Anaerobic Energy Utilization Research Articles

The continuous physiological changes of zebrafish (Danio rerio) based on metabolism under controlled thallium stress

In this research, the continuous physiological changes of zebrafish (Danio rerio) in 0.1 μg/L thallium (Tl) in 15 days were investigated. The results showed that Tl(I) stress had a significant positive linear correlation with zebrafish ammonia nitrogen excretion (ANE) (p < 0.001), and the mean value of ANE in Tl(I) treatment (435 ± 227 mg/kg/h) was approximately 2 times higher than in the control group (239 ± 168 mg/kg/h), which suggested that ANE was suitable for Tl(I) stress assessment. A substantial difference based on oxygen consumption rate (OCR) between the control group (587 ± 112 mg/kg/h) and Tl(I) treatment (260 ± 88 mg/kg/h) with a high significance p < 0.001 could be observed, and the results indicated that Tl(I) played a negative role in OCR of zebrafish. The characteristics of both ANE and OCR changes under slight Tl(I) stress could be reflected by the ammonia quotient (AQ). It was noteworthy that AQ increased rapidly in first 6 h from 0.66 to 4.50, which was 3 times higher than 1.2, indicating rapid increase in both anaerobic energy utilization and protein metabolism in 0.1 μg/L Tl(I) exposure. It is concluded that the physiological changes of zebrafish based on metabolism can be regarded as a sensitive biological indicator of Tl(I) pollution, which could work as a substitute of potassium that disrupts the normal biological metabolism in the process of transport.

Discussion of “Effect of plasma donation and blood donation on aerobic and anaerobic responses in exhaustive, severe-intensity exercise”

I readwith interest the paper by Hill and co-workers recently published in Applied Physiology, Nutrition, and Metabolism (Hill et al. 2013), and I would like to discuss some differences with previous work from my lab. Similarly toHill’s study,weexercise testedhealthyuniversity studentsprior, and2h, 2days, and7days after a standardblood-bank donation (450mLextraction;Mora-Rodriguez et al. 2012).We focused on the physiological responses during steady-state submaximal pedaling (60 min at 154 W) while Hill studied O2 kinetics during cycle ergometer short test to exhaustion ( 4 min at 274 W). Our experiments were conducted in different environments (35 °C vs. 22 °C); however, in each study, all trials took place in the same environment and thus the effects of blood donation should have been similar. Hill’s finding of unchanged O2 kinetic during exercise after blood donation expands our findings of unchanged O2 consumption rates upon donation when exercising at submaximal workloads (MoraRodriguez et al. 2012). We found that the relation between oxygen consumption (VO2) and external work intensity was independent of hemoglobin concentration. The maintenance of the rates of oxygen delivery and consumption despite reductions in the main blood oxygencarrier (i.e., hemoglobin) requires a tightly regulated increase in cardiac output, which time course after donation is depicted in our Fig. 4 (Mora-Rodriguez et al. 2012). This cardiovascular adjustment to maintain oxygen rates of consumption after venesection was shown in the classic study of Woodson et al. (1978) and more recently by Beng Saltin’s group (Koskolou et al. 1997). While we agree that blood donation does not affect the VO2 response during submaximal exercise, we found that CO2 production is affected by a standard blood-bank donation. We reported increased carbon dioxide production (VCO2) for the same VO2 and thus increased calculated carbohydrate oxidation when exercising 2 h after blood donation. Furthermore, in contrast to Hill’s data, we found blood lactate concentration elevated when exercising after donation. Ekblom et al. (1976) also found a higher blood lactate concentration during submaximal exercise after venesection of 800 mL of whole blood. Both papers suggest a higher anaerobic energy yield in a situation of reduced O2 availability per liter of blood (i.e., after blood donation). The unchanged end of exercise plasma lactate concentration in Hill’s study andothers (Panebianco et al. 1995;Duda et al. 2003) could be an artifact of the different energy demand in their trials. Two hours after donation subjects exercised for 19% less time than in the trial before donation (218 vs. 268 s), expending less energy. However, final plasma lactate concentration was similar between trials. To me, this suggests that the rates of anaerobic energy utilization were larger to achieve similar lactate concentrationwith 19% less exercise duration. Another factor that could have influenced plasma lactate concentration is blood bicarbonate availability. Blood bicarbonate elevation by dietary supplementation increases blood lactate concentration during exercise (Zinner et al. 2011). In contrast, blood donation lowers plasma bicarbonate concentration (Duda et al. 2003), likely reducing the buffering of the dissociated hydrogen proton of the lactic acid and thus lactate incorporation into blood. Again, similar plasma lactate with lower plasma bicarbonate (Duda et al. 2003) suggests a higher reliance on glycolysis. In summary, our elevations in VCO2 and blood lactate data during submaximal exercise upon a standard blood-bank donation suggest a higher contribution of glycolysis and anaerobicmetabolism in this situation of reduced O2 availability. I realize that Hill’s thesis is that the “capacity” of the anaerobic system to produce energy during short-fatiguing exercise is not undermined by blood donation. Presently, I argue that anaerobic energy contribution to exercise is increased after blood donation based on our submaximal exercise results (Mora-Rodriguez et al. 2012). I amunclear if both findings can co-exist and I would like to know Dr. Hill’s opinion on this issue.

