Lactate Removal Research Articles

Regulation of the exercise-induced expression of the monocarboxylate transporters MCT1 and MCT4 in skeletal muscle

Lactate is a dynamic substrate that has great potential as an energy source. During exercise, lactate is transported out of contracting muscle cells and is oxidized by the heart and oxidative types of muscles. The diffusion of monocarboxylates, such as lactate and pyruvate, across the plasma membranes of mammalian cells is facilitated by a family of integral membrane transport proteins called monocarboxylate transporters (MCTs). Currently, 14 unique members of the MCT family have been identified. In skeletal muscle, 2 isoforms with different kinetic properties, MCT1 and MCT4, are expressed and have been identified as key transporters regulating lactate flux across the plasma membrane. MCT1 is primarily expressed in oxidative fibers, in which lactate can be used as fuel for mitochondrial oxidation, and is closely associated with the rate of lactate uptake. MCT4 is highly expressed in glycolytic fibers and may be responsible for the removal of lactate produced by glycolysis. Rapid changes in the expression of MCT1 and MCT4 can occur in response to acute exercise, the regulation of which may involve transcriptional and post-transcriptional mechanisms. Increased MCT expression may be the primary factor enhancing the rate of lactate flux. However, the molecular regulatory mechanisms by which exercise upregulates MCT expression in muscle are not yet fully understood. It is important to understand how exercise regulates MCT expression so that training programs can be designed to increase the muscle oxidative disposal of lactate.

Bringing Light into the Dark: Effects of Compression Clothing on Performance and Recovery

To assess original research addressing the effect of the application of compression clothing on sport performance and recovery after exercise, a computer-based literature research was performed in July 2011 using the electronic databases PubMed, MEDLINE, SPORTDiscus, and Web of Science. Studies examining the effect of compression clothing on endurance, strength and power, motor control, and physiological, psychological, and biomechanical parameters during or after exercise were included, and means and measures of variability of the outcome measures were recorded to estimate the effect size (Hedges g) and associated 95% confidence intervals for comparisons of experimental (compression) and control trials (noncompression). The characteristics of the compression clothing, participants, and study design were also extracted. The original research from peer-reviewed journals was examined using the Physiotherapy Evidence Database (PEDro) Scale. Results indicated small effect sizes for the application of compression clothing during exercise for short-duration sprints (10-60 m), vertical-jump height, extending time to exhaustion (such as running at VO2max or during incremental tests), and time-trial performance (3-60 min). When compression clothing was applied for recovery purposes after exercise, small to moderate effect sizes were observed in recovery of maximal strength and power, especially vertical-jump exercise; reductions in muscle swelling and perceived muscle pain; blood lactate removal; and increases in body temperature. These results suggest that the application of compression clothing may assist athletic performance and recovery in given situations with consideration of the effects magnitude and practical relevance.

Differences in lactate exchange and removal abilities between high-level African and Caucasian 400-m track runners

The present study aimed to investigate (1) whether high-level 400-m track runners of different ethnic origin displayed divergent post-run blood lactate concentrations (p400m[La]) and (2) if this discrepancy was based on differences in lactate exchange and removal abilities. Twenty male African (n = 12) and Caucasian (n = 8) runners, paired in terms of personal record, performed (1) an all-out 400-m run to measure p400m[La] at 3, 5 and 7 min into recovery and (2) a 1-min 25.2 km h(-1) running (not maximal but standardized) exercise followed by 90-min passive recovery to determine individual blood lactate recovery curves (IBLRC). IBLRCs were fitted to a bi-exponential time function: [Formula: see text] where γ 1 and γ 2 denote lactate exchange ability between the previously worked muscles and blood, and overall ability for lactate removal, respectively. The quantity of lactate accumulated at the end of the 1-min exercise (Q LaA) was also estimated. Our study showed that after the all-out 400-m run, p400m[La] was lower in African than in Caucasian runners at 3 and 5 min but not at 7 min into recovery. After the standardized exercise, γ 1 and γ 2 were lower (p < 0.01) and Q LaA was higher (p < 0.05) in African than in Caucasian runners. These data suggest that for similar performance levels, ethnicity involves differences in lactate accumulation, exchange and removal.

