Blood Lactate Clearance Research Articles

Blood lactate clearance during active recovery after an intense running bout depends on the intensity of the active recovery

High-intensity exercise training contributes to the production and accumulation of blood lactate, which is cleared by active recovery. However, there is no commonly agreed intensity or mode for clearing accumulated blood lactate. We studied clearance of accumulated blood lactate during recovery at various exercise intensities at or below the lactate threshold after high-intensity interval runs that prompted lactate accumulation. Ten males repeated 5-min running bouts at 90% of maximal oxygen uptake ([Vdot]O2max), which increased blood lactate concentration from 1.0 ± 0.1 to 3.9 ± 0.3 mmol · l−1. This was followed by recovery exercises ranging from 0 to 100% of lactate threshold. Repeated blood lactate measurements showed faster clearance of lactate during active versus passive recovery, and that the decrease in lactate was more rapid during higher (60–100% of lactate threshold) than lower (0–40% of lactate threshold) (P < 0.05) intensities. The more detailed curve and rate analyses showed that active recovery at 80–100% of lactate threshold had shorter time constants for 67% lactate clearance and higher peak clearance rates than 40% of lactate threshold or passive recovery (P < 0.05). Finally, examination of self-regulated intensities showed enhanced lactate clearance during higher versus lower intensities, further validating the intensity dependence of clearance of accumulated blood lactate. Therefore, active recovery after strenuous exercise clears accumulated blood lactate faster than passive recovery in an intensity-dependent manner. Maximum clearance occurred at active recovery close to the lactate threshold.

Effects of compression stockings during exercise and recovery on blood lactate kinetics

This study aimed to investigate if wearing compression stockings (CS) during exercise and recovery could affect lactate profile in sportsmen. Eight young healthy trained male subjects performed two maximal exercise tests on a cycle ergometer on two different occasions performed randomly: CS during both exercise and recovery, and no CS. Blood lactate concentration was taken during exercise and at 0, 3, 5, 10, 15, 30 and 60 min post-exercise. The individual blood lactate recovery curves were fitted to a biexponential time function: La(t) = La(0) + A1(1 - e(-gamma1t)) + A2(1 - e(-gamma2t)), where gamma(1) and gamma(2) denote the abilities to exchange lactate between the previously active muscles and the blood and to remove lactate from the organism, respectively. A significantly higher blood lactate value at the end of the maximal exercise was found (12.1 +/- 0.5 vs. 10.8 +/- 0.5 mmol l(-1)) wearing CS as compared to no CS (P < 0.05). Lower gamma(1) and higher gamma(2) values were observed with CS during recovery, as compared to no CS. It was concluded that CS during graded exercise leads to a significant higher blood lactate value at exhaustion. Since lactate exchanges were expected to be decreased during exercise due to CS, this result was likely attributable to a higher lactate accumulation related to a greater overall contribution of anaerobic glycolysis. Although the lactate removal ability was significantly improved when wearing CS during recovery, its efficacy in promoting blood lactate clearance after high-intensity exercise is limited.

Effects of oral supplementation of mint extract on muscle pain and blood lactate

Effects of oral supplementation of mint extract on muscle pain and blood lactate Study aim: To determine the effects of mint extract on muscle pain and blood lactate levels after a 400-m run. Material and methods: A group of 16 physical education students (mean age 21.81 ± 2.13 years) volunteered to participate in the study. The subjects were randomly assigned into 3 groups: mint, placebo or control. The mint group was given orally mint extract (5 ml/kg of body mass) and the placebo group was given unsweetened tea (5 ml/kg) in a double-blind fashion and cross-over design one hour before a 400-m running test. Subjects in the control group remained untreated. The effect of mint extract on muscle pain was recorded by an inquiry; blood lactate levels were measured after the running test. Results: Oral administration of mint extract significantly (p&lt;0.01) decreased blood lactate concentrations but muscle pain levels remained unchanged in all groups. Conclusions: Oral administration of mint extract may have a beneficial effect on blood lactate clearance and therefore may increase athletic performance.

