Capillary Blood Lactate Concentration Research Articles

Physiological Features of the Response of the Respiratory and Circulation Systems to Physical Load in Students Engaged in Winter Football

Adaptive changes in the circulatory and respiratory systems under the influence of winter football training were studied. 50 men aged 21-25 years — 3rd-4th year students — were examined: control group — 25 people specializing in “soccer” (S), main group — 25 people studying in the specialization “winter football” (WF). The examination was performed twice — before and after physical activity. Running (average pace, 180 steps/min) for 15 minutes was used as dosed physical activity. The loads were performed either indoors at a temperature of plus 22–24°C, or in winter outside at a temperature of minus 18–20°C. Indoor and outdoor surveys were carried out on different days. Assessment of peripheral blood flow in the lower extremities was performed using rheography; to assess the main blood flow in the femoral artery, Doppler ultrasound was used. The study of external respiration functions was carried out using pneumotachography. The lactate concentration in capillary blood was determined photometrically. It has been shown that physical activity performed in the cold in adapted athletes (WF group) promotes increased integration between the respiratory and circulatory systems, ensuring the formation of a functional system characterized by stronger connections for optimal adaptation to the combined effects of physical activity and cold. In athletes training indoors (group S) under conditions of a combination of physical activity and cold exposure, on the contrary, desynchronization of the interaction of the respiratory and circulatory systems occurs, which leads to a decrease in adaptive reserves. Thus, sports training in winter football triggers phenotypic adaptive changes and creates a number of physiological mechanisms that promote increased integration between the respiratory and circulatory systems, providing optimal adaptation to the combined effects of physical activity and cold. The obtained facts will be useful for the development of special training programs aimed at increasing the functional reserve of the cardiorespiratory system of athletes training in cold conditions.

Relationship of peak capillary blood lactate accumulation and body composition in determining the mechanical energy equivalent of lactate during sprint cycling

AimA 15-s all-out sprint cycle test (i.e., νLamax-test) and the post-exercise change in capillary blood lactate concentration is an emerging diagnostic tool that is used to quantify the maximal glycolytic rate. The goal of this study was to determine the relation between 15 s-work, change in capillary blood lactate concentration (∆La) and body composition in a νLamax-test.MethodFifty cyclists performed a 15 s all-out sprint test on a Cyclus2 ergometer twice after a previous familiarization trial. Capillary blood was sampled before and every minute (for 8 min) after the sprint to determine ∆La. Body composition was determined employing InBody720 eight-electrode impedance analysis.ResultSimple regression models of fat-free mass (FFM) and also the product of FFM and ∆La showed similar ability to predict 15 s-work (R2 = 0.79; 0.82). Multiple regression combining both predictors explains 93% of variance between individuals. No differences between males and females were found regarding 15 s-work relative to the product of fat-free mass and ∆La. Considering pairs of similar FFM, a change 1 mmol/l of ∆La is estimated to be equal to 12 J/kg in 15 s-work (R2 = 0.85).DiscussionFifteen s-work is both closely related to FFM and also the product of ∆La and lactate-distribution space approximated by FFM. Differences in 15 s-work between males and females disappear when total lactate production is considered. Considering interindividual differences, the mechanical energy equivalent of blood lactate accumulation seems a robust parameter displaying a clear relationship between ∆La and 15 s-work relative to FFM.

Reliability of power output, maximal rate of capillary blood lactate accumulation, and phosphagen contribution time following 15-s sprint cycling in amateur cyclists.

Based on Mader's mathematical model, the rate of capillary blood lactate concentration (νLamax) following intense exercise is thought to reflect the maximal glycolytic rate. We aimed to investigate the reliability of important variables of Mader's model (i.e. power output, lactate accumulation, predominant phosphagen contribution time frames (tP Cr)) and resulting νLamax values derived during and after a 15-s cycling sprint. Fifty cyclists performed a 15-s all-out sprint test on a Cyclus2 ergometer three times. The first sprint test was considered a familiarization trial. Capillary blood was sampled before and every minute (for 8 min) after the sprint to determine νLamax. Test-retest analysis between T2 and T3 revealed excellent reliability for power output (Pmean and Ppeak; ICC = 0.99, 0.99), ∆La and νLamax with tPCr of 3.5 s (ICC = 0.91, 0.91). νLamax calculated with tPCr = tP peak (ICC = 0.87) and tP Cr = tPpeak-3.5% (ICC = 0.79) revealed good reliability. tPpeak and tPpeak-3.5% revealed only poor and moderate reliability (ICC = 0.41, 0.52). Power output and ∆La are reliable parameters in the context of this test. Depending on tPCr, reliability of νLamax varies considerably with tP Cr of 3.5 s showing excellent reliability. We recommend standardization of this type of testing especially tP Cr.

