Gender differences in anaerobic power tests

The purpose of this study was to determine if the differences in anaerobic power between males and females could be accounted for by differences in body composition, strength, and neuromuscular function. A total of 82 untrained men and 99 women took part in the study. Body composition, somatotype, isometric strength, neuromuscular function were measured, and four anaerobic power tests performed. The men were significantly different from the women on all strength, power, and neuromuscular measurements except reaction time and on all anthropometric and somatotype dimensions except ectomorphy. Strength and anthropometric dimensions were similarly related to anaerobic power values within each sex. Relative fat (%fat) exerted different degrees of influence on sprint and jump performances in each sex. Removing the influence of anthropometric, strength, and neuromuscular differences by analysis of covariance reduced, but did not remove, the significant differences between the sexes. Therefore, factors other than lean body mass, leg strength, and neuromuscular function may be operating in short-term, explosive power performances to account for the differences between the sexes. The task-specific nature of anaerobic power tests and the relatively large influence of anthropometric factors on power production were confirmed.     

Peak anaerobic power in master athletes

The age-related decline in maximal physical performance of healthy subjects may be attributed both to the aging process per se and/or to a progressive reduction in physical activity. In two groups of master athletes, power (P) or endurance (E) trained (n = 115; aged 40-78 years), the degree and rate of the age-related deterioration of the maximal instantaneous muscle power (peak power, Wpeak), and the relative contribution of quantitative (muscle mass) and qualitative factors possibly underlying such deterioration were determined. Two groups of young athletes (n = 20; 17-26 years) and healthy untrained subjects (U, n = 37; 22-67 years) were also tested for comparison. The following two variables were assessed, firstly the lower limb muscle plus bone volume (LMV) by anthropometry, and secondly Wpeak, by means of a standardized vertical jump off both feet, performed on a force platform. The results obtained were that LMV of E and P, as well as of U, was about the same between age 20 and 45 years, whereas at older ages a progressive reduction was observed; the LMV values were higher in P than in E and U.(ABSTRACT TRUNCATED AT 250 WORDS)     

The kinetics of anaerobic metabolism following the initiation of high-intensity exercise.

A mathematical study is made of the kinetics of anaerobic metabolism following the initiation of high-intensity exercise. Power and energy relationships are proposed for oxygen-independent glycolysis, phosphocreatine utilisation and the utilisation of endogenous ATP. The power relations consist of two components, one describing the build-up phase, the other the controlled-utilisation phase. The controlled-utilisation phase of oxygen-independent glycolysis and the build-up of aerobic metabolism are shown to be closely inter-related. The theoretical relations display trends consistent with published experimental results. Some property values are derived, but because of the scatter of the experimental results, the values are, in general, to be regarded as tentative.     

Influence of anaerobic culture acclimation on the degradation kinetics of various substrates

The adaptation of an anaerobic culture (anaerobic sludge) to a specific substrate brings significant changes to its microbial population. These changes can be described by the sludge's ability to treat various substrates such as carbohydrates or proteins or "intermediate" products of anaerobic metabolism such as L-lactic, propionic, and acetic acids. The activity of the sludge with respect to a specific substrate is a critical parameter, because the anaerobic degradability of wastewaters depends strongly on it. This work examines and quantifies the differentiation of two anaerobic sludges of the same origin, following an adaptation period of about 18 months to lactose and gelatin, respectively. The acclimation has a significant effect on the maximum specific utilization rates of various compounds and on their apparent consumption kinetics. It is noticeable, however, that even if the anaerobic cultures were not exposed to a specific substrate for a prolonged period of time (more than a year), they still kept the ability of hydrolyzing or degrading it. In addition, the acclimation has an unquestionable effect on the stoichiometry of the production of volatile fatty acids and L-lactate. Finally, from codigestion experiments it is shown that codigestion of lactose and gelatin appears to have no effect on their hydrolysis kinetics in any of the lactose or gelatin acclimated cultures; specifically, the hydrolysis kinetics remained the same as calculated when lactose or gelatin were the only fed substrates. Similarly, the kinetics of L-lactate and D-glucose biodegradation seemed to be unchanged. On the other hand, codigestion has a significant effect on the production of L-lactic, propionic, and acetic acids, which can be attributed to the increased hydrogen production accompanying gelatin biodegradation.     

Evaluation of a new anaerobic power testing system

The purpose of this study was to evaluate the reliability of a new anaerobic athletic performance system. This system is proposed to assess vertical jump height, anaerobic power through repetitive jumping, and reaction to both an auditory and visual stimulus. One hundred twenty-three subjects (92 men and 31 women; mean +/- SD: age, 20.5 +/- 2.1 years; body weight, 83.1 +/- 20.4 kg; height, 176.0 +/- 9.2 cm) volunteered to participate. To assess reliability of the new testing device, subjects were tested on 3 separate occasions (T1, T2, and T3). At least 72 hours but not more than 1 week separated each laboratory visit. During each testing session subjects performed a countermovement jump (CMJ), a 30 consecutive jumps anaerobic power test (30JT), and reaction to both an auditory and visual stimulus. Results showed no differences between T1, T2, and T3 in either CMJ height or 30JT assessments. However, reaction to an audible or visual stimulus significantly improved during each testing session. Intraclass reliability of the CMJ and the 30JT was greater than 0.96 across the 3 trials. Pearson correlation coefficients of r > 0.90 were seen for the CMJ and 30JT, indicating a high test-retest reliability. The test-retest reliability for the reaction tests were lower (r ranging from 0.72 to 0.83). A Bland-Altman plot showed limited agreement between methods of vertical jump height assessment. Results indicate that this new testing device shows high reliability to assess both CMJ height and anaerobic power. In addition, anaerobic power assessment in a jump test provides a specific measure of anaerobic power for many sports incorporating similar performance patterns.     