EMF-2: End Expiratory Carbon Dioxide Concentrations to Predict Blood Lactate Concentration and Lactate Clearance in Emergency Department Patients With Sepsis

EMF-2: End Expiratory Carbon Dioxide Concentrations to Predict Blood Lactate Concentration and Lactate Clearance in Emergency Department Patients With Sepsis

Relationships Between Blood Lactate Clearance and Measures of Aerobic Capacity in Elite Women's Ice Hockey

Successful performance in ice hockey relies on a combination of anaerobic and aerobic energy systems. The relationships between blood lactate and indirect measures of aerobic capacity have not been investigated in elite female ice hockey players. PURPOSE: To determine relationships between blood lactate clearance, the difference between lactate immediately following an on-ice Repeat Sprint Skate Test (RSS) (Bracko & George, 2001) and lactate after 4-6 mins recovery, and other measures of aerobic capacity in elite female ice hockey players. METHODS: Players on the University of Alberta women's ice hockey team (n=80, 21.1±2.6 yrs) completed pre-season tests of aerobic fitness (Leger test [Leger, 1988]) (off-ice) and RSS. Blood lactate clearance, drop-off times on RSS (difference between first and third repeat), heart rate drop-offs (post-RSS HR - recovery HR differences), and Leger test estimates of VO2max were used as proxies for aerobic capacity. Bivariate Pearson correlations were run (SPSS Mac Version 10.0), with a significance level set a priori at p<0.05. RESULTS: No significant relationships were found between lactate clearance and any aerobic measures (r= −.034 to .113, p>0.10). However, higher VO2max estimates from the Leger test were significantly related to better scores for on-ice measures of aerobic capacity (RSS drop-off, r=-.460, -.490, p=.000; HR drop-off; r=.293, p =.017). CONCLUSIONS: Lactate clearance is not related to on and off-ice measures of aerobic capacity in elite female hockey players; however, high predicted VO2max is correlated to better drop-off time and HR recovery after sprint skating.

Scavenging and anti-fatigue activity of fermented defatted soybean peptides

Many bioactive peptides possess specific biological properties that make these potential ingredients of health-promoting foods. Increasing attention is being focused on physiologically active peptides derived from soybean proteins. In this study, soybean peptides were produced by fermentation of defatted soybean meal with Bacillus subtilis SHZ and purified by ultrafiltration and gel chromatogram. Free radical scavenging property and the effect on anti-fatigue of the peptides were evaluated in vitro and in vivo, respectively. Swimming endurance tests of mice were carried out after 20 days of soybean peptides administration (0, 100, 200, 400 mg/kg BW/day for control, low-dose, middle-dose and high-dose group, respectively). And the blood lactate and hepatic glycogen of mice were determined. Results showed that the purified peptides exhibited significant (P < 0.01) scavenging potencies on superoxide (62%) and hydroxyl (96%) at a concentration of 10 mg/ml. The average swimming time of the low-, middle- and high-dose group was increased by 20.91, 45.45 and 70% compared with that of control group, respectively. And administration with soybean peptides could significantly accelerate the clearance of blood lactate after mice swimming (P < 0.01). The hepatic glycogen storage of middle and high dose groups were obviously increased (P < 0.05). It suggested that the soybean peptides produced by fermentation could significantly alleviate physical fatigue of the mice.

Efeitos de três programas de fisioterapia respiratória (PFR) em portadores de DPOC

