Anaerobic Cycling Research Articles

Effects of Ribose Supplementation on Repeated Sprint Performance in Men

This study used a randomized, placebo-controlled, crossover design to evaluate the effects of oral ribose supplementation on short-term anaerobic performance. After familiarization, subjects performed 2 bouts of repeated cycle sprint exercise (six 10-second sprints with 60-second rest periods between sprints) in a single day. After the second exercise, bout subjects ingested 32 g of ribose or cellulose (4 X 8-g doses) during the next 36 hours. After supplementation, subjects returned to the laboratory to perform a single bout of cycle sprinting (as described above). After a 5-day washout period, subjects repeated the protocol, receiving the opposite supplement treatment. Ribose supplementation lead to statistically significant increases in mean power and peak power in sprint 2 (10.9 and 6.6%, respectively) and higher (although not significant) absolute values in sprints 1, 3, and 4. In conclusion, ribose supplementation did not show reproducible increases in performance across all 6 sprints. Therefore, within the framework of this investigation, it appears that ribose supplementation does not have a consistent or substantial effect on anaerobic cycle sprinting.

Microbial cycling of iron and sulfur in acidic coal mining lake sediments

Lakes caused by coal mining processes are characterized by low pH, low nutrient status, and high concentrations of Fe(II) and sulfate due to the oxidation of pyrite in the surrounding mine tailings. Fe(III) produced during Fe(II) oxidation precipitates to the anoxic acidic sediment, where the microbial reduction of Fe(III) is the dominant electron-accepting process for the oxidation of organic matter, apparently mediated by acidophilic Acidiphilium species. Those bacteria can reduce a great variety of Fe(III)-(hydr)oxides and reduce Fe(III) and oxygen simultaneously which might be due to the small differences in the redox potentials under low pH conditions. Due to the absence of sulfide, Fe(II) formed in the upper 6 cm of the sediment diffuses to oxic zones in the water layer where itcan be reoxidized by Acidithiobacillus species. Thus, acidic conditions are stabilized by the cycling of iron which inhibits fermentative and sulfate-reducing activities. With increasing sediment depth, the amount of reactive iron decrease, the pH increases above 5, and fermentative and as yet unknown Fe(III)-reducing bacteria are also involved in the reduction of Fe(III). Sulfate is reduced apparently by the activity of spore-forming sulfate reducers including new species of Desulfosporosinus that have their pH optimum similar to in situconditions and are not capable of growth at pH 7. However, generation of alkalinity via sulfate reduction is reduced by the anaerobic reoxidation of sulfide back to sulfate. Thus, the microbial cycling of iron at the oxic-anoxic interface and the anaerobic cycling of sulfur maintains environmental conditions appropriate for acidophilic Fe(III)-reducing and acid-tolerant sulfate-reducing microbial communities.

Popular sports supplements and ergogenic aids.

This article reviews the evidence-based ergogenic potential and adverse effects of 14 of the most common products in use by recreational and elite athletes today. Both legal and prohibited products are discussed. This is an aggressively marketed and controversial area of sports medicine worldwide. It is therefore prudent for the clinician to be well versed in the more popular supplements and drugs reputed to be ergogenic in order to distinguish fact from fiction.Antioxidants, proteins and amino acids are essential components of diet, but additional oral supplementation does not increase endurance or strength. Caffeine is ergogenic in certain aerobic activities. Creatine is ergogenic in repetitive anaerobic cycling sprints but not running or swimming. Ephedrine and pseudoephedrine may be ergogenic but have detrimental cardiovascular effects. Erythropoietin is ergogenic but increases the risk of thromboembolic events. beta-Hydroxy-beta-methylbutyrate has ergogenic potential in untrained individuals, but studies are needed on trained individuals. Human growth hormone and insulin growth factor-I decrease body fat and may increase lean muscle mass when given subcutaneously. Pyruvate is not ergogenic. The androgenic precursors androstenedione and dehydroepiandrosterone have not been shown to increase any parameters of strength and have potentially significant adverse effects. Anabolic steroids increase protein synthesis and muscle mass but with many adverse effects, some irreversible. Supplement claims on labels of product content and efficacy can be inaccurate and misleading.

