Aerobic Energy Production Research Articles

Multidimensional analysis of metabolism contributions involved in running track tests

It is difficult to interpret the training induced changes in middle-distance running, since numerous aerobic and anaerobic determinants of the performance are interdependent. Several aerobic and anaerobic tests are available but their results, particularly those from anaerobic tests, may be discordant, not providing univocal interpretation of training. The purpose of this study is to use a multidimensional approach to distinguish aerobic and anaerobic capacities assessed by two running tests on a track: the maximal anaerobic running test (MART) and V(O2max) tests. Eleven runners carried out two maximal tests on a synthetic track before and after a 4-week training period: (i) a maximal test to determine V(O2max), the velocity associated with V(O2max) (vV(O2max)) and the velocity at the lactate threshold (v(LT)), (ii) a maximal anaerobic running test to estimate anaerobic capacity. An all-out test run at v(LT)+50% of the difference between v(LT) and vV(O2max), known to be affected by both aerobic and anaerobic energy production, was used to test this approach. A principal components analysis (PCA) shows that two components (i.e., aerobic and anaerobic) explained 79% of the variation in the physiological variables. The PCA suggests that V(O2max) and MART tests assess the aerobic and the anaerobic capacities, respectively. In contrast, the performance in the all-out test is affected by both aerobic and anaerobic energy production. The PCA shows that v(LT) and DeltaP (difference between the maximal power of the MART and V(O2max)) are clear markers of the long-term endurance and the anaerobic capacity, respectively. This multidimensional approach can be a useful way to disentangle the aerobic and anaerobic components of track tests.

Plasma Membrane Electron Transport: A New Target for Cancer Drug Development

The view that mitochondrial electron transport is the only site of aerobic respiration and the primary bioenergetic pathway in mammalian cells is well established in the literature. Although this paradigm is widely accepted for most tissues, the situation is less clear for proliferating cells. Increasing evidence indicates that glycolytic ATP production contributes substantially to fulfilling the energy requirements of rapidly dividing somatic cells, many tumour cells, and self-renewing stem cells in hypoxic environments. Glycolytic cells have been shown to consume oxygen at the cell surface via plasma membrane electron transport (PMET), a process that oxidises intracellular NADH, supports glycolytic ATP production and may contribute to aerobic energy production. PMET, as determined by reduction of a cell-impermeable tetrazolium dye, is highly active in rapidly-dividing tumour cell lines, where it ameliorates intracellular reductive stress, originating from the mitochondrial TCA cycle. Thus, mitochondrial NADH production is linked to dye reduction outside the cell via the malate-aspartate shuttle. PMET activity increases several-fold under hypoxic conditions, consistent with the view that oxygen competes for electrons from this PMET system. In addition, rho(o) cells that lack mitochondrial electron transport are characterised by elevated PMET presumably to recycle NADH, a role traditionally assumed by lactate dehydrogenase. PMET presents an excellent target for developing novel anticancer drugs that exploit its unique plasma membrane localisation. We propose that PMET is a ubiquitous, high-capacity acute NADH redox-regulatory system responsible for maintaining the mitochondrial NADH/NAD+ ratio. Blocking this pathway compromises the viability of rapidly proliferating cells that rely on PMET.

Rapid evolution of cytochrome c oxidase subunit II in camelids (Tylopoda, Camelidae)

Within cetartiodactyl species, both New and Old World camelids are uniquely adapted to the extremely hot and dry climates of African-Asian territories and to the high altitude cold and hypoxic environment of the whole Andean area. In order to investigate the potential association between these particular adaptations and mitochondrial aerobic energy production, we examined the camelid genes of cytochrome c oxidase subunits I, II, and III and the replacement of amino acids inferred. We found that all subunits had undergone a number of replacements in sites otherwise conserved in other cetartiodactyls. Changes of COXI and COXIII were mainly located in the transmembrane helices of proteins. For COXII, although most of the changes did not occur in sites directly involved in electron transfer, a shift of D by T at 115 position of Old World camelid might modify electrostatic interactions with cytochrome c. COXII also showed an increased relative evolutionary rate respect to other cetartiodactyls compared.

