Search results for "isometric"
showing 10 items of 535 documents
Effect of chronic unloading and rehabilitation on human Achilles tendon properties: a velocity-encoded phase-contrast MRI study
2008
The objective of this study was to measure and monitor changes in Achilles tendon mechanical properties and force production capability of triceps surae muscles after 4 wk of limb suspension and 6 wk of physical rehabilitation. Five healthy volunteers underwent unilateral lower limb suspension followed by weekly physiotherapy. A velocity-encoded, phase-contrast magnetic resonance imaging (VE-PC-MRI) technique was used to estimate the tendon strain as a function of force produced during the submaximal isometric contractions. After limb suspension, triceps surae muscle strength decreased to 53.2 ± 15.6% (mean ± SD) of the presuspension level ( P < 0.05). Young's modulus, estimated from the…
Interrelationships between electromyographic, mechanical, muscle structure and reflex time measurements in man.
1981
Reaction time (TRT) with its premotor (PMT) and motor time (MT) components, patellar reflex time (TRfT) with its latency (LAT) and motor time (RfMT) were studied together with isometric force production and relaxation time variables in one leg isometric knee extension. These variables were intercorrelated together with muscle biopsy variables taken from m. vastus lateralis. From these computations MT proved to demonstrate significant correlations to rate of isometric force development (RFD) (P less than 0.001), maximum force (P0) (P less than 0.001) and per cent distribution of ST fibers (P less than 0.001). It is speculated that these relationships are determined by the pattern of the moto…
Do bone geometric properties of the proximal femoral diaphysis reflect loading history, muscle properties, or body dimensions?
2019
Abstract Objectives: The aim of this study was to investigate activity‐induced effects from bone geometric properties of the proximal femur in athletic vs nonathletic healthy females by statistically controlling for variation in body size, lower limb isometric, and dynamic muscle strength, and cross‐sectional area of Musculus gluteus maximus. Methods: The material consists of hip and proximal thigh magnetic resonance images of Finnish female athletes (N = 91) engaged in either high jump, triple jump, soccer, squash, powerlifting, endurance running or swimming, and a group of physically active nonathletic women (N = 20). Cross‐sectional bone geometric properties were calculated for the lesse…
Bilateral and Unilateral Neuromuscular Function and Muscle Cross-Sectional Area in Middle-Aged and Elderly Men and Women
1996
Forty-eight healthy men (M) and women (W), divided into two different age groups, i.e., M50 yrs (range 44-57; n = 12), W50 yrs (range 43-57; n = 12), M70 yrs (range 59-75; n = 12), and W70 yrs (range 62-75; n = 12), volunteered as subjects for examination of muscle cross-sectional area (CSA), maximal voluntary forces, force-time curves, and electromyographic activity of the knee extensor muscles during bilateral and unilateral isometric contractions. The maximal bilateral knee extension force and the average CSA values in M50 were greater (p < .05) than in M70 and in W50 were greater (p < .05-.001) than those recorded for W70. The early forces in the force-time curve were greater (p < .05) …
Muscle cross-sectional area and voluntary force production characteristics in elite strength- and endurance-trained athletes and sprinters
1989
Seven male elite strength-trained athletes (SA) from different weight categories, six elite sprinters (SPA) and seven elite endurance-trained athletes (EA) volunteered as subjects for examination of their muscle cross-sectional area (CSA), maximal voluntary isometric force, force-time and relaxation-time characteristics of the leg extensor muscles. The SA group demonstrated slightly greater CSA and maximal absolute strength than the SPA group, while the EA group demonstrated the smallest values both in CSA and especially in maximal strength (p<0.05). When the maximal forces were related to CSA of the muscles, the mean value for the SA group of 60.8±10.0 N·cm−2 remained slightly greater than…
Effects of Stretching on Upper-Body Muscular Performance
2008
The purpose of this investigation was to examine the influence of upper-body static stretching and dynamic stretching on upper-body muscular performance. Eleven healthy men, who were National Collegiate Athletic Association Division I track and field athletes (age, 19.6 +/- 1.7 years; body mass, 93.7 +/- 13.8 kg; height, 183.6 +/- 4.6 cm; bench press 1 repetition maximum [1RM], 106.2 +/- 23.0 kg), participated in this study. Over 4 sessions, subjects participated in 4 different stretching protocols (i.e., no stretching, static stretching, dynamic stretching, and combined static and dynamic stretching) in a balanced randomized order followed by 4 tests: 30% of 1 RM bench throw, isometric ben…
Should Exercises be Painful or not? Effects on Clinical and Experimental Pain in Individuals with Shoulder Pain
2021
Exercise can reduce pain, however the effect of painful versus non-painful exercises is uncertain. The primary aim of this randomized crossover study was to compare the effect of painful versus nonpainful isometric shoulder exercises on pain intensity after exercise in individuals with rotator cuff-related shoulder pain. Secondary exploratory aims were to describe the effects on pressure pain thresholds (PPTs), conditioned pain modulation (CPM) and muscle strength. On separate days, 35 individuals performed painful isometric shoulder exercises (external rotation; 20% above pain threshold), nonpainful isometric shoulder exercises (external rotation; 20% below pain threshold), and a rest cond…
Trunk muscle activation patterns and spine kinematics when using an oscillating blade: influence of different postures and blade orientations.
2009
Abstract Sanchez-Zuriaga D, Vera-Garcia FJ, Moreside JM, McGill SM. Trunk muscle activation patterns and spine kinematics when using an oscillating blade: influence of different postures and blade orientations. Objective To compare trunk muscle activation patterns and trunk kinematics when using an oscillating blade in standing and unsupported sitting postures, and with different orientations of the blade. Design A cross-sectional survey of trunk muscle activities and lumbar motion. Setting Biomechanics research laboratory. Participants Healthy men (N=13). Interventions An oscillating blade was held with 2 hands and oscillated with vertical and horizontal orientations of blade. These exerci…
Non‐uniform displacement within ruptured Achilles tendon during isometric contraction
2021
The purpose of this study was investigate tendon displacement patterns in non-surgically treated patients 14 months after acute Achilles tendon rupture (ATR) and to classify patients into groups based on their Achilles tendon (AT) displacement patterns. Twenty patients were tested. Sagittal images of AT were acquired using B-mode ultrasonography during ramp contractions at a torque level corresponding to 30% of the maximal isometric plantarflexion torque of the uninjured limb. A speckle tracking algorithm was used to track proximal-distal movement of the tendon tissue at 6 antero-posterior locations. Two-way repeated measures ANOVA for peak tendon displacement was performed. K-means cluster…
Force and EMG power spectrum during eccentric and concentric actions
2000
This study was designed to examine the force and activation levels of elbow flexor muscles during preactivated eccentric, concentric and isometric actions.Force, average EMG (aEMG), and the EMG power spectrum were investigated at different constant movement velocities (1 rad x s(-1), 2 rad x s(-1), 3 rad x s(-1), and 4 rad x s(-1)) at different joint angles.Average force at a 110 degree elbow angle was lower and aEMG was higher in concentric actions as compared with eccentric and isometric actions. At a 55 degree elbow angle, there was no difference in aEMG, or it was slightly higher in eccentric actions. MF was higher in the concentric as compared with eccentric actions at the three fastes…