Preventing dance injuries: current perspectives

Dancers are clearly athletes in the degree to which sophisticated physical capacities are required to perform at a high level. The standard complement of athletic attributes – muscular strength and endurance, anaerobic and aerobic energy utilization, speed, agility, coordination, motor control, and psychological readiness – all are essential to dance performance. In dance, as in any athletic activity, injuries are prevalent. This paper presents the research background of dance injuries, characteristics that distinguish dance and dancers from traditional sports and athletes, and research-based perspectives into how dance injuries can be reduced or prevented, including the factors of physical training, nutrition and rest, flooring, dancing en pointe, and specialized health care access for dancers. The review concludes by offering five essential components for those involved with caring for dancers that, when properly applied, will assist them in decreasing the likelihood of dance-related injury and ensuring that dancers receive optimum attention from the health care profession: (1) screening; (2) physical training; (3) nutrition and rest; (4) specialized dance health care; and (5) becoming acquainted with the nature of dance and dancers.

MITOCHONDRIAL CYTOPATHIES IN CHILDREN AND ADULTS

ABSTRACT Mitochondrial cytopathies represent a heterogenous group of disorders with abnormal mitochondrial structure or function as the defining entity and with clinical onset across all age groups. Given that the mitochondria provide the majority of cellular adenosine 5′-triphosphate (ATP), the clinical symptoms can manifest with a myriad of presentations. Cellular pathology includes a reduction in aerobic energy transduction, an increase in anaerobic energy utilization (lactate production), and, in some cases, higher oxidative stress. Diagnostic criteria include history (classic multisystem involvement), blood test abnormalities (elevated lactate, alanine, and creatine kinase activity), urine organic acids (3-methylglutaconic acid, ethylmalonic acid, fumarate), muscle enzymology (reduction in activity), exercise testing (low maximum oxygen consumption [V˙O2max], early lactate production) and other ancillary tests, including MRI, MR spectroscopy, and near-infrared spectroscopy. Treatment is multifactorial and supportive, including optimization of nutrition and deficiency (folate and vitamin B12) replacement, gastrostomy tube if necessary (failure to thrive), treatment of secondary neurologic issues, vitamin and cofactor therapy (creatine monohydrate, coenzyme Q10, α-lipoic acid, etc), and exercise.

Live high, train low at natural altitude

For decades altitude training has been used by endurance athletes and coaches to enhance sea-level performance. Whether altitude training does, in fact, enhance sea level performance and, if so, by what means has been the subject of a number of investigations. Data produced principally by Levine and Stray-Gundersen have shown that living for 4 weeks at 2500 m, while performing the more intense training sessions near sea level will provide an average improvement in sea level endurance performance (duration of competition: 7-20 min) of approximately 1.5%, ranging from no improvement to 6% improvement. This benefit lasts for at least 3 weeks on return to sea level. Two mechanisms have been shown to be associated with improvement in performance. One is an increase in red cell mass ( approximately 8%) that results in an improved maximal oxygen uptake ( approximately 5%). That must be combined with maintenance of training velocities and oxygen flux to realize the improvement in subsequent sea level performance. We find no evidence of changes in running economy or markers of anaerobic energy utilization. Our results have been obtained in runners ranging from collegiate to elite. Wehrlin et al. have recently confirmed these results in elite orienteers. While there are no specific studies addressing the use of living high, training low in football players, it is likely that an improvement in maximal oxygen uptake, all other factors equal, would enhance football performance. This benefit must be weighed against the time away (4 weeks) from home and competition necessary to gain these benefits.

