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At least 19 recordsLinked to original sources
PubMed1988

Aerobic threshold, anaerobic threshold, and maximal oxygen uptake of Japanese speed-skaters.

The purpose of this study was to investigate the physiologic and metabolic parameters of speed-skaters with different training regimes and performance level and examine some physiologic prerequisites for speed-skating. The subjects were 25 male speed-skaters including members of the 1984 Japanese National Speed Skating Team whose ages ranged from 19 to 25 years. Aerobic threshold (AerT), anaerobic threshold (AnT), and VO2max were determined during a progressive bicycle ergometer exercise. The power was increased by 12.25 W every 3 min to exhaustion. AerT was determined using gas exchange variables; nonlinear increase in VE and VCO2, and peak VO2.VE-1. AnT was estimated from breakaway VE and the onset of decrease in FECO2.VO2max was measured during another incremental exercise on a bicycle ergometer. Mean AerT, AnT, and VO2max for skaters (n = 25) were 2.47 +/- 0.36.min-1 (61.1 +/- 7.2 %VO2max), 2.93 +/- 0.33.min-1 (73.4 +/- 5.9 %VO2max), and 4.06 +/- 0.42.min-1, respectively. All-arounders had higher AerT values but the same VO2max as sprinters. AnT of all-arounders was significantly higher than those of sprinters. A significant difference between the top ten elite skaters and the other skaters (n = 15) was found only in VO2max expressed as l.min-1. However, no significant correlation was noted between measured physiologic variables (AerT, AnT, and VO2max) and performances expressed as mean velocities at various events.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Anaerobic threshold, individual anaerobic threshold, and maximal lactate steady state in rowing.

Anaerobic threshold, also termed 4.0 mmol.l-1 threshold (AT4), and individual anaerobic threshold (IAT), presumably indicate the workload corresponding to maximal lactate steady state (MLSS) during an incremental workload test. MLSS is the highest blood lactate concentration (BLC) resulting in a steady state during constant workload. The purpose of the present investigation was to ascertain the validity of AT4 and IAT as related to MLSS during rowing ergometry. Nine rowers (mean +/- SD age 20.2 +/- 1.6 yr; HT 187.2 +/- 4.9 cm; WT 81.1 +/- 6.3 kg) performed an incremental load test to determine AT4, IAT and maximal workload and several 30 min constant workloads for MLSS measurement on a mechanical rowing ergometer. The incremental load test was conducted at 215 W and increased by 35 W every 3.0 min. The first 30 min constant workload was conducted at 60% of maximal workload (363.3 +/- 45.1 W). If a constant load test resulted in a steady state of BLC subsequent constant load tests were performed and workload increased by 3% to 10% after each constant load test until no steady state of BLC could be observed. AT4 (287.0 +/- 20.5 W), IAT (287.1 +/- 25.1 W), and BLC at IAT (4.2 +/- 0.8 mmol.l-1) were higher (P < 0.001) compared to MLSS workload (255.1 +/- 17.5 W) and MLSS (3.0 +/- 0.6 mmol.l-1), respectively. Independent of the practical application of AT4 and IAT, in rowing AT4 and IAT do not represent MLSS workload.

Anaerobic Threshold↗
PubMed1984

Precision of ventilatory and gas exchange alterations as a predictor of the anaerobic threshold.

Anaerobic threshold has been defined as the oxygen uptake (VO2) at which blood lactate (La) begins to rise systematically during graded exercise (Davis et al. 1982). It has become common practice in the literature to estimate the anaerobic threshold by using ventilatory and/or gas exchange alterations. However, confusion exists as to the validity of this practice. The purpose of this study was to examine the precision with which ventilatory and gas exchange techniques for determining anaerobic threshold predicted the anaerobic threshold resolved by La criteria. The anaerobic threshold was chosen using three criteria: (1) systematic increase in blood La (ATLa), (2) systematic increase in ventilatory equivalent for O2 with no change in the ventilatory equivalent for CO2 (ATVE/VO2), and (3) non-linear increase in expired ventilation graphed as a function of VO2 (ATVE). Thirteen trained male subjects performed an incremental cycle ergometer test to exhaustion in which the load was increased by 30 W every 3 minutes. Ventilation, gas exchange measures, and blood samples for La analysis were obtained every 3rd min throughout the test. In five of the thirteen subjects tested the anaerobic threshold determined by ventilatory and gas exchange alterations did not occur at the same VO2 as the ATLa. The highest correlation between a gas exchange anaerobic threshold and ATLa was found for ATVE/VO2 and was r = 0.63 (P less than 0.05). These data provide evidence that the ATLa and ATVE do not always occur simultaneously and suggest limitations in using ventilatory or gas exchange measures to estimate the ATLa.

