Search results for "lihakset"
showing 10 items of 173 documents
Energy cost of individual lower leg muscles in walking : comparison between young and elderly men at different walking speeds
2015
The cost of transport (COT) in elderly subjects is increased in comparison to young adults, independently of the walking speed. The changes in the neuromuscular activity of the lower extremity muscles could explain this phenomenon. The objective of this thesis was to qualitatively compare the muscle activity pattern of the lower extremities between healthy young and elderly subjects, over a range of walking speeds in order to infer the contributions of individual muscles to changes in COT in both age groups. 26 participants were recruited (13 young aged 18-30; 13 old aged 70-80). Mean oxygen consumption was used to calculate COT and electromyography signals from 10 leg muscles were used to …
Three-dimensional architecture of the whole human soleus muscle in vivo
2018
Background Most data on the architecture of the human soleus muscle have been obtained from cadaveric dissection or two-dimensional ultrasound imaging. We present the first comprehensive, quantitative study on the three-dimensional anatomy of the human soleus muscle in vivo using diffusion tensor imaging (DTI) techniques. Methods We report three-dimensional fascicle lengths, pennation angles, fascicle curvatures, physiological cross-sectional areas and volumes in four compartments of the soleus at ankle joint angles of 69 ± 12° (plantarflexion, short muscle length; average ± SD across subjects) and 108 ± 7° (dorsiflexion, long muscle length) of six healthy young adults. Microdissection and…
Using deep learning to generate synthetic B-mode musculoskeletal ultrasound images
2020
Background and objective\ud Deep learning approaches are common in image processing, but often rely on supervised learning, which requires a large volume of training images, usually accompanied by hand-crafted labels. As labelled data are often not available, it would be desirable to develop methods that allow such data to be compiled automatically. In this study, we used a Generative Adversarial Network (GAN) to generate realistic B-mode musculoskeletal ultrasound images, and tested the suitability of two automated labelling approaches.\ud \ud Methods\ud We used a model including two GANs each trained to transfer an image from one domain to another. The two inputs were a set of 100 longitu…
Myostatin and related proteins on the control of skeletal muscle mass and capillary density
2013
Skeletal muscle wasting is a feature of many pathological conditions such as muscular dystrophies, cancer and diabetes. Human ageing also results in the progressive loss of muscle mass and strength, a condition known as sarcopenia (or myopenia). Therefore, interventions that can reverse or slow down muscle loss are highly desirable. The TGF-β member myostatin is a well-known inhibitor of skeletal muscle growth, but it may also, if deleted, decrease muscle oxidative capacity. We have used the activin receptor 2B (ActR2B) fused to the Fc region of immunoglobulin G (ActR2B-Fc) as a trap to sequester myostatin and inhibit its activity. We sought to evaluate possible differences between doses an…
In vivo 3D muscle architecture quantification based on 3D freehand ultrasound and magnetic resonance imaging
2023
Muscle architecture parameters, such as the fascicle length, pennation angle, and volume, are important muscle morphology characteristics. Accurate in vivo quantification of these parameters allows to detect changes due to pathologies, interventions, and rehabilitation trainings, which ultimately impact on muscles’ force-producing capacity. In this study, we compared three-dimensional (3D) muscle architecture parameters of the tibialis anterior and gastrocnemius medialis, which were quantified by 3D freehand ultrasound (3DfUS) and a magnetic resonance imaging (MRI) technique, diffusion tensor imaging (DTI), respectively. Sixteen able-bodied subjects were recruited where seven of them receiv…
Electromyographic evaluation of specific elastic band exercises targeting neck and shoulder muscle activation
2020
Background: Specific strength training at a high intensity is effective in reducing work related neck/shoulder pain. However, it remains to be documented as to which exercises most specifically target neck and shoulder muscles at high activation level while using simple equipment as e.g., elastic bands. We hypothezised that selected exercises would specifically target the respective muscles, as follows: (1) shrugs and reverse flyes: the upper trapezius muscle, (2) cervical extension and lateral flexion: the upper neck extensor muscle, and (3) cervical flexion and rotation: the sternocleidomastoideus muscle. Methods: Eleven healthy males (25.9 ±
The metabolic responses to electrical pulse-induced contractions in C2C12 myotubes are greater in high glucose medium
2021
Osaa liikunnan terveyshyötyjen mekanismeista on vaikeaa tutkia ihmisillä tai koe-eläimillä. Viljeltyjen C2C12 myotuubien sähköpulssistimulaatiolla (EPS, engl. electrical pulse stimulation) voidaan mallintaa lihassupistuksia ja liikuntaa in vitro –olosuhteissa. EPS:n vaikutusta C2C12 myotuubien aineenvaihduntaan ei kuitenkaan tunneta tarkasti. Lisäksi C2C12 myotuubeja viljellään yleensä korkeassa ei-fysiologisessa 25 mM glukoosipitoisuudessa, mikä voi vaikuttaa EPS-vasteisiin. Tässä tutkimuksessa C2C12 myotuubeja sähköpulssistimuloitiin 24 tunnin ajan sekä matalan 5.5 mM (MG) että korkean 25 mM (KG) glukoosipitoisuuden olosuhteissa, ja aineenvaihduntatuotteiden konsentraatiot analysoitiin se…
Specific distribution of cross-sectional area in each hamstring muscle of sprint runners and relationship between those and sprint performance
2018
The purpose of the present study was to examine characteristics of muscle anatomical cross-sectional area (CSA) for different regions from proximal to distal parts of each muscle of the hamstring muscles in high-level sprinters, and to examine the relationship with those and the sprint performance. The CSA of the semitendinosus (ST), semimembranosus (SM), biceps femoris long head (BFL) and biceps femoris short head (BFS) at the four different region of hamstring muscles for twenty sprinters (SPRINT) and twenty healthy male control subjects (CTRL) were measured by using B-mode ultrasonography. The measured regions were divided into four parts from proximal to distal parts (PRO1, PRO2, DIS2, …
Muscle-Tendon Interaction During Human Dolphin-Kick Swimming
2019
Without high impact forces, it is not clear how humans can utilize tendon elasticity during low-impact activities. The purpose of the present study was to examine the muscle-tendon behavior together with the electromyographic (EMG) activities of the vastus lateralis (VL) muscle during the human dolphin-kicking. In a swimming pool, each subject (n = 11) swam the 25 m dolphin-kicking at two different speeds (NORMAL and FAST). Surface EMGs were recorded from the VL and biceps femoris (BF) muscles. Simultaneous recordings of the knee joint angle by electro-goniometer and of the VL fascicle length by ultrasonography were used to calculate the muscle-tendon unit and tendinous length of VL(L-MTU a…
Motor unit activation and force production during eccentric, concentric and isometric actions
2002
The aim of the present series of studies is to examine force and myoelectrical activity in human forearm flexors and knee extensors during dynamic and isometric muscle actions. The main purposes are 1) to clarify the methodological issues regarding the measurements of maximal force, EMG and EMG power spectrum in eccentric, concentric and isometric conditions, 2) to examine the motor unit activation patterns during dynamic and isometric actions by following the behavior of the EMG power spectrum and by utilizing selective intramuscular fine wire electrodes, and 3) to examine the effects of fatigue on force production, aEMG and EMG power spectrum in eccentric and concentric actions.