Search results for "isometric"

The Temporal Structure of Vertical Arm Movements

2011

Import JabRef | WosArea Life Sciences and Biomedicine - Other Topics; International audience; The present study investigates how the CNS deals with the omnipresent force of gravity during arm motor planning. Previous studies have reported direction-dependent kinematic differences in the vertical plane; notably, acceleration duration was greater during a downward than an upward arm movement. Although the analysis of acceleration and deceleration phases has permitted to explore the integration of gravity force, further investigation is necessary to conclude whether feedforward or feedback control processes are at the origin of this incorporation. We considered that a more detailed analysis of…

Understanding the effect of window length and overlap for assessing sEMG in dynamic fatiguing contractions: A non-linear dimensionality reduction and…

2020

The Short-Time Fourier transform (STFT) is a helpful tool to identify muscle fatigue with clinical and sports applications. However, the choice of STFT parameters may affect the estimation of myoelectrical manifestations of fatigue. Here, we determine the effect of window length and overlap selections on the frequency slope and the coefficient of variation from EMG spectrum features in fatiguing contractions. We also determine whether STFT parameters affect the relationship between frequency slopes and task failure. Eighty-eight healthy adult men performed one-leg heel-rise until exhaustion. A factorial design with a window length of 50, 100, 250, 500, and 1000 ms with 0, 25, 50, 75, and 90…

Behavior of fascicles and the myotendinous junction of human medial gastrocnemius following eccentric strength training

2009

This study is the first in which measurements of thickness, fascicle angle and length, and tendon elongation were combined to examine the impact of eccentric strength training on both muscle architecture and tendinous structures. Eighteen healthy male subjects were divided into an eccentric strength training group (n = 10) and a control group (n = 8). The training program consisted of 18 sessions of eccentric exercises over a 7-week period. All subjects were tested at baseline and after the last training session. Using ultrasound imaging, the fascicle angle and length and thickness of the medial gastrocnemius (MG) were analyzed at rest (i.e., theta(p), Fl(p), and t(p), respectively), at 50%…

Intermittent cooling during judo training in a warm/humid environment reduces autonomic and hormonal impact

2018

Carballeira, E, Morales, J, Fukuda, DH, Granada, ML, Carratalá-Deval, V, López Díaz de Durana, A, and Stout, JR. Intermittent cooling during Judo training in a warm/humid environment reduces autonomic and hormonal impact. J Strength Cond Res 33(8): 2241-2250, 2019-The purpose of this study was to identify the effects of superficial cooling on physiological responses while training in a warm, humid environment during an international Judo training camp. Sixteen judokas (8 women and 8 men) participated in the experiment. Four high-level women and 4 men were randomly assigned to wear a cooling vest (vest group [VG]) during the recovery periods within a training session (i.e., 8 bouts of 5-minu…

Acute Neuromuscular and Hormonal Responses to Different Exercise Loadings Followed by a Sauna.

2020

Rissanen, JA, Hakkinen, A, Laukkanen, J, Kraemer, WJ, and Hakkinen, K. Acute neuromuscular and hormonal responses to different exercise loadings followed by a sauna. J Strength Cond Res 34(2): 313-322, 2020-The purpose of this study was to investigate acute responses of endurance (E + SA), strength (S + SA), and combined endurance and strength exercise (C + SA) followed by a traditional sauna bath (70° C, 18% relative humidity) on neuromuscular performance and serum hormone concentrations. Twenty-seven recreationally physically active men who were experienced with taking a sauna participated in the study. All the subjects performed a sauna bath only (SA) first as a control measurement follo…

Changes in strength and power performance and serum hormone concentrations during 12 weeks of task-specific or strength training in conscripts.

2020

Abstract The purpose of this study was to investigate the effects of two different training programs on strength and power performance and serum hormone concentrations. A total of 104 male soldiers volunteered and took part in the 12‐week training period with baseline, mid‐, and post‐measurements of body composition, muscle strength, lower and upper body power, and blood samples to determine serum hormone concentrations. The mean (±SD) age of subjects was 20 ± 1 years, height 180 ± 6 cm and body mass 72.4 ± 8.8 kg. The subjects were divided into three different training groups: soldier task‐specific training (TS), strength training (ST), and control (CON). Each group had a total of 18 train…

Effects of Basic Training on Acute Physiological Responses to a Combat Loaded Run Test

2010

ABSTRACTThe purpose of the study was to examine the effects of an 8-week basic training (BT) with added strength training (ST) or endurance training (ET) on both the performance of a 3K-combat loaded run test and the acute neuromuscular and hormonal responses. All training groups improved (p < 0.001) their run-test times: ST by 12.4%, ET by 11.6%, and normal training (NT) by 10.2%. Significant acute decreases were observed in maximal isometric force of leg extensors (p < 0.01–0.05) in all subject groups following the run. Increases were observed in acute testosterone responses (p < 0.001) after the test in all groups both at pre- and post-training. However, ET and NT demonstrated lower (p <…

Human isometric force production and electromyogram activity of knee extensor muscles in water and on dry land.

1999

This study was designed to determine trial-to-trial and day-to-day reproducibility of isometric force and electromyogram activity (EMG) of the knee extensor muscles in water and on dry land as well as to make comparisons between the two training conditions in muscle activity and force production. A group of 20 healthy subjects (12 women and 8 men) were tested three times over 2 weeks. A measurement session consisted of recordings of maximal and submaximal isometric knee extension force with simultaneous recording of surface EMG from the vastus medialis, vastus lateralis and biceps femoris muscles. To ensure identical measurement conditions the same patient elevator chair was used in both th…

Effects of a 21 days space flight on the mechanical performance and the EMG power spectrum of the leg muscles

2002

Electromechanical delay in human skeletal muscle under concentric and eccentric contractions.

1979

In contraction of skeletal muscle a delay exists between the onset of electrical activity and measurable tension. This delay in electromechanical coupling has been stated to be between 30 and 100 ms. Thus, in rapid movements it may be possible for electromyographic (EMG) activity to have terminated before force can be detected. This study was designed to determine the dependence of the EMG-tension delay upon selected initial conditions at the time of muscle activation. The right forearms of 14 subjects were passively oscillated by a motor-driven dynamometer through flexion-extension cycles of 135 deg at an angular velocity of approximately equal to 0.5 rad/s. Upon presentation of a visual s…