Effects of Three Respiratory Physical Therapy Programs on Patients with COPD Objective: To evaluate the effects of three respiratory physical therapy programs consisting of physical training on a treadmill and/or respiratory muscle training (RMT), on patients with COPD. Methods: Twenty-five patients of both sexes with moderateto-severe COPD were randomized into three groups: the first group (G1) underwent RMT at 30% of the maximal inspiratory pressure obtained each week; the second group (G2) underwent physical training at 70% of the heart rate achieved in the symptom-limited cardiorespiratory exercise test (CRET); and the third group (G3) underwent RMT together with physical training, at the same intensities mentioned above. All of the programs consisted of three sessions per week for six consecutive weeks. Results: Following treatment, significantly increased respiratory muscle strength was observed in G1. In G2, there was significantly increased walking distance and decreased heart rate and expiratory minute ventilation in CRET at the same velocity (isovelocity), and improvement in the functional capacity domain of the quality of life (QOL) questionnaire. In G3, there was significantly increased respiratory muscle strength, increased walking distance, decreased systolic arterial pressure and decreased blood lactate in CRET at the same velocity, and improvement in QOL. Conclusion: These findings suggest that physical training together with RMT was the best therapeutic alternative among the programs investigated in the present study. As well as providing an evident improvement in effort tolerance and QOL in the patients, it provided an additional effect regarding physiological adaptations to exercise with greater efficacy in clearance and/or lower production of blood lactate during effort.

Effects of Aging on the Renal Function after Physical Exercise

PURPOSE: The effects of aging on renal function (RF) following exhaustive exercise are unknown. This study was conducted to investigate these effects on 352 healthy subjects after an exhaustive treadmill run. METHODS: The subjects were of both sexes, and ranged in age from 8 to 76 years. Urinary excretion of protein (uTP), blood lactate (bLA), blood pressure(BP) and creatinine clearance (Ccr) were measured as an index of glomerular nitration rate (GFR). RESULTS: Ccr was found to decrease significantly directly after exercise and to recover to its pre-exercise level 30–60 min later. Ccr in males under 25 years of age decreased to 55.3% of the pre-exercise level directly after exercise, while in males 25 to 50 years old and those over 50, Ccr decreased to 68.8% and 86.9%, respectively, of the pre-exercise level. Similar levels of decrease in Ccr were observed in females directly after exercise. The net decrease in Ccr([[Unsupported Character - #8895;]] Ccr) directly after exercise was remarkable in younger subjects, and it was found to decrease with aging. Nevertheless, no difference in [[Unsupported Character - &#8895;]] Ccr was found in subjects from 8 to 40 years of age. NetuTP measured 30 min after exercise also decreased in relation to aging. A significant coefficient of correlation (r=−0.695, p <0.001) was found between [[Unsupported Character -#8895;]] Ccr and maximum heart rate (HRmax). CONCLUSIONS: The present results indicate that the younger the subject, the longer he or she is able to run before reaching exhaustion. A remarkable decrease in Ccr, and increases in BP, bLA and HRmax were induced after exhaustive exercise by younger subjects.

Oxygen uptake-to-delivery relationship: a way to assess adequate flow

Invasive and noninvasive monitoring facilitates clinical evaluation when resuscitating patients with complex haemodynamic disorders. If the macrocirculation is to be stable, then it must adapt to blood flow or blood flow must be optimized. The objective of flow monitoring is to assist with matching observed oxygen consumption (VO2) to pathophysiological needs. If an adequate balance cannot be maintained then dysoxia occurs. In this review we propose a simple schema for global reasoning; we discuss the limitations of VO2 and arterial oxygen delivery (DaO2) assessment; and we address concerns about increasing DaO2 to supranormal values or targeting pre-established levels of DaO2, cardiac output, or mixed venous oxygen saturation. All of these haemodynamic variables are interrelated and limited by physiological and/or pathological processes. A unique global challenge, and one that is of great prognostic interest, is to achieve rapid matching between observed and needed VO2 – no more and no less. However, measuring or calculating these two variables at the bedside remains difficult. In practice, we propose a distinction between three situations. Clinical and blood lactate clearance improvements can limit investigations in simple cases. Intermediate cases may be managed by continuous monitoring of VO2-related variables such as DaO2, cardiac output, or mixed venous oxygen saturation. In more complex cases, three methods can help to estimate the needed VO2 level: comparison with expected values from past physiological studies; analysis of the relationship between VO2 and oxygen delivery; and use of computer software to integrate the preceding two methods.

