Acute L-arginine alpha ketoglutarate supplementation fails to improve muscular performance in resistance trained and untrained men

Background

Dietary supplements containing L-arginine are marketed to improve exercise performance, but the efficacy of such supplements is not clear. Therefore, this study examined the efficacy of acute ingestion of L-arginine alpha-ketoglutarate (AAKG) muscular strength and endurance in resistance trained and untrained men.

Methods

Eight resistance trained and eight untrained healthy males ingested either 3000mg of AAKG or a placebo 45 minutes prior to a resistance exercise protocol in a randomized, double-blind crossover design. One-repetition maximum (1RM) on the standard barbell bench press and leg press were obtained. Upon determination of 1RM, subjects completed repetitions to failure at 60% 1RM on both the standard barbell bench press and leg press. Heart rate was measured pre and post exercise. One week later, subjects ingested the other supplement and performed the identical resistance exercise protocol.

Results

Our data showed statistical significant differences (p<0.05) between resistance trained and untrained males for both 1RM and total load volume (TLV; multiply 60% of 1RM times the number of repetitions to failure) for the upper body. However, 1RM and TLV were not statistically different (p>0.05) between supplementation conditions for either resistance trained or untrained men in the bench press or leg press exercises. Heart rate was similar at the end of the upper and lower body bouts of resistance exercise with AAKG vs. placebo.

Conclusion

The results from our study indicate that acute AAKG supplementation provides no ergogenic benefit on 1RM or TLV as measured by the standard barbell bench press and leg press, regardless of the subjects training status.     

Multicommuted flow system for the determination of glucose in animal blood serum exploiting enzymatic reaction and chemiluminescence detection

An automatic flow procedure based on multicommutation dedicated for the determination of glucose in animal blood serum using glucose oxidase with chemiluminescence detection is described. The flow manifold consisted of a set of three-way solenoid valves assembled to implement multicommutation. A microcomputer furnished with an electronic interface and software written in Quick BASIC 4.5 controlled the manifold and performed data acquisition. Glucose oxidase was immobilized on porous silica beads (glass aminopropyl) and packed in a minicolumn (15 x 5 mm). The procedure was based on the enzymatic degradation of glucose, producing hydrogen peroxide, which oxidized luminol in the presence of hexacyanoferrate(III), causing the chemiluminescence. The system was tested by analysing a set of serum animal samples without previous treatment. Results were in agreement with those obtained with the conventional method (LABTEST Kit) at the 95% confidence level. The detection limit and variation coefficient were estimated as 12.0 mg l(-1) (99.7% confidence level) and 3.5% (n = 20), respectively. The sampling rate was about 60 determinations h(-1) with sample concentrations ranging from 50 to 600 mg l(-1) glucose. The consumptions of serum sample, hexacyanoferrate(III) and luminol were 46 mul, 10.0 mg and 0.2 mg/determination, respectively.     

A noninvasive technique to determine peripheral blood flow and heat generation in a human limb

The temperature at the surface of a human body is strongly related to heat generation in underlying tissue, and its perfusion by blood. The phenomena of heat generation and dissipation unfold the thermo-regulatory control of a human body. Excursions of body temperatures from “normal” have long been considered as evidence of ill health or abnormal physiological states. In this paper, a noninvasive technique is presented to determine the peripheral rates of heat generation and blood flow in a human limb from its recorded skin surface temperature. The technique involves an analysis based on calculus-of-variation, and features the well-known circadian cycle of mammalian body temperature. The method can readily be adapted to different body parts given appropriate heat transfer models. Further, the method may confirm or contribute to greater reliability of medical diagnosis of individuals for whom recorded skin surface temperatures are available. The technique is demonstrated for a set of skin surface temperature data.     