Adult↗
PubMed1991

[Effect of blood hemoglobin concentration on anaerobic threshold].

Anaerobic threshold (AT) has been advocated as an objective method of evaluating exercise capacity in patients with chronic congestive heart failure. The factors that determine AT, however, remain still unclear. To assess the influence of oxygen transport capacity on AT, patients with iron deficiency anemia were studied before and after treatment with iron. Twenty-nine female subjects were studied. They were divided into the following 3 groups: 1) iron deficiency anemia (group IDA: Hgb less than 11 g/dl and ferritin less than 10 ng/ml) consisting of 4 athletes and 6 non-athletes, 2) latent iron deficiency (group Lat-ID: Hgb greater than or equal to 11 g/dl and ferritin less than 10 ng/ml) consisting of 4 athletes, and normal (group Nor: Hgb greater than or equal to 11 g/dl and ferritin greater than or equal to 10 ng/ml) consisting of 15 athletes and 6 non-athletes. By bicycle ergometer using ramp protocol, peak oxygen uptake (peak VO2) and AT were measured in each group. Following the 1st exercise testing, groups IDA and Lat-ID were treated by oral iron for 1-1.5 months. The 2nd exercise testing was then performed. Furthermore, to investigate whether muscle cell energy metabolism itself is altered by iron deficiency, P magnetic resonance spectroscopy (MRS) was performed in 2 relatively severe anemic patients during forearm exercise while assessing the changes in phosphocreatine and inorganic phosphate. Peak VO2 and AT in non-athletes were significantly lower in IDA group than Nor group (peak VO2 (ml/min/kg): 23.7 +/- 5.1 vs 33.3 +/- 3.8, p less than 0.01, AT (ml/min/kg): 15.9 +/- 3.3 vs 21.3 +/- 1.3, p less than 0.01). After iron administration, Hgb was increased significantly in IDA group (from 9.0 +/- 1.8 to 12.1 +/- 0.8 g/dl, p less than 0.01) accompanied by an improvement in peak VO2 and AT (peak VO2 (ml/min/kg): from 34.2 +/- 12.4 to 40.0 + 13.0, p less than 0.001, AT (ml/min/kg): from 20.9 +/- 6.3 to 25.0 +/- 8.0, p less than 0.001). Lat-ID and Nor groups showed no changes. MRS indices of cell energy metabolism of the 2 severely anemic patients did not differ from those of normal controls, and no changes were observed after iron treatment. It is concluded from these results in iron deficiency anemia that oxygen transport is a determinant of anaerobic threshold.

Adolescent↗
PubMed1996

Is the intracellular pH threshold an anaerobic threshold from the view point of intracellular events?: a brief review.

Intracellular biochemical changes could be monitored noninvasivery and continuously by using nuclear magnetic resonance (NMR). In about the last decade, intracellular behavior of phosphorus compounds and pH during muscle contraction in man have been studied by 31P nuclear magnetic resonance spectroscopy (31P-MRS). During incremental load, lactic acidosis was followed by a decline in intracellular pH. 31P-MRS studies has been definitely proved that this change in intracellular pH shows the threshold behavior. Some reports discussed the intracellular pH threshold (pHT) as an anaerobic threshold (AT) from the view point of intracellular events. However, our studies revealed that pHT did not reflect the onset of lactate production. In this article, studies of intracellular pH of working muscle were reviewed in relation to an anaerobic threshold.