Modelling of aerobic and anaerobic energy production in middle-distance running

A mathematical model of performance describing aerobic and anaerobic energy production during exercise was applied to middle-distance running data from world records (WR) and from a group of elite runners (NL). The model is based on the assumption that, above a critical power (Pc), a continuous rate of anaerobic energy production occurs, until the entire anaerobic stores (W') are depleted. The fraction of metabolic power above Pc provided by anaerobic metabolism is denoted alpha. A second power threshold (Pt) sets the limit above which any further increase in power is met exclusively by anaerobic sources. The oxygen uptake kinetics was described by a monoexponential equation with time constant tau. The results show that the model successfully fits the WR over 1,500-5,000 m. However, in the range of distances from 800 to 5,000 m the performance over 800 and 1,000 m were overestimated. Contrary to Pc and the anaerobic contribution at steady state oxygen uptake, the estimate of W' was sensitive to the value assigned to tau in the range from 0 to 30 s. Using best performances from 1,500 to 5,000 m in NL resulted in Pc estimates not significantly different from the metabolic power at the lactate threshold. The anaerobic contribution at steady state oxygen uptake increased from zero at Pc to 8.3% (WR) and 7.8+/-3.1% (NL) at Pt. This suggests that a substantial contribution of anaerobic processes occurs in the range between Pc and Pt, even though the exercise does not elicit maximal aerobic power.

P53 aerobics: The major tumor suppressor fuels your workout

In addition to its role as the central regulator of the cellular stress response, p53 can regulate aerobic respiration via the novel transcriptional target SCO2, a critical regulator of the cytochrome c oxidase complex (Matoba et al., 2006). Loss of p53 results in decreased oxygen consumption and aerobic respiration and promotes a switch to glycolysis, thereby reducing endurance during physical exercise.

Temperature-dependent stress response in oysters, Crassostrea virginica: Pollution reduces temperature tolerance in oysters

Combined effects of temperature and a toxic metal, cadmium (Cd), on energy metabolism were studied in a model marine bivalve, the eastern oyster Crassostrea virginica, acclimated at 20, 24 and 28 °C and exposed to 50 μg l −1 of Cd. Both increasing temperature and Cd exposure led to a rise in standard metabolic rates, and combined stressors appeared to override the capability for aerobic energy production resulting in impaired stress tolerance. Oysters exposed to elevated temperature but not Cd showed no significant change in condition, survival rate and lipid peroxidation, whereas those exposed to both Cd and temperature stress suffered high mortality accompanied by low condition index and elevated lipid peroxidation. Furthermore, RNA/DNA ratios indicative of protein synthesis rate, and levels of glutathione, which is involved in metal detoxification, increased in Cd-exposed oysters at 20 °C but not at 28 °C. Implications of the synergism between elevated temperatures and cadmium stress on energy metabolism of oysters are discussed in the light of the potential effects of climate change on oyster populations in polluted areas.

Modelling of aerobic and anaerobic energy production during exhaustive exercise on a cycle ergometer

An extension of the original hyperbolic model (Model-2) was proposed by using power output required to elicit maximal oxygen uptake (Pt). This study aimed to test this new model (Model-alpha) using mechanical work produced during cycle ergometry. Model alpha assumed that power exceeding a critical power (Pc) was met partly by the anaerobic metabolism. The parameter alpha was the proportion of the power exceeding Pc provided by anaerobic metabolism, while power exceeding Pt was exclusively met by anaerobic metabolism. Aerobic power was assumed to rise monoexponentially with a time constant tau. The exhaustion was assumed to be reached when the anaerobic work capacity W' was entirely utilised. Twelve subjects performed one progressive ramp test to assess the power at ventilatory threshold (P(VT)) and Pt and five constant-load exercise to exhaustion within 2-30 min, with one to estimate the maximal accumulated oxygen deficit (MAOD). Parameters from Model alpha were fitted with tau equal to 0, 10, 20 and 30 s. Results in goodness-of-fit was better than Model-2 whatever the value assumed for tau (P < 0.05). The value of tau did not affect much the estimates for P (c) and alpha. P (c) estimates were significantly correlated with Pc from Model-2 and with P(VT). W' estimates, which were dependent on the value ascribed to tau, were not statistically different than MAOD. These two variables were, however, not significantly correlated. In conclusion, Model alpha could provide useful information on the critical power and the anaerobic contribution according to exercise intensity, whereas W' estimates should be used with care because of the sensitivity to the assumption on aerobic power kinetics tau.