A verification phase adds little value to the determination of maximum oxygen uptake in well-trained adults.

The objective was to investigate if performing a sub-peak or supra-peak verification phase following a ramp test provides additional value for determining 'true' maximum oxygen uptake ( O2). 17 and 14 well-trained males and females, respectively, performed two ramp tests each followed by a verification phase. While the ramp tests were identical, the verification phase differed in power output, wherein the power output was either 95% or 105% of the peak power output from the ramp test. The recovery phase before the verification phase lasted until capillary blood lactate concentration was ≤ 4mmol·L-1. If a O2 plateau occurred during ramp test, the following verification phase was considered to provide no added value. If no O2 plateau occurred and the highest O2 ( O2peak) during verification phase was < 97%, between 97 and 103%, or > 103% of O2peak achieved during the ramp test, no value, potential value, and certain value were attributed to the verification phase, respectively. Mean (standard deviation) O2peak during both ramp tests was 64.5 (6.0) mL·kg-1·min-1 for males and 54.8 (6.2) mL·kg-1·min-1 for females. For the 95% verification phase, 20 tests showed either a O2 plateau during ramp test or a verification O2peak < 97%, indicating no value, 11 showed potential value, and 0 certain value. For the 105% verification phase, the values were 26, 5, and 0 tests, respectively. In well-trained adults, a sub-peak verification phase might add little value in determining 'true' maximum O2, while a supra-peak verification phase adds no value.

Роль быстрого бега в предотвращении негативных влияний пребывания человека в невесомости

The prospects of deep space exploration necessitate modification of the principles and methods underlying the system designed to prevent negative impact of weightlessness on the human body. This work aimed to determine how fast running, as part of locomotor training during a space flight (SF), helps maintain physical ability of a person. The study involved 10 cosmonauts; their physical performance was assessed at all stages of the SF with the help of the Individual Strategies Test (IST). The parameters registered when the participants were doing the IST included heart rate (HR), gas exchange, capillary blood lactate concentration. The cosmonauts were divided into two groups based on the differences in the mean distance covered while fast running on a treadmill (single session). Group A (n = 4) run 949 m/day on average, group B (n = 6) — 2669 m/day. After SF, HR in group A increased at speeds from 5 to 8 km/h (p &lt; 0.05), pulmonary ventilation indicators grew at speeds from 8 to 15 km/h (p &lt; 0.05), and the capillary blood lactate concentration measured during the post-test recovery period increased by 37% (p = 0.03). Moreover, after SF, the pulse sum recorded under load and during recovery was 14% (p = 0.02) and 15% (p = 0.03) in group A, respectively, while in group B we registered no differences. Thus, our hypothesis that fast running triggers sensory reactions simulatingEarth conditions for the body, which consequently activates physiological mechanisms counteracting the negative effects of weightlessness, has been confirmed in a space experiment.

Restricted nasal-only breathing during self-selected low intensity training does not affect training intensity distribution.

Introduction: Low-intensity endurance training is frequently performed at gradually higher training intensities than intended, resulting in a shift towards threshold training. By restricting oral breathing and only allowing for nasal breathing this shift might be reduced. Methods: Nineteen physically healthy adults (3 females, age: 26.5 ± 5.1years; height: 1.77 ± 0.08m; body mass: 77.3 ± 11.4kg; VO2peak: 53.4 ± 6.6mL·kg-1min-1) performed 60min of self-selected, similar (144.7 ± 56.3 vs. 147.0 ± 54.2 W, p = 0.60) low-intensity cycling with breathing restriction (nasal-only breathing) and without restrictions (oro-nasal breathing). During these sessions heart rate, respiratory gas exchange data and power output data were recorded continuously. Results: Total ventilation (p < 0.001, ηp 2 = 0.45), carbon dioxide release (p = 0.02, ηp 2 = 0.28), oxygen uptake (p = 0.03, ηp 2 = 0.23), and breathing frequency (p = 0.01, ηp 2 = 0.35) were lower during nasal-only breathing. Furthermore, lower capillary blood lactate concentrations were found towards the end of the training session during nasal-only breathing (time x condition-interaction effect: p = 0.02, ηp 2 = 0.17). Even though discomfort was rated marginally higher during nasal-only breathing (p = 0.03, ηp 2 = 0.24), ratings of perceived effort did not differ between the two conditions (p ≥ 0.06, ηp 2 = 0.01). No significant "condition" differences were found for intensity distribution (time spent in training zone quantified by power output and heart rate) (p ≥ 0.24, ηp 2 ≤ 0.07). Conclusion: Nasal-only breathing seems to be associated with possible physiological changes that may help to maintain physical health in endurance athletes during low intensity endurance training. However, it did not prevent participants from performing low-intensity training at higher intensities than intended. Longitudinal studies are warranted to evaluate longitudinal responses of changes in breathing patterns.