The Effects of Cordyceps and Rhodiola Supplementation on Physiological Performance Indices During Cycling in Males

1172 Cordyceps sinensis (Cs), an herb used in traditional Chinese medicine to treat a multitude of ailments, and Rhodiola rosea (Rr), an herb used in traditional Eastern European and Asian medicine to stimulate the nervous system, have both been reported to enhance performance. PURPOSE: The purpose of this research was to examine the effects of a formula containing Cs and Rr (Cs-Rr) on the potential relationships between maximum oxygen consumption (VO2max), time to exhaustion (TE), muscle tissue oxygen saturation (StO2), and blood lactate (BLa) in male participants during maximal exercise. METHODS: This study followed a double blind, randomized, treatment-control, pretest-posttest design. Cs-Rr or placebo capsules were administered randomly. The treatment group was given the supplement Cs-Rr taking 6 capsules (2000mg) every morning with water for 6 days followed by 3 capsules (1000mg) each morning with water for 7 days while the control group was given a placebo. Eight (8) subjects performed two graded exercise stress tests to volitional fatigue on a cycle lode ergometer. The workload began at 50 watts (w) of power and increased after two minutes by 25w. Thereafter, power was increased every four minutes by 25w until volitional fatigue. Dependent variables measured were VO2max (L*min.−1), TE (min), StO2 (%), and BLa (mM). Statistical procedures included a Repeated Measures ANOVA to determine within subject as well as between subject differences in physiological measures between tests. A Pearson Product R Correlation Coefficient was run to determine associations between physiological measures between tests. Statistical significance was set at p ≤ 0.05. RESULTS: Treatment participant characteristics were: age 33.0 (12.6) y, height 177.3 (9.5) cm, and weight 77.3 (5.1) kg. Control participant characteristics were: age 23.8 (2.9) y, height 179.5 (3.9) cm, and weight 76.4 (9.4) kg. The Repeated Measures ANOVA revealed no significant differences in performance between the treatment and control group. The Pearson Product R Correlation Coefficient revealed significant associations between variable thresholds (LaT, StO2T, HRT, and VT) prior to supplementation (pretest). CONCLUSION: Cs-Rr does not enhance VO2max, TE, StO2, or BLa clearance in males.

COMPARING POST EXERCISE BLOOD LACTATE BETWEEN SEA LEVEL AND ALTITUDE NATIVES

Blood lactate appearance and clearance has been closely linked to fatigue (Grassi et al., 1996). At altitude and during intense levels of exercise, there is an increase in lactate formation, a drop in pH and an increased fatigue rate. PURPOSE: It is the purpose of this study to compare percent recovery, based on post-exercise (PE) blood lactate (La), with sea level and altitude natives. METHODS: Fourteen (N = 14) subjects living and training at sea level (n = 7) and altitude (n = 7) were matched by demographic measures. Each subject completed a cycle ergometer protocol with increasing workload every three (3) minutes until volitional fatigue. Resting La (mM), peak La and recovery La (20 min. PE) were taken via finger-stick to determine percent recovery. RESULTS: Percent recovery and maximal heart rate were significantly greater in the sea level subjects when compared to their altitude counterparts.Table 1: Mean (SD) Measures between Sea Level and Altitude NativesConclusion: The following conclusions were established: (1) lactate clearance is enhanced in sea level cyclists, and (2) sea level cyclists reach greater maximal heart rates when compared to altitude cyclists. Lactate removal is enhanced through a greater circulatory component and/or an enhanced oxidative metabolism of lactate, facilitated by an increased partial pressure of oxygen.

Performance evaluation of swimmers: scientific tools.