Assembly of mitochondrial cytochrome c-oxidase, a complicated and highly regulated cellular process

Cytochrome c-oxidase (COX), the terminal enzyme of the mitochondrial respiratory chain, plays a key role in the regulation of aerobic production of energy. Biogenesis of eukaryotic COX involves the coordinated action of two genomes. Three mitochondrial DNA-encoded subunits form the catalytic core of the enzyme, which contains metal prosthetic groups. Another 10 subunits encoded in the nuclear DNA act as a protective shield surrounding the core. COX biogenesis requires the assistance of >20 additional nuclear-encoded factors acting at all levels of the process. Expression of the mitochondrial-encoded subunits, expression and import of the nuclear-encoded subunits, insertion of the structural subunits into the mitochondrial inner membrane, addition of prosthetic groups, assembly of the holoenzyme, further maturation to form a dimer, and additional assembly into supercomplexes are all tightly regulated processes in a nuclear-mitochondrial-coordinated fashion. Such regulation ensures the building of a highly efficient machine able to catalyze the safe transfer of electrons from cytochrome c to molecular oxygen and ultimately facilitate the aerobic production of ATP. In this review, we will focus on describing and analyzing the present knowledge about the different regulatory checkpoints in COX assembly and the dynamic relationships between the different factors involved in the process. We have used information mostly obtained from the suitable yeast model, but also from bacterial and animal systems, by means of large-scale genetic, molecular biology, and physiological approaches and by integrating information concerning individual elements into a cellular system network.

Energetics of osmoregulation: I. oxygen consumption by Fundulus heteroclitus

We have developed a flow-through method for measuring oxygen consumption in fish which allows continuous monitoring over periods of days with good accuracy. Our goal was to determine the changes in basal metabolic rate in estuarine fish as a function of salinity. We show that in Fundulus heteroclitus, the oxygen consumption drops by 50% during the first 12 hr in the respirometer, as the fish cease exploratory movements. We have determined the influence of temperature and body size on resting respiratory rate, but failed to find any circadian or tidal rhythm in aerobic respiration. With these variables controlled, we determined that changing from 10 to 30 ppt water had no demonstrable effect on oxygen uptake. Since there must be a large change in osmotic flux due to this change in salinity, it appears that the fish might be diverting energy from other uses rather than increasing aerobic energy production to meet the increased osmoregulatory work load.

Relationship Between Physiological Profiles and On-Ice Performance of a National Collegiate Athletic Association Division I Hockey Team

Ice hockey is a game that relies heavily on both aerobic and anaerobic energy production systems as players perform in various game situations. However, we found no studies evaluating the relationship between a player's physical condition and individual success in games throughout a competitive hockey season. The purpose of this study was to determine the relationship between a player's aerobic fitness (VO(2)max), blood lactate, and percent body fat to his total minutes played during a season (Tmin) and net scoring chances (SCn). Players' (N = 29) preseason VO(2)max, lactate at the fourth stage of an incremental treadmill test (Lac 4), and percent body fat values from the 1999- 2001 National Collegiate Athletic Association Division I hockey seasons were archived and retrieved for this study. The players' Tmin and SCn were used as the on-ice performance variables and were compared with their fitness measures. Lactate at 4th treadmill stage (r = 0.41, p < 0.03) and percent body fat (r = 0.39, p < 0.03) but not VO(2)max (r = 0.20, p < 0.24) were significantly related to Tmin. Both Lac 4 and percent body fat were entered into a stepwise regression model that accounted for 25% of the variance in Tmin among players (p < 0.02). Both VO(2)max (r = 0.41, p < 0.03) and Lac 4 (r = 0.33, p < 0.05) were significantly related to the players' SCn, but percent body fat was not (r = 0.10, p < 0.57). Only VO(2)max significantly predicted the players' SCn, accounting for 17% of the variance. These findings suggest a relationship between a player's conditioning level and on-ice performance. Our results support the value of implementing seasonal physiological testing, which will help strength and conditioning coaches make individualized modifications to a player's fitness regimens in an effort to improve specific physiological attributes.

