Effect of creatine supplementation during cast-induced immobilization on the preservation of muscle mass, strength, and endurance.
ABSTRACT Muscle and strength loss will occur during periods of physical inactivity and immobilization. Creatine supplementation may have a favorable effect on muscle mass and strength independently of exercise. The purpose of this study was to determine the effects of creatine supplementation on upper limb muscle mass and muscle performance after immobilization. Before the study, creatine-naïve men (n = 7; 18-25 years) were assessed for lean tissue mass (dual-energy X-ray absorptiometry), strength (1-repetition maximum [1RM] isometric single arm elbow flexion/extension), and muscle endurance (maximum number of single-arm isokinetic elbow flexion/extension repetitions at 60% 1RM). After baseline measures, subjects had their dominant or nondominant (random assignment) upper limb immobilized (long arm plaster cast) at 90 degrees elbow flexion. Using a single-blind crossover design, subjects received placebo (maltodextrin; 4 x 5 gxd-1) during days 1-7 and creatine (4 x 5 gxd-1) during days 15-21. The cast was removed during days 8-14 and 22-29. The dependent measures of lean tissue mass, strength, and endurance were assessed at baseline, postcast, and after the study. During immobilization, compared with isocaloric placebo, creatine supplementation better maintained lean tissue mass (Cr +0.9% vs. PLA -3.7%, p < 0.05), elbow flexor strength (Cr -4.1% vs. PLA -21.5%, p < 0.05), and endurance (Cr -9.6% vs. PLA -43%, p < 0.05), and elbow extensor strength (Cr -3.8% vs. PLA -18%, p < 0.05) and endurance (Cr -6.5% vs. PLA -35%, p < 0.05). These results indicate that short-term creatine supplementation attenuates the loss in muscle mass and strength during upper-arm immobilization in young men.
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ABSTRACT: The pleiotropic effects of creatine (Cr) are based mostly on the functions of the enzyme creatine kinase (CK) and its high-energy product phosphocreatine (PCr). Multidisciplinary studies have established molecular, cellular, organ and somatic functions of the CK/PCr system, in particular for cells and tissues with high and intermittent energy fluctuations. These studies include tissue-specific expression and subcellular localization of CK isoforms, high-resolution molecular structures and structure-function relationships, transgenic CK abrogation and reverse genetic approaches. Three energy-related physiological principles emerge, namely that the CK/PCr systems functions as (a) an immediately available temporal energy buffer, (b) a spatial energy buffer or intracellular energy transport system (the CK/PCr energy shuttle or circuit) and (c) a metabolic regulator. The CK/PCr energy shuttle connects sites of ATP production (glycolysis and mitochondrial oxidative phosphorylation) with subcellular sites of ATP utilization (ATPases). Thus, diffusion limitations of ADP and ATP are overcome by PCr/Cr shuttling, as most clearly seen in polar cells such as spermatozoa, retina photoreceptor cells and sensory hair bundles of the inner ear. The CK/PCr system relies on the close exchange of substrates and products between CK isoforms and ATP-generating or -consuming processes. Mitochondrial CK in the mitochondrial outer compartment, for example, is tightly coupled to ATP export via adenine nucleotide transporter or carrier (ANT) and thus ATP-synthesis and respiratory chain activity, releasing PCr into the cytosol. This coupling also reduces formation of reactive oxygen species (ROS) and inhibits mitochondrial permeability transition, an early event in apoptosis. Cr itself may also act as a direct and/or indirect anti-oxidant, while PCr can interact with and protect cellular membranes. Collectively, these factors may well explain the beneficial effects of Cr supplementation. The stimulating effects of Cr for muscle and bone growth and maintenance, and especially in neuroprotection, are now recognized and the first clinical studies are underway. Novel socio-economically relevant applications of Cr supplementation are emerging, e.g. for senior people, intensive care units and dialysis patients, who are notoriously Cr-depleted. Also, Cr will likely be beneficial for the healthy development of premature infants, who after separation from the placenta depend on external Cr. Cr supplementation of pregnant and lactating women, as well as of babies and infants are likely to be of benefit for child development. Last but not least, Cr harbours a global ecological potential as an additive for animal feed, replacing meat- and fish meal for animal (poultry and swine) and fish aqua farming. This may help to alleviate human starvation and at the same time prevent over-fishing of oceans.Amino Acids 03/2011; 40(5):1271-96. DOI:10.1007/s00726-011-0877-3 · 3.65 Impact Factor
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ABSTRACT: In this study, Raman spectroscopy was employed in order to provide information about the effects of different doses of creatine on bone tissue composition of phosphate apatite (960 cm −1), carbonate apatite (1170 cm −1) representing the mineral content and collagen matrix (amide I, 1665 cm −1). The animals (27 Balb-C male) were divided into three groups (n = 9 per group): control (CON), supplemented with 0.5 g/kg (Cre-0.5) and with 2.0 g/kg (Cre-2.0) creatine. The experiment was carried out for thirty days. After this time, the right femur of each animal was harvested. The specimens were assessment by FT-Raman spectroscopy and in a total of 81 spectra were acquired in the medial diaphysis of the femur. The Raman data strongly suggest that only the creatine supplementation of 0.5 g/kg effective to the bone constitution. Furthermore, the present results demonstrate that creatine ingestion provokes decrease in the relative presence of carbonate in the chemical constitution of bones. The decrease in the carbonate content can be associated to a significantly bone resistance altered to several mammalians. The analysis evidenced that the mineral concentrations in the Raman spectroscopy could be a feasible method for non-invasive or minimally invasive assessment of bone tissue composition. Probably this high sensitivity can be employed to determine spectral profiles, such as wavelength of maximum absorption and maximum intensity of absorption of each wavelength, of several bone diseases.Spectroscopy 01/2011; 25(5):225-233. DOI:10.3233/SPE-2011-0508 · 0.83 Impact Factor
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ABSTRACT: It is well documented that damage to DNA could be very harmful for all cells and is the source of several consequences such as cancer development, apoptosis or genetic diseases. In contrast, RNA damage is a poorly examined field in biomedical research, despite its potential to affect cell physiology. For example, a significant loss of RNA integrity has been demonstrated in advanced human atherosclerotic plaques as compared with non-atherosclerotic mammary arteries, and oxidative RNA damage has been described in several neurodegenerative diseases including Alzheimer disease. In the present study, we investigated whether RNA damage could be related to the exposure of particular xenobiotics and then we studied the potential protective activity of creatine against RNA-damaging activity of a series of chemicals with different mechanisms of action [ethyl methanesulfonate (EMS), H(2)O(2), doxorubicin, spermine NONOate, S-nitroso-N-acetylpenicillamine (SNAP)]. Since the protective effect against RNA damage can be mediated by different mechanisms, such as alterations of the rates of toxic agent absorption and uptake, trapping of electrophiles as well as free radicals, and protection of nucleophilic sites in RNA, we used two different treatment protocols (pre- and co-treatment) for understanding the mechanism of the inhibitory activity of creatine. We demonstrated that total RNA is susceptible to chemical attack by doxorubicin, H(2)O(2), spermine and SNAP. Creatine significantly reduced the RNA-damaging activity of only two of the toxic tested agents (H(2)O(2) and doxorubicin), while it lacked activity in counterstaining the RNA damage induced by the NO donors spermine and SNAP. Its inhibitory activity could be at least partially dependent on its capacity to directly scavenge free radicals and/or to maintain phosphocreatine store and ATP regeneration.Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 08/2009; 670(1-2):59-67. DOI:10.1016/j.mrfmmm.2009.07.005 · 4.44 Impact Factor