A model of neutrophil dynamics in response to inflammatory and cancer chemotherapy challenges

A mathematical model of neutrophil and granulocyte colony stimulating factor (G-CSF) dynamics is developed to capture the response of circulating neutrophil levels to inflammatory and anticancer drug challenges. Severe infection or trauma induces inflammation, leading to: (i) the recruitment of neutrophils to the site of infection; (ii) misdirected neutrophil recruitment to healthy tissue, which may cause tissue damage; and (iii) an increase in neutrophil production through the G-CSF signaling cascade. The model is calibrated using fast (endotoxin challenge) and slow (docetaxel chemotherapy) response data and used to examine neutrophil dynamics in response to different chemotherapy schedules and G-CSF mitigation of, or rescue from, neutropenia. The explicit incorporation of biology in this model provides a superior structure for use in designing and evaluating treatments aimed at modulating neutrophil dynamics in chemotherapy and responses to severe infection or trauma.     

An impedance model for blood flow in the human arterial system. Part I: Model development and MATLAB implementation

An impedance model capable of predicting the time-dependent blood pressure and flow profiles in all of the vessels in the human arterial network has been developed. The model is based on a Womersley-type one-dimensional in space approximation of the pulsatile flow of a viscous fluid within elastic vessels. Nominal values from the literature are used to provide the input aortic pressure wave, the geometric dimensions of large arteries, various blood properties, vessel elasticity, etc. The necessary information to characterize the smaller arteries, arterioles and capillaries is taken from a physical scaling model [West, G. (1999). The origin of scaling laws in biology. Physica Acta, 263, 104-113]. The parameters, input setup, and the subsequent solution to the model equations have been efficiently implemented within MATLAB, which also allows for a variety of output information displays. The MATLAB implementation also allows for a comprehensive sensitivity analysis of the results to various input parameter values to be effortlessly obtained.     

A sportomics strategy to analyze the ability of arginine to modulate both ammonia and lymphocyte levels in blood after high-intensity exercise

ABSTRACT: BACKGROUND: Exercise is an excellent tool to study the interactions between metabolic stress and the immune system. Specifically, high-intensity exercises both produce transient hyperammonemia and influence the distribution of white blood cells. Carbohydrates and glutamine and arginine supplementation were previously shown to effectively modulate ammonia levels during exercise. In this study, we used a short-duration, high-intensity exercise together with a low carbohydrate diet to induce a hyperammonemia state and better understand how arginine influences both ammonemia and the distribution of leukocytes in the blood. METHODS: Brazilian Jiu-Jitsu practitioners (men, n = 39) volunteered for this study. The subjects followed a low-carbohydrate diet for four days before the trials and received either arginine supplementation (100 mg.kg-1 of body mass.day-1) or a placebo. The intergroup statistical significance was calculated by a one-way analysis of variance, followed by Student's t-test. The data correlations were calculated using Pearson's test. RESULTS: In the control group, ammonemia increased during matches at almost twice the rate of the arginine group (25 mmol.L-1.min-1 and 13 mumol.L-1.min-1, respectively). Exercise induced an increase in leukocytes of approximately 75%. An even greater difference was observed in the lymphocyte count, which increased 2.2-fold in the control group; this increase was partially prevented by arginine supplementation. The shape of the ammonemia curve suggests that arginine helps prevent increases in ammonia levels. CONCLUSIONS: These data indicate that increases in lymphocytes and ammonia are simultaneously reduced by arginine supplementation. We propose that increased serum lymphocytes could be related to changes in ammonemia and ammonia metabolism.     