DISRUPTION OF MITOCHONDRIAL FUNCTION IN INTERPOPULATION HYBRIDS OF TIGRIOPUS CALIFORNICUS

Electron transport system (ETS) function in mitochondria is essential for the aerobic production of energy. Because ETS function requires extensive interactions between mitochondrial and nuclear gene products, coadaptation between mitochondrial and nuclear genomes may evolve within populations. Hybridization between allopatric populations may then expose functional incompatibilities between genomes that have not coevolved. The intertidal copepod Tigriopus californicus has high levels of nucleotide divergence among populations at mitochondrial loci and suffers F2 hybrid breakdown in interpopulation hybrids. We hypothesize that hybridization results in incompatibilities among subunits in ETS enzyme complexes and that these incompatibilities result in diminished mitochondrial function and fitness. To test this hypothesis, we measured fitness, mitochondrial function, and ETS enzyme activity in inbred recombinant hybrid lines of Tigriopus californicus. We found that (1) both fitness and mitochondrial function are reduced in hybrid lines, (2) only those ETS enzymes with both nuclear and mitochondrial subunits show a loss of activity in hybrid lines, and (3) positive relationships exist between ETS enzyme activity and mitochondrial function and between mitochondrial function and fitness. We also present evidence that hybrid lines harboring mitochondrial DNA (mtDNA) and mitochondrial RNA polymerase (mtRPOL) from the same parental source population have higher fitness than those with mtDNA and mtRPOL from different populations, suggesting that mitochondrial gene regulation may play a role in disruption of mitochondrial performance and fitness of hybrids. These results suggest that disruption of coadaptation between nuclear and mitochondrial genes contributes to the phenomenon of hybrid breakdown.

Transcriptomic profiling of the canine tachycardia-induced heart failure model: global comparison to human and murine heart failure

Alterations of cardiac gene expression are central to ventricular dysfunction in human heart failure (HF). The canine tachycardia pacing-induced HF model is known to reproduce the main hemodynamic, echocardiographic and electrophysiological changes observed in human HF. In this study, we use this HF model to compare gene expression profiles in the left and right ventricles (LV, RV) of normal and end-stage failing canine hearts and compare the transcription profiles to those in human and murine models of HF. In end-stage HF, the LV exhibits down regulation of genes involved in energy production, cardiac contraction, and modulation of excitation–contraction coupling as compared with normal LV. The majority of transcriptomic changes between normal and end-stage canine HF were shared by the RV and LV. Genes down regulated only in the LV included those involved in aerobic energy production pathways, regulation of actin filament length, and enzyme-linked receptor protein signaling pathways. In normal canine hearts, genes encoding specific components of the contractile apparatus exhibit LV–RV asymmetric expression patterns; in failing hearts, cardiac fetal transcription factors MEF2 and MITF and the stress-responsive transcription factor ATF4 showed interventricular differences in expression. The comparison among the canine tachypacing, mouse transgenic, and human HF reveals that human disease involves down regulation of genes in a broad range of biological processes while experimentally induced HF is associated with down regulation of energy pathways, and that human ischemic HF and canine HF share a similar over representation of transcriptional pathways in the up regulated genes. This study provides insights into the molecular pathways leading to end-stage tachycardia-induced HF, and into global transcriptomic differences between the animal HF models and human HF.