Maternal and umbilical cord blood lactate for predicting perinatal death: a secondary analysis of data from a randomized controlled trial

BackgroundIn high resource settings, lactate and pH levels measured from fetal scalp and umbilical cord blood are widely used as predictors of perinatal mortality. However, the same is not true in low resource settings, where much of perinatal mortality occurs. The scalability of this practice has been hindered by difficulty in collecting fetal scalp and umbilical blood sample. Little is known about the use of alternatives such as maternal blood, which is easier and safer to obtain. Therefore, we aimed to compare maternal and umbilical cord blood lactate levels for predicting perinatal deaths.MethodsThis was secondary analysis of data from a randomized controlled trial assessing the effect of sodium bicarbonate on maternal and perinatal outcomes among women with obstructed labour at Mbale regional referral hospital in Eastern Uganda. Lactate concentration in maternal capillary, myometrial, umbilical venous and arterial blood was measured at the bedside using a lactate Pro 2 device (Akray, Japan Shiga) upon diagnosis of obstructed labour. We constructed Receiver Operating Characteristic curves to compare the predictive ability of maternal and umbilical cord lactate and the optimal cutoffs calculated basing on the maximal Youden and Liu indices.ResultsPerinatal mortality risk was: 102.2 deaths per 1,000 live births: 95% CI (78.1–130.6). The areas under the ROC curves were 0.86 for umbilical arterial lactate, 0.71 for umbilical venous lactate, and 0.65 for myometrial lactate, 0.59 for maternal lactate baseline, and 0.65 at1hr after administration of bicarbonate. The optimal cutoffs for predicting perinatal death were 15 0.85 mmol/L for umbilical arterial lactate, 10.15mmol/L for umbilical venous lactate, 8.75mmol/L for myometrial lactate, and 3.95mmol/L for maternal lactate at recruitment and 7.35mmol/L after 1 h.ConclusionMaternal lactate was a poor predictor of perinatal death, but umbilical artery lactate has a high predictive value. There is need for future studies on the utility of amniotic fluid in predicting intrapartum perinatal deaths.

200m breaststroke post-competition blood lactate removal characteristics

The goal of this study was to define the individual model characteristics of lactic acid removal after 200m breaststroke competitive load in a female swimmer in relation to different pool lengths (25m vs. 50m). The second goal was methodological and referred to the presentation of newly applied metrological procedures for the Individual Lactate Recovery Profile modeling. Six races from the competitive season 2021/22 were selected, in which the athlete achieved the most valuable results in relation to the FINA score. To establish the metabolic response of the organism to the competition effort, the method of determining the level of lactate concentration in capillary blood (La in mmol/L) was used. Differences between the mean values of variables were established using ANOVA. The polynomial curve equation function was used to create a blood lactate concentration in a function of recovery time model (La-trecovery). The ANOVA showed that there was no statistically significant difference between the monitored variables and the pool length function (p=.097). The maximum achieved blood lactate concentration in the acute race recovery phase was 13.17 ± 2.81 and 12.08 ± 1.80 mmol/L and the given concentration initially occurred in the time of 240.0 ± 85.6 s and 169.3 ± 79.9 s in the 25 and 50m pool, respectively. In relation to the time of complete passive recovery required to establish acidosis at the level of 2 mmol/L (25 and 50m pool) occurred in 1191.7 ± 481.3 s and 1326.7 ± 405.1 s, while the full index of intensity of blood lactate clearance was 135.7 ± 60.7 s/mmol/L and 124.0 ± 60.7 s/mmol/L for 25m and 50m pool, respectively. Although no statistically significant difference was found between the parameters of recovery in relation to pool length, the offered mathematical models enabled a practical individual approach to controlling the specific adaptation to training for achieving a higher competitive level performance.