Effects of glucogenic and ketogenic feeding strategies on splanchnic glucose and amino acid metabolism in postpartum transition Holstein cows

Nine periparturient Holstein cows catheterized in major splanchnic vessels were used in a complete randomized design with repeated measurements to investigate effects of glucogenic and ketogenic feeding strategies on splanchnic metabolism of glucose and amino acids. At parturition, cows were assigned to 1 of 3 feeding strategies: a glucogenic diet (GLCG) based on sodium hydroxide treated wheat grain (56.5% of diet dry matter); a ketogenic diet (KETO) based on fodder beets (40.5% of diet dry matter); or an alfalfa-glucogenic strategy (ALF-GLCG) supplying 100% alfalfa (Medicago sativa L.) haylage at the day of parturition, followed by a 6-d linear shift to the GLCG diet. Samples were obtained 14d before expected parturition as well as at 4, 15, and 29d in milk (DIM). The net portal release of glucose was greatest with GLCG, reflecting the higher intake of ruminal escape starch with GLCG, as compared with a lower starch intake with KETO. Postpartum, the portal recovery of feed starch was greater (28±3%, mean ± SEM) with KETO as compared with GLCG (15±4%). At 4 DIM, the net hepatic release of glucose was greatest with KETO and least with ALF-GLCG, whereafter it increased as lactation progressed with ALF-GLCG and GLCG, but not with KETO. The high alfalfa haylage allowance at 4 DIM with the ALF-GLCG treatment induced the lowest net release of nutrients from the splanchnic tissues at 4 DIM. The hepatic removal of lactate as percent of total influx (mean ± SEM) increased from 27±3% prepartum to 56±3% at 4 DIM. The hepatic removal of lactate as percent of net portal release increased from 144±10% prepartum to 329±17% at 4 DIM with ALF-GLCG and KETO as compared with 242±20% in GLCG. No clear evidence for an amino acid sparing effect in splanchnic tissues from increasing small intestinal glucose absorption was observed. In conclusion, the glucogenic feeding strategy induced the highest glucogenic status among the tested feeding strategies due to greater release of glucose from splanchnic tissues. In contrast, the immediate postpartum high allowance of alfalfa haylage provided the lowest amount of nutrients from the splanchnic tissues, inducing low glucogenic status, pointing to the importance of allocating highly digestible diets to postpartum transition cows. Salvaging glucogenic carbon via interorgan transfer of lactate from peripheral tissues supported the immediate postpartum incremental increase in hepatic glucose release rather than hepatic catabolism of amino acids.

Capillary electrophoresis – A new tool for ionic analysis of exhaled breath condensate

Exhaled breath condensate has been analyzed for its ionic content by capillary electrophoresis with capacitively coupled contactless conductometric detection. A simple device for collection of small volumes (100–200μL) of exhaled breath condensate in less than 2min was developed. A method for simultaneous determination of inorganic cations, inorganic anions and organic anions from the samples using dual-opposite end injection principle with a short fused silica capillary (35cm, 50μm I.D.) was developed. A background electrolyte composed of 20mM 2-(N-morpholino)ethanesulfonic acid, 20mM l-histidine, 30μM cetyltrimethylammonium bromide and 2mM 18-crown-6 was used. The analysis time was less than 3min with limits of detection reaching low μM levels for most of the anions and cations. It has been shown that changes of nitrite could be observed in acute inflammation of upper airways and in a person with diagnosed mild chronic obstructive pulmonary disease, while changes of other ions could also be observed. Lactate concentrations could also be monitored and about 4-fold increase of lactate concentration in exhaled breath condensate was determined following an exhaustive cycling exercise. The developed non-invasive sampling of exhaled breath condensate, followed by rapid capillary electrophoretic analysis, could be very useful in lung inflammatory disease screening as well as in monitoring fast metabolic processes such as lactate build-up and removal.

The kinetics of lactate production and removal during whole-body exercise.