Modeling biofilm kinetics for a low-loaded expanded-bed anaerobic reactor

The effect of surface coverage of biomass on biofilm kinetics in an expanded-bed, granular activated carbon an aerobic reactor was evaluated. Acetate was used as the sole organic carbon source. An assumption of 10% surface coverage of biofilm was examined and compared to 100% coverage. Best estimated values of k(a) and K(sa) did not differ significantly from one case to the other. The confidence region analysis also showed that the biofilm was fully penetrated in the expanded-bed reactor for the case of 10% coverage, as well as when 100% coverage was assumed. Because the biofilm was fully penetrated, a model having no internal diffusion resistance and using the best estimates of k(a) and K(sa) obtained from the 10 and 100% coverage assumptions was capable of giving good predictions of effluent acetate concentrations for an in dependent experiment having a reduced liquid detention time. Consideration of biofilm surface-loading criteria demonstrated how the results can be applied to other reactors for the purpose of predicting when the extent of surface coverage and internal diffusion resistance are not significant factors in biofilm modeling.     

Metabolism and kinetics of pentachlorophenol transformation in anaerobic granular sludge

Summary Granular sludge from an upflow anaerobic sludge blanket (UASB) reactor operated for 18 months on a mineral medium containing pentachlorophenol (PCP), phenol, and glucose was studied. Under methanogenic conditions PCP was dechlorinated to lower chlorinated phenols, primarily di-, and monochlorophenols. The initial dechlorination of PCP and the removal of the intermediate 3,5-dichlorophenol (3,5-DCP), seemed to be rate-limiting. Addition of sulphate was slightly inhibitory for PCP transformation in the presence of glucose but had little or no effect on dechlorination in vials without glucose Nitrate was strongly inhibitory. The consortium had a high affinity for PCP, with an apparent half-saturation constant (K _s) value of 580 g/1. Addition of various easily degradable carbon compounds including acetate, butyrate, formate, hydrogen/carbon dioxide, ethanol, and glucose together with extra PCP, to cultures already dechlorinating PCP showed that only glucose had a stimulatory effect on the dechlorination rate. Counts of bacteria from a sample f disintegrated granular sludge showed that the number of dechlorinating organisms was low compared to the numbers of glucose degraders and methanogens. Correspondence to: B. K. Ahring     

Dynamic determination of anaerobic acetate kinetics using membrane mass spectrometry

A small, stirred, 14.4-mL tank reactor was designed to serve as a measurement cell for short-term investigation of microbial kinetics. A mass spectrometer membrane probe allowed the measurement of the dissolved gases of hydrogen, methane, oxygen, and carbon dioxide. pH was measured by an electrode and controlled by addition of acid or alkali. The highly sensitive measurement of gases with low solubility allowed rapid measurements at very low conversion. In kinetic experiments, a stepwise increase of substrate concentration (method A) and continuous feed of substrate (method B) were used, allowing quick estimation of substrate kinetics. Acetate conversion in mixed culture biofilms from a fluidized bed reactor was investigated. Substrate inhibition was found to be negligible in the concentration range studied. Experiments at various pH values showed that the undissociated acid form was the kinetic determinant. Kinetic parameters for Haldane kinetics of protons were KSH = 1.3 x 10(-5) mol m-3 and KIH = 8.1 x 10(-3) mol m-3. With free acid (HAc) as the rate determining species, the kinetic parameters for method A were KSHAc = 0.005 mol m-3 and KIHAc = 100 mol m-3 and for method B were KSHAc = 0.2 mol m-3 and KIHAc = 50 mol m-3. The maximum biomass activity occurred at around pH 6.5. Acetate was exclusively converted to methane and CO2 at pH > 6. Copyright 1998 John Wiley & Sons, Inc.     

Adsorption and decolorization kinetics of methyl orange by anaerobic sludge

Adsorption and decolorization kinetics of methyl orange (MO) by anaerobic sludge in anaerobic sequencing batch reactors were investigated. The anaerobic sludge was found to have a saturated adsorption capacity of 36 ± 1 mg g MLSS⁻¹ to MO. UV/visible spectrophotometer and high-performance liquid chromatography analytical results indicated that the MO adsorption and decolorization occurred simultaneously in this system. This process at various substrate concentrations could be well simulated using a modified two-stage model with apparent pseudo first-order kinetics. Furthermore, a noncompetitive inhibition kinetic model was also developed to describe the MO decolorization process at high NaCl concentrations, and an inhibition constant of 3.67 g NaCl l⁻¹ was estimated. This study offers an insight into the adsorption and decolorization processes of azo dyes by anaerobic sludge and provides a better understanding of the anaerobic dye decolorization mechanisms.     