Glucose and Fructose Supplementation and Their Acute Effects on Anaerobic Endurance and Resistance Exercise Performance in Healthy Individuals: A Double-Blind Randomized Placebo-Controlled Crossover Trial.

The effects of glucose, fructose and a combination of these on physical performance have been subject of investigation, resulting in diverse findings. The aim of this study was to investigate how an individualized amount of glucose, fructose, and a combination of these compared to placebo (sucralose) alter endurance performance on a cycle ergometer, lower and upper body resistance exercise performance at individualized thresholds in healthy young individuals. A total of 16 healthy adults (9 females) with an age of 23.8 ± 1.6 years and a BMI of 22.6 ± 1.8 kg/m2 (body mass (BM) 70.9 ± 10.8 kg, height 1.76 ± 0.08 m) participated in this study. During the screening visit, the lactate turn point 2 (LTP2) was defined and the weights for chest-press and leg-press were determined. Furthermore, 30 min prior to each exercise session, participants received either 1 g/kg BM of glucose (Glu), 1 g/kg BM of fructose (Fru), 0.5 g/kg BM of glucose/fructose (GluFru) (each), or 0.2 g sucralose (placebo), respectively, which were dissolved in 300 mL of water. All exercises were performed until volitional exhaustion. Time until exhaustion (TTE) and cardio-pulmonary variables were determined for all cycling visits; during resistance exercise, repetitions until muscular failure were counted and time was measured. During all visits, capillary blood glucose and blood lactate concentrations as well as venous insulin levels were measured. TTE in cycling was 449 ± 163 s (s) (Glu), 443 ± 156 s (Fru), 429 ± 160 s (GluFru) and 466 ± 162 s (Pla) (p = 0.48). TTE during chest-press sessions was 180 ± 95 s (Glu), 180 ± 92 s (Fru), 172 ± 78 s (GluFru) and 162 ± 66 s (Pla) (p = 0.25), respectively. Pre-exercise supplementation of Glu, Fru and a combination of these did not have an ergogenic effect on high-intensity anaerobic endurance performance and on upper and lower body moderate resistance exercise in comparison to placebo.

Maximal Fat Metabolism Explained by Lactate-Carbohydrate Model

(1) Background: Maximal fat oxidation (MFO), its associated exercise intensity (Fatmax) and the cross-over point (COP) are known indirect calorimetry-based diagnostics for whole-body metabolic health and exercise. However, large inter- and intra-individual variability in determining their corresponding intensity makes their use inconsistent, whether the intensity is based on power output or oxygen uptake. Blood lactate concentration (BLC) has often reflected a range in MFO and COP, which may offer another non-indirect calorimetry dimension based on the near equilibrium between lactate and pyruvate at the molecular level, which biochemically determines an interchange between lactate and relative rate of carbohydrate (relCHO) and relative rate of fat utilization (relFAO). This paper proposes a new testing approach describing relCHO as a function of BLC, with an individualized half-maximal activation constant of relCHO (kel), to explain and predict the variability in MFO, Fatmax and COP. (2) Methods: Following ethical approval, twenty-one healthy males participated in the incremental cardiorespiratory maximal test, and capillary BLC was measured. Indirect calorimetry relCHO and relFAO were calculated, and a constant kel that reflected 50% of CHO saturation level was estimated as a sigmoid function of BLC (mmol·L−1): relCHO = 100/(1 + kel/BLC2). (3) Results: 86% of relCHO variability was explained by BLC levels. The individualized kel estimations, which were 1.82 ± 0.95 (min/max 0.54/4.4) (mmol·L−1)2 independently explained 55% MFO and 44% of COP variabilities. Multiple regression analysis resulted in kel as the highest independent predictor of Fatmax (adjusted r-square = 22.3%, p &lt; 0.05), whilst classic intensity-based predictors (peak power, maximal oxygen uptake, fixed BLC at 4 mmol·L−1) were not significant predictors. (4) Conclusions: The BLC-relCHO model, with its predictor kel explains the inter- and intra-individual variability in MFO, its exercise intensity Fatmax and power outs at COP through dynamic changes in BLC, fat and carbohydrates regardless of the intensity at which exercise takes place. kel capability as a predictor of MFO, Fatmax and COP independently of their associated intensities provides a new diagnostic tool in physiological exercise testing for health and exercise performance.