Energetics of kayaking at submaximal and maximal speeds

The energy cost of kayaking per unit distance (C(k), kJ x m(-1)) was assessed in eight middle- to high-class athletes (three males and five females; 45-76 kg body mass; 1.50-1.88 m height; 15-32 years of age) at submaximal and maximal speeds. At submaximal speeds, C(k) was measured by dividing the steady-state oxygen consumption (VO(2), l x s(-1)) by the speed (v, m x s(-1)), assuming an energy equivalent of 20.9 kJ x l O(-1)(2). At maximal speeds, C(k) was calculated from the ratio of the total metabolic energy expenditure (E, kJ) to the distance (d, m). E was assumed to be the sum of three terms, as originally proposed by Wilkie (1980): E = AnS + alphaVO(2max) x t-alphaVO(2max) x tau(1-e(-t x tau(-1))), were alpha is the energy equivalent of O(2) (20.9 kJ x l O(2)(-1)), tau is the time constant with which VO(2max) is attained at the onset of exercise at the muscular level, AnS is the amount of energy derived from anaerobic energy utilization, t is the performance time, and VO(2max) is the net maximal VO(2). Individual VO(2max) was obtained from the VO(2) measured during the last minute of the 1000-m or 2000-m maximal run. The average metabolic power output (E, kW) amounted to 141% and 102% of the individual maximal aerobic power (VO(2max)) from the shortest (250 m) to the longest (2000 m) distance, respectively. The average (SD) power provided by oxidative processes increased with the distance covered [from 0.64 (0.14) kW at 250 m to 1.02 (0.31) kW at 2000 m], whereas that provided by anaerobic sources showed the opposite trend. The net C(k) was a continuous power function of the speed over the entire range of velocities from 2.88 to 4.45 m x s(-1): C(k) = 0.02 x v(2.26) (r = 0.937, n = 32).

Effect of substrate manipulation on reducing ischemia/reperfusion injury in isolated perfused rat hearts

The objective of this investigation was to assess the effect of substrate manipulationon reducing ischemia/reperfusion injury (IRI). Isolated rat hearts were perfused with modified Krebs-Henseleit buffer containing either (in mM): glucose 11 (G1), glucose 22 (G2), or glucose 11 with either xylitol 11 (GX), mannitol 11 (GM), L-leucine 1 (GL), or L-glutamic acid 2 (GGA), respectively. Hearts were subjected to 10 min of global no-flow ischemia, followed by 20 min of reperfusion. Mean tissue perfusion, oxygen consumption, and peak left ventricular pressure (PLVP) were determined at baseline, in the first minute of regular heart rhythm following ischemia, and after 20 minutes of reperfusion. Reperfusion arrhythmia (in sec) was significantly (all p < 0.05) shorter in GGA (115 ± 33) vs G1 (315 ± 29) and G2 (273 ± 33), and also in GL (161 ± 26) vs G1. Dry/wet heart weight ratios were also greater in GGA (0.20), when compared with G2 (0.16), GX (0.17), GM (0.17), GM (0.17), and GL (0.17) (all p < 0.02), suggesting less cellular/interstitial edema. Percent recovery in PLVP was improved (p < 0.03) in GL (81 ± 2) and GGA (81 ± 2) vs. G2 (71 ± 3), without significant alterations in oxygen consumption. Thus, cardiac IRI can be diminished by substrate manipulation, especially by augmentation of glutamate and leucine, most likely due to an improved anaerobic energy generation and utilization.

Muscle Glucose Metabolism during Exercise

Substrate utilization during exercise is determined by the intensity and duration of exercise as well as by training status and the availability of substrate. The major energy source at rest and during low intensity exercise is fat oxidation while oxidation of carbohydrates and anaerobic energy utilization predominates at higher intensities. Hypoxia will induce a similar change in substrate utilization as an increase of the exercise intensity and it is suggested that O2 availability is an important determinant of muscle metabolism during exercise. Muscle glucose uptake increases during exercise and can reach values that are 30-50 times higher than at rest. The increase in muscle glucose uptake is related to the work load and the duration of the exercise, and corresponds to the output of glucose from the liver. Animal experiments have shown that muscle contraction can induce an increase in glucose uptake in the absence of insulin. Studies in man have shown that insulin and exercise at low intensity have a synergistic effect on glucose uptake, possibly due to an increased insulin inflow to the muscle. Intracellular glucose concentration is low at rest but can under certain conditions such as intensive exercise and hypoxia increase to maximum values of 3-4 mmol/l of intracellular water which demonstrates that glucose uptake under certain conditions can be in excess of the utilization of glucose.