Anaerobiosis↗
PubMed1992

Is the anaerobic threshold truly anaerobic?

This study was done to address the question as to whether there was an exercise metabolic rate below which the O2 supply to the muscles was adequate to meet the O2 requirement and above which the O2 supply was inadequate, ie, an anaerobic threshold (AT). The question was addressed using 2 approaches: (1) The arterial lactate/pyruvate ratio was measured to see if it increased at an O2 uptake (VO2) threshold or continuously as a log function over the entire range of exercise work rates. (2) Anticipating that the VO2 would be affected by reducing O2 supply only for work rates above the AT, the effect of reducing O2 delivery on VO2 for work rates over the entire range of the subject's work capacity was determined. Lactate (L) and pyruvate (P) were measured in arterial blood in 10 normal subjects. The L/P ratio was found not to increase until a threshold work rate was reached, the VO2 being that identified as the AT. Above that VO2, the L/P ratio climbed steeply. Arterial L/P ratio measurements fit a threshold model considerably better than a continuous model, supporting the concept that exercise done at low and moderate work rates can be performed without a change in cell redox state; but redox state does change rapidly in relation to the work rate increase above the AT. In the second study, the cardiorespiratory responses to various levels of exercise were studied in 10 normal subjects before and after carboxyhemoglobin (COHb) was increased to 10% and 20%. The lactic acidosis threshold and VO2 kinetics were examined. Blood lactate concentration increased only above the AT. The AT was systematically decreased by the percent of COHb increase. Importantly, VO2 was reduced and VO2 kinetics were slowed in response to exercise only for the metabolic rates above the AT. These studies demonstrate that lactate increase in response to exercise is O2 flow sensitive, and there is a threshold work rate above which this sensitivity becomes manifest.

Acidosis, Lactic↗
PubMed1982

Comparison of prolonged exercise tests at the individual anaerobic threshold and the fixed anaerobic threshold of 4 mmol.l(-1) lactate.

Prolonged physical exercise tests (50 min) at the threshold of 4 mmol . l-1 lactate (ATc) and at the individual anaerobic threshold (IAT) were applied in 19 rowing athletes. In each of the rowers (n = 19) work loads corresponding to the IAT did not result in a gradual lactase accumulation or exhaustion within 50 min of exercise. Means of lactate concentration and heart rate at the end of exercise were 4.0 +/- 1.6 mmol . l-1 and 182 +/- 13.0 beats . min-1, respectively. In 15 of 19 rowers, the IAT corresponded to lower work loads than the ATc. In these cases, prolonged exercise tests at the ATc showed gradual increases in lactate concentrations to a mean of 9.6 +/- 1.2 mmol . l-1, associated with exhaustion at a mean working time of 14.4 +/- 6.3 min and a mean heart rate of 192 +/- 10.4 beats . min-1. In four rowers, the IAT was found at identical (n = 3) or higher (n = 1) work loads than the ATc. In these cases, after an initial increase no further rise in lactate concentrations in blood was observed, and exhaustion did not occur during the prolonged exercise tests. These findings support the conclusion derived from the lactate kinetics model that the IAT defines the work load at the maximal lactate steady state.

Adolescent↗
PubMedDate not supplied

[Changes in hemodynamics and catecholamines during single-level exercise at the anaerobic threshold and 120% of the anaerobic threshold in normal subjects].

