Search results for "H reflex"
showing 9 items of 49 documents
Interaction between muscle stiffness and stretch reflex sensitivity after long-term stretch-shortening cycle exercise
1998
The short latency stretch-reflex component (M1) and its interactions with muscle stiffness and with muscle performance were investigated before and after long-term stretch-shortening cycle (SSC) exercise. Dramatic fatigue induced reduction in maximal SSC performance capability, and electromyographic activity was accompanied by a consistent decrease in the M1 reflex component and eccentric peak stiffness of the muscle. It can be suggested, therefore, that the decreased muscle performance is not simply a direct effect of central or peripheral fatigue, but is partly due to impairment of the ability to utilize stiffness-related elastic energy.
Acute (0-2h) and delayed (2-8D) effects of exercise-induced muscle damage and soreness on elbow target movements.
2011
The aim was to examine the acute and delayed effects of exercise-induced muscle damage and soreness on elbow target movements (TM) performance and control. Ten males performed an exercise of 50 maximal eccentric elbow actions. TMs were performed at three movement ranges. Maximal forces, active stretch reflex and TM were tested, and muscle soreness, creatine kinase and elbow joint stiffness were determined acute (after and 2 h) and delayed (2, 4, 6, 8d) postexercise. Both the long lasting muscle soreness and force drop were observed after the exercise. Joint stiffness was increased at 2 h postexercise. The highest deterioration in flexion-TM performance was found at the time (2 h) and at the…
Leg and joint stiffness in human hopping
2010
The present study investigated the regulation of leg and joint stiffness in hopping at different intensity levels. Eight male subjects performed bilateral hopping at various intensity levels that were determined by peak vertical ground reaction force (GRF). In addition to the GRF, the measurements included hopping kinematics and electromyography (EMG) of selected leg muscles. While the leg and ankle joint stiffness remained invariant, the knee joint stiffness increased significantly (P<0.01) with the hopping intensity. EMG analysis revealed a significant increase in averaged EMG for all the measured muscles before and during the early phase of ground contact (P<0.05-0.001) with increasing h…
Medial Gastrocnemius Muscle Architecture Is Altered After Exhaustive Stretch-Shortening Cycle Exercise
2019
Muscle architecture is an important component of muscle function, and recent studies have shown changes in muscle architecture with fatigue. The stretch-shortening cycle is a natural way to study human locomotion, but little is known about how muscle architecture is affected by this type of exercise. This study investigated potential changes in medial gastrocnemius (MG) muscle architecture after exhaustive stretch-shortening cycle exercise. Male athletes (n = 10) performed maximal voluntary contractions (MVC) and maximal drop jump (DJ) tests before and after an exercise task consisting of 100 maximal DJs followed by successive rebound jumping to 70% of the initial maximal height. The exerci…
Voimaharjoittelun vaikutukset dynaamiseen ja staattiseen tasapainoon nuorilla ja ikääntyneillä
2017
Tasapainolle ei ole olemassa universaalia määritelmää mutta se tiedetään, että sitä kontrolloivat useat eri mekanismit. Ikääntyminen aiheuttaa siinä heikkenemistä, joka aiheutuu muutoksista sekä sensorisissa että motorisissa prosesseissa. Kaatumisesta aiheutuneiden vammojen määrä kasvaa koko ajan ikääntyneillä. Heidän onkin havaittu pärjäävän nuoria huonommin sekä staattisissa että dynaamisissa testeissä mutta dynaamisissa testeissä ero on vieläkin suurempi. Erityisesti dynaamisten ominaisuuksin tutkiminen on tärkeää sillä staattiset testit eivät välttämättä paljasta tasapaino-ongelmia tai ikääntymiseen liittyviä eroja yhtä hyvin kuin dynaamiset testit. Tämän tutkimuksen suoritti loppuun 4 …
Stretch reflex modulation during exercise and fatigue
2003
Muscle and joint stiffness regulation during normal and fatiguing stretch-shortening cycle exercise
2010
Modulations of corticospinal excitability following rapid ankle dorsiflexion in skill- and endurance-trained athletes
2022
Abstract Purpose Long-term sports training, such as skill and endurance training, leads to specific neuroplasticity. However, it remains unclear if muscle stretch-induced proprioceptive feedback influences corticospinal facilitation/inhibition differently between skill- and endurance-trained athletes. This study investigated modulation of corticospinal excitability following rapid ankle dorsiflexion between well-trained skill and endurance athletes. Methods Ten skill- and ten endurance-trained athletes participated in the study. Corticospinal excitability was tested by single- and paired-pulse transcranial magnetic stimulations (TMS) at three different latencies following passive rapid ankl…