Habitual Intake of Guaraná and Metabolic Morbidities: An Epidemiological Study of an Elderly Amazonian Population
Cristina da Costa Krewer   Phytotherapy Research   Early View

The aim of the present study was to evaluate the associations of metabolic disorders and anthropometric and biochemical biomarkers of lipid, glucose and oxidative metabolism and the habitual ingestion of guaraná (Paullinia cupana, Mart. Var. sorbilis) by an elderly population residing in the Amazon Riverine region of the Maués municipality (Brazil). A case-controlled study was performed that included 637 elderly (≥60 years of age) patients classified as either those who habitually drank guaraná (GI, n = 421) or those who never drank guaraná (NG, n  = 239) based upon their self-reported intake of guaraná. Indeed, the prevalence of various metabolic disorders was associated with guaraná ingestion. The prevalence of hypertension, obesity and metabolic syndrome in the GI group was lower than the prevalence found in the NG group. The NG group exhibited lower systolic and diastolic blood pressure values. The males in the GI group exhibited a lower waist circumference, on average, than the circumference found in the NG group, whereas the females in the GI group had lower cholesterol (total and LDL-c) levels than the control cohort. Additionally, a significant association was found between lower levels of advanced oxidative protein product (AOPP) and habitual guaraná consumption. The results constitute the first epidemiological study to suggest a potentially protective effect of habitual guaraná ingestion against metabolic disorders in elderly subjects.

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Prostaglandin F2α stimulates PI3K/ERK/mTOR signaling and skeletal myotube hypertrophy
James F. Markworth Am J Physiol Cell Physiol March 2011   vol. 300 no. 3 C671-C682

Cyclooxygenase (COX) enzymes mediate the synthesis of proinflammatory prostaglandin (PG) species from cellular arachidonic acid. COX/PGs have been implicated in skeletal muscle growth/regeneration; however, the mechanisms by which PGs influence skeletal muscle adaptation are poorly understood. The present study aimed to investigate PGF2α signaling and its role in skeletal myotube hypertrophy. PGF2α or the FP receptor agonist fluprostenol increased C2C12 myotube diameter. This effect was abolished by the FP receptor antagonist AL8810 and mammalian target of rapamycin (mTOR) inhibition. PGF2α stimulated time- and dose-dependent increases in the phosphorylation of extracellular receptor kinase (ERK)1/2 (Thr202/Tyr204), p70S6 kinase (p70S6K) (Thr389 and Thr421/Ser424), and eukaryotic initiation factor 4G (eIF4G) (Ser1108) without influencing Akt (Ser473). Pretreatment with the phosphoinositide 3-kinase (PI3K) inhibitor LY294002 and the ERK inhibitor PD98059 blocked F prostanoid receptor signaling responses, whereas rapamycin blocked heightened p70S6K/eIF4G phosphorylation without influencing ERK1/2 phosphorylation. These data suggest that activation of the F prostanoid receptor is coupled to C2C12 myotube growth and intracellular signaling via a PI3K/ERK/mTOR-dependent pathway.

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Short-term consumption of a high-fat diet impairs whole-body efficiency and cognitive function in sedentary men
Lindsay M. Edwards The FASEB Journal   vol. 25 no. 3 1088-1096

We recently showed that a short-term high-fat diet blunted exercise performance in rats, accompanied by increased uncoupling protein levels and greater respiratory uncoupling. In this study, we investigated the effects of a similar diet on physical and cognitive performance in humans. Twenty sedentary men were assessed when consuming a standardized, nutritionally balanced diet (control) and after 7 d of consuming a diet comprising 74% kcal from fat. Efficiency was measured during a standardized exercise task, and cognition was assessed using a computerized assessment battery. Skeletal muscle mitochondrial function was measured using 31P magnetic resonance spectroscopy. The diet increased mean ± se plasma free fatty acids by 44% (0.32±0.03 vs. 0.46±0.05 mM; P<0.05) and decreased whole-body efficiency by 3% (21±1 vs. 18±1%; P<0.05), although muscle uncoupling protein (UCP3) content and maximal mitochondrial function were unchanged. High-fat diet consumption also increased subjects' simple reaction times (P<0.01) and decreased power of attention (P<0.01). Thus, we have shown that a high-fat diet blunts whole-body efficiency and cognition in sedentary men. We suggest that this effect may be due to increased respiratory uncoupling.

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The secular trend for grip strength in Canada and the United States
Irwin W. Silvermana Journal of Sports Sciences 28 February 2011

Worldwide, body weight has risen dramatically in recent decades, raising the question of whether there were concomitant changes in physical fitness. Past research with children and adolescents has shown that body weight and grip strength are positively correlated. Therefore, it was predicted that grip strength had increased on average in children and adolescents over the past four or five decades. To test this prediction, relevant data were extracted from 18 studies for males (N = 5676 in total) and 17 studies for females (N = 5489 in total). The studies were conducted in Canada and the United States from about 1966 on, with participants’ ages ranging from 6 through 19 years. Weighted least squares regression analyses showed that grip strength was significantly predicted by age but not by country. Male grip strength decreased significantly over the period covered, but the change was very small, accounting for far less than 1% of the variance in male grip strength. Discussion focuses on potential explanations for why grip strength did not change over time as predicted.

