Search results for " Muscle"
showing 10 items of 1495 documents
Mechanisms contributing to knee extensor strength loss after prolonged running exercise.
2002
The aim of this study was to identify the mechanisms that contribute to the decline in knee extensor (KE) muscles strength after a prolonged running exercise. During the 2 days preceding a 30-km running race [duration 188.7 ± 27.0 (SD) min] and immediately after the race, maximal percutaneous electrical stimulations (single twitch, 0.5-s tetanus at 20 and 80 Hz) were applied to the femoral nerve of 12 trained runners. Superimposed twitches were also delivered during isometric maximal voluntary contraction (MVC) to determine the level of voluntary activation (%VA). The vastus lateralis electromyogram was recorded. KE MVC decreased from pre- to postexercise (from 188.1 ± 25.2 to 142.7 ± 29.7…
Changes in motor unit activity and metabolism in human skeletal muscle during and after repeated eccentric and concentric contractions.
1977
This study was designed to investigate electromyographic (EMG), muscle glycogen and blood lactate changes in quadriceps muscle group during repeated 40 maximal eccentric and concentric contractions, and to follow the recovery in EMG, muscle glycogen and serum creatine kinase values during a 4 day period following the work test. The subjects were normal males and the test order (eccentric or concentric) was randomly selected. The results indicated first, that the EMG parameters (IEMG, AMUP), muscle glycogen and blood lactate changed in a similar manner during the both fatigue loads. Despite the high tension work no selective depletion of glycogen could be observed in the slow or fast twitch …
Comparison between voluntary and stimulated contractions of the quadriceps femoris for growth hormone response and muscle damage
2007
This study aimed to compare voluntary and stimulated exercise for changes in muscle strength, growth hormone (GH), blood lactate, and markers of muscle damage. Nine healthy men had two leg press exercise bouts separated by 2 wk. In the first bout, the quadriceps muscles were stimulated by biphasic rectangular pulses (75 Hz, duration 400 μs, on-off ratio 6.25–20 s) with current amplitude being consistently increased throughout 40 contractions at maximal tolerable level. In the second bout, 40 voluntary isometric contractions were performed at the same leg press force output as the first bout. Maximal voluntary isometric strength was measured before and after the bouts, and serum GH and blood…
Neuromuscular Fatigue After a Ski Skating Marathon
2003
The aim of this study was to characterize neuromuscular fatigue in knee extensor muscles after a marathon skiing race (mean ± SD duration = 159.7 ± 17.9 min). During the 2 days preceding the event and immediately after, maximal percutaneous electrical stimulations (single twitch, 0.5-s tetanus at 20 and 80 Hz) were applied to the femoral nerve of 11 trained skiers. Superimposed twitches were also delivered during maximal voluntary contraction (MVC) to determine maximal voluntary activation (%VA). EMG was recorded from the vastus lateralis muscle. MVC decreased with fatigue from 171.7 ± 33.7 to 157.3 ± 35.2 Nm (-8.4%; p < 0.005) while %VA did not change significantly. The RMS measured du…
The effects of short-term resistance training on endocrine function in men and women.
1998
This investigation examined hormonal adaptations to acute resistance exercise and determined whether training adaptations are observed within an 8-week period in untrained men and women. The protocol consisted of a 1-week pre-conditioning orientation phase followed by 8 weeks of heavy resistance training. Three lower-limb exercises for the quadriceps femoris muscle group (squat, leg press, knee extension) were performed twice a week (Monday and Friday) with every other Wednesday used for maximal dynamic 1 RM strength testing. Blood samples were obtained pre-exercise (Pre-Ex), immediately post-exercise (IP), and 5 min post-exercise (5-P) during the first week of training (T-1), after 6 weeks…
Similar increases in strength after short-term resistance training due to different neuromuscular adaptations in young and older men
2014
This study investigated whether differences in neuromuscular performance and muscle hypertrophy occur between young and older men. Twenty-three young (29 ± 9 years) and 26 older men (64 ± 8 years) completed 10 weeks of high-volume, medium load “hypertrophic” resistance training with low frequency (twice per week) with 10 young (34 ± 11 years) and 11 older men (65 ± 3 years) acting as nontraining control subjects. Training consisted of 2–5 sets of 8–14 repetitions (1- to 2-minute rest). Lower-limb dynamic (leg press) and isometric maximum leg extension force, as well as lower-limb lean mass and vastus lateralis cross-sectional area were assessed before and after the training period. Training…
Frequent blood flow restricted training not to failure and to failure induces similar gains in myonuclei and muscle mass
2021
The purpose of the present study was to compare the effects of short-term high-frequency failure vs non-failure blood flow–restricted resistance exercise (BFRRE) on changes in satellite cells (SCs), myonuclei, muscle size, and strength. Seventeen untrained men performed four sets of BFRRE to failure (Failure) with one leg and not to failure (Non-failure; 30-15-15-15 repetitions) with the other leg using knee-extensions at 20% of one repetition maximum (1RM). Fourteen sessions were distributed over two 5-day blocks, separated by a 10-day rest period. Muscle samples obtained before, at mid-training, and 10-day post-intervention (Post10) were analyzed for muscle fiber area (MFA), myonuclei, an…
Effects of long-term home-based exercise on health-related quality of life in patients with chronic neck pain: A randomized study with a 1-year follo…
2012
To evaluate whether long-term neck and upper body exercises conducted in economical community-based outpatient clinic and home-based settings could improve health-related quality of life (HRQoL)for individuals affected by chronic neck pain. The effect of baseline HRQoL and neck pain values on training adherence was also studied.Subjects (n = 101, 91 women/10 men, mean age 41.0 ± 9.5 years) with chronic non-specific neck pain were randomized to a combined strength-training and stretching-exercise group (CSSG, n = 49) or to a stretching exercise group (SG, n = 52). HRQoL was assessed at baseline and after 12 months using the RAND-36 questionnaire. Comparisons between groups were performed usi…
Comparison of electromyographic pattern of sensory experts and untrained subjects during chewing of Mahon cheese
2002
Use of electromyography (EMG) to monitor mastication is a relatively new concept in assessing food physical and sensory properties. Although expert assessment of cheese characteristics is widely used, the effect of training in sensory analysis on mastication patterns, as assessed using EMG is not well known. Nine samples of the same Mahon cheese (60 days ripening) were given to 24 subjects (8 experts, 16 untrained) and EMG recorded for each chewing sequence. Three samples were tested in a single session by each subject, and three sessions carried out on different days. EMG was recorded from four masticatory muscles for each subject. From EMG records the following was extracted: number of ch…
Evolution of electromyographic signal, running economy, and perceived exertion during different prolonged exercises
2000
International audience; The purpose of this study was to compare the electromyographic (EMG) signal of the vastus lateralis muscle obtained during a run section of a triathlon and at the end of a prolonged run performed at the same running velocity. Seven subjects were studied on three occasions: a 2 h 15 min triathlon (30 min swimming, 60 min cycling, and 45 min treadmill running at 75% of the maximal aerobic speed), a 2 h 15 min run, where the last 45 min (Prolonged Run, PR) were run at the same speed as the Triathlon Run (TR) on a motorized treadmill, and a 45 min Isolated Run (IR) performed at the same TR and PR velocity. The three experimental trials were randomised. Oxygen uptake (VO …