Unexpected occurrence of hopanoids at gas seeps in the Black Sea

High concentrations of free C 32 bis-homohopanoic acids (up to 433 μg/g dry wt) occur in microbial mats at methane seeps in anoxic Black Sea waters. These compounds show a strong preference for the ‘geological’ 17α(H),21β(H)- over the ‘biological’ 17β(H),21β(H)-configuration (αβ/ββ ratios up to 30.7) and indicate the potential formation of αβ-hopanoids in modern environments. Strong 13C-depletions (δ 13C as low as −78.4‰ PDB) indicate an in situ generation of these hopanoids by biota involved in the anaerobic cycling of methane carbon. The inferred presence of hopanoids indigenous to a permanently anoxic marine environment is significant because these lipids are not known to occur in strictly anaerobic bacteria.

EFFECTS OF NINE WEEKS OF LOWER BODY ANAEROBIC TRAINING ON PEAK POWER OF MALE ADULTS

The effects of training on performance have focused mainly on the aerobic rather than the anaerobic component. PURPOSE: To compare the effects of nine weeks of anaerobic cycle ergometer training on absolute (PP) and relative (PP/KG) peak power of young male adults. METHODS: Thirty-nine college students were randomly assigned to one of the three experimental (EG) and one non-exercising control group (CG - n = 10; age = 22.4 ± 3.4 year). The EGs trained 3 times per week for 9 weeks, at maximum, with a workload of 7.5% of their respective body weights. The total relative work was equated among groups: EG1 −3 sprints of 30 s with 3 min of active recovery between sprints (n = 10, age = 20.6 ± 2.5 years); EG2 −3 sprints of 30 s with 5 min of active recovery between sprints (n = 10, age = 22.1 ± 3.4 years); EG3 −9 sprints of 10 s with a 3 min active recovery between sprints (n = 9; age = 21.0 ± 3.5 years). RESULTS: A factorial ANOVA with repeated measures (4×2) followed by Tukey is test for unequal samples showed that all EGs increased significantly (p ≤0.05) in PP (EG1: 657.6 ± 119.4 and 826.5 ± 109.8; EG2: 675.8 ± 112.3 and 789.1 ± 112.7; EG3: 688.5 ± 94.0 and 797.5 ± 128.0) and PP/KG (EG1: 10.2 ± 1.3 and 12.8 ± 1.1; EG2: 10.4 ± 1.1 and 12.2 ± 1.0; EG3: 10.6 ± 0.9 and 12.0 ± 1.0) from the pre-training values. No significant differences were observed among the EGs at post-training. CONCLUSIONS: The present results suggest that anaerobic cycle training with workloads of 7.5% of body weight, for nine weeks, may elicit significant gains in PP and PP/KG. Nevertheless, when the total relative work time is maintained constant, training with diferent stimuli and intervals, may not elicit better improvements in anaerobic power.

Response to a letter to the editor from Dr. Baker regarding our article “Anaerobic cycling performance characteristics in prepubescent, adolescent and young adult females” [Doré et al., Eur J Appl Physiol (2001) 84:476-48l

Response to a letter to the editor from Dr. Baker regarding our article “Anaerobic cycling performance characteristics in prepubescent, adolescent and young adult females” [Doré et al., Eur J Appl Physiol (2001) 84:476-48l

Gene expression analysis of the response by Escherichia coli to seawater.

