Search results for "Muscle force"
showing 8 items of 18 documents
Decreased motor unit firing rate and force control in older men
2006
Introduction Ageing is related to muscle atrophy that leads to decreases in muscle force. The largest changes are found in fast muscle fibres and fast force production, reducing the capability to recover from sudden balance disturbances. Also ageing-related decrease in force control has been found, as indicated by an increase in force fluctuations and motor unit (MU) firing variability (Galganski et al. 1993). Possibly due to differences in measurement protocols and muscles, the results concerning the effects of ageing on motor unit firing rate are, however, somewhat contradictory (for review, see Roos et al. 1997). The purpose of the present study was to investigate the age-related changes…
Model Free Control for muscular force by Functional Electrical Stimulation using pulse width modulation
2016
International audience; Functional Electrical Stimulation (FES) is a useful technique for restoring functions for patients with neurological disorders. Muscle activities can be artificially driven through delivery of electrical pulses to skeletal muscles. Typically, muscles are activated by using constant stimulation train with a fixed parameters (amplitude, frequency and pulse width). In addition, the FES systems do not adapt the parameters stimulation to obtain a desired force response during the rehabilitation session. The purpose of this study is to investigate a real-time FES system for adapting automatically the stimulation parameters (stimulation pulse width) to track a desired force…
Aging of the musculoskeletal system: How the loss of estrogen impacts muscle strength.
2019
Skeletal muscle weakness occurs with aging and in females this is compounded by the loss of estrogen with ovarian failure. Estrogen deficiency mediates decrements in muscle strength from both inadequate preservation of skeletal muscle mass and decrements in the quality of the remaining skeletal muscle. Processes and components of skeletal muscle that are affected by estrogens are beginning to be identified. This review focuses on mechanisms that contribute to the loss of muscle force generation when estrogen is low in females, and conversely the maintenance of strength by estrogen. Evidence is accumulating that estrogen deficiency induces apoptosis in skeletal muscle contributing to loss of…
99 Muscle-tendon Properties During Recovery From Complete Achilles Tendon Rupture – A Case Study
2014
Introduction Achilles tendon is the most common tendon to suffer for complete rupture. Physically active young adults are often treated with surgery. Most of the patients do not suffer from activity limitations after injury 3 but performance level is often significantly decreased. 1,2 The purpose of this study was to follow recovery of Achilles tendon and triceps surae muscles after complete Achilles tendon rupture and subsequent surgery. This study served as a pilot phase for future research project. Methods Three subjects were recruited to this pilot phase of the study. Subjects were first time measured 2 to 8 months after injury and followed 6 to 8 months. Plantarflexion strength was mea…
Tensiomyography reliability and prediction of changes in muscle force following heavy eccentric strength exercise using muscle mechanical properties
2015
AbstractThe current study involved the completion of two distinct experiments. Experiment 1 analyzed the inter-day reliability of tensiomyography (TMG) muscle mechanical properties based on the amplitude of the muscle belly radial deformation, the time it takes to occur, and its velocity under maximal and submaximal stimuli, in the muscles rectus femoris, biceps femoris, and gastrocnemius lateralis, from 20 male sport students. Experiment 2 investigated whether changes in maximal voluntary isometric contraction (MVIC) could be predicted based on changes in TMG properties following 24 h after different squat training protocols (MS = multiple sets; DS = drop sets; EO = eccentric overload; FW …
Bilaterale Acetabulumfrakturen der vorderen Pfeiler und Wirbelkörperfraktur nach alkoholinduziertem Krampfanfall
1996
The case of a 54-year-old male with a compression fracture of the T 12 vertebral body and a bilateral anterior column fracture of the acetabulum is presented. The origin of this rare combination of fractures is explained by the action of the patient's own muscle force on bone of very poor quality. The treatment of these lesions is comparable to the treatment of similar fractures in bone of normal quality.
Walking and Running Require Greater Effort from the Ankle than the Knee Extensor Muscles.
2016
The knee and ankle extensors as human primary antigravity muscle groups are of utmost importance in a wide range of locomotor activities. Yet, we know surprisingly little about how these muscle groups work, and specifically, how close to their maximal capacities they function across different modes and intensity of locomotion. Therefore, to advance our understanding of locomotor constraints, we determined and compared relative operating efforts of the knee and ankle extensors during walking, running, and sprinting.Using an inverse dynamics biomechanical analysis, the muscle forces of the knee and ankle extensors during walking (1.6 m·s), running (4.1 m·s), and sprinting (9.3 m·s) were quant…
A control strategy based on intelligent algorithm (PSO) to perform electrical stimulation systems
2017
International audience; Adjusting stimulation parameters using control strategy based on reliable mathematical model that can predict perfectly the muscle response, may improve the efficiency of Functional Electrical Stimulation (FES) systems. In the present project, we investigate the PID control tuning based on the Particle Swarm Optimization (PSO) algorithm at the first time in neuro-muscular systems for updating automatically the stimulation pulse amplitude to track a desired force profiles. In the beginning, The PSO algorithm is used to identify unknown force model parameters. Next, optimal PID gains are found by the same intelligent algorithm to improve the control system. The obtaine…