BackgroundBased on a literature review, the current study aimed to construct mathematical models of lactate production and removal in both muscles and blood during steady state and at varying intensities during whole-body exercise. In order to experimentally test the models in dynamic situations, a cross-country skier performed laboratory tests while treadmill roller skiing, from where work rate, aerobic power and blood lactate concentration were measured. A two-compartment simulation model for blood lactate production and removal was constructed.ResultsThe simulated and experimental data differed less than 0.5 mmol/L both during steady state and varying sub-maximal intensities. However, the simulation model for lactate removal after high exercise intensities seems to require further examination.ConclusionsOverall, the simulation models of lactate production and removal provide useful insight into the parameters that affect blood lactate response, and specifically how blood lactate concentration during practical training and testing in dynamical situations should be interpreted.

Physiologic Responses of Competitive Canadian Cross-Country Skiers With Disabilities

To examine the acute cardiorespiratory and metabolic responses in competitive cross-country skiers with disabilities. Cross-sectional comparisons using a select group of Canadian athletes training for the Vancouver 2010 Paralympic Winter Games. Canmore Nordic Centre Provincial Park, Canmore, Alberta. Nine competitive cross-country skiers (4 with visual impairment, 1 with traumatic brain injury, 3 with spinal cord injury, and 1 with cerebral palsy). Three-minute and 12-minute exercise tests in the standing or sitting skiing position to voluntary fatigue. Cardiorespiratory responses using a telemetric system to compare the physiologic responses among the athletes with different disabilities. Heart rate (HR) and capillary lactate were measured at 2, 5, and 10 minutes of recovery. The t test results indicated that the peak values of the absolute and relative oxygen uptake (VO2peak), HR, and ventilation rate were significantly higher during the 12-minute compared with the 3-minute protocol during standing skiing. However, the oxygen pulse and ventilatory equivalent for oxygen ratio were not significantly (P > 0.05) different between the 2 protocols. Analysis of variance revealed no significant (P > 0.05) differences among the 3 trials for these peak physiologic responses during sitting skiing. Cross-sectional comparisons of the peak physiologic responses between the standing and sitting skiers indicated significantly (P < 0.05) higher values in the standing compared with the sitting position. Cardiorespiratory respiratory efficiency was significantly (P < 0.05) lower in the sitting compared with the standing position. HR during 10 minutes of recovery was significantly correlated with VO2peak. Pearson correlations were not significant between VO2peak and lactate removal during recovery. These descriptive findings during the standing and sitting skiing protocols provide preliminary data that would be useful in testing, training, and classification of competitive skiers with disabilities.

High-pressure phase behavior of propyl lactate and butyl lactate in supercritical carbon dioxide

Lactate esters synthesized with lactic acid and ester are used as solvents and reactants in various industries, including agricultural chemistry, pharmaceuticals, electronics, and fine chemicals. Among lactate esters, high purity propyl lactate and butyl lactate are used to produce fine chemicals and in the synthesis of chiral intermediates for use in pesticides and drugs. However, distillation for the removal of propyl lactate and butyl lactate alters or degenerates products due the high boiling points of these two lactate esters. This problem can be solved by supercritical fluid extraction (SCFE) at lower temperatures. SCFE process requires high-pressure phase behavior data on CO 2 and lactates for its design and operation. In this study, high-pressure phase behavior of propyl lactate and butyl lactate in CO 2 was measured from (323.2 to 363.2) K using a variable-volume view cell apparatus. Experimental data were well correlated by the Peng–Robinson equation of state using the van der Waals one-fluid mixing rules. The critical constants were estimated by the Joback method, the Constantinou–Gani method, and the Nannoolal–Rarey method. Acentric factor was estimated by the Lee–Kesler method.

Bicarbonate, NBCe1, NHE, and Carbonic Anhydrase Activity Enhance Lactate-H+Transport in Bovine Corneal Endothelium

To identify and localize the monocarboxylate transporters (MCTs) expressed in bovine corneal endothelial cells (BCEC) and to test the hypothesis that buffering contributed by HCO(3)(-), sodium bicarbonate cotransporter (NBCe1), sodium hydrogen exchanger (NHE), and carbonic anhydrase (CA) activity facilitates lactate flux. MCT1-4 expression was screened by RT-PCR, Western blot analysis, and immunofluorescence. Endogenous lactate efflux and/or pH(i) were measured in BCEC in HCO(3)(-)-free or HCO(3)(-)-rich Ringer, with and without niflumic acid (MCT inhibitor), acetazolamide (ACTZ, a CA inhibitor), 5-(N-Ethyl-N-isopropyl)amiloride (EIPA) (Na(+)/H(+) exchange blocker), disodium 4,4'-diisothiocyanatostilbene-2,2'-disulfonate (DIDS; anion transport inhibitor), or with NBCe1-specific small interfering (si) RNA-treated cells. MCT1, 2, and 4 are expressed in BCEC. MCT1 was localized to the lateral membrane, MCT2 was lateral and apical, while MCT4 was apical. pH(i) measurements showed significant lactate-induced cell acidification (LIA) in response to 20-second pulses of lactate. Incubation with niflumic acid significantly reduced the rate of pHi change (dpH(i)/dt) and lactate-induced cell acidification. EIPA inhibited alkalinization after lactate removal. Lactate-dependent proton flux was significantly greater in the presence of HCO(3)(-) but was reduced by ACTZ. Efflux of endogenously produced lactate was significantly faster in the presence of HCO(3)(-), was greater on the apical surface, was reduced on the apical side by ACTZ, as well as on the apical and basolateral side by NBCe1-specific siRNA, DIDS, or EIPA. MCT1, 2, and 4 are expressed in BCEC on both the apical and basolateral membrane (BL) surfaces consistent with niflumic acid-sensitive lactate-H(+) transport. Lactate dependent proton flux can activate Na(+)/H(+) exchange and be facilitated by maximizing intracellular buffering capacity through the presence of HCO(3)(-), HCO(3)(-) transport, NHE and CA activity.

Effects of cooldown methods and durations on equine physiological traits following high-intensity exercise

This study was initiated to investigate the physiologic effects of cooldown methods and durations on recovery following high-intensity exercise (3000 m, 10 m/s) of 25 Jeju crossbred horses. Heart rate (HR) was measured and blood samples were collected for glucose, blood lactate concentration, packed cell volume (PCV), total protein (TP), and hemoglobin (Hb) analysis. The cooldown methods employed involved walk rest (WR) or trot rest (TR), and the durations compared were 15, 30, and 60 min. A passive rest group (PR) was used as a control. According to the analysis, HR decreased after a 15 min rest in all groups, showing a faster recovery in the active rest groups, WR and TR, than in the PR group after 30 min ( P < 0.05). In the case of glucose, the decrease was faster in the WR15 group then the WR30 group suggesting that active rest is more effective in controlling this parameter ( P < 0.05). As for lactate, TR15 showed a 75% decrease which was a significantly positive effect. There were no differences in PCV between the groups. Horses in the PR group showed faster recovery for TP and Hb than those in the active rest groups ( P < 0.05), while lactate removal was faster in active rest groups than in the PR group, suggesting that the cooldown process plays an important role in recovery. This study showed that the cooldown method and duration employed after high-intensity exercise of horses makes a difference with regard to their physiologic status. Also, 15 min rest after exercise appears to be the most significant period in terms of duration. In conclusion, active rest was necessary for rapid recovery and a 15 to 30 min cooldown walk or trot was beneficial to the horses in which physical fatigue had accumulated. In particular, the active exercise method of trotting was found to be more effective than walking to remove lactate. In addition, the cooldown duration is expected to be more effective when adjusted according to the individual training state of the horse.

Minimally-invasive catheterization of the portal, hepatic and cranial mesenteric veins and the abdominal aorta for quantitative determination of hepatic metabolism in dairy cows

The objective of this study was to establish a minimally-invasive, ultrasound (US)-guided technique for the placement of indwelling catheters into the portal, hepatic, and cranial mesenteric veins as well as the abdominal aorta. Catheters were placed in eight healthy dairy cows on day 1. The patency of catheters was tested daily until day 14 when a necropsy was carried out. On day 6, energy intake and hepatic net output of glucose, removal of lactate, and oxygen were determined in seven cows. Post mortem examination revealed that all implanted catheters were in the intended locations. Loss of patency in one portal vein catheter on day 9 was attributable to a fibrin clot. Significant correlations were found between mean energy intake and mean hepatic plasma flow (r=0.91; P=0.004), hepatic glucose output (r=0.81; P=0.027) and hepatic removal of lactate (r=-0.70; P=0.08) and oxygen (r=-0.77; P=0.039), as well as between hepatic glucose net output and removal of lactate (r=-0.92; P=0.004). Minimally-invasive, US-guided transcutaneous catheter placement into the cranial mesenteric, portal and hepatic veins as well as the technique for catheterization of the abdominal aorta appear to be safe, and suitable for studies of quantitative hepatic metabolism in cattle.

Comparação de índices neuromusculares e fisiológicos de judocas em diferentes categorias de peso

This study aimed to compare physiological and neuromuscular indexes of judokas in different weight categories. Eighteen male judokas took part of the study grouped into three categories: extra-light/half-light, light/half-middle and middle/half-heavy weight. The following evaluations were performed: Counter Movement Jump (CMJ); Special Judo Fitness Test (SJFT); match simulation to obtain the peak blood lactate (LACmax) and the percentage of the blood lactate removal (BLR); incremental test to obtain anaerobic threshold (vAT) and peak velocity (PV) and pull test in the judogui to obtain the rate of force development (RFD). Only LACmax and CMJ showed differences in the categories, where judokas middle/half-heavy weight category showed higher values (p

Effects of Mo(VI) on phototrophic hydrogen production by Rhodobacter sphaeroides

Effects of Mo6+ concentration on phototrophic hydrogen production of Rhodobacter sphaeroides were investigated using lactate as the sole carbon source. Results showed that an increase of Mo6+ from nil to 1000 µg l−1 led to increases in hydrogen yield, maximum production rate, conversion efficiency, biomass yield and lactate removal. At 100 µg‐Mo l−1, the maximum rate was 12.0 ml h−1 l−1 with a conversion efficiency of 36.1%, the cell yields were 1.11 g‐cell g−1‐lactate and 2.4 g‐cell g−1‐TOC removed. Further increase of Mo6+ improved hydrogen production only marginally. Degradation of lactate by R. sphaeroides produced not just hydrogen but also acetate, butyrate, i‐valerate, i‐caproate, hexanoate and some unidentified organic intermediates, but did not produce propionate and alcohols. Nitrogenase activity, as measured by the acetylene reduction method, had no clear correlation with either Mo6+ concentration or hydrogen yield.

Effect of Different Types of Recovery on Blood Lactate Removal After Maximum Exercise

Effect of Different Types of Recovery on Blood Lactate Removal After Maximum Exercise Introduction. Despite physiological changes caused by immersion in liquid medium, few studies have been conducted to determine the kinetics of blood lactate removal under these conditions. The aim of this study was to verify the effect of active recovery, using a specific water bike, on the blood lactate concentration after maximum intensity exercise. Material and method. Ten healthy cycling athletes performed an Anaerobic Threshold Test by Heart Rate (HR) on a bicycle ergometer and an Anaerobic Threshold Test by Subjective Effort Perception on an aquatic bicycle ergometer. Three maximal test was performed immediately before each recovery type, in three different days: Passive Recovery on Land - PRL (horizontal position for 60 minutes), Passive Recovery in the Water - PRW (horizontal position, with the help of floats, in swimming pool for 60 minutes) and Active Recovery in the Water - ARW (the volunteer performed exercises on a water bicycle to an intensity corresponding to 85% of the intensity of LA in water, for 30 minutes, and remained in the same position of the PRW for another 30 minutes). Blood samples were collected 5, 15, 30 and 60 minutes after the maximal test, for lactate analysis. Results. The [La] blood did not show the difference between the three types of recovery at 5th min. From 15th min on, the difference between the ARW and the other two types of passive recovery was significant, and the ARW showed lower values. There was no significant difference between the PRW and PRL. Conclusion. Mere immersion in water is not enough to maximize the removal of blood lactate. This study demonstrates that active recovery held in water is effective for the removal of blood lactate in cyclists.

The Effects Of Different Recovery Protocols On Lactate Removal After A Maximal Swim Effort

Following high-intensity exercise, performance may be improved through active recovery, which may limit metabolite accumulation and therefore prevent the onset of acidosis in competitors. PURPOSE: To examine the effect of different active-recovery swimming protocols on the removal of lactate following a maximal swim effort.FigureMETHODS: 4 experienced swimmers were recruited for this pilot study. Each participant took part in 4 days of testing, including a familiarization session. On 3 different occasions, the participants completed a standardized warm up, a single 200 yd maximal effort swim, and 15 min of backstroke (BR), freestyle (FR), or passive (PR) recovery. Recovery paces for BR and FR were set at 175% of 100 yd trial time. PR consisted of quiet sitting for 15 min. Blood lactate samples were collected before warming up (PRE), 3-min post 200 yd maximal effort trial (POST), after 5-min of recovery (P5), 10-min of recovery (P10), and 15-min of recovery (P15). A 3 × 5 ANOVA with repeated measures was conducted. Alpha was set at 0.05. Tukey's post hoc analysis was used to further examine main effects. RESULTS: The RM ANOVA indicated a significant interaction between protocol and trial on the effect of lactate clearance, F(6.42, 25.68) = 2.54, p < 0.05. A significant main effect was also found between trials, F(3.21, 25.68) = 54.51, p < 0.001. CONCLUSIONS: The significant interaction between protocol and trial suggests that active recovery may be more effective in clearing blood lactate, than passive recovery. However, a clear distinction between active recovery patterns was not not discerned. Future research, with a larger sample size may provide further insight into the effectiveness of different active-recovery swimming protocols.

Relationship of aerobic and neuromuscular indexes with specific actions in judo

The aim of this study was to verify the relationship of aerobic and neuromuscular indexes with specific situations in judo. Eighteen male judokas took part in the study. The following assessments were performed: vertical jump (CMJ) on a force platform; Special Judo Fitness Test (SJFT) to obtain the number of throws and percentage of the maximal heart rate (%HRmax) one minute after the test; match simulation to obtain the peak blood lactate (LACmax) and the percentage of the blood lactate removal (BLR); incremental test to obtain the velocity at the anaerobic threshold (vAT) and peak velocity (PV) reached in the test. A significant correlation was observed between the number of throws in the SJFT, the vAT (r = 0.60; P < 0.01), PV (r = 0.70; P < 0.01) and CMJ (r = 0.74; P < 0.01). A significant inverse correlation was found between the LACmax and vAT (r = −0.59; P = 0.01). It can be concluded that the performance in the SJFT was determined by the aerobic capacity and power and the muscle power. Athletes with greater aerobic ability (vAT) presented lower blood lactate accumulation after the match. Analyser les relations entre indices aérobies et neuromusculaires avec des actions spécifiques du judo. Dix-huit judokas ont participé à cette étude. Ont été réalisées les évaluations suivantes : saut vertical (CMJ) ; Special Judo Fitness Test (SJFT) pour l’obtention du nombre de lancements et du pourcentage de la fréquence cardiaque maximale (%FCmax) ; simulation de match pour l’obtention du taux maximal de lactate sanguin (LACmax) et du pourcentage de la diminution de lactate (DLS) ; test incrémental pour l’obtention de la vitesse au seuil anaérobie (SA) et du sommet de la vitesse (SV) atteint dans l’essai. Il a été observé une corrélation significative entre le nombre de lancements dans le SJFT, la VLAn (r = 0,60 ; p < 0,01), SV (r = 0,70 ; p < 0,01) et le CMJ (r = 0,74 ; p < 0,01). Il a été trouvé une corrélation significative inverse entre le LACmax et la SA (r = −0,59 ; p = 0,01). On peut conclure que la performance dans SJFT a été déterminée par la capacité de la puissance maximale aérobie et par la puissance musculaire. Les athlètes ayant la plus grande capacité aérobie (SA) ont présenté une moindre accumulation de lactate sanguin après le match.

Extractive fermentation of l-(+)-lactic acid by Pediococcus pentosaceus using electrodeionization (EDI) technique

In this work, extractive fermentation of l-(+)-lactic acid (lactate) was carried out using an electrodeionization (EDI) technique. Pediococcus pentosaceus was used as the biocatalyst because of its homo-fermentative characteristic. The effect of initial lactate concentrations on microbial growth was initially investigated. A mathematical simulation of the product inhibition was successfully illustrated. It was found that the critical lactate concentration was approximately 80 g/L. Various operating conditions were investigated to assess the EDI performance. The system was subsequently applied for in situ removal of lactate from the fermentation broth. The specific deactivation constant ( k d) was substantially reduced from 0.026 h −1 to 0.0054 h −1 resulting in a much improved half life of the biocatalyst. The highest lactate concentration in the receiving solution was 185 g/L.

Blood Lactate Concentration and Clearance in Elite Swimmers During Competition

Blood lactate concentration, [BLa], after swimming events might be influenced by demographic features and characteristics of the swim race, whereas active recovery enhances blood lactate removal. Our aims were to (1) examine how sex, age, race distance, and swim stroke influenced [BLa] after competitive swimming events and (2) develop a practical model based on recovery swim distance to optimize blood lactate removal. We retrospectively analyzed postrace [BLa] from 100 swimmers who competed in the finals at the Canadian Swim Championships. [BLa] was also assessed repeatedly during the active recovery. Generalized estimating equations were used to evaluate the relationship between postrace [BLa] with independent variables. Postrace [BLa] was highest following 100-200 m events and lowest after 50 and 1500 m races. A sex effect for postrace [BLa] was observed only for freestyle events. There was a negligible effect of age on postrace [BLa]. A model was developed to estimate an expected change in [BLa] during active recovery (male = 0; female = 1): [BLa] change after active recovery = -3.374 + (1.162 × sex) + (0.789 × postrace [BLa]) + (0.003 × active recovery distance). These findings indicate that swimmers competing at an elite standard display similar postrace [BLa] and that there is little effect of age on postrace [BLa] in competitive swimmers aged 14 to 29 y.

Effectiveness of low-frequency vibration recovery method on blood lactate removal, muscle contractile properties and on time to exhaustion during cycling at VO2max power output

The aim of the study was to determine the effectiveness of low-frequency vibration recovery (LFV-rec) on blood lactate removal, muscle contractile properties, and on time to exhaustion during cycling at maximal oxygen uptake power output (pVO(2max)). Twelve active males carried out three experimental sessions. In session 1, participant's maximal oxygen uptake (VO(2max)) and pVO(2max) were determined, and in sessions 2 and 3, the participants performed a fatiguing exercise (2 min of cycling at pVO(2max)) and then a 15 min recovery period using one of two different methods: LFV-rec which consisted on sitting with feet on the vibratory platform (20 Hz; 4 mm) and passive recovery (P-rec), sitting without vibration stimulus. After that, participants performed an all-out exercise test on cycle ergometer at pVO(2max). In the recovery period, variables such as heart rate (HR), blood lactate concentration [Lac], and tensiomyographic parameters (D (m): maximal radial displacement; T (s): time of contraction maintenance, and T (r): relaxation time) were measured. In an all-out exercise test, mean time to exhaustion (TTE), total distance covered (TD), mean cycling velocity (V (m)), and maximal HR (HR(max)) were also assessed. The results showed no effect of recovery strategy on any of the assessed variables; nevertheless, higher values, although not significant, were observed in TTE, TD, and V (m) after LFV-rec intervention. In conclusion, LFV-rec strategy applied during 15 min after short and intense exercise does not seem to be effective on blood lactate removal, muscle contractile properties, and on time to exhaustion during cycling at pVO(2max).

Physical testing prior to returning to normal sports activity for elite athletes following ACL injury

Anterior cruciate ligament (ACL) injury is among the most frequent sports-related injuries especially in contact sports such as football, basketball, soccer and skiing. In professional sports, ACL injury has a...