Gene expression of Escherichia coli cells exposed to seawater for 20 h was compared to that of exponentially growing cells (mops-glucose 0.2%) using DNA microarray technology. The expression of most (ca. 3,000) of the 4,228 open reading frames on the microarray remained unchanged; the relative expression of about 320 genes decreased in seawater, whereas that of ca. one fourth (937) increased. Clearly coherent expression patterns were observed for several functional gene groups. Induced genes were numerous in groups specifying the degradation of small molecules (carbon compounds, amino acids and fatty acids), energy metabolism (aerobic and anaerobic respiration, pyruvate dehydrogenase and TCA cycle), chemotaxis and mobility, flagella biosynthesis, surface structures and phage related functions. Repressed genes were clustered in two groups, cell division and nucleotides biosynthesis, indicating a cessation of growth.

Influence of Hip Orientation on Wingate Power Output and Cycling Technique

The effect of altered hip orientation angle ([HOA] angle of hip joint center to bottom bracket relative to horizontal) on Wingate anaerobic test results and cycling technique while maintaining a constant body configuration angle (included angle between torso, hip, and bottom bracket) and maximum hip-to-pedal distance was examined. Nineteen recreational cyclists, all men, with no recent recumbent cycling experience completed 30-second Wingate tests in 3 recumbent positions (HOA = -20 degrees, -10 degrees, and 0 degrees ) and the standard cycling position (SCP) (HOA = 75 degrees ). Peak, average, and minimum power output, as well as fatigue index, were not significantly different across all positions (p < 0.01). Average hip and knee extension angles increased slightly, and ankle angle did not change as HOA increased. These findings indicate that although HOA does have a small effect on cycling kinematics, these effects are not large enough to alter short-term power output. Therefore, anaerobic power output may be evaluated and compared in the recumbent positions and the SCP.

How anaerobic is the Wingate Anaerobic Test for humans?

The Wingate Anaerobic Test (WAnT) is generally used to evaluate anaerobic cycling performance, but knowledge of the metabolic profile of WAnT is limited. Therefore the energetics of WAnT was analysed with respect to working efficiency and performance. A group of 11 male subjects [mean (SD), age 21.6 (3.8) years, height 178.6 (6.6) cm, body mass 82.2 (12.1) kg] performed a maximal incremental exercise test and a WAnT. Lactic and alactic anaerobic energy outputs were calculated from net lactate production and the fast component of the kinetics of post-exercise oxygen uptake. Aerobic metabolism was determined from oxygen uptake during exercise. The WAnT mean power of 683 (96.0) W resulted from a total energy output above the value at rest of 128.1 (23.2) kJ x 30 s(-1) [mean metabolic power=4.3 (0.8) kW] corresponding to a working efficiency of 16.2 (1.6)%. The WAnT working efficiency was lower (P < 0.01) than the corresponding value of 24.1 (1.7)% at 362 (41) W at the end of an incremental exercise test. During WAnT the fractions of the energy from aerobic, anaerobic alactic and lactic acid metabolism were 18.6 (2.5)%, 31.1 (4.6)%, and 50.3 (5.1)%, respectively. Energy from metabolism of anaerobic lactic acid explained 83% and 81% of the variance of WAnT peak and mean power, respectively. The results indicate firstly that WAnT requires the use of more anaerobically derived energy than previously estimated, secondly that anaerobic metabolism is dominated by glycolysis, thirdly that WAnT mechanical efficiency is lower than that found in aerobic exercise tests, and fourthly that the latter finding partly explains discrepancies between previously published and the present data about the metabolic profile of WAnT.