The purpose of this article is to provide a critical commentary of the physiological and psychological tools used in the evaluation of swimmers. The first-level evaluation should be the competitive performance itself, since it is at this juncture that all elements interplay and provide the 'highest form' of assessment. Competition video analysis of major swimming events has progressed to the point where it has become an indispensable tool for coaches, athletes, sport scientists, equipment manufacturers, and even the media. The breakdown of each swimming performance at the individual level to its constituent parts allows for comparison with the predicted or sought after execution, as well as allowing for comparison with identified world competition levels. The use of other 'on-going' monitoring protocols to evaluate training efficacy typically involves criterion 'effort' swims and specific training sets where certain aspects are scrutinised in depth. Physiological parameters that are often examined alongside swimming speed and technical aspects include oxygen uptake, heart rate, blood lactate concentration, blood lactate accumulation and clearance rates. Simple and more complex procedures are available for in-training examination of technical issues. Strength and power may be quantified via several modalities although, typically, tethered swimming and dry-land isokinetic devices are used. The availability of a 'swimming flume' does afford coaches and sport scientists a higher degree of flexibility in the type of monitoring and evaluation that can be undertaken. There is convincing evidence that athletes can be distinguished on the basis of their psychological skills and emotional competencies and that these differences become further accentuated as the athlete improves. No matter what test format is used (physiological, biomechanical or psychological), similar criteria of validity must be ensured so that the test provides useful and associative information concerning current or future performance. The practical worth of any proposed testing or monitoring protocol should be carefully evaluated. In addition, the developmental stage of the athlete(s) in question should be reflected in the testing/monitoring programme. Finally, increasing technological innovations will bring to the pool deck or dry-land training area simple, fast and advanced diagnostic tools, particularly in the areas of blood-borne markers of training response and neuromuscular excitability.

Effects of high and low blood lactate concentrations on sweat lactate response.

Sweat lactate results from eccrine gland metabolism, however, the possible clearance of blood lactate through sweat has not been resolved. On separate days in an environmental chamber (32 +/- 1 C) 12 subjects completed a constant load (CON) (30 min at 40% VO2 max) and an interval cycling trial (INT) (15 one-min intervals at 80% VO2 max, each separated by one min rest) each designed to elicit different blood lactate responses. Each 30 min cycling trial was preceded by 15 min warm-up (30 watts) and followed by 15 min passive rest. Sweat and blood were analyzed for lactate concentration at 15, 25, 35, 45, and 60 min during CON and INT. Total body water loss was used to calculate sweat rate (ml/hr). Blood lactate was significantly greater (p < or = 0.05) at 25, 35, 45, and 60 min during INT compared to CON (approximately 5 mmol/L vs 1.5 mmol/L). Sweat lactate was not significantly different (p>0.05) between trials at any time (approximately 10 mmol/L). Sweat rates (approximately 600ml/hr) and estimated total lactate secretion were not significantly different (CON vs. INT) (p > 0.05). Elevated blood lactate was not associated with changes in sweat lactate concentration. Sweat lactate seems to originate in eccrine glands independent of blood lactate.

Oxygen consumption, blood lactate and inter-individual variation in the gulf killifish, Fundulus grandis, during hypoxia and recovery

Rates of oxygen consumption ( M ̇ O 2 ) for Fundulus grandis, the gulf killifish, were measured in air-saturated water, at four progressively lower levels of oxygen and upon normoxic recovery. The pattern of M ̇ O 2 versus oxygen partial pressure ( P wO 2) was that of an oxygen regulator, with a critical oxygen pressure ( P c) of 34 torr (1 torr=133.3 Pa). Below this value, M ̇ O 2 decreased and the concentration of blood lactate increased, indicating anaerobic metabolism during hypoxia. Recovery was characterized by elevated M ̇ O 2 compared to the initial normoxic exposure, coupled with the rapid clearance of blood lactate. Variation in M ̇ O 2 among the individual fish was appreciable and, in general, it was greater at higher levels of P wO 2. This inter-individual variation was significantly larger than the variation between replicate measures of M ̇ O 2 for a given individual, i.e. it cannot be attributed solely to random error. Furthermore, values for M ̇ O 2 during normoxia were found to be repeatable when the same fish were used in multiple experimental trials. The observation of significant, repeatable inter-individual variation in M ̇ O 2 suggests that such variation is a real and potentially important feature of fish metabolism.

