Search results for "eccentric"

Alterations of mechanical characteristics of human skeletal muscle during strength training

1983

To investigate the influence of strength training on the mechanical characteristics of human skeletal muscle, 14 male subjects went through training of combined heavy concentric and eccentric contractions three times a week for 16 weeks. The strength training program consisted mainly of dynamic exercises for leg extensors with loads of 80 to 120% of one maximum repetition. The force-time curves produced during various vertical jumps were the basis for calculation of various mechanical parameters. In addition to a great increase (p less than 0.001) in maximal isometric force, heavy resistance strength training also caused significant (p less than 0.05-0.01) increases in heights and in variou…

Effects of ageing on motor unit activation patterns and reflex sensitivity in dynamic movements.

2009

Both contraction type and ageing may cause changes in H-reflex excitability. H reflex is partly affected by presynaptic inhibition that may also be an important factor in the control of MU activation. The purpose of the study was to examine age related changes in H-reflex excitability and motor unit activation patterns in dynamic and in isometric contractions. Ten younger (YOUNG) and 13 elderly (OLD) males performed isometric (ISO), concentric (CON) and eccentric (ECC) plantarflexions with submaximal activation levels (20% and 40% of maximal soleus surface EMG). Intramuscular EMG data was analyzed utilizing an intramuscular spike amplitude frequency histogram method. Average H/M ratio was a…

Effects of an eccentric training programme on hamstring strain injuries in women football players

2015

Summary Study aim: to test the hypothesis that an eccentric training programme applied on women football players would reduce the hamstring injury rate by improving thigh muscle balance and, particularly, hamstring strength. Material and methods: three football teams were recruited for this randomised controlled trial. They played in the first and second divisions in Spain. Players were randomised within clubs either to the intervention (eccentric exercises, n = 22) or control (control exercises, n = 21) groups, and randomisation was stratified according to previous history of thigh strains. The eccentric programme was divided into 3 phases, and each phase was composed of 7 weeks. Complianc…

Influence of the muscle mode of contraction on the exercise induced neuroplastic effects

2018

Along with cardiovascular and neuromuscular changes, mono-articular and locomotor exercises may induced neuroplastic changes from muscles involved, or non-involved, in the exercise. If the effect of exercise intensity or duration on neuroplastic changes has been previously investigated, the effect of the mode of muscle contraction remains unclear. The aim of this thesis was to investigate the effects of the mode of muscle contraction on neuroplastic changes induced a locomotor or a single-joint exercise. The first study showed that the increase in the corticospinal excitability of a non-exercised hand muscle, observed after a walking/ running exercise, was not modulated by the knee extensor…

Analisi teorico-sperimentale del comportamento flessionale di colonne in calcestruzzo fibrorinforzato

2009

Review of Some Development of the Hole Drilling Method

1990

This paper contains a survey of some developments of the hole drilling method. It is mainly based on the research work carried out at the University of Palermo in the years from 1978 to 1989. The paper considers the relationship between the relaxed strain and the residual stresses for a rosette with an off-centre hole, the influence of hole eccentricity on the determination of residual stresses and of rosette calibration constants, the sensitivity of strain relaxation.

Force and EMG power spectrum during eccentric and concentric actions

2000

This study was designed to examine the force and activation levels of elbow flexor muscles during preactivated eccentric, concentric and isometric actions.Force, average EMG (aEMG), and the EMG power spectrum were investigated at different constant movement velocities (1 rad x s(-1), 2 rad x s(-1), 3 rad x s(-1), and 4 rad x s(-1)) at different joint angles.Average force at a 110 degree elbow angle was lower and aEMG was higher in concentric actions as compared with eccentric and isometric actions. At a 55 degree elbow angle, there was no difference in aEMG, or it was slightly higher in eccentric actions. MF was higher in the concentric as compared with eccentric actions at the three fastes…

Assessment of Neuromuscular Function After Different Strength Training Protocols Using Tensiomyography

2015

The purpose of the study was to analyze tensiomyography (TMG) sensitivity to changes in muscle force and neuromuscular function of the muscle rectus femoris (RF) using TMG muscle properties after 5 different lower-limb strength training protocols (multiple sets; DS = drop sets; eccentric overload; FW = flywheel; PL = plyometrics). After baseline measurements, 14 male strength trained athletes completed 1 squat training protocol per week over a 5-week period in a randomized controlled order. Maximal voluntary isometric contraction (MVIC), TMG measurements of maximal radial displacement of the muscle belly (Dm), contraction time between 10 and 90% of Dm (Tc), and mean muscle contraction veloc…

Electromechanical behaviour of human muscles in vertical jumps

1982

The relationships of muscle structure to the potentiation of myoelectrical activity and to the use of prestretching in five lower limb muscles were studied in different vertical jumping conditions. The subjects for the study were six male students, divided according to the muscle fiber distribution in m. vastus lateralis into “fast” and “slow” groups. The subjects performed vertical jumps (1) from a static squatting position (SJ), (2) with a preliminary counter movement (CMJ) and (3) after dropping (DJ) from five different heights. Myoelectrical (EMG) activity was recorded from mm. gluteus maximus, vastus lateralis, vastus medialis, rectus femoris and gastrocnemius in each jumping condition…

Sleep monitoring of a six-day microcycle in strength and high-intensity training

2015

This study examined the effect of microcycles in eccentric strength and high-intensity interval training (HIT) on sleep parameters and subjective ratings. Forty-two well-trained athletes (mean age 23.2 ± 2.4 years) were either assigned to the strength (n = 21; mean age 23.6 ± 2.1 years) or HIT (n = 21; mean age 22.8 ± 2.6 years) protocol. Sleep monitoring was conducted with multi-sensor actigraphy (SenseWear Armband™, Bodymedia, Pittsburg, PA, USA) and sleep log for 14 days. After a five-day baseline phase, participants completed either eccentric accented strength or high-intensity interval training for six days, with two training sessions per day. This training phase was divided into two h…