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Paavo V. Komi

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https://www.readbyqxmd.com/read/27699696/neuromechanical-modulation-of-the-achilles-tendon-during-bilateral-hopping-in-patients-with-unilateral-achilles-tendon-rupture-over-1-year-after-surgical-repair
#1
Hiroyuki Oda, Kanae Sano, Yoko Kunimasa, Paavo V Komi, Masaki Ishikawa
BACKGROUND: Patients who have had an Achilles tendon (AT) rupture repaired are potentially at higher risk for re-rupture than those without previous rupture. Little attention has been given to the neuromechanical modulation of muscle-tendon interaction and muscle activation profiles during human dynamic movements after AT rupture repair. OBJECTIVE: The purpose of this study was to examine muscle-tendon behavior and muscle activation during bilateral hopping. METHODS: We enrolled nine subjects who had undergone surgical repair of unilateral AT rupture within the past 1-2 years...
October 3, 2016: Sports Medicine
https://www.readbyqxmd.com/read/26146894/age-specific-neuromuscular-interaction-during-elderly-habitual-running
#2
K Sano, M Akiyama, M Hoffrén-Mikkola, A Ito, P V Komi, M Ishikawa
AIM: It has been reported that advancing age causes tendons to become more compliant and fascicles length shorter. This could then lead to enhancement of movement efficiency provided that the elderly adults can activate their muscles in the same way as the younger adults (YOUNG) during dynamic movements. This study was designed to examine the age-specific behaviour of the medial gastrocnemius (MG) fascicles and tendinous tissues together with lower-leg muscle activities when the well-trained elderly runners ran on the treadmill at preferred speeds...
October 2015: Acta Physiologica
https://www.readbyqxmd.com/read/25479729/neuromuscular-mechanics-and-hopping-training-in-elderly
#3
RANDOMIZED CONTROLLED TRIAL
Merja Hoffrén-Mikkola, Masaki Ishikawa, Timo Rantalainen, Janne Avela, Paavo V Komi
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...
May 2015: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/25476746/can-measures-of-muscle-tendon-interaction-improve-our-understanding-of-the-superiority-of-kenyan-endurance-runners
#4
Kanae Sano, Caroline Nicol, Masanobu Akiyama, Yoko Kunimasa, Toshiaki Oda, Akira Ito, Elio Locatelli, Paavo V Komi, Masaki Ishikawa
PURPOSE: Leg muscle activation profiles and muscle-tendon interaction were studied with eleven internationally high-level Kenyan and eleven national level Japanese distance runners. METHODS: Ultrasonography and kinematics were applied together with surface electromyography (EMG) recordings of leg muscles when subjects ran on treadmill at 9.0 (SLOW) and 13.9 km h(-1) (MEDIUM). RESULTS: At each speed, both groups presented similar contact and flight times...
April 2015: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/25324763/motor-unit-discharge-rate-in-dynamic-movements-of-the-aging-soleus
#5
Jouni Kallio, Karen Søgaard, Janne Avela, Paavo V Komi, Harri Selänne, Vesa Linnamo
Aging is related to a variety of changes at the muscular level. It seems that the age-related changes in motor unit activation are muscle- and intensity dependent. The purpose of this study was to examine the motor unit discharge rate (MUDR) in both isometric and dynamic contractions of the aging soleus muscle. Eight elderly males participated in the study. The subjects performed isometric and dynamic plantar flexions while seated in an ankle dynamometer. The force levels studied were 10, 20, 40, 60, 80 and 100% of the isometric (ISO) maximal voluntary contractions (MVC) in ISO and 10, 20 and 40% in concentric (CON) and eccentric (ECC) contractions...
2014: Frontiers in Human Neuroscience
https://www.readbyqxmd.com/read/24149597/short-term-bone-biochemical-response-to-a-single-bout-of-high-impact-exercise
#6
Timo Rantalainen, Ari Heinonen, Vesa Linnamo, Paavo V Komi, Timo E S Takala, Heikki Kainulainen
Bone response to a single bout of exercise can be observed with biochemical markers of bone formation and resorption. The purpose of this study was to examine the response of bone biochemical markers to a single bout of exhaustive high-impact exercise. 15 physically active young subjects volunteered to participate. The subjects performed continuous bilateral jumping with the ankle plantarflexors at 65 % of maximal ground reaction force (GRF) until exhaustion. Loading was characterized by analyzing the GRF recorded for the duration of the exercise...