Relationship Between Physiological Profiles And On Ice Performance Of A Division I NCAA Hockey Team

Ice hockey relies heavily on both aerobic and anaerobic energy production systems. However, there is little research determining the relationship between a player's physical condition and individual success in games. PURPOSE The purpose of this study was to determine the relationship between a player's aerobic fitness (VO2max,) blood lactate, and % body fat and total minutes played and net scoring chances. METHODS Players' (n=29) preseason VO2max, lactate at the 4th stage of an incremental treadmill test, and % fat values from the 1999–2001 seasons of a Division I NCAA hockey team, were archived and retrieved for this study. Total minutes played and net scoring chances were used as the on ice performance variables and compared to the fitness measures. RESULTS The table shows anthropometric, physiologic, and performance measures obtained during an NCAA ice hockey season.TableLactate at the 4th treadmill stage (r=0.41; P<0.03) and % fat (r=0.39; P<0.03) but not VO2max (r=0.20; P<0.24) were significantly related to total minutes played. Both lactate at 4th stage and % fat entered into a stepwise regression model that accounted for 25% of the variance in minutes played among players (p<0.02). Both VO2max (r=0.41; P<0.03) and lactate at 4th stage (r=0.33; P<0.05) were significantly related to the players net scoring chances, but % fat was not (r=0.10; P<0.57). Only VO2max significantly predicted the players net scoring chances, accounting for 17% of the variance. CONCLUSION These findings suggest a relationship between a player's conditioning level and on-ice performance. Further research that includes a larger sample size and players at different competitive levels is warranted. Seasonal physiological testing may allow strength and conditioning coaches to make individualized modifications to player's fitness regimens in an effort to improve particular physiological attributes.

Comparative effects of the Roundup and glyphosate on mitochondrial oxidative phosphorylation

The potential toxicity of the herbicide Roundup and its fundamental substance (glyphosate) was tested in bioenergetic functions of isolated rat liver mitochondria. Roundup stimulates succinate-supported respiration twice, with simultaneous collapse of transmembrane electrical potential, while glyphosate used in the same concentrations does not induce any significant effect. Additionally, Roundup depresses state 3 respiration by about 40%, at 15 mM, whereas uncoupled respiration in the presence of FCCP is depressed by about 50%. Depression of uncoupled respiratory activity is mediated through partial inhibition of mitochondrial complexes II and III, but not of complex IV. The phosphorylative system was affected by both a direct and an indirect effect on the F 0F 1 ATPase activity. The addition of uncoupled concentrations of Roundup to Ca 2+-loaded mitochondria treated with Ruthenium Red resulted in non-specific membrane permeabilization, as evidenced by mitochondrial swelling in isosmotic sucrose medium. Therefore, the uncoupling of oxidative phosphorylation is also related to the non-specific membrane permeabilization induced by Roundup. Glyphosate alone does not show any relevant effect on the mitochondrial bioenergetics, in opposition to Roundup formulation products. The differences in the toxicity observed could be either attributed to some products of Roundup or to a synergic effect of glyphosate and formulation products. Bearing in mind that mitochondria is provided with a variety of bioenergetic functions mandatory for the regulation of intracellular aerobic energy production and electrolyte homeostasis, these results question the safety of Roundup on animal health.

Rapid electrostatic evolution at the binding site for cytochrome c on cytochrome c oxidase in anthropoid primates

Cytochrome c (CYC) oxidase (COX), a multisubunit enzyme that functions in mitochondrial aerobic energy production, catalyzes the transfer of electrons from CYC to oxygen and participates in creating the electrochemical gradient used for ATP synthesis. Modeling three-dimensional structural data on COX and CYC reveals that 57 of the >1,500 COX residues can be implicated in binding CYC. Because of the functional importance of the transfer of electrons to oxygen, it might be expected that natural selection would drastically constrain amino acid replacement rates of CYC and COX. Instead, in anthropoid primates, although not in other mammals, CYC and COX show markedly accelerated amino acid replacement rates, with the COX acceleration being much greater at the positions that bind CYC than at those that do not. Specifically, in the anthropoid lineage descending from the last common ancestor of haplorhines (tarsiers and anthropoids) to that of anthropoids (New World monkeys and catarrhines) and that of catarrhines (Old World monkeys and apes, including humans), a minimum of 27 of the 57 COX amino acid residues that bind CYC were replaced, most frequently from electrostatically charged to noncharged residues. Of the COX charge-bearing residues involved in binding CYC, half (11 of 22) have been replaced with uncharged residues. CYC residues that interact with COX residues also frequently changed, but only two of the CYC changes altered charge. We suggest that reducing the electrostatic interaction between COX and CYC was part of the adaptive evolution underlying the emergence of anthropoid primates.

