China
Africa
Explore chapters and articles related to this topic
Nutrition and Metabolic Factors
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
As mentioned above, stored protein is remodeled by a continuous process of anabolism and catabolism. For example, daily remodeling amounts to about 3–4% of whole-body protein in adults (52) and potentially there could be a greater percentage among athletes during intense training. However, compared to carbohydrate or fat turnover, the breakdown and replacement of protein is less efficient, accounting for 10–25% of the RMR (52, 168). A common method of measuring protein turnover includes the examination of nitrogen balance, which provides an estimate of nitrogen intake versus loss and a reasonable estimate of protein balance. Simply, a negative nitrogen balance occurs when nitrogen loss is larger than intake (state of catabolism) and a positive nitrogen balance occurs when intake is greater than loss (state of anabolism). The formula for nitrogen balance is as follows:
Nutritional management in pulmonary rehabilitation
Published in Claudio F. Donner, Nicolino Ambrosino, Roger S. Goldstein, Pulmonary Rehabilitation, 2020
Rosanne J.H.C.G. Beijers, Emiel F.M. Wouters, Annemie M.W.J. Schols
Muscle mass is determined by the net balance of muscle protein synthesis and protein degradation, and muscle loss occurs when degradation exceeds synthesis. Whole-body protein turnover has been shown to be increased in patients with stable COPD (47,48). However, the relative contribution of protein turnover in muscle versus other tissues is still unknown. One study observed an increase in myofibrillar protein breakdown in cachectic COPD patients compared with non-cachectic patients and controls (48), and one study showed depressed muscle protein synthesis rates in malnourished patients with emphysema (49). Analyses of the effector pathways of protein degradation showed consistent elevation of components of the ubiquitin-26S proteasome system and enhanced autophagy, while distal protein synthesis−signalling cues, such as insulin-like growth factor I and phospho-Akt expression, are mainly unaltered (50). Recently, a comprehensive muscle biopsy analysis of a large COPD cohort study showed that both muscle protein synthesis and protein degradation signalling (i.e. muscle protein turnover) in COPD were increased and even more prominent in the subgroup with low muscle mass (51). Together with an observed increased myogenic signalling response, this pattern mirrors molecular alterations associated with muscle repair and remodelling which could be the result of catabolic triggers.
Protein and amino acids
Published in Jay R Hoffman, Dietary Supplementation in Sport and Exercise, 2019
At present, the protein intake in which to maximally stimulate MPS and to also minimize the “muscle-full” effect during resistance training is not well known. This is mainly due to the varying types and intensities of resistance exercise in which many people engage. For instance, it is known that a dose-response occurs in a sigmoidal fashion between resistance exercise intensity and MPS such that intensities greater than 60% of the one-repetition maximum (1-RM) elicit greater responses in MPS, even when the intensity is lowered to 20–40% 1-RM and the repetitions increased (38). Knowing this, the mindset for most avid resistance exercise enthusiasts is established relative to their training regimen, compounded by the thought that providing copious amounts of protein peri-exercise, and at regular intervals throughout the day, will further maximize the response in MPS. In this regard, muscle protein turnover becomes of extreme importance relative to the role that protein supplementation can play in the maintenance or accrual of muscle mass in response to resistance training.
Photoperiod-dependent changes in oxidative stress markers in the blood of Shetland pony mares and stallions involved in recreational horseback riding
Published in Chronobiology International, 2022
Natalia Kurhaluk, Oleksandr Lukash, Halyna Tkachenko
Exercise can induce the activity of the proteasome complex, which is involved in the degradation of oxidatively modified proteins (Radák et al. 2008). Increased activity of proteasomes could be an important determinant of the rate of protein turnover and the remodeling of skeletal muscle after injury (Radák et al. 2000). An increased rate of protein turnover during exercise decreases the accumulation of oxidative damage, thereby exerting a beneficial effect on the physiological function of proteins. The proteasome complex plays a critical role in this process (Radák et al. 2008). Thus, the significant decrease in the aldehydic and ketonic derivatives of OMP in the plasma of ponies after the exercise is the result of exercise-induced adaptation, especially in the autumn and winter periods (Figure 2).
A multimodal approach to cancer-related cachexia: from theory to practice
Published in Expert Review of Anticancer Therapy, 2021
Alice Avancini, Ilaria Trestini, Daniela Tregnago, Massimo Lanza, Jessica Menis, Lorenzo Belluomini, Michele Milella, Sara Pilotto
Cancer-cachexia may hardly be managed and reversed using a single intervention, given its multifactorial nature. It is reasonable to hypothesize that a multimodal management may offer the best treatment strategy [73,74]. Indeed, integrated exercise-based, and nutritional interventions combined with an appropriate pharmacological therapy could produce a synergistic effect, leading to effectively control or even counteract cachexia [64]. For instance, the increase in muscle mass may be synergistically influenced by the four interventions. Exercise can provide an important anabolic stimulus to increase size and number of fast-twitching fibers that may also be improved by specific drugs. However, protein turnover requires adequate protein intake. In that respect, nutritional counseling can offer an optimal strategy to increase the quality of food assumption, while appetite-stimulating drugs could favor hunger and, consequently, lead to a higher caloric assumption [75].
The application of proteomics in muscle exercise physiology
Published in Expert Review of Proteomics, 2020
Stuart J Hesketh, Ben N Stansfield, Connor A Stead, Jatin G Burniston
Little information currently exists regarding which changes to protein abundance are controlled by synthesis, degradation or a combination of the two. To date, the primary focus of interest has been on synthesis and/or the ‘synthetic arm’ including gene transcription [42] and ribosomal translation (e.g [34].). However, more recently the role of degradation in maintaining proteome health has been emphasized [41] and we found alterations to the degradation rate of proteins can be the dominant factor controlling changes in the abundance of some muscle proteins in response to an endurance exercise stimulus [61]. Synthesis and degradation are regulated independently on a protein-by-protein basis to maintain homeostasis and/or to facilitate muscle adaptation. The regulatory processes of protein degradation are convoluted, and little is known about the sequence of events linking particular stimuli to the degradation of specific individual proteins. This contrasts sharply against our understanding of the regulators of protein synthesis, where a more tangible ‘audit trail’ exists between genetic regulation and the synthesis of new proteins. Protein degradation is essential to adaptation, and even during ‘steady-state’ conditions proteins must continuously be renewed (i.e. protein turnover) to maintain proteostasis and prevent the accumulation of damaged proteins from causing cell dysfunction.