Dietary Influence on Muscle Protein Synthesis and Hypertrophy
Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse in The Routledge Handbook on Biochemistry of Exercise, 2020
Skeletal muscle hypertrophy specifically refers to the increase in size, through the addition of protein, of existing muscle fibres and thus whole muscle, without an increase in the fibre number. Hypertrophy is the consequence of cumulative periods of MPS exceeding MPB, leading to a positive muscle NBAL over time and thus net protein accretion. Exercise is the foundation, and nutrition plays a role in regulating skeletal muscle mass, and they act synergistically to promote increased MPS and muscle hypertrophy (113). RET has been repeatedly shown to elicit skeletal muscle hypertrophy, as demonstrated by a ∼5–10% increase of muscle cross-sectional area following 10 weeks of RET (31), which is augmented to a mild degree with appropriate nutritional strategies such as increased protein consumption (23, 82). Increasing the abundance of muscle tissue provides significant athletic advantages and confers important protective benefits against disease development during periods of disuse and reduced physical activity with advancing age.
Applications of Fenugreek in Sports Nutrition
Dilip Ghosh, Prasad Thakurdesai in Fenugreek, 2022
The preclinical evidence suggests that the galactomannans from fenugreek seeds might be the responsible phytoconstituent for significant anabolic potential without any androgenic effects as demonstrated in a study using castrated rats (Aswar et al. 2008). During the subacute oral administration (10 and 35 mg/kg, once a day, 4 weeks), fenugreek derived galactomannans significantly increased the weight of the levator ani, a skeletal muscle, suggesting anabolic effects without a change in testosterone levels (Aswar et al. 2008). An increase in a skeletal muscle’s weight reflects muscle hypertrophy or an increase in the cross-sectional area of the muscle. The direct and positive correlation between a muscle’s cross-sectional area and the overall strength of that particular muscle has been reported previously (Jones et al. 2008; Maughan, Watson, and Weir 1983). Therefore, the levator ani’s increased weight suggested fenugreek extract’s potential for strength increase through a non-hormone mediated channel, even though strength measurements were not assessed in this study (Aswar et al. 2008).
Bone, Muscle, and Tooth
Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard in Toxicologic Pathology, 2018
Myocyte hypertrophy, an enlargement of muscle cells due to the addition of sarcomeres and supporting organelles, is usually most convincingly recognized as an increase in myocyte cross-sectional area. However, because the cellular enlargement may be difficult to detect with routine light microscopy when diffusely present at a low level, quantitative methods (morphometry) may be needed to confidently identify this change. With appropriate and consistent dissection techniques, muscle wet weights can provide a useful and sensitive endpoint for muscle hypertrophy. Muscle hypertrophy is an expected physiologic response to exercise and may occur as a compensatory response in regions of individual fiber atrophy. Xenobiotic-induced muscle hypertrophy has long been recognized following treatment with growth factors and hormones, such as growth hormone (Prysor-Jones and Jenkins 1980) and, more recently, inhibitors of myostatin (Whittemore et al. 2003). Hypertrophy as an unexpected or off-target toxicity is seldom reported.
Intense resistance training induces pronounced metabolic stress and impairs hypertrophic response in hind-limb muscles of rats
Published in Stress, 2019
Vinicius Guzzoni, Larissa Briet, Rafaela Costa, Rodrigo W. A. Souza, Fernanda R. Carani, Maeli Dal-Pai-Silva, Kleiton A. S. Silva, Tatiana S. Cunha, Fernanda K. Marcondes
Resistance training (RT) is a modality of exercise training indicated to achieve specific training outcomes, including skeletal muscle hypertrophy and strength (Kwon, Jang, Cho, Jang, & Lee, 2018). Training variables (intensity, volume, and frequency) must be strictly controlled in order to evoke substantial muscular fitness (Burd et al., 2010a; Ogasawara, Arihara, Takegaki, Nakazato, & Ishii, 2017). Training volume consists of the total number of repetitions performed during a training session, multiplied by the load used, and reflects the duration for which muscles are being stressed (Lorenz, Reiman, & Walker, 2010). Interaction of these variables results in training overload (Bågenhammar & Hansson, 2007). Accordingly, combination of large volumes and low loads have been shown to induce greater muscle hypertrophy (Burd et al., 2010b; Ikezoe, Kobayashi, Nakamura, & Ichihashi, 2017). However, evidence regarding the role of rest intervals on metabolic stress and muscular adaptations in response to RT are inconclusive (Fink, Schoenfeld, Kikuchi, & Nakazato, 2017; Grgic, Lazinica, Mikulic, Krieger, & Schoenfeld, 2017). Thus, whether the combination of high loads, large volume, elevated frequency, and short rest intervals evoke maladaptation in skeletal muscle and intense metabolic stress is not fully elucidated.
Is low load blood flow restriction training an effective intervention in improving clinical outcomes in adults with lower extremity pathology: a systematic review
Published in Physical Therapy Reviews, 2019
Michael Mirando, Abby Reusser, Beth Sherer, Carlton Reinhart, Leigh Murray
BFR is a relatively new treatment option and is an emerging topic in the field of physical therapy [1]. The concept behind BFR involves the use of an extremity tourniquet placed on the proximal aspect of a limb [2] to occlude venous blood flow, while maintaining partial arterial inflow [3]. Current recommendations are a 60–80% reduction in the lower extremity blood flow and a 40–50% reduction in the upper extremity blood flow [4]. This reduces oxygen supply to the muscle cells during an exercise period. The anaerobic environment that is created has been found to promote muscle hypertrophy through a variety of mechanisms, including the initiation of ‘cell signaling and hormonal changes that stimulate protein synthesis, proliferation of myogenic satellite cells, and preferential activation and mobilization of type II muscle fibers’ [3, p. 2507].
Histopathological changes in extraocular muscles of rabbits following injection of bupivacaine 5mg/Ml versus 7.5mg/Ml
Published in Cutaneous and Ocular Toxicology, 2022
Randa Mohamed Abdel-Moneim El-Mofty, Rehab R. Kassem, Lubna O. Abdel-Salam
Later, two further studies were conducted by Hopker and co-authors5,6 to analyse the histopathological effects of BUP 1.5% injection in rabbits’ extraocular muscles. These two studies used a higher concentration than the present and previous studies. Moreover, these two studies performed a staged evaluation at 7, 28, 60 and 92 days, while the present study performed it at 6 weeks only. Although the present studies evaluated multiple parameters (Tables 1 and 2), these previous ones determined only the changes in the cross-sectional area (CSA) of myofibres and their subtype distribution based on the myosin isoform expression. Myofiber area measurement decreased 7 days after BUP injection followed by an increasing trend after 28 days and normalisation after 92 days. The present study evaluated muscle hypertrophy at 6 weeks. Atrophy was mild in both groups and hypertrophy was documented in 60% of Group B5 and 37.5% of Group B7. Comparison to the 2 previous studies is impossible due to different timing and parameters used for evaluation.
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