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Objective: Strenuous exercise can induce apoptosis in a variety of tissues. We investigated the effects of creatine loading on apoptosis markers after downhill running. Design: Twenty-two middle-aged men were randomly assigned to either a creatine or a placebo group. Crossover design, double-blind controlled supplementation was performed using 20 g/d-1 of creatine ormaltodextrin for 7 days. Downhill running (12% incline) at 70% of heart ratemaximum for 40 mins was performed on the eighth day. Blood samples were taken on the day before supplementation, after supplementation and after running. Results: There were no significant changes in the caspase-3, caspase-9, p53, Bax, and IGF-1 concentrations from presupplementation to postsupplementation in both groups of creatine and placebo (P > 0.05). There were significant increases (P < 0.05) in serum caspase-3, caspase- 9, p53, andBax after running in the placebo group. Thesemarkerswere not noticeably changed in the creatine group (P > 0.05). Bcl-2was unchanged in the placebo group but substantially increased (P < 0.05) in the creatine group. No significant changes were observed in IGF-1 concentration after running comparing to prerunning in both groups (P > 0.05). Lactate levels increased similarly in both groups (P < 0.05). Conclusions: The findings indicate that creatine supplementation could prevent exercise-induced apoptotic markers. [ABSTRACT FROM AUTHOR]

Abstract We have developed a novel, intraluminal preservation solution that is tailored to the metabolic requirements of the intestine. This organ-specific solution addresses many of the problems associated with low temperature organ storage including energy, oxidative and osmotic stresses. However, conservation of energy levels remains one of the most difficult obstacles to overcome due to the inherent sensitivity of the mucosa to ischemia. Creatine-loading has become a popular and scientifically proven method of augmenting energy reserves in athletes performing anaerobic burst work activities. We hypothesized that if we could develop a method that was able to augment cellular energy levels, the structure and function of the mucosa would be more effectively preserved. The purpose of this study was to determine if creatine-loading is a feasible and effective strategy for preserving the intestine. Our data indicate that creatine loading has significant impact on energy levels during storage with corresponding improvements in mucosal structure and function. Both of our rodent models, a) continuous perfusion for 4 h and b) a single flush with our intraluminal preservation solution supplemented with 50 mM creatine, demonstrated significant improvements in creatine phosphate, ATP, Energy Charge and ATP/AMP following cold storage (P < 0.05). Notably, after 10 h creatine phosphate was 324% greater in Creatine-treated tissues compared to Controls (P < 0.05). Preferential utilization of glutathione in the Creatine group was effective at controlling oxidative injury after 10 h storage (P < 0.05). Improvements in barrier function and electrophysiology with creatine-treatment reflected superior mucosal integrity after 10 h storage; Permeability and Transepithelial resistance measurements remained at fresh tissue values. This was in stark contrast to Control tissues in which permeability rose to >300% of fresh tissue values (P < 0.005) and transepithelial resistance dropped by 95% (P < 0.005). After 10 h storage, Park's grading of histologic injury reflected extensive villus denudation (grade 4) in control tissues compared to healthy tissue (grade 0) in the Creatine group. This study demonstrates that a strategy of creatine supplementation of our intraluminal preservation solution facilitates the preservation of the intestinal mucosa during storage. [ABSTRACT FROM AUTHOR]

Summary Introduction The purpose of this study was to examine the effects of 3, 5 and 7 days of creatine loading coupled with resistance exercise on resting testosterone and cortisol concentrations, systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), heart rate and rate pressure product (RPP). These measures were compared to those in placebo group. Summary of facts Twenty active males were randomly assigned to either a creatine group (Cr) or placebo group (Pl). Participants performed resistance exercises at day 3, 5, and 7; and also tested at day 4, 6, and 8. Subjects of the Cr group showed significant increases in testosterone concentrations and decreases in cortisol concentrations, in comparison with Pl and baseline, after 5 and 7 days of Cr loading ( P < 0.05). There were no significant changes in heart rate, SBP, DBP, MAP, and RPP for both groups at all times (P > 0.05). Conclusion Results of the present study suggest that more than 5 days of creatine supplementation, associated with resistance exercises is sufficient for increasing testosterone concentrations and decrement in cortisol concentrations. [ABSTRACT FROM AUTHOR]