Effect of endurance training on blood lactate clearance after maximal exercise

The aim of this study was to measure serial changes in the rate of blood lactate clearance (gamma2) in response to sequential periods of training and detraining in four male triathletes aged 22-44 years. There were two major phases of training and taper, each lasting 4-5 weeks (training 1=5 weeks, taper 1=2 weeks, training 2= 4 weeksand taper 2=2 weeks), in preparation for a triathlon competition. The training stimulus absorbed by each subject was carefully quantified from the duration and intensity of the training exercise. A serial weekly measure of each trainee's physical response to training was evaluated as the peak power, termed a ‘criterion performance’, developed by a subject during a 30 W .min-1 ramp cycle ergometer test to exhaustion each week. During 30 min of recovery after this test, 13 samples of venous blood were drawn sequentially from a subject to measure the blood lactate recovery curve. The rate constant of blood lactate clearance was estimated by a non-linear least-squares regression technique. In addition, the concurrent time to peak lactate concentration and the peak lactate concentration were also estimated to help define changing lactate kinetics. The criterion performance generally declined throughout each period of incremental training and improved during each taper period, rising iteratively in this way to be clearly above baseline by the end of the second taper. The blood lactate clearance rate increased transiently in early training before declining from the middle of the first training period to the middle of the first taper; thereafter, gamma2 increased above baseline in each trainee throughout the remaining first taper and the major portion of the second training period, decreasing only in the final criterion performance test. The time to peak lactate declined from baseline throughout all phases of training and taper. Peak blood lactate increased in all subjects to the end of the first taper before declining by the end of the second training period, rising again to baseline levels during the second taper. The change in gamma2 was examined relative to the work rate achieved in cycle ergometry above an initial baseline score (DeltaCP) and against concurrent peak blood lactate. There was a clear upward shift in gamma2 above baseline throughout the first and second training and taper in two subjects; this was less clear in the remaining two subjects, each of whom had a lower DeltaCP. We conclude that this indicates improved lactate clearance, manifest by the change in gamma2 induced by endurance training.

Effect of music on perceived exertion, plasma lactate, norepinephrine and cardiovascular hemodynamics during treadmill running.

We examined the effects of listening to headphone music in ten well trained men (25.1 +/- 6 years) during treadmill running. Maximal oxygen consumption, determined by open circuit spirometry, was followed by two submaximal work bouts 72 hours apart. The work bouts consisted of a supine rest, a 15 minute run at 70% of maximal oxygen consumption, and a three minute active recovery period. Participants listened to music during one of the two trials. Hemodynamic variables and perceived exertion were recorded at three minute intervals during each trial. A venous blood sample, obtained prior to and following each trial, was assayed for norepinephrine and plasma lactate. Analysis of variance revealed significant differences (p < 0.05) between the no music versus the exercise with music trial for (aggregate data 3,6,9,12,15 minutes): heart rate 152.9 +/- 5.3 to 145.9 +/- 4.7 beats x min(-1); systolic blood pressure, 158.1 +/- 3.7 to 151.7 +/- 3.3 mmHg; rate-pressure product 242.2 +/- 11.5 to 222.1 +/- 11.4; exercise lactate 2.75 +/- 0.15 to 2.13 +/- 0.18 mmol x l(-1); and perceived exertion 14.4 +/- 0.4 to 12.9 +/- 0.4. A 17.5% lower level of norepinephrine (841.5 +/- 314.7 to 694.1 +/- 254.5 pg x ml[-1]) in the exercise and music trial was not statistically significant (p<0.05); however a moderate effect size (ES = 0.52) was calculated and may be of practical significance considering the variability of the sample. Higher values for hemodynamics and lactate in the no music trial is suggestive of a greater metabolic demand; however, oxygen consumption was not different. Perhaps the music allowed individuals to relax reducing muscle tension thereby increasing blood flow and lactate clearance while decreasing lactate production in working muscle. The combined results of this study suggest the introduction of music has a psychobiological impact on the exerciser demonstrated by changes in perceived effort, lactate and norepinephrine.