Anaerobic Cycling Power Output with Variations in Recumbent Body Configuration

While the recumbent cycling position has become common for high-performance human-powered vehicles, questions still remain as to the influence of familiarity on recumbent cycling, the optimal riding position, and how recumbent cycling positions compare to the standard cycling position (SCP). Eight recumbent-familiar cyclists and 10 recreational control cyclists were compared using the 30-s Wingate test in 5 recumbent positions as well as the SCP. For the recumbent positions, hip position was maintained 15° below the bottom bracket while the backrest was altered to investigate body configuration angle (BCA: the angle between the bottom bracket, hip, and a marker at mid-torso) changes from 100° to 140° in 10° increments. Between-groups analysis found that only 4 of the 126 analyzed parameters differed significantly, with all trends in the same direction. Therefore both groups were combined for further analysis. Whole-group peak power (14.6 W/kg body mass) and average power (9.9 and 9.8 W/kg body mass, respectively) were greatest in the 130° and 140° BCA positions, with power dropping off as BCA decreased through 100° (peak = 12.4 W/kg body mass; avg. = 9.0 W/kg body mass). Power output in the SCP (peak = 14.6 W/kg body mass; avg. = 9.7 W/kg body mass) was similar to that produced in the 130° and 140° recumbent BCA. Average hip and ankle angles increased (became more extended/ plantar-flexed), 36° and 10°, respectively, with recumbent BCA, while knee angles remained constant. The lower extremity kinematics of the 130° and 140° BCA were most similar to those of the SCP. However, SCP hip and knee joints were slightly extended and the ankle joint was slightly plantar-flexed compared to these two recumbent positions, even though the BCA of the SCP was not significantly different. These findings suggest: (a) the amount of recumbent familiarity in this study did not produce changes in power output or kinematics; (b) BCA is a major determinant of power output; and (c) recumbent-position anaerobic power output matches that of the SCP when BCA is maintained, even though lower extremity kinematics may be altered.

A new straight-chain hydrocarbon biomarker associated with anaerobic methane cycling

13C-depleted E and Z n-tricos-10-enes are prominent biomarkers in an anaerobic microbial mat at Black Sea methane seeps. These n-alkenes co-occur with archaeal irregular C25 isoprenoid hydrocarbons, namely 2,6,10,15,19-pentamethylicosane (PMI) and -enes (PMIΔ). Low δ13C-values (−73 and −77‰) for n-tricosenes and PMI imply the anabolism of methane carbon by their source biota. The n-tricosenes apparently originate from microorganisms closely associated with, if not identical to isoprenoid-producing, methane-metabolizing Archaea. Methane-seep deposits of Tertiary to Jurassic ages showed the absence of n-tricosenes, but 13C-depleted n-tricosane (δ13C as low as −87‰), a plausible diagenetic product, was observed in enhanced concentrations in 7 out of 9 samples studied. It is proposed that a preference of n-tricosane over the enveloping n-alkanes may provide a specific hydrocarbon fingerprint for the anaerobic cycling of methane in ancient settings.

Oxygenation trends in vastus lateralis muscle during incremental and intense anaerobic cycle exercise in young men and women.

The purposes of this study were to compare the acute cardiorespiratory responses and muscle oxygenation trends during incremental cycle exercise to exhaustion with those observed during 30 s and 45 s Wingate tests in healthy men and women, and to examine the relationships between selected variables among these tests. Seventeen healthy junior badminton players, nine men [mean age, height, body mass and maximal oxygen uptake (VO2max) were 15.8 (SD 0.8) years, 1.73 (SD 0.08) m, 65.6 (SD 6.3) kg and 50.6 (SD 6.9) ml x kg(-1) x min(-1) respectively] and eight women [mean age, height, body mass and VO2max were 16.6 (SD 1.0) years, 1.65 (SD 0.03) m, 62.7 (SD 4.5) kg and 42.0 (SD 5.0) ml x kg(-1) x min(-1) respectively] completed a stepwise incremental exercise test to voluntary exhaustion and two Wingate tests lasting 30 s and 45 s in three separate sessions in random order. Cardiorespiratory responses were monitored breath-by-breath using a metabolic cart interfaced with an electrocardiogram. Tissue absorbancy trends were continuously recorded from the right vastus lateralis muscle using dual wavelength near infrared spectroscopy. Oxygen uptake and heart rate were significantly higher during the incremental test when compared to the two Wingate tests in the men and women. However, the oxygen pulse (oxygen utilization per heart beat, i.e., the product of stroke volume and arterio-venous oxygen difference) was not significantly different among the three tests in both sexes. The minimal tissue absorbancy, an index of muscle deoxygenation, was also not significantly different among the three tests in both sexes. Significant relationships were observed for the oxygen uptake (r2=0.72) and oxygen pulse (r2=0.60) between the incremental and 45 s Wingate tests in the sample for both sexes combined. The minimal tissue absorbancy, however, was not significantly related between the two tests. It was concluded that the significantly higher oxygen uptake during the incremental test was due to the higher heart rate because: firstly, oxygen pulse was not significantly different among the three tests, and secondly, peripheral factors, as indicated by the changes in muscle oxygenation, were not significantly different among the three test conditions. Although the peak values of the oxygen pulse during the incremental and 45 s Wingate tests were significantly correlated, the common variance of the minimal tissue absorbancy measurements between these two tests was quite low, suggesting considerable variation in the peripheral contribution during these two tests.