Improvement of the kinetics of anaerobic digestion of molasses by the removal of phenolic compounds

Summary Removal of most of the phenolic compounds (88.5%) present in molasses by an aerobic pretreatment with Geotrichum candidum considerably increased the kinetics of anaerobic digestion of this wastewater. Inhibition phenomena were not observed in the range of COD studied (2.3–12.9 g/l). The yield coefficient of methane was 51 % higher than for untreated molasses.     

Investigation of the kinetics of anaerobic metabolism by analysis of the performance of elite sprinters

The principal motivation for the present work was the study of the kinetics of anaerobic metabolism. A new mathematical model of the bioenergetics of sprinting, incorporating a three-equation representation of anaerobic metabolism, is developed. Results computed using the model are compared with measured data from the mens' finals of the 100m event at the 1987 World Championships. The computed results closely predict the overall average performance of the competitors over the course of the entire race. Further calculations show the three-equation model of anaerobic metabolism to be a significant improvement over the previous one-equation model. Representative values of time constants that govern the rate of anaerobic energy release have been determined for elite male athletes. For phosphocreatine utilisation, values for lambda(2)=0. 20s(-1) and psi(2)=3.0s(-1) are consistent with data previously reported in the literature. New values of lambda(3)=0.033s(-1) and psi(3)=0.34s(-1) are proposed as offering an improved representation of the kinetics of oxygen-independent glycolysis. For the first time, tentative values for the time constants of ATP utilisation, lambda(1)=0.9s(-1) and psi(1)=20s(-1), are suggested. The maximum powers developed during sprinting by oxygen-independent glycolysis, PCr utilisation and endogenous ATP utilisation were calculated as 34. 1, 30.1 and 16.6Wkg(-1), respectively, with an overall maximum anaerobic power of 51.6Wkg(-1). Sample calculations show the mathematical model can be used in principle to derive data on the kinetics of anaerobic metabolism of individual athletes.     

A simple assembly for anaerobic spectrophotometric reaction kinetics studies.

Details are given for the construction and use of a simple spectrophotometer cuvetteclosure that makes possible the study of reaction rates and enzyme assays under anaerobic conditions. The preparation of solutions and assembly of the cuvette unit is carried out in a N2 atmosphere in a glove box, but the spectrophotometric studies are conducted in a spectrophotometer with no modification except for the cell compartment cover.     

Sedimentation and breakdown kinetics of organic matter in the anaerobic zone of Lake Vechten

The turnover and exchange rates, as well as the sedimentation rates concerning the input and output of carbon in the anaerobic hypolimnion and the sediment in Lake Vechten were studied. The carbon input data were derived from those on sedimentation. By comparison of C-fixation data, sedimentation rates measurements and microbial reduction rates of observed fluxes of electron acceptors a mineralization of 20–30% of the limnetic C-fixation was found in the hypolimnion. The rate-limiting step of methanogenesis in anaerobic mineralization is the breakdown of algal cell wall components to their main product, namely acetate. This intermediate has a relatively fast turnover rate to the end-products, namely the gases CH₄ and CO₂. Finally, from the data on the diffusion of low-molecular weight metabolic intermediates and on the rates of formation of CH₄ and CO₂ the output of carbon and its cycling in Lake Vechten are discussed.     

On the kinetics of enzyme reactions

The Abel type differential equation governing the kinetics of the enzyme reactions is derived. Approximate solutions of this equation corresponding to the transient phase of the reaction, before a steady state is reached, are considered. It is shown that in several cases it is possible to obtain explicit, approximate solutions to the transient phase.     

Electrically conductive magnetite particles enhance the kinetics and steer the composition of anaerobic TCE-dechlorinating cultures

The interaction of anaerobic dechlorinating cultures with soil and aquifer geochemical components is largely unknown, although this has potentially a major impact on the bioremediation of chlorinated solvent-contaminated sites. In this study, we found that addition of magnetite (Fe₃O₄) – the end-product of Fe(III)-reduction by dissimilatory iron reducing bacteria – to anaerobic dechlorinating cultures enhances the kinetics of trichloroethene dechlorination up to 1.5-times, compared to unamended controls. Specifically, a low concentration (approx. 10 mg/L as total Fe) of small size particles (200 nm-filtered) resulted in a greater stimulatory effect compared to the addition of a higher concentration (approx. 300 mg/L as total Fe) of unfiltered particles. Notably, Desulforomonas spp. were substantially enriched in microcosms supplemented with magnetite, whereas Dehalococcoides mccartyi spp. was found to be markedly inhibited or outcompeted. Multiple lines of evidence, including the direct visualization of microbial cells and magnetite particles via Confocal Laser Scanning Microscopy (CLSM), suggest that electrically conductive particles promoted the establishment of a cooperative metabolism, based on direct interspecies electron transfer, between dechlorinating and non-dechlorinating microorganisms.