http://fitmarker.com/ Stories tagged muscle en-us Mon, 21 May 2012 15:25:09 -0500 http://fitmarker.com/foodnutrition/enhanced-amino-acid-sensitivity-of-myofibrillar-protein-synthesis-persists-for-up-to-24-h-after-resistance-exercise-in-young-men/ Abstract: We aimed to determine whether an exercise-mediated enhancement of muscle protein synthesis to feeding persisted 24 h after resistance exercise. We also determined the impact of different exercise intensities (90% or 30% maximal strength) or contraction volume (work-matched or to failure) on the response at 24 h of recovery. Fifteen men (21 ± 1 y, BMI = 24.1 ± 0.8 kg · m(-2)) received a primed, constant infusion of l-[ring-(13)C(6)]phenylalanine to measure muscle protein synthesis after protein feeding at rest (FED; 15 g whey protein) and 24 h after resistance exercise (EX-FED). Participants performed unilateral leg exercises: 1) 4 sets at 90% of maximal strength to failure (90FAIL); 2) 30% work-matched to 90FAIL (30WM); or 3) 30% to failure (30FAIL). Regardless of condition, rates of mixed muscle protein and sarcoplasmic protein synthesis were similarly stimulated at FED and EX-FED. In contrast, protein ingestion stimulated rates of myofibrillar protein synthesis above fasting rates by 0.016 ± 0.002%/h and the response was enhanced 24 h after resistance exercise, but only in the 90FAIL and 30FAIL conditions, by 0.038 ± 0.012 and 0.041 ± 0.010, respectively. Phosphorylation of protein kinase B on Ser473 was greater than FED at EX-FED only in 90FAIL, whereas phosphorylation of mammalian target of rapamycin on Ser2448 was significantly increased at EX-FED above FED only in the 30FAIL condition. Our results suggest that resistance exercise performed until failure confers a sensitizing effect on human skeletal muscle for at least 24 h that is specific to the myofibrillar protein fraction. ]]> Wed, 25 Apr 2012 02:06:26 -0500 http://fitmarker.com/foodnutrition/enhanced-amino-acid-sensitivity-of-myofibrillar-protein-synthesis-persists-for-up-to-24-h-after-resistance-exercise-in-young-men/ http://fitmarker.com/weight-training/muscles-exercise-and-obesity-skeletal-muscle-as-a-secretory-organ/ Abstract: During the past decade, skeletal muscle has been identified as a secretory organ. Accordingly, we have suggested that cytokines and other peptides that are produced, expressed and released by muscle fibres and exert either autocrine, paracrine or endocrine effects should be classified as myokines. The finding that the muscle secretome consists of several hundred secreted peptides provides a conceptual basis and a whole new paradigm for understanding how muscles communicate with other organs, such as adipose tissue, liver, pancreas, bones and brain. However, some myokines exert their effects within the muscle itself. Thus, myostatin, LIF, IL-6 and IL-7 are involved in muscle hypertrophy and myogenesis, whereas BDNF and IL-6 are involved in AMPK-mediated fat oxidation. IL-6 also appears to have systemic effects on the liver, adipose tissue and the immune system, and mediates crosstalk between intestinal L cells and pancreatic islets. Other myokines include the osteogenic factors IGF-1 and FGF-2; FSTL-1, which improves the endothelial function of the vascular system; and the PGC-1α-dependent myokine irisin, which drives brown-fat-like development. Studies in the past few years suggest the existence of yet unidentified factors, secreted from muscle cells, which may influence cancer cell growth and pancreas function. Many proteins produced by skeletal muscle are dependent upon contraction; therefore, physical inactivity probably leads to an altered myokine response, which could provide a potential mechanism for the association between sedentary behaviour and many chronic diseases. ]]> Thu, 12 Apr 2012 01:41:55 -0500 http://fitmarker.com/weight-training/muscles-exercise-and-obesity-skeletal-muscle-as-a-secretory-organ/ http://fitmarker.com/foodnutrition/how-much-protein-the-body-can-use-in-a-single-meal/ Tue, 10 Apr 2012 11:16:39 -0500 http://fitmarker.com/foodnutrition/how-much-protein-the-body-can-use-in-a-single-meal/ http://fitmarker.com/muscle-gain/build-muscle-lose-fat-lets-ask-the-experts-how-its-done/ Tue, 10 Apr 2012 00:56:49 -0500 http://fitmarker.com/muscle-gain/build-muscle-lose-fat-lets-ask-the-experts-how-its-done/ http://fitmarker.com/research/muscle-fatigue-linked-to-changes-in-the-interaction-between-neuronal-structures/ Tue, 06 Dec 2011 19:18:31 -0600 http://fitmarker.com/research/muscle-fatigue-linked-to-changes-in-the-interaction-between-neuronal-structures/ http://fitmarker.com/weight-training/resistance-exercise-inter-set-cooling-strategy-study/ "Incorporating inter-set external cooling augments the number of repetitions per set during RE without inducing an additional muscle damage biomarker response. Basically, ice your muscles in between sets. ]]> Mon, 26 Sep 2011 14:17:25 -0500 http://fitmarker.com/weight-training/resistance-exercise-inter-set-cooling-strategy-study/ http://fitmarker.com/weight-training/similar-increases-in-muscle-size-and-strength-after-training-with-maximal-shortening-or-lengthening-contractions/ The Abstract Training exclusively with eccentric (lengthening) contractions can result in greater muscular adaptations than training with concentric (shortening) contractions. We aimed to determine whether training-induced increases in muscle size and strength differed between muscles performing maximal lengthening (LC) or maximal shortening (SC) contractions when total external work is equivalent. Nine healthy young males completed a 9-week isokinetic (0.79 rad/s) resistance training program of the elbow flexors whereby they performed LC with one arm and an equivalent volume of total external work with the contralateral arm as SC. Training increased isometric peak torque for both LC (~10%) and SC (~20%) with no difference (P = 0.14) between conditions. There were also similar increases in isokinetic peak torque at both slow (0.79 rad/s) and fast (5.24 rad/s) shortening and lengthening peak torque for both LC (~8-10%) and SC (~9-20%). Training increased work per repetition similarly for both LC (~17%) and SC (~22%), in spite of ~40% greater work per repetition with LC. The increase in muscle cross-sectional area with training was also similar (P = 0.37) between LC (~6.5%) and SC (~4.6%). We conclude that increases in muscle size and strength with short-term unilateral resistance training are unrelated to muscle contraction type when matched for both exercise intensity (i.e. maximal contractions) and total external work. ]]> Wed, 27 Jul 2011 15:21:40 -0500 http://fitmarker.com/weight-training/similar-increases-in-muscle-size-and-strength-after-training-with-maximal-shortening-or-lengthening-contractions/ http://fitmarker.com/weight-loss/too-much-emphasis-on-breakfast-when-dieting-will-cost-you-muscle-mass/ Tue, 14 Jun 2011 16:45:41 -0500 http://fitmarker.com/weight-loss/too-much-emphasis-on-breakfast-when-dieting-will-cost-you-muscle-mass/ http://fitmarker.com/motivation/actions-habits-and-outcomes/ Fri, 03 Jun 2011 12:00:10 -0500 http://fitmarker.com/motivation/actions-habits-and-outcomes/ http://fitmarker.com/bodybuilding/a-beginners-guide-for-building-muscle/ Sat, 21 May 2011 03:17:05 -0500 http://fitmarker.com/bodybuilding/a-beginners-guide-for-building-muscle/