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Effects of Cell Phone Radiofrequency Signal Exposure on Brain Glucose Metabolism
Nora D. Volkow     JAMA. 2011;305(8):808-813

The dramatic increase in use of cellular telephones has generated concern about possible negative effects of radiofrequency signals delivered to the brain. However, whether acute cell phone exposure affects the human brain is unclear.

Objective:

To evaluate if acute cell phone exposure affects brain glucose metabolism, a marker of brain activity.

Design, Setting, and Participants:

Randomized crossover study conducted between January 1 and December 31, 2009, at a single US laboratory among 47 healthy participants recruited from the community. Cell phones were placed on the left and right ears and positron emission tomography with (18F)fluorodeoxyglucose injection was used to measure brain glucose metabolism twice, once with the right cell phone activated (sound muted) for 50 minutes (“on” condition) and once with both cell phones deactivated (“off” condition). Statistical parametric mapping was used to compare metabolism between on and off conditions using paired t tests, and Pearson linear correlations were used to verify the association of metabolism and estimated amplitude of radiofrequency-modulated electromagnetic waves emitted by the cell phone. Clusters with at least 1000 voxels (volume >8 cm3) and P < .05 (corrected for multiple comparisons) were considered significant.

Outcome Measure Brain glucose metabolism computed as absolute metabolism (μmol/100 g per minute) and as normalized metabolism (region/whole brain).

Whole-brain metabolism did not differ between on and off conditions. In contrast, metabolism in the region closest to the antenna (orbitofrontal cortex and temporal pole) was significantly higher for on than off conditions (35.7 vs 33.3 μmol/100 g per minute; mean difference, 2.4 [95% confidence interval, 0.67-4.2]; P = .004). The increases were significantly correlated with the estimated electromagnetic field amplitudes both for absolute metabolism (R = 0.95, P < .001) and normalized metabolism (R = 0.89; P < .001).

In healthy participants and compared with no exposure, 50-minute cell phone exposure was associated with increased brain glucose metabolism in the region closest to the antenna. This finding is of unknown clinical significance.

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THE EFFECT OF A MULTI-INGREDIENT HIGH CAFFEINE PRE-EXERCISE SUPPLEMENT ON STRENGTH POWER AND BODY COMPOSISION IN 8 WEEKS OF RESISTANCE TRAINING
JSCR 2011 25 (3) p: 112 R. KUDRNA, N. MOODIE, M. MCCARTNEY, J. BUSTAMANTE, A. FRY, AND P. GALLAGHER

Pre-workout supplements are broadly marketed to athletes and recreational exercisers with claims of improved performance or exercise effectiveness. Many such supplements contain a variable blend of known ergogenic aids and often include caffeine.

PURPOSE:

The purpose of this study was to examine the effects of amulti-component high caffeine pre-workout supplement on lean body mass (LBM) and measures of muscle performance during an eight week strength training exercise program.

METHODS:

Thirty physically active, resistance trained, college age (19.5 6 0.269 yr) males were recruited for this double blind taste placebo control investigation. Subjects were randomly assigned into 2 groups: 1) Experimental (EXP) (n = 15) and 2) Control (CON) (n = 15). Subjects in the EXP drank the supplement containing a variety of common ergogenic aids including 450mg caffeine 15 minutes before each training session. Subjects in the CON drank a noncaloric placebo mixture at the same times. Both groups completed an eight week exercise program consisting of three days of strength training per week and all subjects completed the same training protocol. The following tests were performed prior to the training protocol and after 8 weeks of training: Body Weight, Body Composition via dual-energy X-ray absorptiometry (DEXA); maximal strength was determined using 1 RM tests for 8 different exercises; squat and bench press power was determined using an external dynamometer; and vertical jump. Twenty-five subjects completed the training protocol (EXP n = 14 and CON n = 11). Separate repeated measures ANOVAs were performed to test for differences between EXP and CON groups for strength, power, and body composition. The criteria for statistically significant differences were identified as an p value # 0.05.

RESULTS:

A main effect for time was identified for each of the 1RM strength measures tested (p,0.05) except biceps curls (p = 0.34). A significant group x time interaction was found for the bench press exercise (F1/22 = 4.843, p = 0.039). Significant main effects were found for lean body mass (F1/22 = 20.32, p,0.001), but there were no significant group 3 time interactions for changes in LBM (F1/22 = 0.142 p = 0.710). Squat power measurements also showed a significant group x time interaction (F1/22 = 4.857, p = 0.038). Vertical Jump and bench press power did not differ between groups.

CONCLUSIONS:

Significant improvements in strength and lean body mass were observed in both the EXP and CON groups as would be expected with a resistance exercise training program. The primary purpose of this study was to examine the effectiveness of the supplement as an ergogenic aid. Two measures of muscle performance, bench press 1RM and squat power, increased more in the EXP group, but LBM changes did not differ.

PRACTICAL APPLICATIONS:

8 weeks of pre-workout supplementation may provide some muscle performance benefit when combined with resistance exercise training. Significant improvements in LBM over the placebo drink were not observed however. ACKNOWLEDGEMENT: This study was funded by LaBrada Nutrition Inc, Houston, TX. *Denotes Equal Author Contribution.

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