Exercise training usually involves the sustained performance of exercise at a prescribed intensity. The effects of exercise performed at the anaerobic threshold (AT) have been widely studied. The effects of single-level exercise on catecholamines and cardiac function were assessed at the AT, and at 120% of the AT in eight healthy Japanese men (mean age 21.9 +/- 1.8 years). 1) Symptom-limited exercise testing utilized the ramp protocol with a bicycle ergometer (20 watts/min) for measuring AT and peak oxygen uptake (peak VO2). 2) Exercise testing was repeated on another day, following the same protocol, with blood sampled to measure norepinephrine (NE) and epinephrine (E) in the resting control state and at the AT and peak exercise. 3) Single-level exercise testing at the AT and at 120% of AT utilized the bicycle ergometer on yet another day. Blood for measurement of NE and E was drawn at 3 and 7 min after achieving a steady-state condition. In addition, the cardiac index (CI) and stroke index (SI) were measured by the CO2 rebreathing method. (1) Mean AT and peak VO2 were 18.3 +/- 1.3 and 40.2 +/- 3.0 ml/min/g, respectively. (2) NE and E measured during ramp exercise testing increased rapidly when the intensity of exercise exceeded the AT. NE measured after 3 and 7 min at the AT during single-level exercise equalled 94.7% and 94.5% of the NE value measured at the AT of ramp exercise, respectively. NE measured after 3 and 7 min at 120% of the AT during single-level exercise was 124.7% and 144.7% at the AT of ramp exercise, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1982

A computer linear regression model to determine ventilatory anaerobic threshold.

The anaerobic threshold has generally been determined by simple visual inspection of ventilation or other gas-exchange data obtained during incremental exercise. To establish objective criteria for the determination of anaerobic threshold, a computer algorithm has been developed that models the ventilatory response to exercise using multisegment linear regression. The best-fit regression model is chosen by minimizing the pooled residual sum of squares . The anaerobic threshold is reported as the first break point in that model. The computer-determined anaerobic threshold values for 37 subjects were compared with subjectively determined values as chosen by four independent observers. The observers' estimates, when pooled to yield a single a single value for each subject, gave a mean value for the gas-exchange anaerobic threshold of 2.26 +/- 0.69 l/min. The estimates by the computer method averaged 2.21 +/- 0.65 l/min. The correlation coefficient for these two methods was 0.94.

Adult↗
PubMed1990

Evidence that the metabolic acidosis threshold is the anaerobic threshold.

We evaluated maximal O2 uptake (VO2max), the metabolic acidosis threshold determined by the V-slope analysis [plot of CO2 output (VCO2) as a function of oxygen uptake (VO2)], the ratio of increase in VO2 to work rate increment (delta VO2/delta WR), the upper slope (S2) of the V-slope analysis, and the VO2 for work below and above the metabolic acidosis threshold to determine whether the changes in O2 transport caused by increased carboxyhemoglobin (HbCO) affected these parameters and variables. Ten normal subjects (aged 32.8 +/- 7.1 yr) performed symptom-limited incremental exercise tests in a ramp pattern on a cycle ergometer while breathing air and air with added carbon monoxide to cause HbCO to be approximately 11% and 20%. VO2max decreased by 11.6 and 19.3%, the metabolic acidosis threshold decreased by 11.9 and 19.6%, delta VO2/delta WR decreased by 8.9 and 14.0%, and S2 increased by 13.6 and 21.8% when HbCO was increased to 11 and 20%, respectively. Most importantly, VO2 was unchanged related to work rate below the metabolic acidosis threshold during the tests with increased HbCO but was reduced at the work rates above the metabolic acidosis threshold. These findings are consistent with the concept that the metabolic acidosis threshold is synonymous with an anaerobic threshold, i.e., the latter demarcating the VO2 above which the contracting muscles are not adequately supplied with O2 but below which they are.

Acidosis↗
PubMed1986

Effect of training on anaerobic threshold, maximal aerobic power and anaerobic performance of preadolescent boys.

To evaluate the effect of a 9-week interval training program on aerobic capacity, anaerobic capacity, and indices of anaerobic threshold of preadolescent boys, 28 10.2- to 11.6-year-old boys were tested. The test included laboratory evaluation of anaerobic capacity (Wingate anaerobic test) and evaluation of VO2 max and anaerobic threshold indices from a graded exercise test and measurement of blood lactate. The tests also included a 1200-m run to investigate the relationship of laboratory fitness indices, VO2 max, anaerobic threshold indices, and indices of anaerobic capacity to the performance of the run. It was found that in 10- to 11-year-old boys, a 9-week interval training increased the indices of anaerobic capacity: mean power by 10% and peak power by 14%. No change was found in percent fatigue. The training also increased VO2 max by 7% in absolute terms and by 8%/kg body weight. A significant increase was also found in the running velocity at the anaerobic threshold (running velocity at inflection point of lactate accumulation curve), but in relative terms (percent of VO2 max), the anaerobic threshold decreased by approximately 4.4%. It is concluded that proper training may improve maximal aerobic power and anaerobic capacity of preadolescent boys. It is also concluded that anaerobic threshold measures are less sensitive to the training regimen than VO2 max and that the 1200-m running performance is strongly associated with both aerobic and anaerobic capacities and less with the anaerobic threshold, which in preadolescent boys seems to be higher than in adults.

