elderly. The muscle strength data of two different pace walks of each subject were imported into SPSS 20.0 for statistical analysis, and paired t-test was performed. RESULTS AND CONCLUSION: (1) By establishing the skeletal muscle model of the subjects and the movement model of walking with different steps, the muscle strength curves of the important muscles of the lower limbs in the process of walking with different steps were derived. (2) Through statistical analysis, there were significant differences in the muscle strength of walking with different paces (P > 0.05). (3) The change rules of step length and lower limb muscle strength were summarized: within a certain range, with the increase of step length, the muscle strength of rectus femoris, medial femoris and semitendinosus increased significantly, while the muscle strength of ilium, psoas maximus, gluteus maximus, gluteus medius and adductor magnus increased slightly. (4) It is shown that walking with increased step length can improve lower limb muscle strength and can provide a theoretical basis for the elderly to choose correct walking style, rehabilitation training and exercise prescription development. [ABSTRACT FROM AUTHOR]

Abstract (Chinese): 背景: 目前人口老龄化日趋严重, 老年人不耐受高强度锻炼, 骨骼、肌肉退化, 常由于跌倒导致伤残或死亡, 如何提高老年人的下肢肌力 成为当前的研究热点问题. 目的: 分析行走步长对老年人(> 60岁)下肢肌力的影响, 探索高效的行走方式, 为日常锻炼提供指导. 方法: 选择30名健康老年人为受试者, 均为男性, 年龄65-75岁, 测量其形态参数, 导入仿真软件Opensim 4.0, 分别建立各受试者骨肌模 型. 应用Vicon 2.3三维动作捕捉系统, 实时记录各受试者正常步长、大步长行走的运动轨迹; 同时采用足底三维测力台记录步行中足底受 到的地面反作用力; 将各受试者运动数据导入Opensim 4.0软件建立运动模型, 进行动力学仿真, 结合足底测力台数据验证其有效性. 模 型经验证后仿真各受试者在不同步长行走过程中, 髂肌、腰大肌、股直肌、臀大肌、臀中肌、股二头肌、半腱肌、大收肌的肌力变化; 将 各受试者2次不同步长行走肌力数据分别导入SPSS 20.0进行统计分析, 行配对t检验. 结果与结论: ①建立了各受试者骨骼肌肉模型及不同步长行走的运动模型, 导出各受试者不同步长行走过程中下肢重要肌肉的时间-肌力 变化曲线; ②经统计学分析, 不同步长行走肌力差异有显著性意义(P > 0.05); ③步长与肌力变化的规律: 正常步频下, 增大步长幅度, 股 直肌、股二头肌、半腱肌肌力显著增加, 髂肌、腰大肌、臀大肌、臀中肌、大收肌轻度增加; ④提示增大步长行走可以提高下肢肌力, 为 老年人选择正确行走方式、相关康复训练以及运动处方开发提供理论基础. [ABSTRACT FROM AUTHOR]

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المؤلفون: Sahd, Lauren¹ (AUTHOR), Bennett, Nigel C.² (AUTHOR), Kotzé, Sanet H.^1,3 (AUTHOR) shk@sun.ac.za

المصدر: Journal of Anatomy. Jan2022, Vol. 240 Issue 1, p23-33. 11p.

مصطلحات موضوعية: *HINDLIMB, *RECTUS femoris muscles, *VASTUS lateralis, *FLEXOR muscles, *GLUTEAL muscles, *DRUM playing, KNEE muscles

مستخلص: Several species of African mole‐rats use seismic signalling by means of hind foot drumming for communication. The present study aimed to create three‐dimensional reconstructions and compare volumetric measurements of 27 muscles of the hind limb of two drumming (Georychus capensis and Bathyergus suillus) and one non‐drumming (Cryptomys hottentotus natalensis) species of African mole‐rats. Diffusible iodine contrast‐enhanced micro‐computed tomography (diceCT) scans were performed on six specimens per species. Manual segmentation of the scans using VGMAX Studio imaging software allowed for individual muscles to be separated while automatically determining the volume of each muscle. The volume of the individual muscles was expressed as a percentage of the total hind limb volume and statistically compared between species. Subsequently, three‐dimensional reconstructions of these muscles were created. Musculus gracilis anticus had a significantly larger percentage of the total hind limb muscle volume in both drumming species compared to the non‐drumming C. h. natalensis. Furthermore, several hip and knee extensors, namely mm. gluteus superficialis, semimembranosus, gluteofemoralis, rectus femoris and vastus lateralis, had significantly larger muscle volume percentages in the two drumming species (G. capensis and B. suillus) compared to the non‐drumming species. While not statistically significant, G. capensis had larger muscle volume percentages in several key hip and knee extensors compared to B. suillus. Additionally, G capensis had the largest summed percentage of the total hind limb volume in the hip flexor, hip extensor, knee extensor and ankle plantar flexor muscle groups in all the three species. This could be indicative of whole muscle hypertrophy in these muscles due to fast eccentric contractions that occur during hind foot drumming. However, significantly larger muscle volume percentages were observed in the scratch digging B. suillus compared to the other two chisel tooth digging species. Moreover, while not statistically significant, B. suillus had larger muscle volume percentages in several hip extensor and knee flexor muscles compared to G. capensis (except for m. vastus lateralis). These differences could be due to the large relative size of this species but could also be influenced by the scratch digging strategy employed by B. suillus. Therefore, while the action of hind foot drumming seems to influence certain key muscle volumes, digging strategy and body size may also play a role. [ABSTRACT FROM AUTHOR]

المؤلفون: McCormick, Joseph B., Drusch, Alexander S., Lynch, Darragh J., Seeber, Gesine H., Wilford, Katherine F., Hooper, Troy L., Allen, Brad S., O'Connell, Dennis G., Mena-Iturriaga, Maria J., Cooper, Kinyata J., Sizer, Phillip S.