2009: Journal of Sports Science & Medicine
https://www.readbyqxmd.com/read/23405069/motor-unit-firing-behaviour-of-soleus-muscle-in-isometric-and-dynamic-contractions
#7
Jouni Kallio, Karen Søgaard, Janne Avela, Paavo V Komi, Harri Selänne, Vesa Linnamo
INTRODUCTION: Understanding the detailed control of human locomotion and balance can be improved, when individual motor units can be isolated and their firing rates followed in natural movement of large, fuctionally important muscles. For this reason the present study investigated the motor unit discharge rate (MUDR) in isometric and dynamic contractions of the soleus muscle. METHODS: Eleven males performed isometric (10-100% MVC) and dynamic (10-40% MVC) plantar flexions...
2013: PloS One
https://www.readbyqxmd.com/read/22466309/age-related-fascicle-tendon-interaction-in-repetitive-hopping
#8
Merja Hoffrén, Masaki Ishikawa, Janne Avela, Paavo V Komi
Increasing age can influence the interaction of muscle fascicles and tendon during dynamic movements. The object of the present study was to examine occurrence and possible reasons for the age-specific behavior of fascicles and tendons and their interaction during hopping with different intensities. Nine young and 24 elderly subjects performed repetitive hopping with maximal effort as well as with 50, 65, 75 and 90 % intensities. During hopping joint kinematics and ground reaction, forces were measured together with recordings of ultrasound images of both the fascicle and the muscle-tendon junction part of the gastrocnemius medialis (GaM) muscle...
December 2012: European Journal of Applied Physiology
https://www.readbyqxmd.com/read/21458294/age-related-muscle-activation-profiles-and-joint-stiffness-regulation-in-repetitive-hopping
#9
Merja Hoffrén, Masaki Ishikawa, Timo Rantalainen, Janne Avela, Paavo V Komi
It is well documented that increasing effort during exercise is characterized by an increase in electromyographic activity of the relevant muscles. How aging influences this relationship is a matter of great interest. In the present study, nine young and 24 elderly subjects did repetitive hopping with maximal effort as well as with 50%, 65%, 75% and 90% intensities. During hopping joint kinematics were measured together with electromyographic activity (EMG) from the soleus, gastrocnemius medialis, gastrocnemius lateralis and tibialis anterior muscles...
June 2011: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/20193974/achilles-tendon-length-changes-during-walking-in-long-term-diabetes-patients
#10
RANDOMIZED CONTROLLED TRIAL
Neil J Cronin, Jussi Peltonen, Masaki Ishikawa, Paavo V Komi, Janne Avela, Thomas Sinkjaer, Michael Voigt
BACKGROUND: Diabetes leads to numerous side effects, including an increased density of collagen fibrils and thickening of the Achilles tendon. This may increase tissue stiffness and could affect stretch distribution between muscle and tendinous tissues during walking. The primary aim of this study was to examine stretch distribution between muscle and tendinous tissues in the medial gastrocnemius muscle-tendon unit in long-term diabetes patients and control subjects during walking. METHODS: Achilles tendon length changes were investigated in 13 non-neuropathic diabetes patients and 12 controls, whilst walking at a self selected speed across a 10 m force platform...
June 2010: Clinical Biomechanics
https://www.readbyqxmd.com/read/20064728/disturbed-motor-control-of-rhythmic-movement-at-2-h-and-delayed-after-maximal-eccentric-actions
#11
Reijo Bottas, Kari Miettunen, Paavo V Komi, Vesa Linnamo
The aim of this study was to examine the influence of exercise-induced muscle damage on elbow rhythmic movement (RM) performance and neural activity pattern and to investigate whether this influence is joint angle specific. Ten males performed an exercise of 50 maximal eccentric elbow flexions in isokinetic machine with duty cycle of 1:15. Maximal dynamic and isometric force tests (90 degrees , 110 degrees and 130 degrees elbow angle) and both active and passive stretch reflex tests of elbow flexors were applied to the elbow joint...
