Knee position affects medial gastrocnemius and soleus activation during dynamic plantarflexion: no evidence for an inter-muscle compensation in healthy young adults.

Knee joint position influences ankle torque, but it is unclear whether the soleus compensates to counteract the reductions in gastrocnemius output during knee-flexed versus knee-extended plantarflexions. Therefore, the purpose of this study was to determine the effects of knee joint position and plantarflexion contraction velocity on ankle plantarflexion torque and electromyography activity of the medial gastrocnemius and soleus in healthy young adults. Healthy male participants (n=30) performed concentric plantar flexions in a custom-built dynamometer from 15° dorsiflexion to 30° plantarflexion at gradually increasing velocities during each contraction at 30, 60, 120, 180, and 210° s-1 in a supine position with the knee fully extended and while kneeling with the knee fixed in 90° flexion.

Effects of knee joint position on the triceps Suræ torque-size relationship during plantarflexion in healthy young adults.

We determined the effects of knee joint position on the relationship between maximal voluntary contraction (MVC) isometric plantar flexor torque and architectural properties of the plantar flexors measured at rest in healthy young adults. We obtained 3-D reconstructed muscle architecture data of the right plantar flexor muscles of nine physically active males using T1 and DTI MRI sequences with the knee in ∼5° flexion and at rest. Muscle volume, fascicle length, pennation angle, and physiological cross-sectional area were estimated for the medial and lateral gastrocnemius and the soleus muscle.

An Acute Transition from Rearfoot to Forefoot Strike does not Induce Major Changes in Plantarflexor Muscles Activation for Habitual Rearfoot Strike Runners.

Footstrike pattern has received increased attention within the running community because there is a common belief that forefoot strike running (FFS) is more advantageous (i.e., improve performance and reduce running injuries) than rearfoot strike running (RFS) in distance running.

The effects of eccentric hamstring exercise training in young female handball players.

Purpose: The multidimensional role of hamstring muscle group strength in athletic performance and injury prevention is well documented, and nordic hamstring exercise (NHE) is a popular method for the development of hamstring strength. Our aim was to examine the EMG characteristics of the eccentric NHE as well as the effects of long-term eccentric NHE training on muscle strength and vertical jump performance in 10- to 11-year-old female handball players.

Methods: Players from the same handball team were randomly assigned to an eccentric NHE training (13 players) or a control group (10 players).

Lower leg muscle-tendon unit characteristics are related to marathon running performance.

The human ankle joint and plantar flexor muscle-tendon unit play an important role in endurance running. It has been assumed that muscle and tendon interactions and their biomechanical behaviours depend on their morphological and architectural characteristics. We aimed to study how plantar flexor muscle characteristics influence marathon running performance and to determine whether there is any difference in the role of the soleus and gastrocnemii.

Individualized Whole-Body Vibration: Neuromuscular, Biochemical, Muscle Damage and Inflammatory Acute Responses.

. We aimed to investigate the acute residual hormonal, biochemical, and neuromuscular responses to a single session of individualized whole-body vibration (WBV) while maintaining a half-squat position. Twenty male sport science students voluntarily participated in the present study and were randomly assigned to an individualized WBV group (with the acceleration load determined for each participant) or an isometric group (ISOM).

Age-specific modifications in healthy adults' knee joint position sense.

Right-handed young adults perform target-matching tasks more accurately with the non-dominant (ND) compared to the dominant (D) limb, but it is unclear if age affects this disparity. We determined if age affects target-matching asymmetry in right-side dominant healthy adults. Young ( = 12, age: 23.

Creatine Supplementation Supports the Rehabilitation of Adolescent Fin Swimmers in Tendon Overuse Injury Cases.

Our purpose was to investigate the effect of creatine (Cr) supplementation on regeneration periods in tendon overuse injury rehabilitation of adolescent fin swimmers. The participants of this study were injured adolescent competitive fin swimmers (n = 18). The subjects were randomly assigned the creatine (CR) or placebo (PL) groups with a double-blind research design.

Somatosensory Electrical Stimulation Does Not Augment Motor Skill Acquisition and Intermanual Transfer in Healthy Young Adults-A Pilot Study.

Sensory input can modify motor function and magnify interlimb transfer. We examined the effects of low-intensity somatosensory electrical stimulation (SES) on motor practice-induced skill acquisition and intermanual transfer. Participants practiced a visuomotor skill for 25 min and received SES to the practice or the transfer arm.

Relationship Between Reactive Agility and Change of Direction Speed in Amateur Soccer Players.

The aim of the study was to assess the relationship between reactive agility and change of direction speed (CODS) among amateur soccer players using running tests with four directional changes. Sixteen amateur soccer players (24.1 ± 3.

The EMG activity-acceleration relationship to quantify the optimal vibration load when applying synchronous whole-body vibration.

Purpose: To date are lacking methodological approaches to individualizing whole-body vibration (WBV) intensity. The aim of this study was: (1) to determine the surface-electromyography-root-mean-square (sEMG(RMS))-acceleration load relationship in the vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), lateral gastrocnemius (LG) muscles during synchronous WBV, and (2) to assess the reliability of the acceleration corresponding to the maximal sEMG(RMS).