Impact of probiotic supplementation on exercise endurance among non-elite athletes: study protocol for a randomized, placebo-controlled, double-blind, clinical trial

BackgroundSome probiotics appear to improve athletic performance, endurance, and recovery after intense exercise. Other formulations may provide performance-related benefits via immune and gastrointestinal functions in athletic individuals. However, few formulations have been studied for both types of effects among non-elite athletes. The primary objective of this study is to assess the ergogenic effects of a probiotic on high-intensity endurance running performance in non-elite runners. Secondary objectives include assessment of perceived exertion, blood chemistry, immune and stress biomarkers, cold and flu symptoms, and gastrointestinal health after the probiotic intervention.MethodsThis 9-week randomized, placebo-controlled, double-blind, parallel trial will assess the ergogenic effects of a probiotic (5 billion colony-forming units/day, for 6 weeks) in healthy, non-elite runners (N=32; 18–45 years). Participants will be monitored via daily and weekly questionnaires during the 2-week pre-baseline, 6-week intervention, and 1-week washout. Questionnaires will inquire about activity, muscle soreness, gastrointestinal symptoms, cold and flu symptoms, stool form and frequency, and adverse events. During the pre-baseline visit, maximal oxygen uptake (V̇O2 max) is assessed to set appropriate individualized workload settings for the treadmill time-to-exhaustion endurance tests. These time-to-exhaustion endurance running tests will be completed at an intensity of 85% VO2max at baseline and final visits. During these tests, self-perceived exercise effort will be rated via the Borg Rating of Perceived Exertion scale and finger sticks assessing capillary blood glucose and lactate concentrations will be collected every 3 min. Additional questionnaires will assess diet and motivation to exercise. Body composition will be assessed using air displacement plethysmography at the baseline and final visits. Hypotheses will be tested using two-sided tests, and a linear model and with a type I error rate of α=0.05. Primary and secondary outcomes will be tested by comparing results between the intervention groups, adjusting for baseline values.DiscussionThese results will build evidence documenting the role of probiotics on running endurance performance and physiological responses to exercise in non-elite athletes. Understanding the potential mechanisms of probiotic effects and how they mitigate the intestinal or immune discomforts caused by running could provide additional strategy means to help runners improve their performance.Trial registration numberClinicalTrials.govNCT04588142. Posted on October 19, 2020.Protocol version: July 2, 2021, version 1.2

Is Rating of Perceived Exertion a Valuable Tool for Monitoring Exercise Intensity During Steady-State Conditions in Elite Endurance Athletes?

Rating of perceived exertion (RPE) is a widely used tool to assess subjective perception of effort during exercise. The authors investigated between-subject variation and effect of exercise mode and sex on Borg RPE (6-20) in relation to heart rate (HR), oxygen uptake (VO2), and capillary blood lactate concentrations. A total of 160 elite endurance athletes performed a submaximal and maximal test protocol either during cycling (n = 84, 37 women) or running (n = 76, 32 women). The submaximal test consisted of 4 to 7 progressive 5-minute steps within ∼50% to 85% of maximal VO2. For each step, steady-state HR, VO2, and capillary blood lactate concentrations were assessed and RPE reported. An incremental protocol to exhaustion was used to determine maximal VO2 and peak HR to provide relative (%) HR and VO2 values at submaximal work rates. A strong relationship was found between RPE and %HR, %VO2, and capillary blood lactate concentrations (r = .80-.82, all Ps < .05). The between-subject coefficient of variation (SD/mean) for %HR and %VO2 decreased linearly with increased RPE, from ∼10% to 15% at RPE 8 to ∼5% at RPE 17. Compared with cycling, running induced a systematically higher %HR and %VO2 (∼2% and 5%, respectively, P < .05) with these differences being greater at lower intensities (RPE < 13). At the same RPE, women showed a trivial, but significantly higher %HR and %VO2 than men (<1%, P < .05). Among elite endurance athletes, exercise mode influenced RPE at a given %HR and %VO2, with greater differences at lower exercise intensities. Athletes should manage different tools to evaluate training based on intensity and duration of workouts.

Muscle Recovery after a Single Bout of Functional Fitness Training.