We investigated effects of creatine (Cr) supplementation (CrS) on exercise-induced muscle damage. Untrained males and females (N = 27) ages 18-25, with no CrS history in the past 4 months, were randomly assigned to CrS (creatine and carbohydrate) (n = 9), placebo (P) (carbohydrate only) (n = 9), or control (C) (no supplements) groups (n = 9). Participants followed a 5- day Cr loading protocol of 40 g.day-1, divided for 5 days prior to exercise, reduced to 10 g g.day-1 for 5 days following exercise. Testing consisted of 5 maximal isometric contractions at 90° arm flexion with the preferred arm on a CYBEX NORM dynamometer, assessed prior to, immediately following, and 24, 48, 72, and 96 hours post muscle-damaging procedures. Damage was induced to the elbow flexor muscles using 6 sets of 10 eccentric contractions at 75 °/sec, 90 °/sec and 120 °/sec. Participants were asked to rate their muscle soreness on a scale of 1-10. Data was analyzed using repeated-measures ANOVA, with an alpha of 0.05. No significant differences were found between muscle force loss and rate of recovery or muscle soreness between groups over the 96 hr recovery period (p > 0.05). Across all 3 experimental groups an initial decrease in force was observed, followed by a gradual recovery. Significant differences were found between baseline and all others times (p = 0.031,0 .022, 0.012, 0.001 respectively), and between the 48 hour and 96 hour time periods (p = 0.034). A weak negative correlation between subjectively rated muscle soreness and mean peak isometric force loss (R2 = 0.0374 at 96 hours), suggested that muscle soreness and muscle force loss may not be directly related. In conclusion, 5 days of Cr loading, followed by a Cr maintenance protocol did not reduce indices of muscle damage or speed recovery of upper body muscles following eccentrically induced muscle damage. [ABSTRACT FROM AUTHOR]

Résumé: But: Ces dernières années, la supplémentation de créatine a retenu la plus grande attention des médias populaires et scientifiques. Néanmoins, il n’y a pas d’information valide sur les effets secondaires de ce supplément. C’est pourquoi nous formulons l’hypothèse que le chargement de monohydrate de créatine (CrM) augmente l’activité d’enzymes de sérum comme des marqueurs indirects de dommages cellulaires. Donc, l’étude présente a été faite pour étudier l’effet à cour terme d’une supplémentation en créatine sur la lactico-déshydrogénase (LDH), la créatine phosphokinase (CK) et l’isoforme CK du myocarde (CKMB) sériques chez de jeunes footballeurs. Méthodes: Dans une étude aléatoire en double aveugle, 18 jeunes footballeurs ont participé volontairement et ont été divisés en deux groupes égaux (le groupe de Créatine et le groupe de Placebo). Le premier groupe (CrM) a consommé le supplément de créatine (0,3g/kg par jour pendant sept jours), mais le groupe de placebo (Pl) n’a pas pris des supplément. Tous les sujets ont participés à un programme d’entraînement (huit exercices, trois séries, 15 répétitions, et 60 % one repetition maximum [1RM]). Afin de détecter l’activité enzymatique (IU/L), les échantillons de sang veineux ont été prélevés avant le chargement en créatine et 24heures après la dernière séance d’entraînement. De plus, VO2max de chaque sujet a été obtenu avec le test navette (20m). Les données ont été exprimées en moyens (±SD) et elles ont analysées par les t-tests dépendant et indépendant en ... [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the influence of short-term creatine supplementation on sprint running performance (100 and 200 m) and circulating hormone [growth hormone (GH), testosterone and cortisol] concentrations. Twenty amateur male runners were randomly divided into a creatine supplementation group, or placebo group. Subjects were provided with capsules containing either creatine monohydrate or identical powdered cellulose placebo. Daily creatine monohydrate supplementation was 20 g/day parceled into three equal dosages to be consumed with each major meal. Subjects were tested for performance and resting blood hormone concentrations before and after six days. A double-blind research design was employed in this study. After this creatine loading, the mean running performance time of the creatine supplementation group decreased significantly in the 100 m, but not the 200 m. Serum GH, testosterone, and cortisol concentrations were not affected by creatine supplementation. It can therefore be concluded that although short-term creatine supplementation was found to improve sprint performance in the 100 m in amateur runners, this performance improvement did not appear to be hormonally mediated. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the influence of short-term creatine supplementation on hormonal responses to resistance exercise. 27 trained men were randomly divided into a creatine supplementation group [the CR group (n=15), taking 4×5 g creatine monohydrate/day] or a placebo supplementation group [the PL group (n=12), taking 4×7.5 g maltodextrin/day]. A double-blind research design was employed for a 7-day supplementation period. After this period, the participants performed exercise testing. Blood tests occurred on day 1 prior to supplementation loading (1Pre) and after this period [on the exercise testing day: pre-exercise (Pre), immediately post-exercise (IP), and 15 (15P) and 30 (30P) minutes post-exercise] for the measurement of the serum growth hormone and testosterone concentrations. Significant differences in the number of repetitions and volume were seen with CR (7.2±1.3 repetitions, 1560±386 kg) compared to PL (5.6±2 repetitions, 1089±341 kg) at set 5 of the exercise protocol (p=.01). Serum growth hormone and testosterone were significantly higher at 15P in CR (6.1±1.8 ng/ml, 70.1±19 pmol/L) compared to PL (4.1±1.7 ng/ml, 44.8±16 pmol/L) [(p=.02), (p=.01)]. The enhanced exercise performance resulted in a significantly greater increase in both the growth hormone and testosterone concentrations, indicating an augmented anabolic hormone response to creatine supplementation. [ABSTRACT FROM AUTHOR]