Cardiorespiratory Training for Dancers

Dance performance has been classified as high-intensity intermittent exercise that utilizes the aerobic and glycolytic energy production systems. Dance class and rehearsal have been shown to inadequately stress these energy systems and supplemental training is one method of preparing the body to meet these demands. The use of interval exercise training to elicit the required training effect has been suggested and the recommended exercise-to-rest ratios are examined in relation to the underlying physiology. The training environment and frequency is also examined with regard to movement specificity and the need for peripheral adaptations to occur in appropriate muscle fibers. Finally, the levels of dancers (professional, vocational student, and recreational) are discussed in relation to the importance of supplemental training to their goals.

Developmental regulation and cellular distribution of human cytosolic malate dehydrogenase (MDH1)

Human cyotsolic malate dehydrogenase (MDH1) is important in transporting NADH equivalents across the mitochondrial membrane, controlling tricarboxylic acid (TCA) cycle pool size and providing contractile function. Cellular localization studies indicate that MDH1 mRNA expression has a strong tissue-specific distribution, being expressed primarily in cardiac and skeletal muscle and in the brain, at intermediate levels in the spleen, kidney, intestine, liver, and testes and at low levels in lung and bone marrow. The observed MDH1 localizations reflect the role of NADH in the support of a variety of functions in different organs. These functions are primarily related to aerobic energy production for muscle contraction, neuronal signal transmission, absorption/resorption functions, collagen-supporting functions, phagocytosis of dead cells, and processes related to gas exchange and cell division. During neonatal development, MDH1 is expressed in human embryonic heart as early as the 3rd month and then is over-expressed from the 5th month until the birth. The expression of MDH1 is maintained in the adult heart but is not present in levels as high as in the fetus. Finally, over-expression of MDH1 is found in left ventricular cardiac muscle of dilated cardiomyopathy (DCM) patients when contrasted to the diseased non-DCM and normal heart muscle by in situ hybridization and Western blot. These observations are compatible with the activation of glucose oxidation in relatively hypoxic environments of fetal and hypertrophied myocardium.

Effects of hibernation on mitochondrial regulation and metabolic capacities in myocardium of painted turtle ( Chrysemys picta)

Painted turtles hibernating during winter may endure long-term exposure to low temperature and anoxia. These two conditions may affect the aerobic capacity of a tissue and might be of particular importance to the cardiac muscle normally highly reliant on aerobic energy production. The present study addressed how hibernation affects respiratory characteristics of mitochondria in situ and the metabolic pattern of turtle myocardium. Painted turtles were acclimated to control (25 °C), cold (5 °C) normoxic and cold anoxic conditions. In saponin-skinned myocardial fibres, cold acclimation increased mitochondrial respiratory capacity and decreased apparent ADP-affinity. Concomitant anoxia did not affect this. Creatine increased the apparent ADP-affinity to similar values in the three acclimation groups, suggesting a functional coupling of creatine kinase to mitochondrial respiration. As to the metabolic pattern, cold acclimation decreased glycolytic capacity in terms of pyruvate kinase activity and increased lactate dehydrogenase (LHD) activity. Concomitant anoxia counteracted the cold-induced decrease in pyruvate kinase activity and increased creatine kinase activity. In conclusion, cold acclimation seems to increase aerobic and decrease anaerobic energy production capacity in painted turtle myocardium. Importantly, anoxia does not affect the mitochondrial functional integrity but seems to increase the capacity for anaerobic energy production and energy buffering.

