Search results for "jänteet"

Mechanical Coupling Between Muscle-Tendon Units Reduces Peak Stresses

2017

The presence of mechanical linkages between synergistic muscles and their common tendons may distribute forces among the involved structures. We review studies, using humans and other animals, examining muscle and tendon interactions and discuss the hypothesis that connections between muscle bellies and within tendons may serve as a mechanism to distribute forces and mitigate peak stresses. peerReviewed

In vivo localized gastrocnemius subtendon representation within the healthy and ruptured human Achilles tendon

2022

The Achilles tendon (AT) is composed of three distinct in-series elastic subtendons, arising from different muscles in the triceps surae. Independent activation of any of these muscles is thought to induce sliding between the adjacent AT subtendons. We aimed to investigate displacement patterns during voluntary contraction (VOL) and selective transcutaneous stimulation of medial (MGstim) and lateral (LGstim) gastrocnemius between ruptured and healthy tendons, and to examine the representative areas of AT subtendons. Twenty-eight patients with unilateral AT rupture performed bilateral VOL at 30% of the maximal isometric un-injured plantarflexion torque. AT displacement was analysed from sagi…

Effect of Training-Induced Changes in Achilles Tendon Stiffness on Muscle–Tendon Behavior During Landing

2018

During rapid deceleration of the body, tendons buffer part of the elongation of the muscle–tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle–tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarf…

Lihas-jännekompleksin pituuden muutokset kävelyn aikana in vivo

2006

Functional muscle architecture in aging

2014

Neuromuscular mechanics and hopping training in elderly.

2014

Purpose The present study examined the effects of repetitive hopping training on muscle activation profiles and fascicle–tendon interaction in the elderly. Methods 20 physically active elderly men were randomly assigned for training (TG) and control groups (CG). TG performed supervised bilateral short contact hopping training with progressively increasing training volume. Measurements were performed before the training period (BEF) as well as after 2 weeks (2 W) and 11 weeks (11 W) of training. During measurements, the gastrocnemius medialis–muscle (GaM) fascicle and its outer Achilles tendon length changes during hopping were examined by ultrasonography together with electromyographic (EMG…

Repeatability and sensitivity of passive mechanical stiffness measurements in the triceps surae muscle‐tendon complex

2021

Measurements of muscle-tendon unit passive mechanical properties are often used to illustrate acute and chronic responses to a training stimulus. The purpose of this study was to quantify the inter-session repeatability of triceps surae passive stiffness measurements in athletic and non-athletic populations, with the view to discussing its usefulness both as a muscle-tendon profiling tool and a control measure for studies with multiple data collection sessions. The study also aimed to observe the effects of quiet standing on passive stiffness parameters. Twenty-nine men (10 cyclists, nine triathletes, 10 controls) visited the laboratory on three separate occasions, where passive stiffness t…

Exploration of muscle–tendon biomechanics one year after Achilles tendon rupture and the compensatory role of flexor hallucis longus

2023

Achilles tendon (AT) rupture leads to long-term structural and functional impairments. Currently, the predictors of good recovery after rupture are poorly known. Thus, we aimed to explore the interconnections between structural, mechanical, and neuromuscular parameters and their associations with factors that could explain good recovery in patients with non-surgically treated AT rupture. A total of 35 patients with unilateral rupture (6 females) participated in this study. Muscle-tendon structural, mechanical, and neuromuscular parameters were measured 1-year after rupture. Interconnections between the inter-limb differences (Δ) were explored using partial correlations, followed by multivar…

Akillesjänteen ja luustolihaksen glukoosin käyttö fyysisen rasituksen aikana positroniemissiotomografialla mitattuna

2001

Jarna Saarinen. Akillesjänteen ja luustolihaksen glukoosin käyttö fyysisen rasituksen aikana positroniemissiotomografialla mitattuna. Liikuntafysiologian Pro Gradu -tutkielma. Liikuntabiologian laitos. Jyväskylän yliopisto. Jänteiden tehtävänä on kiinnittää lihakset luihin ja kuljettaa lihasten synnyttämät voimat luihin. Koska jänteiden solut käyttävät happea ja sisältävät energia-aineenvaihduntajärjestelmän entsyymiketjuja, niiden uskotaan käyttävän glukoosia energia-aineenvaihdunnassaan. Positroniemissiotomografia (PET) on radioaktiivisia isotooppeja hyödyntävä kuvantamismenetelmä, jolla voidaan tutkia elimistön biokemiallisiaja aineenvaihdunnallisia tapahtumia in vivo. Tämän tutkimuksen …

Towards modern understanding of the Achilles tendon properties in human movement research

2023

The Achilles tendon (AT) is the strongest tendon in humans, yet it often suffers from injury. The mechanical properties of the AT afford efficient movement, power amplification and power attenuation during locomotor tasks. The properties and the unique structure of the AT as a common tendon for three muscles have been studied frequently in humans using in vivo methods since 1990's. As a part of the celebration of 50 years history of the International Society of Biomechanics, this paper reviews the history of the AT research focusing on its mechanical properties in humans. The questions addressed are: What are the most important mechanical properties of the Achilles tendon, how are they stud…