Search results for "Musculoskeletal System"
showing 10 items of 795 documents
The relative contribution to the plantar-flexor torque of the soleus motor units activated by the H reflex and M response in humans.
2000
Abstract This study proposes a method of quantifying the relative contribution to the plantar-flexor torque of soleus H and M responses evoked by tibial nerve stimulation. For ten subjects, the amplitude of the twitch produced by the H wave was plotted against the corresponding potential, for stimuli producing H without M (i.e. in the ascending portion of the H-recruitment curve). It was then assumed that the contribution of H to twitches produced by M plus H was similar for similar H waves on the curve-descending portion. Hence, the contribution of M was estimated, for the range of M waves including those accompanying H max . The estimated mechanical contributions of H and M wave increase …
Neuromuscular responses to explosive and heavy resistance loading
2000
The EMG power spectrum may shift towards higher frequencies with higher movement velocities. Fatigue, on the other hand, can cause a decrease in the frequency components. The purpose of this study was to examine acute effects of explosive (EE) and heavy resistance (HRE) concentric leg press exercise on muscle force, EMG and blood lactate. The EE included five sets of ten repetitions with 40+/-6% of the isometric maximum at a 100 degrees knee angle performed as explosively as possible. The same number of repetitions was performed in HRE but with a heavier load (67+/-7% of the isometric maximum at a 100 degrees knee angle). Maximal isometric and single concentric actions of different loads, a…
Differential contributions of ankle plantarflexors during submaximal isometric muscle action: A PET and EMG study
2014
Abstract The objective of this study was to investigate the relative contributions of superficial and deep ankle plantarflexors during repetitive submaximal isometric contractions using surface electromyography (SEMG) and positron emission tomography (PET). Myoelectric signals were obtained from twelve healthy volunteers (27.3±4.2yrs). A tracer ([ 18 F]-FDG) was injected during the exercise and PET scanning was done immediately afterwards. The examined muscles included soleus (Sol), medial gastrocnemius (MG), lateral gastrocnemius (LG), and flexor hallucis longus (FHL). It was found that isometric maximal voluntary contraction (MVC) force, muscle glucose uptake (GU) rate, and SEMG of variou…
Calf Blood Compound (CFC) and Homeopathic Drug Induce Differentiation of Primary Human Skeletal Muscle Cells.
2019
AbstractThe use of injections to treat structural muscle injuries is controversially discussed. In our controlled in vitro study, we investigated the biological impact of Actovegin and Traumeel alone and in combination on primary human skeletal muscle cells. Cells were characterized by immunofluorescence staining for myogenic factor 5 (Myf5) and MyoD, and cultured with or without Actovegin and / or Traumeel. The effects of these agents were assayed by cell viability and gene expression of the specific markers MyoD, Myf5, neural adhesion molecule (NCAM), and CD31. Myotube formation was determined by myosin staining. Neither Actovegin nor Traumeel showed toxic effects or influenced cell viabi…
Intra-individual gait patterns across different time-scales as revealed by means of a supervised learning model using kernel-based discriminant regre…
2017
Objective Traditionally, gait analysis has been centered on the idea of average behavior and normality. On one hand, clinical diagnoses and therapeutic interventions typically assume that average gait patterns remain constant over time. On the other hand, it is well known that all our movements are accompanied by a certain amount of variability, which does not allow us to make two identical steps. The purpose of this study was to examine changes in the intra-individual gait patterns across different time-scales (i.e., tens-of-mins, tens-of-hours). Methods Nine healthy subjects performed 15 gait trials at a self-selected speed on 6 sessions within one day (duration between two subsequent ses…
Behavior of fascicles and the myotendinous junction of human medial gastrocnemius following eccentric strength training
2009
This study is the first in which measurements of thickness, fascicle angle and length, and tendon elongation were combined to examine the impact of eccentric strength training on both muscle architecture and tendinous structures. Eighteen healthy male subjects were divided into an eccentric strength training group (n = 10) and a control group (n = 8). The training program consisted of 18 sessions of eccentric exercises over a 7-week period. All subjects were tested at baseline and after the last training session. Using ultrasound imaging, the fascicle angle and length and thickness of the medial gastrocnemius (MG) were analyzed at rest (i.e., theta(p), Fl(p), and t(p), respectively), at 50%…
Axial loading and posture cues in contraction of transversus abdominis and multifidus with exercise
2020
AbstractAstronauts are at increased risk of spine injury. With a view to developing training approaches for the muscles of the spine in microgravity, this study examined the effects of axial loading and postural cues on the contraction of transversus abdominis and lumbar multifidus in supine lying using a novel exercise device (GravityFit). Thirty (18 males and 12 females) endurance-trained runners without a history of spinal pain aged 33–55 years were recruited. Magnetic resonance imaging (MRI) was performed under one rest and five exercise conditions, which involved variations in axial loading and postural cues. Whole volume of the abdominal and lumbar paraspinal muscles was imaged and tr…
''Alterations with Movement Duration in the Kinematics of a Whole Body Pointing Movement''
2013
Casteran, Matthieu | Manckoundia, Patrick | Pozzo, Thierry | Thomas, Elizabeth; International audience; ''Our aim was to investigate how the organization of a whole body movement is altered when movement duration (MD) is varied. Subjects performed the same whole body pointing movement over long, normal and short MDs. The kinematic trajectories were then analyzed on a normalized time base. A principal components analysis (PCA) revealed that the degree of coordination between the elevation angles of the body did not change with MD. This lack of significant differences in the coordination was interesting given that small spatial and temporal differences were observed in the individual kinemati…
Comparison of implant primary stability between maxillary edentulous ridges receiving intramembranous origin block grafts
2012
Purpose: The purposes of the present study were: to compare the resonance frequency analysis (RFA) values of implant placed in either ramus or calvaria block grafts; and to determine if implant diameter influences RFA implant stability quotient (ISQ) value. Material and Methods: This was a retrospective study that included 16 consecutives healthy patients treated with autogenous onlay block grafts for horizontal bone reconstruction in maxilla. Ten ramus and ten calvaria block graft treated patients were selected and compared. Results: Totally, 59 implants were placed, 35 (59.3%) were placed on the calvaria bone grafts and the remaining 24 (40.7%) were on the ramus bone graft. Of all the imp…
Exposure to nitroaromatic explosives and health effects during disposal of military waste.
2003
To investigate the exposure to dinitrotoluene (DNT) and trinitrotoluene (TNT) and the resulting effects in workers which occur during the disposal of military waste.Eighty two employees from a mechanical plant in Germany were studied, of whom 51 were regularly exposed to ammunition containing TNT and DNT, 19 occasionally, and 12 not at all.Air analyses yielded maximum concentrations of 20 micro g/m(3) for 2,4-DNT and 3250 micro g/m(3) for 2,4,6-TNT, respectively. The maximum concentrations in the urine of workers regularly exposed amounted to 5.0 micro g/l of 2,4,6-TNT, 1464.0 micro g/l of 2-amino-4,6-dinitrotoluene, 6693.0 of micro g/l 4-amino-2,6-dinitrotoluene, 2.1 micro g/l of 2,4-DNT, …