Muscle Strength and Power Adaptations of Summer-Training in Well- Trained Male Adolescent Distance Runners

1415 Endurance exercise performance is largely dictated by parameters associated with aerobic energy production. However, recent studies have also indicated that muscle strength and power may also be important determinants of endurance performance. PURPOSE: The purpose of this study was to examine the effects of pre-season cross-country training on muscular strength and power in a group of high-school runners. METHODS: Eleven males (17.0 ± 0.9 yrs) underwent strength and power testing. Data was collected 2–3 weeks after the subjects' competitive track season at the onset of summer training (Pre), and 1–2 weeks prior to the first competitive crosscountry meet (Post). Isokinetic knee extension strength was measured using a Cybex dynamometer at four movement speeds (60, 120, 180, and 240°/sec). Vertical jump height was measured using a linear transducer and vertical jump power was calculated by the equation (Power = 2.21 × weight (kg) × (√distance (m)). Independent samples t-tests were conducted on height, weight, maximal oxygen uptake (VO2max) absolute (L/min) and relative (ml/kg/min), vertical jump height, and vertical jump power. Twoway ANOVA analysis was used to evaluate torques at each isokinetic knee extension movement speed. RESULTS: VO2max was greater after summer training at both an absolute level (4.6 ± 0.4 to 4.4 ± 0.3 L/min) and a relative level (72.9 ± 4.5 to 70.9 ± 3.5 ml/kg/min) (p < 0.05), height was greater (179.8 ± 4.3 to 179.2 ± 4.3 cm) (p < 0.05), however weight was not different from Pre (62.9 ± 5.7 kg) to Post (63.2 ± 5.3 kg) (p > 0.05). Vertical jump height (55.2 ± 7.9 to 54.6 ± 7.2 cm) and vertical jump power (1034.6 ± 152.3 to 1033.2 ± 138.5 kg-m/sec) did not change over time. Isokinetic knee extension torque measurements Pre were 165.7 ± 22.6, 141.3 ± 20.3, 114.0 ± 23.2, 89.2 ± 23.6 Nm and Post were 144.3 ± 27.6, 124.7 ± 31.5, 100.8 ± 25.5, 77.0 ± 23.0 Nm at 60°/sec, 120°/sec, 180°/sec, and 240°/sec, respectively. Pre measurements were greater than Post measurements as torque decreased over time (p < 0.05), but there was no interaction. CONCLUSION: Pre-season distance run training improves VO2max in high-school cross-country runners, but fails to increase muscle power. Moreover, this type of training appears to be associated with a decrease in isokinetic muscle strength. Contrasts to the adaptations within season training merits further study. Supported by the Office of Academic Research and Sponsored Programs at Ball State University and the Gatorade Sports Science Institute.

Can Anaerobic Capacity be Fully Utilized in Two Minutes of Supra-Maximal Speed Skating Exercise?

0122 Because of the limited phosphagen stores and maximal attainable lactate concentration in muscle, it is assumed that the anaerobic energy production (Ean) has a maximum: the anaerobic capacity. Two minutes of exhausting exercise is assumed to be required for maximal use of anaerobic sources. In time trial events in cycling (500–3000m), we found indications that two minutes might not be sufficient to fully utilize the anaerobic capacity. PURPOSE: To determine if the anaerobic capacity can be fully utilized in two minutes of supra-maximal exercise. METHODS: Because the nature of speed skating emphasizes the importance of the anaerobic system, elite level speed skaters (n = 8) performed a 1500m speed skating race (lasting about 2 min) and sub-maximal efficiency tests. Depending on their specialization, pairs of skaters also skated a 500m, 1000m, 3000m or 5000m. Final time is recorded for all distances. External energy production (Eext) was calculated using aerodynamic models, taking data from video analysis and ice friction measurements as input. The mechanical equivalent of aerobic energy production (Eaer) was calculated from breath-by-breath VO2 and the measured skating efficiency. Ean was determined by subtracting Eaer from Eext. The relative contribution of Ean to the total energy production was calculated (%Ean). Ean on the 500, 1000, 3000 and 5000m was related to the subject's Ean on the 1500m. RESULTS: %Ean is considerable for every skated distance. Furthermore, the results show that Ean increases with the duration of the event.TableCONCLUSION: The anaerobic contribution is substantial in all distances. The present results show that, in accordance with literature, distances < 1500m are too short to fully utilize anaerobic capacity. For the longer distances, Ean exceeds the value as measured at the 1500m, so it can be concluded that even in an exercise of highly anaerobic nature the anaerobic capacity is not fully taxed in the time span as is suggested in literature.