Anaerobic cycling performance characteristics in prepubescent, adolescent and young adult females.

The purpose of this study was to determine whether the relationships between short-term power and body dimensions in young females were similar whatever the age of the individuals. A cohort of 189 prepubescent (mean age 9.5 years), adolescent (mean age 14.4 years) and young adult (mean age 18.2 years) females performed three all-out sprints on a friction-loaded cycle ergometer against three braking forces corresponding to applied loads of 25, 50 and 75 g.kg-1 body mass (BM). For each sprint, peak power including flywheel inertia was calculated. Results showed that a braking load of 75 g.kg-1 BM was too high for prepubescent and adolescent girls. Therefore, when measuring short-term cycling performance in heterogeneous female populations, a braking load of 50 g.kg-1 BM (0.495 N.kg-1 BM) is recommended. During growth, cycling peak power (CPP; defined as the highest peak power obtained during the three sprints) increased, as did total BM, fat-free mass (FFM) and lean leg volume (LLV) (P < 0.001). Analysis of covariance revealed that the slopes of the linear relationships between CPP and biometric characteristics were similar in the three groups (P > 0.7 for the CPP/BM and CPP/FFM relationships, and P > 0.2 for the CPP/LLV relationship). However, the adjusted means were always significantly higher in young women (P < 0.001) compared with both of the other groups. Although differences in performance during anaerobic cycling in growing females are primarily dependent upon body dimensions, other as yet undetermined factors may be involved during late adolescence.

Correlates of simulated hill climb cycling performance

The aim of this study was to assess the relationship between several commonly used aerobic and anaerobic cycle ergometer tests and performance during a treadmill cycling hill climb. Eight competitive cyclists (age 27 +/- 7 years; body mass 73.2 +/- 5.2 kg; height 177 +/- 6 cm; mean +/- s) completed six tests in random order: a lactate minimum test; a Wingate anaerobic power test; and two 6-km climbs at 6% and two 1-km climbs at 12% gradient performed on a motorized treadmill. The mean times and power outputs for the 6-km and 1-km climbs were 16:30 +/- 1:08 min:s and 330 +/- 17.8 W, and 4:19 +/- 0:27 min:s and 411 +/- 24.4 W, respectively. The best individual predictor of 6-km and 1-km performance times was the time for the corresponding climb at the other distance (r = 0.97). The next strongest predictor of both hill climb performances was the average power produced during the Wingate test divided by body mass. Stepwise regression analysis showed that the two variables contributing most to the prediction equation for both climbs were the Wingate average power per unit of body mass and maximal aerobic power divided by total mass (rider + bike), which together accounted for 92 and 96% of the variability in the 6-km and 1-km climbs. In conclusion, among competitive cyclists, the Wingate average power per unit of body mass was the best single predictor of simulated cycling hill climb performance at the distance and gradient used.

