Search results for "Muscle Fibers"
showing 10 items of 94 documents
Medium chain acylcarnitines dominate the metabolite pattern in humans under moderate intensity exercise and support lipid oxidation.
2010
BACKGROUND: Exercise is an extreme physiological challenge for skeletal muscle energy metabolism and has notable health benefits. We aimed to identify and characterize metabolites, which are components of the regulatory network mediating the beneficial metabolic adaptation to exercise. METHODOLOGY AND PRINCIPAL FINDINGS: First, we investigated plasma from healthy human subjects who completed two independent running studies under moderate, predominantly aerobic conditions. Samples obtained prior to and immediately after running and then 3 and 24 h into the recovery phase were analyzed by a non-targeted (NT-) metabolomics approach applying liquid chromatography-qTOF-mass spectrometry. Under t…
Type 1 Muscle Fiber Hypertrophy after Blood Flow–restricted Training in Powerlifters
2018
PURPOSE: To investigate the effects of blood flow restricted resistance exercise (BFRRE) on myofiber areas (MFA), number of myonuclei and satellite cells (SC), muscle size and strength in powerlifters. METHODS Seventeen national level powerlifters (25+/-6 yrs [mean+/-SD], 15 men) were randomly assigned to either a BFRRE group (n=9) performing two blocks (week 1 and 3) of five BFRRE front squat sessions within a 6.5-week training period, or a conventional training group (Con; n=8) performing front squats at ~70% of one-repetition maximum (1RM). The BFRRE consisted of four sets (first and last set to voluntary failure) at ~30% of 1RM. Muscle biopsies were obtained from m. vastus lateralis (VL…
Antiendomysium antibodies assay in the culture medium of intestinal mucosa: an accurate method for celiac disease diagnosis
2011
Background Celiac disease (CD) diagnosis is becoming more difficult as patients with no intestinal histology lesions may also be suffering from CD. Aim To evaluate the diagnostic accuracy of antiendomysium (EmA) assay in the culture medium of intestinal biopsies for CD diagnosis. Patients and methods The clinical charts of 418 patients with CD and 705 non-CD controls who had all undergone EmA assay in the culture medium were reviewed. Results EmA assay in the culture medium had a higher sensitivity (98 vs. 80%) and specificity (99 vs. 95%) than serum EmA/antibodies to tissue transglutaminase (anti-tTG) assay. All patients with CD who were tested as false-negatives for serum EmA and/or anti-…
Immunolocalization of Tenascin-C in Human Type II Fiber Atrophy
2000
Tenascin-C is a multifunctional extracellular matrix glycoprotein with stimulatory and anti-adhesive or inhibitory properties for axon growth. Its location and discontinuous expression are restricted in innervated muscle tissues. Tenascin-C accumulated interstitially among human denervated muscle fibers and close to normal-sized fibers. To expand our knowledge of the expression of tenascin-C in human neuromuscular disorders, we investigated immunohistologically 20 human muscle specimens with type II myofiber atrophy of children and adults. Tenascin-C immunoreactivity in adult type II atrophy was frequent, and accumulation in children was sparse and weak. In both groups, tenascin-C immunorea…
Delayed myonuclear addition, myofiber hypertrophy, and increases in strength with high-frequency low-load blood flow restricted training to volitiona…
2018
The purpose of the present study was to investigate muscle hypertrophy, strength, and myonuclear and satellite cell (SC) responses to high-frequency blood flow-restricted resistance exercise (BFRRE). Thirteen individuals [24 ± 2 yr (mean ± SD), 9 men] completed two 5-day blocks of 7 BFRRE sessions, separated by a 10-day rest period. Four sets of unilateral knee extensions to voluntary failure at 20% of one repetition maximum (1RM) were conducted with partial blood flow restriction (90–100 mmHg). Muscle samples obtained before, during, 3 days, and 10 days after training were analyzed for muscle fiber area (MFA), myonuclei, SC, and mRNA and miRNA expression. Muscle size was measured by ultra…
Effects of electromyostimulation and strength training on muscle soreness, muscle damage and sympathetic activation.
1995
Electromyostimulation (EMS) is known to develop muscular strength and hypertrophy. The aim of this study was to compare EMS exercise-induced damage with concentric (CONC) exercise-induced damage. Twelve male athletes were randomly assigned to concentric exercise (five sets of 6 voluntary contractions) or to EMS (30 contractions of 6 s duration, 20 s rest between contractions) on day 0 (D0). The load was 80% of the maximal isometric force. Criterion measures of plasma creatine kinase (CK) activity and lactate dehydrogenase (LDH) activity, and subjective ratings of muscle soreness and urinary catecholamines, were assessed 1 day before and for 3 days after exercise. Among the members of the EM…
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…
Androgen receptors and testosterone in men—Effects of protein ingestion, resistance exercise and fiber type
2007
The purpose of this study was to examine the impact of protein ingestion on circulating testosterone and muscle androgen receptor (AR) as well as on insulin-like growth factor-I (MGF and IGF-IEa) responses to a resistance exercise (RE) bout in (57-72 year) men. Protein (15 g whey) (n=9) or placebo (n=9) was consumed before and after a RE bout (5 sets of 10 repetition maximums), and vastus lateralis muscle biopsies were taken pre, 1 and 48 h post-RE. The protein ingestion blunted the RE-induced increase in serum free and total testosterone while the RE bout significantly increased muscle AR mRNA levels in older men (P<0.05). However, protein ingestion did not significantly affect AR mRNA or …
Effect of cycling cadence on contractile and neural properties of knee extensors.
2001
LEPERS, R., G. Y. MILLET, and N. A. MAFFIULETTI. Effect of cycling cadence on contractile and neural properties of knee extensors. Med. Sci. Sports Exerc., Vol. 33, No. 11, 2001, pp. 1882–1888. Purpose: This study investigated the effect of prior prolonged cycling exercise performed at different cadences on subsequent neuromuscular characteristics. Methods: Eight well-trained triathletes sustained 80% of their maximal aerobic power during 30 min at three cadences: the freely chosen cadence (FCC), FCC20%, and FCC20%. Maximal isometric and concentric (120°·s 1 and 240°·s 1 ) torques were recorded before and after the exercise. Central activation, neural (M-wave), and contractile (isometric mu…
Intensity- and muscle-specific fascicle behavior during human drop jumps.
2006
The present study was designed to examine fascicle-tendon interaction in the synergistic medial gastrocnemius (MG) and soleus (Sol) muscles during drop jumps (DJ) performed from different drop heights (DH). Eight subjects performed unilateral DJ with maximal rebounds on a sledge apparatus from different DH. During the exercises, fascicle lengths (using ultrasonography) and electromyographic activities were recorded. The results showed that the fascicles of the MG and Sol muscles behaved differently during the contact phase, but the whole muscle-tendon unit and its tendinous tissue lengthened before shortening in both muscles. The Sol fascicles also lengthened before shortening during the g…