The addition of carbohydrate (CHO) to an acute creatine (Cr) loading regimen has been shown to increase muscle total creatine content significantly beyond that achieved through creatine loading alone. However, the potential ergogenic effects of combined Cr and CHO loading have not been assessed. The purpose of this study was to compare swimming performance, assessed as mean swimming velocity over repeated maximal intervals, in high-performance swimmers before and after an acute loading regimen of either creatine alone (Cr) or combined creatine and carbohydrate (Cr + CHO). Ten swimmers (mean ± SD of age and body mass: 17.8 ± 1.8 years and 72.3 ± 6.8 kg, respectively) of international caliber were recruited and were randomized to 1 of 2 groups. Each swimmer ingested five 5 g doses of creatine for 4 days, with the Cr + CHO group also ingesting ∼100 g of simple CHO 30 minutes after each dose of creatine. Performance was measured on 5 separate occasions: twice at “baseline” (prior to intervention, to assess the repeatability of the performance test), within 48 hours after intervention, and then 2 and 4 weeks later. All subjects swam faster after either dietary loading regimen (p < 0.01, both regimens); however, there was no difference in the extent of improvement of performance between groups. In addition, all swimmers continued to produce faster swim times for up to 4 weeks after intervention. Our findings suggest that no performance advantage was gained from the addition of carbohydrate to a creatine-loading regimen in these high-caliber swimmers. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the influence of short-term creatine (Cr) supplementation on exercise-induced transverse relaxation time (T2) and sprint performance during maximum intermittent cycling exercise using the muscle functional magnetic resonance imaging (mfMRI) technique. Twelve men were divided into a Cr supplementation group [the Cr group, taking 4 × (5 g Cr monohydrate + 2.5 g maltodextrin)/day], or a placebo supplementation group (the P group, taking 4×7.5 g maltodextrin/day). The allocation to the groups was based on cycling tests and the subject’s physical characteristics, and thus was not randomized. A double-blind research design was employed for a 5-day supplementation period. mfMR images of the right thigh were collected at rest and immediately after two, five, and ten 6-s sprint bouts of maximum intermittent cycling exercise with a 30-s recovery interval between sets. Before and after supplementation, blood was taken to calculate lactate accumulation, and the muscle volume of the thigh was determined by MRI. Following supplementation, there was significant body mass gain in the Cr group (P<0.05), whereas the P group did not change. The exercise-induced T2, blood lactate levels and sprint performance were not affected by Cr supplementation in any sprint bouts. These results suggest that short-term Cr supplementation does not influence short duration repetitive sprint performance and muscle activation and/or metabolic state during sprint cycling evaluated by mfMRI of the skeletal muscle in humans. [ABSTRACT FROM AUTHOR]