Methods: Twenty-five sportsman voluntarily took part in this study with a single-group, repeated-measures design.

Hormonal and neuromuscular responses to mechanical vibration applied to upper extremity muscles.

Objective: To investigate the acute residual hormonal and neuromuscular responses exhibited following a single session of mechanical vibration applied to the upper extremities among different acceleration loads.

Methods: Thirty male students were randomly assigned to a high vibration group (HVG), a low vibration group (LVG), or a control group (CG). A randomized double-blind, controlled-parallel study design was employed.

Acute effects of whole-body vibration on running gait in marathon runners.

The aim of this study was to investigate the effects of a single bout of whole-body vibration (WBV) on running gait. The running kinematic of sixteen male marathon runners was assessed on a treadmill at iso-efficiency speed after 10 min of WBV and SHAM (i.e.

The effects of short-term exercise training on peak-torque are time- and fiber-type dependent.

We examined the susceptibility of fast and slow twitch muscle fibers in the quadriceps muscle to eccentric exercise-induced muscle damage. Nine healthy men (age: 22.5 ± 1.

Stretch-shortening cycle characteristics during vertical jumps carried out with small and large range of motion.

In the present study we investigated kinematical characteristics of the knee and ankle extensors to estimate the length change properties of the contractile and the passive elements in countermovement jumps (CMJ) and drop jumps (DJ) performed with small (40°) and large (80°) range of joint motion (SRM and LRM). At SRM the accelerations at maximal muscle lengths compared with the last phase of joint flexion were greater for the gastrocnemius and the soleus (124.9% and 79.

Short and long latency response due to transition from bilateral to unilateral contraction.

The aim of this study was to investigate the effect of fast and slow relaxation of the knee extensor muscle of the dominant leg on torque-time curve of the unilaterally contracting contralateral muscle. Eight adult male subjects were recruited without bilateral deficit. In Task 1 subjects exerted bilateral and unilateral torque and bilateral index was calculated.

Effect of whole body vibration applied on upper extremity muscles.

The acute residual effect of whole body vibration (WBV) on upper extremity muscles and testosterone secretion was studied. Eight highly (G1), nine moderately trained gymnasts (G2) and seven physically active persons (CG) were recruited for the investigation. The intervention occurred in push-up position with the elbow flexed at 90°.

Dynamic contractility and efficiency impairments in stretch-shortening cycle are stretch-load-dependent after training-induced muscle damage.

To determine the acute task and stretch-load dependency of neuromuscular impairments after muscle-damaging exercises, we examined the magnitude of strength deficits in isometric and stretch-shortening cycle (SSC) contractions after a single bout of exercise. Ten trained men performed 90 unilateral isokinetic eccentric-concentric knee extensions on a dynamometer. Plasma creatine kinase activity, muscle soreness, maximal isometric torque, short-range stiffness, and peak torque in the eccentric phase of the SSC contraction at 3 stretch-loads (120, 150, and 180 J) were determined in the quadriceps before and 24 hours after exercise.

Muscle activation history at different vertical jumps and its influence on vertical velocity.

In the present study we investigated displacement, time, velocity and acceleration history of center of mass (COM) and electrical activity of knee extensors to estimate the dominance of the factors influencing the vertical velocity in squat jumps (SJs), countermovement jumps (CMJs) and drop jumps (DJs) performed with small (40°) and large (80°) range of joint motion (SROM and LROM). The maximum vertical velocity (v4) was 23.4% (CMJ) and 7.

Uphill racewalking at iso-efficiency speed.

The aim of this study was to investigate the effects of gradients (0, 2, and 7%) on biomechanical parameters during racewalking (RW) at iso-efficiency speed (IES). During the experiment, 12 high-level athletes performed at IES on different slopes. The parameters studied were surface muscular activity (EMG) of 5 muscles of the leg using Muscle Lab (Boscosystem); kinematic parameters were collected using a high-speed camera (210 Hz) analyzed with Dartfish 5.

The interaction between body position and vibration frequency on acute response to whole body vibration.

Purpose: The present study was designed to investigate the electromyographic (EMG) response in leg muscles to whole-body vibration while using different body positions and vibration frequencies.

Methods: Twenty male sport sciences students voluntarily participated in this single-group, repeated-measures study in which EMG data from the vastus lateralis (VL) and the lateral gastrocnemius (LG) were collected over a total of 36 trials for each subject (4 static positions × 9 frequencies).

Results: We found that vibration frequency, body position and the muscle stimulated had a significant effect (P-values ranged from 0.

Footstep analysis at different slopes and speeds in elite race walking.

In order to investigate the effects of speed and slope on kinematic parameters, we studied the step parameters of 12 elite race walkers on a treadmill at different speeds (3.61, 3.89, and 4.

Kinematics of running at different slopes and speeds.

The aim of this study was to verify the influence of the combination of different running speeds and slopes based on main kinematic parameters in both groups of elite (RE) and amateur (RA) marathon runners. All subjects performed various tests on a treadmill at 0, 2, and 7% slopes at different speeds: 3.89, 4.