المصدر: International Journal of Sports Physical Therapy; 2023, Vol. 18 Issue 4, p48-61, 14p

مصطلحات موضوعية: PHYSIOLOGY of abdominal muscles, MUSCLE contraction, RECTUS femoris muscles, ANALYSIS of variance, TORSO, EXERCISE physiology, RECTUS abdominis muscles, ERECTOR spinae muscles, DYNAMICS, MUSCULOSKELETAL system physiology, BODY movement, QUESTIONNAIRES, QUADRICEPS muscle, HAMSTRING muscle, GLUTEAL muscles, WEIGHT lifting, ELECTROMYOGRAPHY, STATISTICAL sampling, DATA analysis software, KINEMATICS

مستخلص: Background Weightlifting is growing in popularity among recreational and competitive athletes. The barbell back squat (BackS) is commonly included in these training programs, while the barbell front squat (FrontS) is commonly performed as a component of other lifts such as the power clean or clean and jerk, it is less commonly practiced in isolation. Hypothesis/Purpose The purpose of this study was to examine the effects of VPAC performance on trunk muscle and LE biomechanical responses during loaded BackS versus FrontS in healthy subjects. Study Design Controlled Laboratory Study Methods Healthy male subjects with the ability to perform a sub-maximal loaded barbell squat lift were recruited. Subjects completed informed consent, demographic/medical history questionnaires and an instructional video. Subjects practiced VPAC and received feedback. Surface electromyography (sEMG) electrodes and kinematic markers were applied. Muscles included were the internal oblique (IO), external oblique (EO), rectus abdominis, iliocostalis lumborum (ICL), superficial multifidi, rectus femoris, vastus lateralis, biceps femoris, and gluteus maximus. Maximal voluntary isometric contractions established reference sEMG values. A squat one-rep-max (1RM) was predicted by researchers using a three to five repetition maximum (3RM, 5RM) load protocol. Subjects performed BackS trials at 75% 1RM while FrontS trials were performed at 75% BackS weight, both with and without VPAC. Subjects performed three repetitions of each condition with feet positioned on two adjacent force plates. Significant interactions and main effects were tested using a 2(VPAC strategy) x 2(squat variation) and 2(VPAC strategy) x 2(direction) within-subject repeated measures ANOVAs. Tukey's Post-Hoc tests identified the location of significant differences. Results Trunk muscle activity was significantly higher during FrontS versus BackS regardless of VPAC condition. (IO: p=0.018, EO: p<0.001, ICL: p<0.001) VPAC increased performance time for both squat variations (p=.0011), which may be associated with decreased detrimental force potential on the lumbar spine and knees. VPAC led to improved ability to maintain a neutral lumbar spine during both squat variations. This finding is associated with decreased detrimental force potential on the lumbar spine. Conclusions Findings could help guide practitioners and coaches to choose squat variations and incorporate VPAC strategies during their treatments and/or training programs. Level of Evidence Level 3 [ABSTRACT FROM AUTHOR]

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المؤلفون: Martinez, Sarah C., Coons, John M., Mehls, Kelton D.

المصدر: European Journal of Sport Science; Jun2023, Vol. 23 Issue 6, p975-982, 8p, 2 Charts, 2 Graphs

مصطلحات موضوعية: HAMSTRING muscle physiology, QUADRICEPS muscle physiology, RESISTANCE training, MUSCLE contraction, RECTUS femoris muscles, WOMEN, EXERCISE physiology, COMPARATIVE studies, EXERCISE intensity, BODY movement, GLUTEAL muscles, DESCRIPTIVE statistics, BIOMECHANICS, ELECTROMYOGRAPHY, WEIGHT-bearing (Orthopedics)

مستخلص: The aim of this study was to compare gluteus maximus-to-hamstring (GM:H) co-activation, hamstrings-to-quadriceps (H:Q) co-activation, and mean muscle activity in the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RM), gluteus maximus (GM), semitendinosus (ST), and bicep femoris (BF) muscles across a range of training loads (40%, 50%, 50%, 70%, 80% 90% 1RM) of the barbell back squat in resistance trained females. Surface electromyography (EMG) was observed in 18 healthy resistance trained females for the VL, VM, RM, GM, ST, and BF during the ascending and descending phase of the back squat. During the ascending phase, the VL, VM, RM, GM, ST, and BF displayed significantly more EMG activation at 90% 1RM compared to 40%–70% (p <.03). During the descending phase, there were no significant differences displayed in mean muscle activity at 40%–80% of 1RM compared to 90% of 1RM. There were no significant differences in H-Q co-activation and GM-H co-activation during the ascending or descending phase across external loads. These findings are similar to the results found in similar studies using male participants and support that higher training intensities (80%–90% 1RM) of the barbell back squat significantly activate muscles surrounding the hip compared to lower loads (40%–70%). The results of this study also suggest that training intensities of 80% 1RM and 90% 1RM elicits the similar musculature activation in the muscle surrounding the hip in resistance trained females. Highlights During the back squat, mean muscle activity of the hip and leg muscles increased linearly with exercise intensity (40%–90% of one-repetition max) in resistance trained females. No significant difference in mean activity were noted between 80% and 90% of one-repetition max during the ascending and descending phases. During the ascending phase, 80% of one-repetition max generated the highest gluteus maximus to hamstring activity co-activation ratio. During the descending phase, 40% of one-repetition max produced a gluteus maximus to hamstring activity co-activation ratio closest to 1.0. [ABSTRACT FROM AUTHOR]

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