Differences between genders in anaerobic capacity during a supramaximal effort

Aim: The present study aimed to verify if there is a difference between genders in anaerobic capacity estimated by energetic equivalents of glycolytic and phosphagen pathways (AC[La-]+EPOCfast). Methods: In this way, 8 men and 8 women (physical education students) were subjected to the following sequence of tests: session 1) graded exercise test to measure the maximal oxygen consumption (VÖ½ O2max) and intensity associated with VÖ½ O2max (iVÖ½ O2max); sessions 2 to 3) familiarization with supramaximal effort at 115% of iVÖ½ O2max; session 4) supramaximal effort at 115% of iVÖ½ O2max to measure AC[La-]+EPOCfast. Results: The AC[La-]+EPOCfast was lower in women compared to men when expressed in absolute and relative values (-38.11%; p=0.01 and -25.71%; p=0.03, respectively). A non-significant difference was observed in performance in the supramaximal effort (-12.08%; p=0.15), besides which, a likely negative inference was observed when comparing women to men. In addition, energetic equivalents of the glycolytic pathway (e[La- ]) were also lower in women when expressed in relative and absolute values (-47.01%; p=0.001 and -36.71%; p=0.001, respectively), however no statistical difference was found for energetic equivalents of the phosphagen pathway (ePCr) (p>0.05). Conclusion: The AC[La-]+EPOCfast is lower in women compared to men, mainly due to differences in the glycolytic pathway.(AU)

Effect of lactic acid levels on the prognosis of critically ill patients after cardiac and non-cardiac surgery:an analysis of 549 cases / 中华危重病急救医学

Objective To compare the impact of mean lactate concentration and lactate variability on postoperative outcome after cardiac surgery and non-cardiac surgery in critical patients, and to explore the prognostic value of the first lactate and the highest lactate during the first 24 hours in intensive care unit (ICU). Methods A retrospective study was conducted. The postoperative patients of cardiac surgery and non-cardiac surgery who were transferred to ICU immediately, and who were at least 18 years old and whose ICU lengths of stay were at least 1 day, and who were admitted to ICU of the First Affiliated Hospital of Zhengzhou University from September 2014 to September 2016 were enrolled. According to the mean lactate concentration, the patients were divided into normal lactate group (0-2 mmol/L), relatively high lactate group (2-4 mmol/L), and absolute high lactate group (> 4 mmol/L), and the relationship between the mean lactate concentration and the prognosis of patients was analyzed. According to the degree of lactate variability, the patients were divided into four groups, and multivariate regression models were used to assess the risk of death in three different lactate variability groups. The value of the first lactate value and the highest lactate value during the first 24 hours in ICU were evaluated to predict the prognosis by the receiver operating characteristic (ROC) curve. Results 268 postoperative patients of cardiac surgery and 281 cases of non-cardiac surgery were selected, and the characteristic of the baseline data in the two groups was balanced. ① Mean lactate concentration and mortality in ICU: in the normal lactate group (0-2 mmol/L), there was no significant difference in mortality between the post-cardiac operative group and post-non-cardiac operative group [7.9% (14/177) vs. 6.5% (14/217), odds ratio (OR) = 1.245, 1 = 0.694]. In the relatively high lactate group (2-4 mmol/L), there was no significant difference between the two groups, either [33.3% (12/36) vs. 23.7% (9/38), OR = 1.611, 1 = 0.442]. In the absolute high lactate group (> 4 mmol/L), ICU mortality in post-non-cardiac operative group was obviously higher than that of post-cardiac operative group [69.2% (18/26) vs. 43.6% (24/55), OR = 0.344, 1 = 0.036]. ② The ranges of lactate variability per quartile (mmol·L-1·d-1) and ICU mortality risk: there was a linear relationship between lactate variability and ICU mortality in post-non-cardiac operative group, < 0.50 (reference), 0.50-0.85 (OR = 1.17, 1 = 0.87), 0.85-1.44 (OR =4.86, 1 = 0.04), > 1.44 (OR = 22.66, 1 < 0.01) , and there was a significant difference between the two groups in the high degree of variability (0.85-1.44 and > 1.44). The risk of death after cardiac surgery tended to increase, < 0.55 (reference), 0.55-1.25 (OR = 0.61, 1 = 0.61), 1.25-2.43 (OR = 3.46, 1 = 0.10), > 2.43 (OR = 12.14, 1 < 0.01), and the risk of death only showed difference in the highest degree of variation (> 2.43). ③ ROC curve showed that the area under ROC curves (AUC) of the highest lactate in 24 hours were larger than that of the first lactate in both groups, with higher sensitivity and specificity. In the post-cardiac operative group and post-non-cardiac operative group, the AUC of the highest lactate in the first 24 hours were 0.877 and 0.875, the cut-off values were 5.35 mmol/L and 5.65 mmol/L, the sensitivity were 81.4% and 67.9%, and the specificity were 93.8% and 96.1%, respectively. Conclusions Patients with post-non-cardiac operation should be more active in controlling hyperlactatemia and lactate variability. The highest lactate in the first 24 hours maybe one of the indicator for the assessment of the prognosis of the postoperative patients.

Blockade of P-Glycoprotein Decreased the Disposition of Phenformin and Increased Plasma Lactate Level

This study aimed to investigate the in vivo relevance of P-glycoprotein (P-gp) in the pharmacokinetics and adverse effect of phenformin. To investigate the involvement of P-gp in the transport of phenformin, a bi-directional transport of phenformin was carried out in LLC-PK1 cells overexpressing P-gp, LLC-PK1-Pgp. Basal to apical transport of phenformin was 3.9-fold greater than apical to basal transport and became saturated with increasing phenformin concentration (2-75 µM) in LLC-PK1-Pgp, suggesting the involvement of P-gp in phenformin transport. Intrinsic clearance mediated by P-gp was 1.9 µL/min while passive diffusion clearance was 0.31 µL/min. Thus, P-gp contributed more to phenformin transport than passive diffusion. To investigate the contribution of P-gp on the pharmacokinetics and adverse effect of phenformin, the effects of verapamil, a P-gp inhibitor, on the pharmacokinetics of phenformin were also examined in rats. The plasma concentrations of phenformin were increased following oral administration of phenformin and intravenous verapamil infusion compared with those administerd phenformin alone. Pharmacokinetic parameters such as Cmax and AUC of phenformin increased and CL/F and Vss/F decreased as a consequence of verapamil treatment. These results suggested that P-gp blockade by verapamil may decrease the phenformin disposition and increase plasma phenformin concentrations. P-gp inhibition by verapamil treatment also increased plasma lactate concentration, which is a crucial adverse event of phenformin. In conclusion, P-gp may play an important role in phenformin transport process and, therefore, contribute to the modulation of pharmacokinetics of phenformin and onset of plasma lactate level.

Differing effects of aquatic movement in either deep or shallow water on the physiological responses among middle-aged, female and recreational synchronized swimmers / 体力科学

This study examined the physiological response to different water depths in recreational synchronized swimming. Nine middle-aged, female, recreational swimmers carried out the same team free routines in deep water (deep-water synchronized swimming: DWS) and shallow water (shallow-water synchronized swimming: SWS). Heart rate (HR) was measured continuously during each performance, combined with estimation of metabolic equivalent (MET) values using individual linear regression equations of HR-oxygen uptake. These equations were created using the results of 12 water activities. Blood lactate concentration and systolic blood pressure were measured at the 1/3 and 2/3 stages and immediately after each performance period. HR and estimated METs during DWS (mean±SD, 152.9±7.5 beats·min^-1 and 7.3±1.2) were significantly higher than those measured during SWS (131.8±11.3 beats·min^-1 and 5.7±0.8). Blood lactate concentration and systolic blood pressure measured immediately after DWS were significantly higher than those measured after SWS. With DWS, blood lactate concentration at the 2/3 stage and immediately after the performance were significantly higher than those measured at the 1/3 stage, whereas in SWS no significant difference was found in these values at any time period. In conclusion, the exercise intensity of DWS was high and SWS moderate. The predominant sources of energy may be phosphocreatine stores and aerobic metabolism during these performances. It is possible that glycolysis may also play an important role in energy requirements during the 2/3 stage and immediately after a DWS performance.

Influência da maturação sexual no limiar de lactato em jogadoras de futebol / Influence of sexual maturation in lactate threshold in female soccer players

Os limiares de lactato são utilizados para a avaliação da capacidade aeróbia em diferentes idades. Estudos demonstram que crianças e adolescentes apresentam menores concentrações sanguíneas de lactato [La], para mesma carga de esforço, do que adultos. Existem evidências de que isto está relacionado ao desenvolvimento maturacional das mesmas. OBJETIVO: Verificar a associação entre a maturação sexual e o limiar de lactato de atletas de futebol de 12 a 15 anos de idade. MÉTODO: A amostra foi do tipo intencional, não probabilística, com um total de 36 meninas, entre 12 a 15 anos, participantes de escolinhas de futebol da prefeitura da cidade de São Paulo. Foram obtidas da amostra a massa corporal, a estatura e a tomada de dobras cutâneas triciptal e panturrilha. A maturação sexual foi feita através da observação direta, por uma médica, do desenvolvimento de órgãos genitais e de pilosidade púbica, por meio de planilhas propostas por Tanner. Para determinação do limiar de lactato foi realizado teste progressivo em pista, onde as jovens realizaram três corridas de 800 metros, com a intensidade do esforço sendo controlada por zonas de frequência cardíaca pré-estabelecidas, com mensurações das [La] no final de cada corrida. Através da interpolação linear foi encontrada a velocidade correspondente a [La] de 2,5mmol (V2,5). Para compreender melhor a natureza das associações entre as variáveis foi utilizada a regressão linear múltipla, tendo como variável dependente o limiar de lactato (V2,5), e como variáveis independentes idade (anos), IMC (kg/m²), estatura (cm) e somatório de dobras cutâneas (mm). RESULTADO: Em mais jovens, pré-púbere, as variáveis de crescimento e a maturação sexual tem pouca associação com o limiar de lactato. Sendo importante uma ponderação sobre a influência da maturação sexual no limiar de lactato. CONCLUSÃO: Levando em consideração a homogeneidade do grupo e o fato de a idade entre 12 e 15 anos ser um período de diversas modificações, o desenvol...

The lactate thresholds are used to assess the aerobic capacity in different ages. Studies show that children and adolescents present less lactate blood concentrations [La] than adults under certain effort loads. There are evidences that this is related to their maturational development. OBJECTIVE: To verify the association between the sexual maturation and the lactate threshold in some adolescent soccer players ranging from 12 to 15 years old. METHOD: The sample was related to the intentional and not probabilistic type involving 36 girls, from 12 to 15 years old, members of the soccer schools held by the Mayority of São Paulo. The body weight, height and the sum of two skinfolds - calf and triceps were obtained from the sample. A physician directly observed the sexual maturation of the genitals and pubic hair development through the Tanner index.To determine the lactate threshold a progressive test, a 3x800m in running track, was performed by adolescents, their effort intensity was controlled by pre-established heart rate zones and the lactate blood concentrations [La] were measured at the end of each run. The velocity corresponding to lactate blood concentrations [La] of 2,5mmol (V2,5) was obtained through the linear interpolation.The multiple linear regression was used to better understand the nature of these associations between the variables, considering the lactate threshold (V2,5) as a dependent variable and the age (years), the body weight index (kg/m2), height (cm) and the sum of the skinfolds (mm) as independent variables. RESULT: The growth variables and the sexual maturation have little association with the lactate threshold in the youngest and pre-adolescent girls. It is important to take in consideration the sexual maturation influence on the threshold lactate. CONCLUSION: Taking in account the group homogeneity and being the range between 12 and 15 years old a period susceptible to many modifications, the maturational development and not the chr...

Métodos de quantificação de carga de treinamento em exercício realizado no máximo estado estável de lactato / Methods of quantification of training load in exercise performed at maximal lactate steady state

O objetivo do presente estudo foi comparar e correlacionar as estimativas de impulso de treinamento (TRIMP) propostos por Banister (TRIMPBanister), Stagno (TRIMPStagno) e Manzi (TRIMPManzi). Os participantes foram submetidos a um teste progressivo em cicloergômetro, com registro da frequência cardíaca e da concentração de lactato sanguíneo. Em uma segunda ocasião, realizaram 30 min. de exercício na intensidade correspondente ao máximo estado estável de lactato, a partir do qual foram calculados o TRIMPBanister, TRIMPStagno e TRIMPManzi. Os valores médios de TRIMPBanister (56,5 ± 8,2 u.a.) e TRIMPStagno (51,2 ± 12,4 u.a.) não diferiram entre si (P > 0,05) e foram altamente correlacionados (r = 0,90), com boa concordância, ou seja, viés reduzido e limites de concordância relativamente estreitos. O TRIMPStagno e TRIMPManzi (73,4 ± 17,6 u.a.) apresentarem alta correlação (r = 0,93), mas com diferença significantes entre eles; ainda, se mostraram pouco concordantes. As estimativas de TRIMPBanister e TRIMPManzi não foram diferentes (P = 0,06) e apresentaram alta correlação (r = 0,82), com baixa concordância. Assim, conclui-se que os métodos de TRIMP não são equivalentes. Na prática, parece ser prudente monitorar o processo de treinamento assumindo apenas uma das estimativas.

The aim of the present study was to compare and correlate training impulse (TRIMP) estimates proposed by Banister (TRIMPBanister), Stagno (TRIMPStagno) and Manzi (TRIMPManzi). The subjects were submitted to an incremental test on cycle ergometer with heart rate and blood lactate concentration measurements. In the second occasion, they performed 30 min. of exercise at the intensity corresponding to maximal lactate steady state, and TRIMPBanister, TRIMPStagno and TRIMPManzi were calculated. The mean values of TRIMPBanister (56.5 ± 8.2 u.a.) and TRIMPStagno (51.2 ± 12.4 u.a.) were not different (P > 0.05) and were highly correlated (r = 0.90). Besides this, they presented a good agreement level, which means low bias and relatively narrow limits of agreement. On the other hand, despite highly correlated (r = 0.93), TRIMPStagno and TRIMPManzi (73.4 ± 17.6 u.a.) were different (P < 0.05), with low agreement level. The TRIMPBanister e TRIMPManzi estimates were not different (P = 0.06) and were highly correlated (r = 0.82), but showed low agreement level. Thus, we concluded that the investigated TRIMP methods are not equivalent. In practical terms, it seems prudent monitor the training process assuming only one of the estimates.

DEVELOPMENT OF ACCUMLATED AND TEMPORARY FATIGUE DURING REPEATED CYCLING SPRINTS / 体力科学

The purpose of this study was to determine whether accumulated and temporary fatigue could be separately observed in repeated cycling sprints (RCS) with combined short and long recovery periods. Eight male performed three RCS with 35-sec (RCS₃₅), 350-sec (RCS₃₅₀) and combined 35-sec and 350-sec recovery periods (RCS_comb). RCS_comb consisted of ten 10-sec cycling sprints (CSs) with 35-sec and 350-sec recovery periods before the 5^th and 9^th CS. In RCS_comb, peak power output (PPO) was restored in the 5^th and not in 9^th CS. Blood lactate concentration ([La]) progressively increased, but there were no significant differences among conditions despite the difference in PPO. In RCS_comb, mean power frequency determined on the vastus lateralis was correlated with PPO and oxygen uptake before CSs (preVO₂) showed high in short recovery periods and low values in long recovery periods. Accumulated and temporary fatigue cannot be explained by effects of preVO₂ and [La].

Arterial Blood Lactate Concentrations as a Prognostic Predictor in Critically Ill Patients: in Comparison with APACHE II Scores / 대한마취과학회지

BACKGROUND: Disordered lactate metabolism which is due to tissue hypoxia and hypoperfusion is frequently encountered in critically ill patients. These patients suffer from a high hospital mortality rate and are at great risk of developing multiple organ failure. The present study was designed to evaluate the prognostic value of blood lactate as a determinant of mortality in comparison with the APACHE II score. METHODS: 29 adult ICU patients participated in this study. Blood lactate concentrations, arterial blood gas analysis, hemodynamic data and APACHE II scores were collected on the first and last days of ICU stay. These data were compared between survivor and non-survivor groups. RESULTS: On the day of admission, blood lactate concentrations and APACHE II scores of non-survivors were 48.5 +/- 27.0 mg/dl and 18.5 +/- 5.9, while those of survivors were 23.7 +/- 12.9 mg/dl and 6.7 3.1. On the day of discharge, arterial blood lactate concentrations and APACHE II scores of non-survivors were 143.2 +/- 54.0 mg/dl and 28.2 +/- 6.0, while those of survivors were 14.9 +/- 7.1 mg/dl and 4.7 +/- 2.2. There was a significant positive correlation between high arterial blood lactate concentration and fatal outcome in critically-ill patients. There was also a significant positive correlation between arterial blood lactate concentration and APACHE II score. Furthermore, decreases in arterial blood lactate levels during the course of ICU stay may indicate a favorable outcome. The mortality increased abruptly in critically-ill patients with an initial arterial blood lactate concentration higher than 40 mg/dl. CONCLUSIONS: The result shows that arterial blood lactate concentration can serve as a reliable prognostic predictor and clinical guide to therapy in critically ill patients.

Exercise intensity during a free routeine in well trained synchronized swimmers / 体力科学

A study was conducted to clarify the exercise intensity and metabolic condition during a free routine of synchronized swimming with respect to heart rate (HR), blood lactate concentration (La) and the rate of perceived exertion (RPE) . Six well trained female synchronized swimmers participated as subjects. HR during the free routine was measured continuously. La and RPE during the free routine were measured intermittently from the start to end of each stage. Maximum heart rate (swimmingHRmax : S-HRmax) was determined by measurement of maximum oxygen uptake using a swimming flume. Peak blood lactate concentration (Peak La) was measured after the maximum front crawl stroke of 100 m. The average values and S. D. of S-HRmax and Peak La were 180.0±3.8 beats · min<SUP>-1</SUP> and 9.6 ± 1.0 mmol · 1<SUP>-1</SUP>, respectively. Average values, S. D. and ranges of HR and %S-HRmax during the free routine were 137.6±25.5 (60-180) beats · min<SUP>-1</SUP> and 76.5± 14.3 (34.5-96.8) %, respectively. HR during the free routine showed a decrease in the breath-holding phase. Average values and S. D. of La, %Peak La and RPE at the fourth stage were 5.4±1.2mmol·1<SUP>-1</SUP>, 57.0±17.2% and 17.7±0.8, respectively. La, %Peak La and RPE at the fourth stage were significantly higher than those at the other stages, and La, %Peak La and RPE at the third stage were significantly higher than those at the second stage. These results suggested that the overall intensity of the free routine was moderate, but that part of the free routine included high-intensity activity and the percentage of anaerobic metabolism during the free routine increased in the final stages

Effect of increases in plasma lactate concentration on intravascular hemolysis during exhaustive exercise / 体力科学

A study was performed to examine the effect of plasma lactate concentration on intravascular hemolysis during exercise. Seven men performed maximal and submaximal exercise on a cycle ergometer. The maximal exercise was performed as a graded exercise until exhaustion. The mean performance time of the maximal exercise was 15 min and 4 s. The submaximal exercise was performed for 30 min at 50% HRmax. Blood samples were obtained before, immediately after, and one hour after exercise. Plasma lactate concentration, hematocrit (Ht), and serum haptoglobin concentration (Hp) were measured. Hp was corrected by Ht for hemoconcentration and expressed as HpC. Plasma lactate concentration was elevated significantly (p<0.05) immediately after maximal exercise, and returned to the baseline values one hour after exercise, whereas plasma lactate concentration did not change after submaximal exercise. Hp and HpC did not change even after maximal exercise. These results suggest that the elevation in plasma lactate concentration may not affect intravascular hemolysis during exercise.

METABOLIC ADAPTATIONS TO ENDURANCE TRAINING MONITORED BY BLOOD LACTATE CONCENTRATION IN MALE RATS / 体力科学

We studied the effects of 8 weeks of endurance training on the metabolism in rats. Different treadmill speeds, which corresponded to 2 mM and 4 mM blood lactate concentrations, were used to vary the intensity of the endurance training. After 8 weeks of training, blood lactate concentrations had decreased whereas β-hydroxyacyl-CoA dehydrogenase activity had increased. Citrate synthase activity in the m.extensor digitorum longus (EDL), and m.tibialis anterior (TA) of rats trained at the 4 mM level was higher than in rats trained at the 2 mM level and in control rats. In addition, muscle glycogen content in the hindlimb was higher and muscle TG content in the m.soleus (SOL) was lower in trained rats. These results suggest that training at 4 mM level significantly increases muscle mitochondrial oxidative capacity, and fatty acids are utilized as an energy source regardless of exercise intensity at least in the 2 to 4 mM intensity range. We concludes that an intensity of 4 mM is a useful level with which to elucidate the various adaptations to endurance training.

LT (LACTATE THRESHOLD) IN 10-12 YEAR OLD BOYS DURING TREADMILL RUNNING / 体力科学

The influence of daily physical exercise on oxygen utilizing capacity of working muscle investigated by means of measureing lactate threshold (LT) during progressive treadmill running from the comparison between soccer group (S group: N=12, 11.9±0.1 years of age) and control group (C group ; N=14, 11.8±0.1 years of age) . LT<SUB>1</SUB> was determined as the point where blood lactate concentration (La) increased from rest level, and LT<SUB>2</SUB> was determined by the gradient, La/VO<SUB>2</SUB>. body weight<SUP>-1</SUP> (2 mM/10 ml. kg<SUP>-1</SUP>, min<SUP>-1</SUP>) .<BR>LT<SUB>1</SUB> and LT<SUB>2</SUB> in S group were significantly higher than those in C group expressed with absolute and relative values of VO<SUB>2</SUB> (1. min<SUP>-1</SUP>, ml. kg<SUP>-1</SUP>. min<SUP>-1</SUP>, % VO<SUB>2</SUB>max) . No significant differences in La, ventilation responses, and heart rate at the point of LT<SUB>1</SUB> and LT<SUB>2</SUB> were observed between S and C group, La showed slight decrease and was kept at lower level in S group with increase of VO<SUB>2</SUB>, compared with C group. On the contrary, La in C group began to increase at lower level of VO<SUB>2</SUB>. From our previous longitudinal study of LT in non-athletic children, we observed that LT shifted to lower level with growth. It was sugesed that La curve of S group, such shift had not occurred. Differences of these patterns in VO<SUB>2</SUB> and La between athletic children and non-athletic children were similar to those observed in adults athletes and non-athletes.<BR>In conclusion it was supposed that sufficient daily physical training in 10-12 year of age might increase oxygen utilizing capacity of leg working muscle during running exercise.