Lactate Metabolism In Rainbow Trout

ABSTRACT We have investigated the metabolic fate of blood lactate in resting rainbow trout and in fish recovering from a bout of exhaustive exercise. At rest and during recovery from exercise, the majority of blood lactate was oxidized, the proportion increasing with increasing oxygen consumption. It is estimated that, during recovery from exhaustive exercise, lactate released from the muscle has the potential to fuel a significant portion of oxidative metabolism. The bulk of the remaining blood lactate reappeared in the muscle lactate pool, probably via direct uptake by the muscle. There was a significant incorporation of blood lactate into the muscle glycogen pool, providing strong evidence for in situ glycogenesis as the mode for muscle glycogen replenishment. To investigate the role of the liver in blood lactate clearance, trout were functionally hepatectomized by ligation of the hepatic portal circulation. The exercise performance of hepatectomized fish was equal to that of sham-operated fish and controls, indicating that muscle relies primarily on endogenous fuel stores. Furthermore, blood lactate levels immediately after exercise were greater and muscle metabolic recovery was faster in hepatectomized fish than in sham-operated fish and controls. These observations suggest that glycogen resynthesis in trout muscle may be retarded because of a non-recoverable loss of substrate (i.e. lactate) from the muscle, because the lactate released is utilized by the liver. These results are discussed in view of what is known about these processes in other ectothermic vertebrates.

Enhancement of blood lactate clearance following maximal swimming. Effect of velocity of recovery swimming.

Swimming is an endurance-intensive sport resulting in accumulation of lactate. Repeat performances are often necessary in championship events. Lactate produced during a maximal effort requires time to metabolize to a base level. If this does not occur, performance in a repeat effort may be impaired. Thus, techniques to enhance lactate clearance are of potential benefit to the athlete. We have demonstrated previously that swimming at 65% of maximum velocity significantly improved lactate clearance over passive resting. This study tested the effect of various swimming velocities on lactate clearance. Following a maximal swim, blood lactate clearance was tracked during a 15 minute cool down swim. Velocities of 55%, 65%, and 75% of maximum were tested. The results confirmed that cool down swimming will return lactate values to near resting levels in the test interval. However, statistical superiority of any of the test velocities was not demonstrated. The intensity of the swim should be below the lactate accumulation level. The 65% of maximum velocity was felt by all swimmers to be most comfortable and is a good target velocity for the athlete to reference.

Mammalian metabolite flux rates in a teleost: lactate and glucose turnover in tuna.

Lactate and glucose turnover rates were measured by bolus injection of [U-14C]lactate and [6-3H]glucose in cannulated lightly anesthetized skipjack tuna, Katsuwonus pelamis. Our goals were to find out whether the high rates of lactate clearance reported during recovery from burst swimming in tuna could be accounted for by high blood lactate fluxes; to extend the observed correlation between lactate turnover and lactate concentration in mammals to a nonmammalian system, and to assess the importance of lactate and glucose as metabolic fuels in tuna and to compare their flux rates with values reported for mammals. Measured lactate turnover rates ranged from 112 to 431 mumol X min-1 X kg-1 and were correlated with blood lactate concentration. Glucose turnover rate averaged 15.3 mumol X min-1 X kg-1. When correcting for body mass and temperature, skipjack tuna has at least as high or even higher lactate turnover rates than those recorded for mammals. Tuna glucose turnover rate is similar to that of mammals but much higher than levels found in other teleosts. Even the highest lactate turnover rate measured in tuna cannot fully account for the rate of blood lactate clearance observed during recovery, suggesting that some of the lactate produced in skeletal muscle must be metabolized in situ. After injection of [U-14C]lactate, less than 5% of the total blood activity was recovered in glucose, suggesting that the Cori cycle is not an important pathway of lactate metabolism in tuna.

Effect of ration of liver oxidation of racemic lactate and of thiamine on blood lactate clearance.

Effect of ration of liver oxidation of racemic lactate and of thiamine on blood lactate clearance.