Evaluation and model of temperature and rainfall effects on response to N sources applied to grassland in spring

Direct and residual effects of urea and calcium ammonium nitrate (CAN) on dry matter (DM) response were measured at a total of 12 application times in early spring over three years. The variation in the direct effect was described by models that included temperature and long-term rainfall for CAN and, additionally, short-term rainfall for urea. The operative temperature was the accumulated mean daily air temperature for combined intervals pre-application and postapplication of N. The effect of rainfall was apparent only when the data were adjusted for temperature.Simulation studies with the models indicated that, although the influence of temperature was dominant, rainfall modified it strongly in terms of the relative efficiencies of the two N sources and the magnitude of response. For instance, the temperature-induced increase in DM response to urea between cold and normal years was 402 kg ha^–1 for a specified period, whereas differences between dry and wet years were decreases of 166 and 259 kg ha^–1 in the case of urea and CAN, respectively. Short-term rainfall had a positive effect on response to urea.The experimental values varied widely both between and within years. The direct effect of the application of urea at 50 kg N ha^–1 varied from 0 to 750 kg DM ha^–1, and the residual effect varied from 0 to 1620 kg DM ha^–1. The corresponding values for apparent N recovery varied from 0.1 to 45% and from 7 to 68%, respectively. The efficiency of urea was comparable to, and in instances better than, CAN.     

Biofiltration of xylene emissions: bioreactor response to variations in the pollutant inlet concentration and gas flow rate

In order to remove xylene vapors from an air stream, an upflow laboratory scale biofilter was operated for a period of 2 months. The experimental study consisted of two different phases: in the first phase, the biofilter was operated at various gas flow rates and the xylene inlet concentration was maintained at 1.39 g m⁻³. In the second phase, various inlet concentrations of the contaminant were tested at a constant gas flow rate of 0.4 m³ h⁻¹ corresponding to an empty bed residence time of 150 s. The biofilter response to steep and abrupt variations in the xylene inlet concentration and gas flow rate was examined. The results obtained revealed that the removal efficiency of the biofilter regained its high values (above 96%) in less than 24 h following the change to low concentrations and gas flow rate. Temperature measurements showed that the biofilter temperature strongly depends on the intensity of the microbial activity in the filter bed. The experimental mass ratio of carbon dioxide produced to the xylene removed was equal to 2.72 indicating that the contaminant was eliminated exclusively by aerobic biodegradation. These findings suggest that a follow up of the amount of carbon dioxide produced in the filter bed can be very helpful in monitoring the performance of the biofilter. For relatively small inlet loads of xylene, the contributions of the different sections of the biofilter to the removal efficiency of the contaminant and the carbon dioxide production were unevenly balanced but became more uniformly distributed for relatively high inlet loads.     

Droplet dynamic response in low-viscosity fluid subjected to a pulsed electric field and an alternating electric field

Droplet dynamic response in low-viscosity fluid under a pulsed direct-current (DC) electric field and a sinusoidal electric field is investigated by experiments and numerical simulations. The coupled level set and volume of fluid method is employed to capture moving interface and the numerical method is validated by experimental results. This article focuses on the effects of waveform, frequency and initial phase on the dynamic response. The deformation period is identical with the electric period for the pulsed DC electric field but the deformation period is half of the electric period for the sinusoidal electric field. As the frequency increases, the maximum deformation degree D_max first climbs steadily to a peak value, then decreases steeply and finally approaches an equilibrium value. The maximum D_max appears at f = 50 Hz for the pulsed DC electric field and appears at f = 100 Hz for the sinusoidal electric field according to numerical results. These results are helpful for the optimization of electro-coalescence.     

On the relative importance of the kinetic and frictional contributions to granular motion in an annular Couette flow

A quantitative assessment is made on the relative importance of the kinetic and frictional contributions to the motion of dry granular materials under shear in an annular Couette flow configuration. The assessment is based on comparing the modelling results using the kinetic-frictional model with the experiments. It is shown that the kinetic-theory-based model with equal weight of the collisional and frictional contributions, commonly used in the literature, gives a great deviation from the experimental results in the point of view of the dominant solids motion, while an increase in the weight of the frictional contribution improves the modelling towards the experimental results. An increase in the weight of the frictional contribution by 25-50% leads to the best match, suggesting the current constitutive relationship with equal weight of the kinetic and frictional contributions need to be refined in order to reflect the real dense granular flows.