OBJECTIVE: We measured the effect of 3 d of creatine (Cr) supplementation on repeated sprint performance and thigh muscle volume in elite power athletes.METHODS: Ten male (mean ± standard deviation of body mass and percentage of fat (81.1 ± 10.5 kg and 9.8 ± 3.5) and ten female (58.4 ± 5.3 kg and 15.0 ± 3.4) athletes were matched for sex and 10-s cycle sprint scores, paired by rank, and randomly assigned to the Cr or placebo (P) group. Subjects completed six maximal 10-s cycle sprints interspersed with 60 s of recovery before and after 3 d of Cr (0.35 g/kg of fat-free mass) or P (maltodextrin) ingestion. Before and after supplementation, 10 contiguous transaxial images of both thighs were obtained with magnetic resonance imaging.RESULTS: Cr supplementation resulted in statistically significant increases in body mass (0.9 ± 0.1 kg, P < 0.03), total work during the first sprint (P < 0.04), and peak power during sprints 2 to 6 (P < 0.10). As expected, total work and peak power values for males were greater than those for their female counterparts during the initial sprint (P < 0.02); however, the reverse was true during the last three sprints (P < 0.01). Imaging data showed a 6.6% increase in thigh volume in five of six Cr subjects (P = 0.05).CONCLUSION: These data indicate that 3 d of Cr supplementation can increase thigh muscle volume and may enhance cycle sprint performance in elite power athletes; moreover, this effect is greater in females as sprints are repeated. [ABSTRACT FROM AUTHOR]

Researchers and practitioners in sports nutrition would greatly benefit from a rapid, portable, and non-invasive technique to measure muscle glycogen, both in the laboratory and field. This explains the interest in MuscleSound®, the first commercial system to use high-frequency ultrasound technology and image analysis from patented cloud-based software to estimate muscle glycogen content from the echogenicity of the ultrasound image. This technique is based largely on muscle water content, which is presumed to act as a proxy for glycogen. Despite the promise of early validation studies, newer studies from independent groups reported discrepant results, with MuscleSound® scores failing to correlate with the glycogen content of biopsy-derived mixed muscle samples or to show the expected changes in muscle glycogen associated with various diet and exercise strategies. The explanation of issues related to the site of assessment do not account for these discrepancies, and there are substantial problems with the premise that the ratio of glycogen to water in the muscle is constant. Although further studies investigating this technique are warranted, current evidence that MuscleSound® technology can provide valid and actionable information around muscle glycogen stores is at best equivocal. [ABSTRACT FROM AUTHOR]

The effects of supplemental dietary creatine and a botanical extract consisting of ginseng and astragalus were evaluated in 44 adults aged 55-84 years participating in a 12-week strength-training program. Participants consumed creatine only (Cr), creatine plus botanical extract (CrBE), or placebo (PL), and performed bench press, lat pull down, biceps curl, leg press, knee extension, and knee flexion for 3 sets of 8-12 reps on 3 days per week for 12 weeks. The 1-repetition maximum for each exercise, body composition (full-body DEXA), blood lipids, and mood states were evaluated before and after the intervention. Training improved (p < 0.05) strength and lean mass for all groups, however greater gains were observed with Cr and CrBE compared with placebo (but no difference was found between Cr and CrBE). Only CrBE improved blood lipids and self-reported vigor, and the CrBE group lost significantly more body fat and gained more bench press strength than Cr. These results indicate that strength and lean mass gains achieved by older adults participating in a strength training program can be enhanced with creatine supplementation, and that ginseng and astragalus may provide additional health and psychological benefits. However, these herbs do not appear to have an additive effect on strength and lean mass gains during training. Key PointsStrength and lean mass can be enhanced with creatine supplementation in older adults participating in a strength training programGinseng and astragalus do not appear to provide any additive effect on strength or massGinseng and astragalus may provide additional health and psychological benefits such as lowering cholesterol levels and improving self-reported levels of vigor.