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Physical and Physiological Reponses and Adaptations
Published in Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan, Strength and Conditioning in Sports, 2023
Michael H. Stone, Timothy J. Suchomel, W. Guy Hornsby, John P. Wagle, Aaron J. Cunanan
Muscle responds to resistance training by enlarging its cross-sectional area (i.e., hypertrophy). In this manner, additional contractile elements (myofibrils) are added to the muscle fiber. The underlying mechanisms are complex and still not completely understood. The primary stimulus for skeletal muscle hypertrophy appears to be a gain in tension and mechanical strain (26, 62). Secondarily, there may be metabolic factors as a result of repeated contractions that also stimulate the hypertrophic adaptations (7, 62). The stimulus causes a cascade of multi-level effects as illustrated in Figure 6.3. The degree to which muscle damage stimulates hypertrophy is unclear and is not likely a major factor (62).
Applications of Fenugreek in Sports Nutrition
Published in Dilip Ghosh, Prasad Thakurdesai, Fenugreek, 2022
Colin Wilborn, Aditya Bhaskaran
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).
Dietary Influence on Muscle Protein Synthesis and Hypertrophy
Published in Peter M. Tiidus, Rebecca E. K. MacPherson, Paul J. LeBlanc, Andrea R. Josse, The Routledge Handbook on Biochemistry of Exercise, 2020
James McKendry, Stuart M. Phillips
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.
Protocols aiming to increase muscle mass in persons with motor complete spinal cord injury: a systematic review
Published in Disability and Rehabilitation, 2023
Jordan M. Fenton, James A. King, Sven P. Hoekstra, Sydney E. Valentino, Stuart M. Phillips, Victoria L. Goosey-Tolfrey
In individuals prone to muscle loss, such as those with sarcopenia or multiple sclerosis, exercise and non-exercise (e.g., dietary, pharmacological) approaches are commonly used to prevent and reverse atrophy. Regular exercise that involves loading of the muscle (i.e., resistance training [RT]) is universally accepted as a fundamental method for maintaining and increasing muscle mass in healthy individuals. However, traditional RT is not feasible for persons with motor complete SCI. Neuromuscular electrical stimulation (NMES) is used in persons with SCI to induce involuntary contractions in the skeletal muscle. Using NMES, simple movements, such as knee extensions [10], and functional movements, such as cycling, rowing, and standing, known as functional electrical stimulation (FES) [11–13], can be performed. Thus, electrical stimulation can facilitate structured RT- and aerobic-based exercise, which can elicit numerous cardio-metabolic benefits, including restoring SMM [14,15]. However, the optimal strategy for inducing muscle hypertrophy has not been systematically evaluated.
Factors influencing thigh muscle volume change with cycling exercises in acute spinal cord injury – a secondary analysis of a randomized controlled trial
Published in The Journal of Spinal Cord Medicine, 2022
Maya G. Panisset, Doa El-Ansary, Sarah Alison Dunlop, Ruth Marshall, Jillian Clark, Leonid Churilov, Mary P. Galea
The prevailing paradigm in exercise science postulates that resisted work is required for muscle hypertrophy.27 Although FESC stimulates both the quadriceps and hamstring muscle groups, average watts was significantly correlated with quadriceps outcomes, but no relationship was shown for hamstrings. There are three possible explanations for this discrepancy. First, it has been noted that in the majority of SCI participants, the quadriceps perform over 80% of the work during FESC. This is postulated to be due to weaker hamstrings, or possibly due to the superficial stimulation of the distal hamstrings as an artifact of the technology.28 Second, biomechanical inefficiencies described as imbalanced co-contractions of antagonistic muscles were found to cause an increase in eccentric work in FESC with SCI subjects.28 Because the external work output recorded by the FESC apparatus represents the net work applied to the pedal crank of both concentric and eccentric power, high amounts of eccentric work would produce a lower external work output reading. In other words, the power output reading may not be a valid measure of the amount of intrinsic work performed by the muscles during FESC, in which case there may indeed be a stronger relationship between intrinsic muscle work and hypertrophy in the present sample that was potentially obscured by the crudeness of the measure. Third, it is likely that a greater proportion of the variance in hamstring outcomes was related to the presence or absence of spasticity, which is more common in the hamstrings.28
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.