Search results for "Muscle"
showing 10 items of 3397 documents
Inertial properties of the arm are accurately predicted during motor imagery
2004
Abstract In the present study, using the mental chronometry paradigm, we examined the hypothesis that during motor imagery the brain uses a forward internal model of arm inertial properties to predict the motion of the arm in different dynamic states. Seven subjects performed overt and covert arm movements with one (motion around the shoulder joint) and two (motion around both the shoulder and elbow joints) degrees of freedom in the horizontal plane. Arm movements were executed under two loading conditions: without and with an added mass (4 kg) attached to the subject’s right wrist. Additionally, movements were performed in two different directions, condition which implies changes in the ar…
The effects of a roundtrip trans-American jet travel on physiological stress, neuromuscular performance, and recovery.
2016
The purpose was to examine the effects of a round trip trans-American jet travel on performance, hormonal alterations, and recovery. Ten matched pairs of recreationally trained men were randomized to either a compression group (COMP) ( n = 10; age: 23.1 ± 2.4 yr; height: 174.8 ± 5.3 cm; body mass: 84.9 ± 10.16 kg; body fat: 15.3 ± 6.0%) or control group (CONT) ( n = 9; age: 23.2 ± 2.3 yr; height: 177.5 ± 6.3 cm; weight: 84.3 ± 8.99 kg; body fat: 15.1 ± 6.4%). Subjects flew directly from Hartford, CT to Los Angeles, CA 1 day before a simulated sport competition (SSC) designed to create muscle damage and returned the next morning on an overnight flight back home. Both groups demonstrated jet…
Neck semispinalis capitis muscle size in sitting and prone positions measured by real-time ultrasonography.
1998
Objective: To examine the reliability of measurements of semispinalis capitis muscle (SECM) cross-sectional area (CSA) in prone and sitting positions, and to compare the muscle size in these two positions. Design: Semispinalis capitis CSA was measured twice a day on two successive days with a real-time ultrasound apparatus. Subjects: Eighteen males (aged 19–34 years) and 28 females (aged 19–34 years) were studied for the reliability test. Seven males and 12 females were randomly selected to compare SECM size in sitting and prone positions. Results: The intraclass correlation coefficient (ICC) for repeatability measurements was r = 0.98 for the two positions. The correlation of the CSA in s…
Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training
2014
This study investigated the effects of vitamin C and E supplementation on acute responses and adaptations to strength training. Thirty-two recreationally strength-trained men and women were randomly allocated to receive a vitamin C and E supplement (1000 mg day(-1) and 235 mg day(-1), respectively), or a placebo, for 10 weeks. During this period the participants' training involved heavy-load resistance exercise four times per week. Muscle biopsies from m. vastus lateralis were collected, and 1 repetition maximum (1RM) and maximal isometric voluntary contraction force, body composition (dual-energy X-ray absorptiometry), and muscle cross-sectional area (magnetic resonance imaging) were measu…
Neuromuscular fatigue induced by an isotonic heavy-resistance loading protocol in knee extensors.
2009
Abstract The main aim of this study was to assess neuromuscular fatigue during a typical high-load, low-repetition loading protocol. Muscle stimulations were used to assess maximum voluntary contraction, resting single- and double-pulse twitch characteristics, and superimposed double-pulse twitch force (used to calculate voluntary activation) before and after an acute knee extension loading protocol. In our participants, who had previous resistance training experience, the mean voluntary activation level was 96.2% in an unfatigued state. Maximum voluntary contraction (−11.8%), resting double-pulse twitch force (−10.6%), and voluntary activation (−2.1%) were markedly decreased as a consequen…
Knee and ankle joint stiffness in sprint running.
2002
Stiffness has often been considered as a regulated property of the neuromuscular system. The purpose of this study was to examine the ankle and knee joint stiffness regulation during sprint running.Ten male sprinters ran at the constant relative speeds of 70, 80, 90, and 100% over a force platform, and ground reaction forces, kinematic, and EMG parameters were collected.The results indicated that with increasing running speed the average joint stiffness (change in joint moment divided by change in joint angle) was constant (7 N x m x deg(-1)) in the ankle joint and increased from 17 to 24 N x m x deg(-1) (P0.01) in the knee joint.The observed constant ankle joint stiffness may depend on (co…
Electromyographic and kinematic analysis of therapeutic knee exercises under water.
2001
Abstract Objective. This study aimed to evaluate muscle function and kinematics during commonly used knee rehabilitation exercises performed in water. Design. Maximal effort single extension and flexion trials in still water and repeated extension–flexion trials in flowing water in barefoot condition were analysed from 18 healthy participants (8 men, 10 women). Background. Despite the fact that water exercises are widely used, there are only few studies involving biomechanical and hydrodynamical analysis of aquatic exercises in rehabilitation. Methods. Electromyography of the quadriceps (vastus medialis, vastus lateralis) and hamstring muscles (biceps femoris, semitendinosus) and angular ve…
Neuromuscular function during therapeutic knee exercise under water and on dry land
2001
Abstract Poyhonen T, Keskinen KL, Kyrolainen H, Hautala A, Savolainen J, Malkia E. Neuromuscular function during therapeutic knee exercise under water and on dry land. Arch Phys Med Rehabil 2001;82:1446-52. Objectives: To compare muscle activity and resistive drag force during knee extension-flexion exercises while barefoot and while wearing a Hydro Boot (increased frontal area) both under water and on dry land. Design: Participants performed the exercises while seated on an elevator chair under water. Setting: A hydrotherapy pool. Participants: Eighteen healthy persons (10 women, 8 men). Interventions: Not applicable. Main Outcome Measures: Isokinetic and isometric forces were measured wit…
Neuromuscular fatigue following constant versus variable-intensity endurance cycling in triathletes
2008
International audience; The aim of this study was to determine whether variable power cycling produced greater neuromuscular fatigue of knee extensor muscles than constant power cycling at the same mean power output. Eight male triathletes (age : 33 ± 5 yr, mass : 74 ± 4 kg, OV&2max : 62 ± 5 ml.kg-1.min-1, maximal aerobic power : 392 ± 17 W) performed two 30 min trials on a cycle ergometer in a random order. Cycling exercise was performed either at a constant power output (CP) corresponding to 75% of the maximal aerobic power (MAP) or a variable power output (VP) with alternating ± 15%, ± 5%, and ± 10% of 75% MAP approximately every 5 min. Maximal voluntary contraction (MVC) torque, maximal…
Neural activation after maximal isometric contractions at different muscle lengths.
2006
DESBROSSES K., N. BABAULT, G. SCAGLIONI, J.-P. MEYER, and M. POUSSON. Neural Activation after Maximal Isometric Contractions at Different Muscle Lengths. Med. Sci. Sports Exerc., Vol. 38, No. 5, pp. 937–944, 2006. Purpose: To investigate i) whether neural activation dependence on muscle length is preserved with neuromuscular fatigue and ii) whether fatigue induced by a maximal isometric exercise is muscle length dependent. Methods: Twelve male subjects performed two fatiguing quadriceps muscle exercises: FS is the fatigue carried out at short muscle length (S) (S = 40- of knee flexion) and FL is the fatigue at long muscle length (L) (L = 100-). Before and after each fatiguing exercise (i.e.…