Anthropometry↗
PubMed1998

Uric acid in chronic heart failure: a measure of the anaerobic threshold.

The anaerobic threshold (AT) is a measure of the balance between aerobic and anaerobic cellular metabolism. Hyperuricemia occurs in conditions that involve an imbalance between cellular oxygen consumption and carbon dioxide production, such as chronic heart failure (CHF). We therefore hypothesized that in CHF, serum uric acid might be related to the AT. Patients with CHF (n=40, aged 58.7+/-1.9 years; New York Heart Association Class I-IV; maximal oxygen consumption [MVO2], 18.7+/-01.1 mL/kg/min; left ventricular ejection fraction, 26%+/-2%) and 10 age-matched healthy controls underwent measurement of the serum uric acid level at rest and assessment of the AT. This was derived from MVO2 and the regression slope relating minute ventilation to carbon dioxide output (VE - VCO2) during a maximal treadmill exercise test. Compared with the healthy controls, patients with CHF had a lower AT (11.8+/-0.7 v 16.9+/-1.1 mL/kg/min, P < .001) and a higher serum uric acid concentration (493.8+/-22.4 v 308.7+/-21.5 micromol/L, P < .001). In univariate analyses of the CHF group, the AT correlated with serum uric acid (r=-.56, P < .001; AT=19.93 - (0.016 x uric acid), R2=.31, P < .001) and plasma creatinine (r=-.43, P < .01), but not with the diuretic dose. In stepwise regression analyses of the CHF group, serum uric acid emerged as a predictor of the AT (standardized coefficient=-.56, P < .001), whereas the diuretic dose and plasma creatinine failed to enter into the final models (multiple R2=.31, P < .001). In conclusion, in CHF there is an inverse relationship between the AT and the resting serum uric acid concentration. This is consistent with the known links between uric acid production and the imbalance in aerobic/anaerobic metabolism that occur in CHF. These findings provide the basis for using the simple measurement of the serum uric acid level as a surrogate measure of the AT.

Anaerobiosis↗
PubMed1990

[Threshold oxygen consumption and anaerobic threshold in patients with ischemic heart disease and healthy subjects].

Gas exchange and central hemodynamic parameters were examined in 70 patients with coronary heart disease and 40 healthy subjects during exercise. A low diagnostic informative value of threshold oxygen consumption values was found in the patients with coronary heart disease. It was shown that it was possible to indicate the anaerobic threshold in the patients by analysing the dynamics of cardiac output during exercise.

Adult↗
PubMed1988

Muscle metabolic profile and oxygen transport capacity as determinants of aerobic and anaerobic thresholds.

Aerobic and anaerobic thresholds determined by different methods in repeated exercise tests were correlated with cardiorespiratory variables and variables of muscle metabolic profile in 33 men aged 20-50 years. Aerobic threshold was determined from blood lactate, ventilation, and respiratory gas exchange by two methods (AerT1 and AerT2) and anaerobic threshold from venous lactate (AnTLa), from ventilation and gas exchange (AnTr) and by using the criterion of 4 mmol.1(-1) of venous lactate (AnT4mmol). In addition to ordinary correlative analyses, applications of LISREL models were used. The 8 explanatory variables chosen for the regression analyses were height, relative heart volume, relative diffusing capacity of the lung, muscle fiber composition, citrate synthase (CS) and succinate dehydrogenase activities, the lactate dehydrogenase--CS ratio, and age. They explained 58% of the variation in AerT1, 73.5% that of AerT2, 71% that of AnTr, 74.5% that of AnTLa, and 67.5% that of AnT4mmol.AerT and AnT alone explained 77% of the variation in each other. Both AerT and AnT were determined mainly by a muscle metabolic profile, with the CS activity of vastus lateralis as the strongest determinant. The factor 'submaximal endurance' which was measured with AerT and AnT seemed to be slightly more closely connected to 'muscle metabolic profile' than was 'maximal aerobic power' (= VO2max), but both also correlated strongly with each other (r = 0.92).