THE EFFECTS OF CONCURRENT AEROBIC AND ANAEROBIC TRAINING VERSUS SEQUENCED TRAINING ON 80 S CYCLING

789 The purpose of this study was to investigate the influence of concurrent versus sequenced aerobic and anaerobic training on supramaximal performance. Twenty-four male and female well trained cyclists (VO2max = 4.2 ± 0.7 L.min−1; mean ± SD) participated in a 19-week training study. A 5 week baseline period was performed to ensure a stable level of fitness. Following the baseline phase, subjects were randomly assigned to one of two groups: either concurrent aerobic and anaerobic training for 12 weeks; or sequenced aerobic training for 6 weeks followed by anaerobic training for 6 weeks. Subjects trained five days per week for a total of 60 sessions of training. After the first 6-week block of training and at the end of the training period, subjects were assessed with physiological (VO2max, lactate equilibrium, maximal anaerobic cycling test [MACT]) tests and an 80 s power test. Although both groups improved significantly in the 80 s test, there was no significant difference between groups. However, the way in which each group progressed towards their final performance in the 80 s power test was different. The concurrent training group improved significantly from the pre test (451 ± 76 W) to the mid test (471 ± 81 W) and then again to the post test (489 ± 90 W). These improvements were associated with an increase in maximal power (Pmax) measured by the MACT (Pre 697 ± 145 W, Mid 770 ± 169 W, Post 795 ± 175) but no changes in aerobic function measured by either VO2max or power output at lactate equilibrium (Pre 205 ± 41 W, Mid 205 ± 45 W, Post 207 ± 40 W). The sequenced group did not improve significantly between pre (444 ± 75 W) and mid (454 ± 68 W) 80 s tests despite a significant improvement in lactate equilibrium (Pre 206 ± 34 W, Mid 213 ± 35 W) and Pmax (Pre 726 ± 119 W, Mid 742 ± 121 W), but showed a larger significant improvement in the post test (486 ± 66 W) associated with a significant increase in Pmax (Post 796 ± 132 W). In conclusion, the order in which the training sessions were performed in this study was not as important as the total training volume performed.

EFFECT OF ORAL CREATINE DURING ENERGY RESTRICTION IN ATHLETES

365 Anaerobic performance and body protein have been shown to decrease with energy restriction. The purpose of this study was to determine whether oral creatine supplementation during energy restriction would affect performance or body composition changes. Sixteen males resistance trainers were tested with anaerobic cycle test (10 sprints of 6 s with 30 s between) before and after 4 d of energy restriction (18 kcal/kg formula) with daily creatine or placebo supplement. Body composition change was assessed with hydrostatic weighing and nitrogen balance. A control group did performance test and hydrostatic testing only and showed no changes over time. Muscle biopsies taken before and after energy restriction showed a 6 and 8% reduction in total creatine and creatine phosphate in P and a 16 and 17% increase in these metabolites in Cr. Cr and P similarly decreased their body weight (−2.5 kg), fat (−7.5 %), nitrogen (−654.6 mg/kg N), but Cr had less reduction in fat-free mass than P (−1.4% vs −2.4%) during energy restriction. CrS tended to perform 3.8% more and P 0.5% less total work during the post performance test (p <0.1). In conclusion, energy restriction in athletes caused a significant reduction in muscle creatine that was reversed by oral creatine. This enhancement of muscle metabolites was not reflected in a benefit on body fat or nitrogen balance but tended to improve anaerobic performance and reduce FFM loss during weight loss. Supported by grants from National Strength and Conditioning Association and Gatorade Sports Science Institute

Physiological Determinants of 40-Meter Sprint Performance in Young Male Athletes

This study examined 20 male athletes on a number of physiological variables to determine which may account for the most variation in 40-m sprint performance. The athletes were tested on 40-m sprint, 10-m sprint, a 5-step jump, vertical jump, Wingate anaerobic cycle power, and isokinetic peak torque of the knee and hip at speeds of 1.05, 3.14, and 7.85 rad · sec−1 and ankle at speeds of 1.05, 3.14, and 5.24 rad · sec−1. With R = 0.897 (p ≤ 0.05) and SEE = 0.151 (sec), the 10-m sprint and ankle dorsiflexion peak torque at 5.24 rad · sec−1 were identified as predictors of 40-m sprint performance. With the 10-m sprint removed as an independent variable, stepwise multiple regression was performed again. With R = 0.909 and SEE = 0.146 sec, the 5-step jump, knee flexion peak torque at 7.85 rad · sec−1, and ankle plantar flexion peak torque at 1.05 rad · sec−1 were identified as predictors of 40-m sprint performance. The results indicate that both 10-m sprint and 5-step jump can be used to predict 40-m sprint performance.