Background: Functional fitness training (FFT) is a new exercise modality that targets functional multi-joint actions via both muscle-strengthening exercises and aerobic training intervals. The aim of the study was to examine muscle recovery over a 20 min period after an FFT workout in trained adults. Materials and methods: Participants were 28 healthy trained subjects. In a single session, a countermovement jump (CMJ) was performed to determine several mechanical variables (jump height, maximum velocity, power) before (preFFT) and 4, 10, and 20 min after the FFT workout (postFFT). In parallel, capillary blood lactate concentrations were measured pre- and 3 min postFFT. Heart rate was also measured before and after the workout, and perceived exertion was measured postFFT. Results: Significant differences between the time points preFFT and 4 min and 10 min postFFT, respectively, were produced in jump height (p = 0.022, p = 0.034), maximum velocity (p = 0.016, p = 0.005), average power relative (p = 0.018, p = 0.049), and average power total (p = 0.025, p = 0.049). No differences were observed in any of the variables recorded preFFT and 20 min postFFT. Conclusions: While mechanical variables indicating muscle fatigue were reduced 4 and 10 min postFFT, pre-exercise jump ability only really started to recover 20 min after FFT although not reaching pre-exercise levels. This means that ideally intervals of around 20 min of rest should be implemented between training bouts.

Blood pressure decrease in elderly after isometric training: does lactate play a role?

This study aimed to investigate the effect of isometric handgrip (IHG) training on the blood pressure (BP) reduction in prehypertensive and hypertensive elderly people, and the possible role of lactate and redox balance. Thirty-three older (75.3±1.3 years old) were allocated to a non-exercise control (CG, n=11), prehypertensive (PHG, n=10), and hypertensive (HG, n=12) groups. PHG and HG performed a total of 8 sets of 1-min bilateral contractions at 30% maximal voluntary isometric contraction, each separated by 1-minute rest-pause. IHG training was performed for 8-week, 3 times a week on non-consecutive days. Systolic BP (SBP) and heart rate (HR) decreased post-training on PHG (-10 mm Hg; -5 bpm) and HG (-16 mm Hg; -9 bpm), respectively. Diastolic BP (DBP) decreased for HG only (-9 mm Hg) (P &lt; 0.05). In addition, the decrease in BP occurred in parallel to a better redox balance and increased bioavailability of nitric oxide in PHG and HG (P &lt; 0.05). Also, the variables that most present association to SBP decrease were capillary blood lactate concentration and muscle strength (P &lt; 0.05). In summary, IHG training may be practical in improving clinical status of prehypertensive and hypertensive patients, by improving BP control, NO- bioavailability and redox balance. Further studies are required to elucidate the pathways of lactate concentration in blood-flow during exercise.

Changes in heart rate and blood lactate concentration during karate kata competition

Background and Study Aim : Karate is going to take part in the Olympic games, for the first time in Tokyo 2020. The aim of this study was to analyse the changes in heart rate (HR) and blood lactate concentration of karate practitioners performing different katas in competitive conditions. Material and Methods : This study consisted of five elite male athletes (26.80±5.97 years), members of the Bulgarian national team in Shotokan karate, competing in the kata discipline. The study was conducted in competitive conditions during national competitions, in which three katas were performed by each of the competitors. Capillary blood lactate concentration (La) was determined at rest and after each kata. Heart rate (HR) was registered and physical activity was monitored by using three-dimensional accelerometers. Results: The mean La increased progressively after each following kata: 1.4±0.32 mmol/L at rest, 4.7±1.91 mmol/L after the first, 6.8±2.59 mmol/L after the second, and 7.1±2.35 mmol/L after the third kata. This increase was significant after the second (р&lt;0.05) and third (р&lt;0.01) kata, in comparison with the registered La at rest. The mean HR values reached 179±11.55 bpm during the first, 180±11.63 bpm during the second, and 181.5±15.44 bpm during the third kata. Conclusions: The La appeared to be a more informative parameter than heart rate, and the moderate increase of the La values (4-6 mmol/L) indicated optimal muscle tension and amplitude of moves when performing katas in competitive conditions. Further research is needed to determine the optimal La levels for the performance of different katas.