August 2010: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/20064632/neuromuscular-performance-and-body-mass-as-indices-of-bone-loading-in-premenopausal-and-postmenopausal-women
#12
Timo Rantalainen, Riku Nikander, Ari Heinonen, Juhani Multanen, Arja Häkkinen, Timo Jämsä, Ilkka Kiviranta, Vesa Linnamo, Paavo V Komi, Harri Sievänen
The strong association between body mass and skeletal robusticity has been attributed to increasing skeletal loading with increasing mass. However, it is unclear whether body mass is merely a coarse substitute for bone loading rather than a true independent predictor of bone strength. As indices of neuromuscular performance, impulse and peak power were determined from vertical ground reaction force during a maximal counter movement jump test in 221 premenopausal and 82 postmenopausal women. Bone compressive (BSI(d) g(2)/cm(4)) and bending (SSImax(mid) mm(3)) strength indices were measured with peripheral quantitative computed tomography (pQCT) at the distal ((d)) and midshaft ((mid)) sites of the tibia...
April 2010: Bone
https://www.readbyqxmd.com/read/19622608/effects-of-prolonged-walking-on-neural-and-mechanical-components-of-stretch-responses-in-the-human-soleus-muscle
#13
Neil J Cronin, Masaki Ishikawa, Richard Af Klint, Paavo V Komi, Janne Avela, Thomas Sinkjaer, Michael Voigt
After repeated passive stretching, tendinous tissue compliance increases in the human soleus (SOL) muscle-tendon unit. During movement, such changes would have important consequences for neural and mechanical stretch responses. This study examined the existence of such effects in response to a 75 min walking intervention. Eleven healthy subjects walked on a treadmill at 4 km h(1) with a robotic stretch device attached to the left leg. Ultrasonography was used to measure SOL fascicle lengths, and surface EMG activity was recorded in the SOL and tibialis anterior (TA) muscles...
September 1, 2009: Journal of Physiology
https://www.readbyqxmd.com/read/19451207/mechanical-and-neural-stretch-responses-of-the-human-soleus-muscle-at-different-walking-speeds
#14
Neil J Cronin, Masaki Ishikawa, Michael J Grey, Richard af Klint, Paavo V Komi, Janne Avela, Thomas Sinkjaer, Michael Voigt
During human walking, a sudden trip may elicit a Ia afferent fibre mediated short latency stretch reflex. The aim of this study was to investigate soleus (SOL) muscle mechanical behaviour in response to dorsiflexion perturbations, and to relate this behaviour to short latency stretch reflex responses. Twelve healthy subjects walked on a treadmill with the left leg attached to an actuator capable of rapidly dorsiflexing the ankle joint. Ultrasound was used to measure fascicle lengths in SOL during walking, and surface electromyography (EMG) was used to record muscle activation...
July 1, 2009: Journal of Physiology
https://www.readbyqxmd.com/read/18815488/muscle-fascicle-and-tendon-behavior-during-human-locomotion-revisited
#15
Masaki Ishikawa, Paavo V Komi
High-speed ultrasonography has revealed that, in human locomotion, the nature of fascicle and tendon length changes varies depending on the task, contraction intensity, and the muscles involved. The findings emphasize that the active fascicles of the gastrocnemius muscle are suddenly stretched, although they are shortening. This short-lasting stretch triggers the stretch reflex, timing of which is dependent on running speed.
October 2008: Exercise and Sport Sciences Reviews
https://www.readbyqxmd.com/read/18483163/effects-of-contraction-intensity-on-muscle-fascicle-and-stretch-reflex-behavior-in-the-human-triceps-surae
#16
Neil J Cronin, Jussi Peltonen, Masaki Ishikawa, Paavo V Komi, Janne Avela, Thomas Sinkjaer, Michael Voigt
The aims of this study were to examine changes in the distribution of a stretch to the muscle fascicles with changes in contraction intensity in the human triceps surae and to relate fascicle stretch responses to short-latency stretch reflex behavior. Thirteen healthy subjects were seated in an ankle ergometer, and dorsiflexion stretches (8 degrees ; 250 degrees /s) were applied to the triceps surae at different moment levels (0-100% of maximal voluntary contraction). Surface EMG was recorded in the medial gastrocnemius, soleus, and tibialis anterior muscles, and ultrasound was used to measure medial gastrocnemius and soleus fascicle lengths...
July 2008: Journal of Applied Physiology
https://www.readbyqxmd.com/read/18460994/effect-of-skiing-speed-on-ski-and-pole-forces-in-cross-country-skiing
#17
Pekka Vähäsöyrinki, Paavo V Komi, Seppo Seppälä, Masaki Ishikawa, Veli Kolehmainen, Jukka A Salmi, Vesa Linnamo
PURPOSE: The present study characterized pole and ski forces in classical technique cross-country skiing. Eight elite junior cross-country skiers performed diagonal skiing at 65%, 75%, 90%, and 100% of maximum speed on a stable 100-m-low uphill (2.5 degrees ). METHOD: : The ski and the pole forces (vertical (Fz) and horizontal (Fy) directions) on the right and left sides were recorded separately when the skier skied over a special custom-made force platform system placed at the end of the uphill course...
June 2008: Medicine and Science in Sports and Exercise
https://www.readbyqxmd.com/read/17937994/adaptive-changes-in-motor-control-of-rhythmic-movement-after-maximal-eccentric-actions
#18
Reijo Bottas, Caroline Nicol, Paavo V Komi, Vesa Linnamo
Effects of an exhaustive eccentric exercise (EE) on the motor control of maximal velocity rhythmic elbow extension/flexion movement (RM) were examined in eight male students. The exhaustive EE consisted of 100 maximal eccentric actions of the elbow flexor muscles. Movement range was 40-170 degrees in EE at an angular velocity of 2rads(-1). A directive scaled RM of 60 degrees with visual feedback was performed in a sitting position, with the right forearm fixed to the lever arm in horizontal plane above protractor...
April 2009: Journal of Electromyography and Kinesiology
https://www.readbyqxmd.com/read/17673559/a-single-bout-of-exercise-with-high-mechanical-loading-induces-the-expression-of-cyr61-ccn1-and-ctgf-ccn2-in-human-skeletal-muscle
#19
Riikka Kivelä, Heikki Kyröläinen, Harri Selänne, Paavo V Komi, Heikki Kainulainen, Veikko Vihko
High mechanical loading was hypothesized to induce the expression of angiogenic and/or lymphangiogenic extracellular matrix (ECM) proteins in skeletal muscle. Eight men performed a strenuous exercise protocol, which consisted of 100 unilateral maximal drop jumps followed by submaximal jumping until exhaustion. Muscle biopsies were taken 30 min and 48 h postexercise from the vastus lateralis muscle and analyzed for the following parameters: mRNA and protein expression of ECM-associated CCN proteins [cysteine-rich angiogenic protein 61 (Cyr61)/CCN1, connective tissue growth factor (CTGF)/CCN2], and mRNA expression of vascular endothelial growth factors (VEGFs) and hypoxia-inducible factor-1alpha...
October 2007: Journal of Applied Physiology
https://www.readbyqxmd.com/read/17473771/bimodal-recovery-pattern-in-human-skeletal-muscle-induced-by-exhaustive-stretch-shortening-cycle-exercise
#20
Erick Dousset, Janne Avela, Masaki Ishikawa, Jouni Kallio, Sami Kuitunen, Heikki Kyröláinen, Vesa Linnamo, Paavo V Komi
INTRODUCTION/PURPOSE: Recovery of force and stretch reflex from exhaustive stretch-shortening cycle (SSC) exercise is usually bimodal, characterized as immediate exercise-induced performance reduction, with its quick recovery followed by a longer-lasting reduction in performance. A clear parallel exists between the respective changes in performance, neural activation, and metabolic or structural exercise-induced changes. This implies the existence of potential coupling between muscle failure and the induced neural adjustments that take place along its recovery...
March 2007: Medicine and Science in Sports and Exercise
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