COMPARISON OF AN UPRIGHT AND A RECUMBENT CYCLE ERGOMETER ON MAXIMAL ANAEROBIC POWER 1129

The Wingate anaerobic power test was developed to assess the power output of the muscles called upon during a short, maximal anaerobic cycling bout usually of 30s duration. This test has traditionally been administered using an upright mechanical cycle ergometer. There is no known evidence in the available literature that the Wingate test has been reliably administered using a recumbent cycle ergometer which is experiencing increasing popularity for both conditioning and rehabilitation, particularly in aging and disabled populations. This study was designed to compare test-retest measures of peak power output (PPO), mean power output (MPO) and fatigue ratio (FR) on electrically braked upright and recumbent cycle ergometers that are pre-programed for the 30s Wingate test protocol (Cybex). Eight college age males (N=5) and females (N=3) volunteered for the study. Each subject performed two trials on the upright cycle and two trials on the recumbent cycle with at least one day of rest between trials. Trials were randomized over a two week period. Resistance was set at 0.075Kg/Kg of body weight. No significant differences were found between any of the upright trials and the recumbent trials for all three variables measured (p>0.05). Significant correlations were found between the mean of the upright trials and the mean of the recumbent trials for PPO, r = 0.97; MPO, r=0.99; and FR, r = 0.84. The results of this study support the recumbent cycle ergometer as a reliable instrument for measuring PPO, MPO, and FR when compared to an upright cycle ergometer using the Wingate test.

Efficient production of vitamin B 12 from propionic acid bacteria under periodic variation of dissolved oxygen concentration

Performance of Propionibacterium freudenreichii in anaerobic, aerobic and periodic fermentations were studied. It was found that oxygen is a key parameter to the metabolic regulation. Cells could grow faster during a short period (6 h) after a DO-shift. However, long time aerobic fermentation (over 6 h) is disadvantageous in cell growth due to the inhibition of oxygen on the synthesis of cytochromes. The propionate was decomposed immediately and pyruvate was accumulated after DO-shift. Low DO concentration was found to be advantageous in cell growth, in decomposition of propionate, and in lowering the production of acetate. A novel cyclic operation where anaerobic and aerobic conditions were alternately implemented was developed to take full advantages of anaerobic and aerobic fermentations in order to enhance the production of vitamin B 12. Propionate was significantly produced and no pyruvate was accumulated in the anaerobic cycle, whilst propionate was decomposed and pyruvate was accumulated in the aerobic cycle. Vitamin B 12 was synthesized in the anaerobic cycle and ceased to be produced in the aerobic cycle. With this operation mode, a low concentration of propionate could be maintained and high cell concentration could be attained. The volumetric production of vitamin B 12 using this method could be increased by about 2-fold as compared with that attained in the anaerobic fermentation.

The Effect of Hip Position/Configuration on Anaerobic Power and Capacity in Cycling

The purpose of this investigation was to determine the effect of systematic changes in hip position/configuration on cycling peak anaerobic power (AP) and anaerobic capacity (AC). Fourteen male recreational cyclists (ages 21-32 yrs) were tested in four hip positions (25, 50, 75, and 100°), as defined by the angle formed by the seat tube and a vertical line. Rotating the seat to maintain a backrest perpendicular to the ground induced a systematic decrease in hip angle from the 25 to the 100° position. The Wingate anaerobic cycling test was used on a Monark cycle ergometer with a resistance of 85 gm/kg of the subject’s body mass. Repeated-measures MANOVAs and post hoc tests revealed that AP and AC in the 75° hip position were significantly greater than in the 25 or 100° position and that a second-order function best describes the trend in AP and AC with changes in hip position.