Adult↗
PubMed1993

A computational method for determination of the individual anaerobic threshold.

The individual anaerobic threshold (IAT) has received attention recently in the field of exercise physiology. The IAT is defined as the point during progressive exercise when lactate elimination from the blood is both maximal and equal to the diffusion from the working muscles. It has been theorized that an individual can maintain exercise for relatively long periods when working at the IAT. A common method for determination of the IAT is to perform a visual determination from plots of lactate concentration versus power output. This paper briefly describes the theoretical basis for determination of the IAT and presents an algorithm for its accurate calculation.

Algorithms↗
PubMed1991

Incremental test protocol, recovery mode and the individual anaerobic threshold.

The individual anaerobic threshold (IAT) is defined as the highest metabolic rate at which blood lactate (LA) concentrations are maintained at a steady-state during prolonged exercise. The purpose of this study was to compare the effects of active and passive recovery on the determination of IAT following both a submaximal or maximal incremental exercise test. Seven males (VO2max = 57.6 +/- 5.8 ml.kg-1.min -1) did two submaximal, incremental cycle exercise tests (30 W and 4 min per step) and two maximal incremental tests. Blood was sampled repeatedly during exercise and for 12 min during the subsequent recovery period, which was passive for one submaximal and one maximal test and active (approximately 35% VO2max) during the other tests. An IAT metabolic rate and power output were calculated for the submax-passive (IATsp, LA = 1.85 +/- 0.42 mmol.l-1), max-passive (IATmp, LA = 3.41 +/- 1.14 mmol.l-1), submax-active (IATsa, LA = 2.13 +/- 0.45 mmol.l-1) and max-active (IATma, LA = 3.44 +/- 0.73 mmol.l-1) protocols. At weekly intervals, the subjects exercised for 30 min at one of the four IAT metabolic rates. Active recovery did not affect the calculation of IAT, but following the maximal incremental tests, IAT occurred at a higher (p less than 0.05) power output, absolute VO2 and %VO2max (71% VO2max) compared with the IAT determined with the submaximal incremental tests (61% VO2max).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Reliability, reproducibility and validity of the individual anaerobic threshold.

The individual anaerobic threshold (IAT) has been defined as the highest metabolic rate at which blood lactate (La) concentrations are maintained at a steady state during prolonged exercise. The validity of this definition, however, has not been substantiated. Eleven men [maximum oxygen uptake (VO2max), mean (SD), 57.8 (6.9) ml.kg-1 x min-1) did two maximal incremental cycle exercise tests (30 W and 4 min per step). Blood was sampled repeatedly during exercise and for 9 min during the subsequent recovery period with light activity. The subjects then exercised at the power output equivalent of IAT for 45 min, until they could no longer continue or until rectal temperature reached 39 degrees C. Subjects performed two additional exercise tests. The intensity of these tests depended upon the LA and acid-base responses during the last 15 min of at least 30 min of exercise at IAT. If a steady state was achieved (La, pH and PCO2 changed by less than 0.5 mmol.l-1, 0.005 pH units and 0.3 kPa, respectively) or decreasing La and increasing pH values were observed, then the second test was performed at IAT +5% VO2max and the third session at either IAT +2.5% or +7.5% VO2max. Conversely if a steady state was not achieved during exercise at the calculated IAT, the intensity of the second test was set at IAT -5% VO2max. Depending on the La and acid-base responses during this test, the final session was performed at either IAT -2.5% or -7.5% VO2max.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