Search results for "Exercise"
showing 10 items of 3151 documents
Activation of human plantar flexor muscles increases after electromyostimulation training
2002
Neuromuscular adaptations of the plantar flexor muscles were assessed before and subsequent to short-term electromyostimulation (EMS) training. Eight subjects underwent 16 sessions of isometric EMS training over 4 wk. Surface electromyographic (EMG) activity and torque obtained under maximal voluntary and electrically evoked contractions were analyzed to distinguish neural adaptations from contractile changes. After training, plantar flexor voluntary torque significantly increased under isometric conditions at the training angle (+8.1%, P< 0.05) and at the two eccentric velocities considered (+10.8 and +13.1%, P < 0.05). Torque gains were accompanied by higher normalized soleus EMG a…
Voluntary activation and mechanical performance of human triceps surae muscle after exhaustive stretch-shortening cycle jumping exercise.
2003
The purpose of this study was to examine neuromuscular factors that may contribute to post exercise force loss and subsequent recovery after exhaustive stretch-shortening cycle (SSC) exercise. Six subjects were fatigued on a sledge apparatus by 100 maximal rebound jumps followed by continuous submaximal jumping until complete exhaustion. Exercise-induced changes in neuromuscular performance were followed up to 7 days post exercise. The total number of jumps in the SSC exercise ranged from 336 to 1392. The SSC exercise induced a significant immediate plantarflexion torque decline of 29, 38 and 44% (P<0.05) in maximal voluntary contraction and evoked maximal twitch and low-frequency (LF) stim…
Co-activation and tension-regulating phenomena during isokinetic knee extension in sedentary and highly skilled humans.
1996
The aim of this study was to examine isokinetic torque produced by highly skilled (HS) and sedentary (S) human subjects, during knee extension, during maximal voluntary and superimposed electrical activation. To verify the level of activation of agonist (vastus lateralis, VL, and vastus medialis, VM) and antagonist muscles (semi-tendineous, ST), during maximal voluntary activation, their myo-electrical activities were detected and quantified as root mean square (rms) amplitude. Ten HS and ten S subjects performed voluntary and superimposed isometric actions and isokinetic knee extensions at 14 angular velocities (from -120 to 300 degrees*s(-1)). The rms amplitude of each muscle was normaliz…
Mechanism of Free Radical Production in Exhaustive Exercise in Humans and Rats; Role of Xanthine Oxidase and Protection by Allopurinol
2000
Exhaustive exercise generates free radicals, However, the source of this oxidative damage remains controversial. The aim of this paper was to study further the mechanism of exercise-induced production of free radicals, Testing the hypothesis that xanthine oxidase contributes to the production of free radicals during exercise, me found not only that exercise caused an increase in blood xanthine oxidase activity in rats but also that inhibiting xanthine oxidase with allopurinol prevented exercise-induced oxidation of glutathione in both rats and in humans. Furthermore, inhibiting xanthine oxidase prevented the increases in the plasma activity of cytosolic enzymes (lactate dehydrogenase, aspar…
Oxidative stress in marathon runners: interest of antioxidant supplementation
2006
We have recently reported that xanthine oxidase is involved in the generation of free radicals in exhaustive exercise. Allopurinol, an inhibitor of xanthine oxidase, prevents it. The aim of the present work was to elucidate the role of exercise-derived reactive oxygen species in the cell signalling pathways involved in the adaptation to exercise in man. We have found that exercise causes an increase in the activity of plasma xanthine oxidase and an activation of NF-κB in peripheral blood lymphocytes after marathon running. This activation is dependent on free radical formation in exercise: treatment with allopurinol completely prevents it. In animal models, we previously showed that NF-κB a…
The relationship between age and fitness profiles in elite male ice hockey players
2021
Background: The present study investigated relationships between age, body composition and performance in elite male ice hockey players.Methods: 199 players performed off-ice tests (countermovement jump height (CMJ) and body composition) and on-ice tests (5-10-5 Pro Agility test, 30-m sprint test and the maximal Yo-Yo Intermittent Recovery Ice Hockey test (Yo-Yo IR1-IHMAX) for assessment of aerobic capacity.Results: No overall correlations between age and performance were present except small-moderate positive associations between age and body-and muscle mass (r=0.24-0.30, ≤0.05). The youngest age group (YOU; 18-21 years) were 4-9% lighter than all other age groups and possessed 7% less mus…
Acute effects of dynamic stretching on mechanical properties result from both muscle-tendon stretching and muscle warm-up
2019
We investigated the acute effects of dynamic stretching on mechanical properties of plantar flexor muscles and tested the hypothesis that it would result from an interaction between muscle-tendon stretching and muscle warm-up. To test the stretching effect, dynamic stretching (DS) was compared to static stretching (SS). To test the warm-up effect, DS was compared to submaximal isometric muscle activity (SIMA) with similar contraction intensity. A control condition served as reference. These four conditioning activities were time matched (2×20s) and tested on separate days on 13 volunteers. Electrical neurostimulation was applied to investigate muscle mechanical properties (peak doublet torq…
Central and peripheral fatigue of the knee extensor muscles induced by electromyostimulation.
2005
The main purpose of this study was to characterise neuromuscular fatigue induced by 30 contractions of the knee extensor muscles evoked by electromyostimulation (EMS). Twelve healthy subjects were tested before and after a typical EMS session (frequency: 75 Hz, on-off ratio: 6.25 s on-20 s off) used for quadriceps femoris muscle strengthening. Surface electromyographic (EMG) activity and torque obtained during maximal voluntary and electrically evoked contractions were analysed to distinguish peripheral from central fatigue. Maximal voluntary torque of the knee extensor muscles decreased approximately 20 % (p < 0.001) following EMS. In the same way, peak torque associated to single (p < 0.0…
Prothrombotic State Induced by Middle-Distance Endurance Exercise in Middle-Aged Athletes
2018
AbstractSince the impact of possible prothrombotic factors on blood coagulation resulting from exercise remains elusive, this study investigated the acute effects of middle-distance endurance running on blood coagulation parameters in middle-aged athletes. The study population consisted of 33 male endurance runners who were engaged in a 21.1 km run under competitive conditions. Blood samples were collected before the run, immediately after the run, and 3 hours after run completion. Samples were assessed for activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen, D-dimer, factor VIII (FVIII), von Willebrand factor antigen (VWF:Ag), endogenous thrombin potential (area…
Determining the Corticospinal Responses to Single Bouts of Skill and Strength Training
2019
Mason, J, Frazer, AK, Jaberzadeh, S, Ahtiainen, JP, Avela, J, Rantalainen, T, Leung, M, and Kidgell, DJ. Determining the corticospinal responses to single bouts of skill and strength training. J Strength Cond Res 33(9): 2299-2307, 2019-Neuroplastic changes in the primary motor cortex accompany performance improvements following motor practice. Recent evidence suggests that the corticospinal responses to strength and skill training are similar, following both a single session and repeated bouts of training, promoting discussion that strength training is a form of motor learning. However, these findings are limited by the lack of a light-load strength training group. Therefore, the aim of the…