Hypoxaemia increases the accumulation of inosine monophosphate (IMP) in human skeletal muscle during submaximal exercise.

The effect of hypoxaemia on the muscle content of inosine monophosphate (IMP) during short-term, low-intensity exercise has been investigated. Six men cycled twice for 5 min at 120 +/- 6 W (mean +/- SE), which corresponded to approximately 50% of their maximal normoxic O2 uptake, breathing air (N) on one occasion and 11% O2 in N2 (H) on the other. Oxygen uptake at the end of the exercise period was similar between treatments. No significant difference was observed between H and N in the muscle metabolite contents at rest. Muscle content of phosphocreatine (PCr) decreased and lactate increased during exercise. Post-exercise PCr during H was 80% of the value during N (P greater than 0.05) and post-exercise muscle lactate was fourfold higher during H than during N (P less than 0.001). Post-exercise muscle content of ADP was significantly higher during H than during N (P less than 0.01), while ATP and AMP remained constant under both H and N exercise (P greater than 0.05 H vs N). IMP was not detectable in pre-exercise muscle samples (less than 0.01 mmol kg-1 dry wt) but increased during N exercise (0.03 +/- 0.01 mmol kg-1 dry wt, wt, P less than 0.05) and even more during H exercise (0.16 +/- 0.05 mmol kg-1 dry wt, P less than 0.05, H vs N). Post-exercise IMP was negatively related to PCr (r = -0.90) and positively related to lactate (r = 0.88). It is concluded that hypoxaemia results in an enhanced accumulation of IMP during submaximal exercise and that the IMP level is related to the degree of anaerobic energy utilization.

Oxygen deficit at the onset of submaximal exercise is not due to a delayed oxygen transport.

Six subjects cycled on two occasions for 10 min at power output of 188 +/- 11 W (means +/- SEM), which corresponded to 70 +/- 2% of their maximal oxygen uptake (VO2 max). The exercise intensity was either increased gradually in a stepwise manner over about 15 min (slow transition-S), or increased directly (direct transition-D) to the predetermined power output. Muscle samples from the quadriceps femoris muscle were taken at rest and immediately after exercise in both trials. During exercise with both D and S muscle lactate increased approximately 10 times (P less than 0.01), phosphocreatine decreased about 50% (P less than 0.01) and ADP increased about 20% (P less than 0.05). There were no significant differences between S and D (P greater than 0.05). Furthermore, blood lactate, O2 deficit, O2 debt, and the calculated increase in muscle content of inorganic phosphate (Pi) were all similar between D and S (P greater than 0.05). It is concluded that the O2 deficit and the anaerobic energy utilization is not affected by the rate of transition from rest to exercise. Consequently, the O2 deficit at the onset of exercise is not due to a delay in O2 transport, but may be due to a limited peripheral O2 utilization as a result of metabolic adjustments at the cellular level. Increases in ADP and Pi are suggested to be primary metabolic regulators which activate both aerobic and anaerobic energy production resulting in the O2 deficit.

Disposal of lactate during and after strenuous exercise in humans.

Heavy dynamic exercise using both arm and leg muscles was performed to exhaustion by seven well-trained subjects. The aerobic and anaerobic energy utilization was determined and/or calculated. O2 uptake during exercise and during 1 h of recovery was measured as well as splanchnic and muscle metabolite exchange. Glycogen and lactate content in the quadriceps femoris was determined before exercise, immediately after exercise, and after a recovery period. In four male subjects the estimated mean lactate production during exercise was 830 mmol. The splanchnic uptake of lactate during recovery was 80 mmol, and the calculated maximum amount oxidized during the recovery period was 330 mmol. About 60 mmol were accounted for in the body water at the end of the rest period. The remaining 360 mmol of lactate were apparently resynthesized into glycogen in muscle via gluconeogenesis. It is concluded that approximately 50% of the lactate formed during heavy exercise is transformed to glycogen via glyconeogenesis in muscle during recovery and that lactate uptake by the liver is only 10%.

Influence of ambient oxygen and random swimming activity on metabolic rates and quotients in the freshwater mulletRhinomugil corsula (Hamilton)

Oxygen consumption and carbon dioxide production increased with increase in random (spontaneous) swimming activity in mullet,Rhinomugil corsula in high oxygen (normoxia), but the oxygen consumption in low oxygen (hypoxia) was negatively correlated with swimming activity in tests at both 30 and 35°C. The RQ of mullet under hypoxia always remained over unity and increased with increase in activity, clearly indicating intense utilization of anaerobic energy. The RQ under normoxia remained near unity irrespective of random swimming activity change. The AQ of normoxic and hypoxic mullet showed opposing trends, the quotient increasing with decreasing activity in the former and increasing with activity increase in the latter. The AQ change suggests increased protein utilization in quieter fish when adequate ambient oxygen is available, but the hypoxic mullet utilizes more protein the more active it is. The latter change in AQ is consonant with the change in hypoxic RQ and it is likely that increased anaerobic energy utilization demanded by the increased activity is accompanied by increased protein breakdown and ammonia release, thereby helping in acid-base balance and ionic (Na+) regulation. Results obtained at 30 and 35°C are almost identical. Within the small range temperature does not seem to cause a marked metabolic difference in mullet.

Respiratory quotient and ammonia quotient in Tilapia mossambica (Peters) with special reference to hypoxia and recovery

At oxygen concentrations below air saturation, R.Q. and A.Q. values of Tilapia mossambica increase with decrease in ambient oxygen at 30 and 35°C, indicating an increase in anaerobic metabolism and protein utilization. The recovery metabolism indicates that T. mossambica accumulates an oxygen debt at 30°C, which was not obvious at 35°C. The post-hypoxic oxygen consumption at 30°C is quite pronounced and the fish repays almost wholly the oxygen debt accumulated. At 30°C, R.Q. and A.Q. reach prehypoxic level immediately after exposure to high oxygenated water. In contrast to this, during recovery the first high R.Q. which is higher than unity and subsequent low R.Qs., almost as low as 0.5, suggest respectively that, anaerobic energy utilization persists and carbon dioxide is retained. The differences in the recovery metabolism of T. mossambica at the two temperatures may be due to changes in metabolism and pathways due to temperature. The recovery metabolism of T. mossambica suggests that energy derived anaerobically could proceed through other pathways than the conventional glycolytic way. The decrease in random activity during the hypoxic phase at 30 and 35°C may have a special significance for survival.

Some recent findings in obesity.

The tendency of some obese subjects to an energy-sparing reaction can be induced temporarily by attempts of the patient to reduce his overweight by prolonged starvation. This regulatory reaction may be induced by regulatory especially thyroid mechanisms. In obesity of both sexes a tendency to anaerobic energy utilization in the muscle can be revealed and so a tendency to decrease energy utilization in general. The differences in insulinemia (IRI) displayed a prevalence of maternal obesity in the group with higher levels of basal and stimulated IRI values, which decline after changes in diet and body weight. This behavior of IRI levels and amount and composition of diet indicate a possible permissive role of previous food consumption habits.

Respiratory quotient and ammonia excretion in Tilapia mossambica

Tilapia mossambica (Peters), acclimated to and tested in fresh water at 30°C, maintained a routine respiratory quotient (R Q) of about unity and an ammonia quotient (A Q) (Vol. NH2/Vol. O2) of about 0.2 at high ambient oxygen concentrations. At low oxygen concentrations (below 2 ppm) R Q and A Q increased sharply to values of 8 and 1, respectively (at 0.6 ppm), indicating a close relationship of increase in anaerobic energy utilization and increase in protein metabolism at inadequate oxygen concentrations. T. mossambica (8 cm), exercised continuously with intervening sampling and flushing stops for 6 h, at a swimming speed of about 2 body lengths/sec, derived some anaerobic energy throughout the exercise (R Q: 1.2), utilizing more protein the longer the exercise. The coupling of the increased protein metabolism and anaerobic energy utilization may be of advantage in preventing acidosis and also in conserving sodium (Na+) in fish.