Effect of Uni and Bilateral High-Intensity Sustained Isometric Contraction Exercise on Fatigue Related Changes in Quadriceps Femoris

Background. It is well established that different types of exercise can provide central and peripheral fatigue. However, there are conflicting findings in the literature, and a consensus has not been reached regarding the different patterns of different ways of performing exercises when the muscle works at long and short lengths and unilaterally and bilaterally. The purpose of this study was to investigate the effect of muscle length and the high-intensity physical exercise when performing unilaterally and bilaterally on fatigue.Methods. Thirteen young healthy physically active volunteering males participated in the study. Maximal voluntary and involuntary contraction was observed during the performance of sustained maximal (uni-)bilateral isometric contraction at long and short quadriceps muscle length. Capillary blood lactate concentration and perceived exertion was observed after high-intensity physical exercise.Results. Maximal voluntary contraction (MVC)% decreased significantly and greatly in (uni-)bilateral exercise at long muscle length. CAR% at the appearance of fatigue was greater at long muscle length and did not depend on (uni-)bilateral contraction.Conclusion. When both legs generate force (bilateral contraction), it is possible to observe a decrease in the rate of force development (RFD) but not in the MVC. Movement performed at long muscle length and (uni-)bilaterally has an effect on a greater motor cortex activation and a sense of movement effort and lactate concentration in capillary blood. Keywords: high intensity interval exercise, sustained isometric contraction, central fatigue, peripheral fatigue, bilateral and unilateral contraction.

A comparison of the effects of intermittent versus continuous exercise on blood glucose control in individuals with Type 1 Diabetes

AbstractExercise has many health benefits for individuals with Type 1 Diabetes (T1D), however it carries the risk of hypoglycaemia. Research has indicated that intermittent high intensity exercise reduces this risk compared to steady state exercise, potentially via a greater anaerobic component inducing increased lactate and catecholamine response.Six physically active males aged 23 ± 5 years, BMI 24.9 ± 1.8 kg•m-2, Vo2 max 47.9 ± 10.1 ml•kg-1•min-1 diagnosed with Type 1 Diabetes for 9 ± 3 years and a HbA1c concentration of 8.6 ± 0.3% participated in a randomised counterbalanced trial. Participants exercised for 60 min on a cycle ergometer on two occasions separated by 7 days, which consisted of a moderate continuous steady state exercise session at 40% o2 max (CONT), or the same exercise intensity interspersed with 7 s high intensity sprints at 100% Vo2 max every 2 min (INT). Blood glucose concentration was assessed via capillary blood sampling every 10 min during exercise and at regular intervals in the 60 min post exercise (Accu-Chek Aviva, Roche, UK). Additional metabolic measures such as blood lactate concentration and carbohydrate oxidation rates were assessed during exercise. Participants ingested small quantities of a carbohydrate drink, if required, to avoid hypoglycaemia during exercise. Magnitude based inferences were used to compare the two exercise trials and Effect Sizes (ES) calculated using Cohen's d and results presented as mean ± SD.Average blood glucose concentration was lower on the INT trial compared to CONT during both the exercise phase (8.9 ± 1.7 mmol•l-1 vs 7.1 ± 1.1 mmol•l-1; ES 0.55) and the 60 min post-exercise recovery phase (8.1 ± 1.9 mmol•l-1 vs 7.0 ± 1.8 mmol•l-1; ES 0.56). Carbohydrate oxidation was greater on the INT trial compared to CONT (1.9 ± 1.4 g•min-1 vs 1.5 ± 0.6 g•min-1; ES 0.35). Capillary blood lactate concentration was markedly elevated on INT when compared to CONT (5.0 ± 1.4 mmol•l-1 vs 2.4 ± 1.1 mmol•l-1; ES 2.48). Carbohydrate ingestion during exercise was 13 ± 11 g and differed little between trials (ES 0.18).Despite greater anaerobic metabolic response, the addition of intermittent high intensity sprints to 60 min steady-state cycle exercise resulted in greater declines in blood glucose concentration during the exercise and post-exercise period, potentially by inhibition of the counter regulatory hormone response expected on the INT trial. These results would indicate that additional exogenous carbohydrate ingestion may be required for individuals with T1D when intermittent sprints are added to prolonged continuous exercise.

Effectiveness of Upper Body Compression Garments Under Competitive Conditions: A Randomised Crossover Study withEliteCanoeists with an Additional Case Study

This study aimed to investigate the effects of upper body compression garments on performance changes in elite canoeists. A total of 23 elite athletes from the German Canoe Federation (6 women and 17 men) were recruited. On a regatta lake, the athletes completed a 1650-m test track with their competition or training boats and paddles. The athletes were randomised into two groups and performed the test track with and without upper body compression garments. Besides split and end times, capillary blood lactate concentrations were assessed. For statistical analysis, an effect-based approach ("Magnitude-Based Inferences") and an additional case study were conducted. For this purpose, the mean and individual effects were examined in relation to the smallest worthwhile changes. On average, the effect-based approach shows that upper body compression garments do not lead to clear changes in performance. The changes in lactate concentrations were clear, but were considered trivial. In contrast to the average statistical analysis, the results of the case study demonstrate that upper body compression garments lead to an improved performance in 13.0 % and a worsened performance in 4.4 % of athletes. Additionally, a decreased lactate concentration was found in 4.4 % and an increased lactate concentration in 17.4 % of athletes. Our study shows that, on average, upper body compression garments have no effects on the performance and lactate concentration of highly trained elite canoeists. In individual cases, however, there are beneficial as well as harmful effects that may have practical relevant consequences for elite athletes.

Urine Lactate after Continuous and Interval Cycling Exercise Bouts Eliciting Different Blood Lactate Concentrations

Post-exercise urine lactate (UL) has been suggested as a novel exercise biomarker of lactate production. The few studies examining the association between post-exercise peak blood lactate (BL) and UL have reported moderate to high linear correlations. However, these studies have not considered BL concentration during exercise. Also, the range of BL values was narrow (about 10 mmol/L), thus limiting the predictive value of UL. PURPOSE: To examine the association between UL and BL concentrations during continuous and interval exercise of equal mean power. METHODS: Eleven healthy young males performed four trials in random, counterbalanced order, one week apart. All trials included 20 min of cycling with equal mean power output, performed either continuously (CON) or in the form of interval training including 48 x 10 s (HIIT10), 16 x 30 s (HIIT30), or 8 x 60 s (HIIT60) bouts at a power output corresponding to 100% of VO2max. Recovery intervals during the HIIT trials included cycling at 15% of VO2max for 150% of the exercise bout time. Capillary BL concentration was measured at rest and every 5 min during exercise, and UL concentration was measured in urine samples obtained pre- and 1 hour post-exercise, with controlled hydration. BL and UL results were analyzed using 2-way ANOVA with repeated measures (trial x time). The association between incremental area under the blood lactate curve (BL-AUC) and UL concentration was determined using linear and exponential functions. RESULTS: BL increased compared with baseline in all trials from the first 5 min of exercise (p < 0.01). BL-AUC increased from CON to HIIT10, HIIT30 and HIIT60 (61.7 ± 21.2, 83.4 ± 29.0, 97.8 ± 34.0, 147.4 ± 44.2 mmol/L x min, respectively, p < 0.01). However, post-exercise UL increased from baseline only in HIIT60 (from 1.2 ± 1.0 to 22.5 ± 23.3 mmol/L, p < 0.001). Exercise BL ranged from 3.0 to 17.7 mmol/L, while post-exercise UL ranged from 0.2 to 76.4 mmol/L. The best function describing the BL-AUC and UL relationship was exponential (r = 0.68, p < 0.05). CONCLUSIONS: The lack of increase in UL despite an increase in BL and their exponential association suggest that there may be a threshold above which BL cannot be disposed within the body and is excreted by the kidneys.

COMPETITIVE BOUT MODEL AS A TOOL FOR ESTIMATION OF FEMALE KARATEKA SPECIFIC ENDURANCE

The aim of this study was to establish the functional state of female karate practitioners during a Shotokan kumite competition by measuring changes in their lactate concentration and also by designing a training exercise model, that matches the workload during competitions. Seven female karate practitioners, between the ages of 18 and 30, took part in this research, which was conducted in two stages: 1) in competitive conditions during the National Shotokan Karate Championship, where capillary blood lactate concentration was measured both after the warm-up and after each bout; 2) in training conditions, where again the blood lactate concentration was determined post warm-up and after performance of the karate kumite model, which consisted of a series of techniques designed to simulate competitive kumite, and in addition to this the heart rate was recorded continuously using a heart-rate telemetry system. According to the results from the maximal aerobic test, the training level of the female karatekas tested was comparable to that of internationally ranked competitors from other countries. The lactate concentrations measured during the competition were a more reliable predictor of the competitive ranking in comparison to VO 2 max. The designed karate kumite training model simulated well the level of competitive load based on a comparison of the measured lactate concentrations and those determined during the competition. In all the women tested, the heart rate measured after the simulated kumite was close to the maximal values (about 180 bpm), and thus did not adequately reflect the work intensity. In conclusion, since lactate concentration accurately reflects competitive output, and correlates with the exercise intensity during a designed training model, it could be used for evaluation of the physical load and specific endurance, particularly of female karate practitioners. Article visualizations: