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Effect of measuring blood lactate concentrations using different automated lactate analysers on blood lactate transition thresholds
Abstract
This study investigated the effect of using three automated blood lactate analysers (Accusport, Lactate Pro, YSI 1500 Sport) on blood lactate transition thresholds (BLTT). Blood lactate concentrations were measured using the three analysers in rowers (n = 17) and kayakers (n = 6) during incremental exercise. The BLTT determined were: 1) ADAPT lactate threshold (data point preceding lactate increase of > or = 0.4 mmol x l(-1)), 2) log-log lactate threshold (point of lactate increase when log lactate plotted against log of relevant exercise parameter), 3) DMAX anaerobic threshold, 4) ADAPT anaerobic threshold (modified DMAX method), 5) Onset of blood lactate accumulation (OBLA, fixed blood lactate concentration of 4 mmol x l(-1)). Measurements of blood lactate concentration differed between analysers (p < 0.0001), resulting in BLTT differing between analysers when expressed as a blood lactate concentration (p < 0.0001), or when the BLTT was defined as a fixed blood lactate concentration (e.g. OBLA) (p < 0.0001). When expressed as a power output or heart rate using BLTT based on relative changes in lactate concentration (log-log, ADAPT and DMAX thresholds) the values were similar between analysers (p > 0.05), except the Accusport provided higher values for the log-log lactate threshold (p < 0.0001). We concluded that, despite providing significantly different lactate concentrations, unless the Accusport was used to determine the log-log lactate threshold, or values were expressed as a blood lactate concentration, the use of different analysers had little effect on the BLTT.
... In recent years, hand-held battery-operated lactate analyzers have gained increasing popularity. These hand-held devices offer a number of advantages to the coach and athlete over the traditional bench-top analyzers, especially the ability to monitor BLa in the field; they also cost less to purchase and require smaller blood samples for analysis (Buckley et al., 2003;Tanner et al., 2010). In order to use these portable analyzers for physiological assessment of athletes; however, it is important to establish their reliability (consistency of measurements) and construct validity (accuracy of measurement), especially when it comes to the identification of the lactate threshold. ...
... The Lactate Pro 2 (LP2: Arkray, Kyota, Japan) is one of the newer and most popular of the portable analyzers, requiring a smaller blood sample and shorter processing time than its predecessor, the Lactate Pro (LP: Arkray, Kyota, Japan) (Arkray, 2015;Rowe & Whyte, 2016). While several studies (Baldari et al., 2009;Bonaventura et al., 2015;Buckley et al., 2003;Medbo et al., 2000;Mc Naughton et al., 2002;Pyne et al., 2000;Tanner et al., 2010;Van Someren et al., 2005) have evaluated the performance of the LP device, only one published study to date (Bonaventura et al., 2015) has examined the reliability of the LP2 and/or assessed its construct validity against a laboratory-based analyzer. In this study the LP2 showed the highest inter-device reliability, as assessed by the coefficient of variation (CV), of all the six portable analyzers tested (Bonaventura et al., 2015). ...
... In addition, the LP2 underscored BLa measurements by the criterion benchtop analyzer, a Radiometer ABL90 (Radiometer, Copenhagen, Denmark), throughout most of the BLa range. Previous research comparing the LP to a criterion analyzer also reported a difference in absolute BLa data between analyzers, with the magnitude of the difference often increasing with increasing BLa, implying heteroscedastic data (Buckley et al., 2003;Medbo et al., 2000;van Someren et al., 2005). Given the importance of the lactate threshold in exercise monitoring and prescription, some investigators have examined whether this discrepancy in absolute BLa data between the LP and a criterion analyzer significantly affects the quantification of heart rate and power at various lactate parameters (Buckley et al., 2003;van Someren et al., 2005). ...
This study evaluated the reliability of the portable Lactate Pro 2 analyzer (LP2), and its validity compared to a laboratory-based analyzer, YSI 1500 Sport (YSI). Blood samples (n = 258) were collected during 44 graded incremental rowing tests, with data from 17 tests used to quantify load, heart rate, and oxygen consumption at lactate threshold. Inter-LP2 reliability was high with coefficient of variation = 3.3%; Bland Altman 95% limits of agreement varied from ± 0.3 mmol.L −1 for blood lactate (BLa) ≤4.0 mmol.L −1 to −1.6 to +1.4 mmol.L −1 for BLa >8.0 mmol.L −1 , with minimal systematic bias. Despite LP2 measurements being ~1.42 times higher than YSI measurements, no significant differences (P > .05) were detected when quantifying load, heart rate, or oxygen consumption data at lactate threshold. The results support using different LP2 devices interchangeably , especially when BLa ≤ 8 mmol.L −1 , and using the LP2 to identify training intensities at lactate threshold.
... The levels of blood lactate were assessed through a portable lactate analyzer (Lactate Pro; FaCT Canada Consulting Ltd; Arkray Inc., Kyoto, Japan).), as it has been shown that this lactate analyzer has both good sensitivity and reliability [21]. ...
... The first study [21,40] performed to evaluate the effects of high blood lactate levels on the excitability of the cerebral cortex found that increases in blood lactate levels and decreases in motor thresholds were significant. ...
... Studies on the effects of high blood lactate levels on cortical areas located outside the frontal lobe were conducted using sensory evoked potential. The increase in blood lactate values, obtained with exhaustive exercise (12.9 mmol/L) or with an intravenous infusion of a lactate solution (5.18 mmol/L), is associated with significant changes in the latency of two components of the visual evoked potentials: P100 and N145 (p < 0.05) [21,30]. In particular, it was observed that the latency of P100 displays a significant reduction after the exercise (0.0341 *), whereas the latency of N145 exhibits an increase of latency 10 min after the end of the exercise (0.0255 *). ...
The present review aims to examine the effects of high blood lactate levels in healthy adult humans, for instance, after a period of exhaustive exercise, on the functioning of the cerebral cortex. In some of the examined studies, high blood lactate levels were obtained not only through exhaustive exercise but also with an intravenous infusion of lactate while the subject was immobile. This allowed us to exclude the possibility that the observed post-exercise effects were nonspecific (e.g., cortical changes in temperature,
acidity, etc.). We observed that, in both experimental conditions, high levels of blood lactate are associated with a worsening of important cognitive domains such as attention or working memory or stress, without gender differences. Moreover, in both experimental conditions, high levels of blood lactate are associated with an improvement of the primary motor area (M1) excitability. Outside the frontal lobe, the use of visual evoked potentials and somatosensory evoked potentials allowed us to observe, in the occipital and parietal lobe respectively, that high levels of blood lactate are associated with an amplitude’s increase and a latency’s reduction of the early components of the evoked responses. In conclusion, significant increases of blood lactate levels could exercise a double-action in the central nervous system (CNS), with a protecting role on primary cortical areas
(such as M1, primary visual area, or primary somatosensory cortex), while reducing the efficiency of adjacent regions, such as the supplementary motor area (SMA) or prefrontal cortex. These observations are compatible with the possibility that lactate works in the brain not only as an energy substrate or an angiogenetic factor but also as a true neuromodulator, which can protect from stress. In this review, we will discuss the mechanisms and effects of lactic acid products produced during an anaerobic exercise lactate, focusing on their action at the level of the central nervous system with particular attention to the primary motor, the somatosensory evoked potentials, and the occipital
and parietal lobe.
... Recently the LP has been superseded by the Lactate Pro 2 (LP2) which requires less blood, calibrates automatically, has an extended detection range and generates results within 15 s. While a number of researchers have compared the LP to a range of other portable lactate analysers [6][7][8][9][10][11][12] , to the best of our knowledge there is only one published report comparing the performance of the LP2 13 . Therefore, the purpose of this study was to compare the lactate concentrations obtained from blood samples taken across a range of exercise intensities using the i-STAT, LP and LP2. ...
... The LP2 has recently replaced the popular LP analyser. Whereas several studies have reported the accuracy and reliability of the LP [6][7][8][9][10][11][12] there is, to our knowledge, only one study that has compared the LP and LP2 13 . Bonaventura et al (2015) compared the performance of both the LP and LP2 against the Radiometer ABL90 and demonstrated the LP2 had a reduced bias, especially at lactate concentrations above 10 mM. ...
... Whereas Dascombe et al (2007) reported a good agreement between the i-STAT and Accusport analysers, our results found lactate concentrations to be ~27% higher when measured by the i-STAT compared to the LP2, reflecting a similar pattern to those reported by Bonaventura et al (2015). Such large disparity in absolute lactate concentrations between analysers is a consistent finding within the literature 3,6,9,11 highlighting the difficulty associated with interpreting data obtained using different analysers. ...
Aim: To evaluate the accuracy of blood lactate measurements using the Lactate Pro (LP), Lactate Pro 2 (LP2) portable lactate analysers and i-STAT point-of-care device.
Methods: Blood samples (N = 284) were taken from 28 subjects during a variety of exercise modes: incremental cycling test, team-sport running simulation or resistance training. Weighted least products regression analysis was used to compare the LP to LP2 and LP2 to i-STAT.
Results: Lactate concentrations ranged between 0.4 – 18.2 mM. There was a strong linear relationship observed between the LP and LP2 analysers (r = 0.976, p < 0.01), although a small proportional bias was apparent. A strong linear relationship was also found between the LP2 and i-STAT analysers; however, both a fixed and proportional bias were revealed. The i-STAT reported higher absolute lactate concentrations (mean ± SD, 1.4 ± 1.3 mM, p < 0.001) which became more marked at moderate to high concentrations (> 4 mM; 2.2 ± 1.0 mM, p < 0.001).
Conclusion: While strong linear relationships existed between all three analysers, the LP and LP2 reported substantially lower lactate values compared with the i-STAT, especially at higher lactate concentrations. These results further highlight the need for caution when interpreting or comparing lactate data obtained using different analysers.
Full text available at
https://researchbank.acu.edu.au/fhs_pub/10904/
... Recently the LP has been superseded by the Lactate Pro 2 (LP2) which requires less blood, calibrates automatically, has an extended detection range and generates results within 15 s. While a number of researchers have compared the LP to a range of other portable lactate analysers [6][7][8][9][10][11][12] , to the best of our knowledge there is only one published report comparing the performance of the LP2 13 . Therefore, the purpose of this study was to compare the lactate concentrations obtained from blood samples taken across a range of exercise intensities using the i-STAT, LP and LP2. ...
... The LP2 has recently replaced the popular LP analyser. Whereas several studies have reported the accuracy and reliability of the LP [6][7][8][9][10][11][12] there is, to our knowledge, only one study that has compared the LP and LP2 13 . Bonaventura et al (2015) compared the performance of both the LP and LP2 against the Radiometer ABL90 and demonstrated the LP2 had a reduced bias, especially at lactate concentrations above 10 mM. ...
... Whereas Dascombe et al (2007) reported a good agreement between the i-STAT and Accusport analysers, our results found lactate concentrations to be ~27% higher when measured by the i-STAT compared to the LP2, reflecting a similar pattern to those reported by Bonaventura et al (2015). Such large disparity in absolute lactate concentrations between analysers is a consistent finding within the literature 3,6,9,11 highlighting the difficulty associated with interpreting data obtained using different analysers. ...
Aim: To evaluate the accuracy of blood lactate measurements using the Lactate Pro (LP), Lactate Pro 2 (LP2) portable lactate analysers and i-STAT point-of-care device. Methods: Blood samples (N = 284) were taken from 28 subjects during a variety of exercise modes: incremental cycling test, team-sport running simulation or resistance training. Weighted least products regression analysis was used to compare the LP to LP2 and LP2 to i-STAT. Results: Lactate concentrations ranged between 0.4 – 18.2 mM. There was a strong linear relationship observed between the LP and LP2 analysers (r = 0.976, p < 0.01), although a small proportional bias was apparent. A strong linear relationship was also found between the LP2 and i-STAT analysers; however, both a fixed and proportional bias were revealed. The i-STAT reported higher absolute lactate concentrations (mean ± SD, 1.4 ± 1.3 mM, p < 0.001) which became more marked at moderate to high concentrations (> 4 mM; 2.2 ± 1.0 mM, p < 0.001). Conclusion: While strong linear relationships existed between all three analysers, the LP and LP2 reported substantially lower lactate values compared with the i-STAT, especially at higher lactate concentrations. These results further highlight the need for caution when interpreting or comparing lactate data obtained using different analysers.
... 11 Ciò detto, le misurazioni della LA differivano tra gli analizzatori (P<0,0001), con conseguenti soglie di transizione del lattato (blood lactate transition threshold, BLTT) diverse tra gli analizzatori quando espresse come concentrazione di lattato ematico (P<0,0001) o quando la BLTT era definita come una concentrazione fissa di lattato ematico (cioè OBLA) (P<0,0001). 83 14,15 during laboratory and on-water testing. No significant differences were observed between canoe and kayak paddlers in post-exercise LA (11.1±3.3 mmol/L and 13.2±2.0 ...
... OBLA) (P<0.0001). 83 Also, it seems that the sample extraction place (finger-ear) is decisive in the obtained LA levels, especially at rest and in the initial phases of an incremental test in kayak ergometer, observing higher LA values in finger than in the earlobe. These differences are significant in baseline LA and at low workload levels within the aerobic zone of the curve, but these differences decreased with the appearance of the anaerobic threshold until the end of the test and the recovery. ...
INTRODUCTION: Flatwater canoeing is an Olympic sport in which two modalities are differentiated, kayak and canoe. However, the term “canoeing” is commonly used for both, which can give rise to confusion in the scientific literature despite the great differences between modalities. Therefore, the aim of this narrative review was to conduct a systematic search of the scientific literature concerning canoeing and kayaking individually to highlight the main determinants of performance of male and female flatwater paddlers.
EVIDENCE ACQUISITION: A thorough search up to June 2020 has been conducted in Scopus, Sport Discus and Web of Sciences databases for published literature on male and female flatwater canoeing and kayaking.
EVIDENCE SYNTHESIS: Male high-level kayakers and canoeists share similar mesomorph structures, with low fat percentages and strong muscled bodies, reporting high values of lean body mass, with kayakers slightly taller than canoeists. In addition, it has also been reported great levels of aerobic and anaerobic capacity together with a distinguished upper-body strength and muscle thickness, especially in arms and shoulders. Female kayakers follow the same trend with lower values than males.
CONCLUSIONS: Canoeing and kayaking successful performance depends on a combination of anthropometric, physiological, biomechanical, neuromuscular, psychological and nutritional factors which differ among specialized kayak and canoe paddlers due their different paddling motor pattern. Hence, the importance of taking into account the specific characteristics and demands of each modality in terms of physical preparation and talent detection of female and male canoeists and kayakers.
... Levels of blood lactate were measured by each participant every time he took a saliva sample. The subject was trained to use a "Lactate Pro 2", a portable lactate analyzer (Arkray Inc, Kyoto, Japan), which has proven to be highly reliable [35]. ...
... Stability of posture was inferred from A95, i.e., from the 95% of the area described by the CoP trajectory calculated while the subject maintained five different postures, each of which was maintained for at least 52 s, with and without visual input. The A95 parameter was chosen since preceding studies have showed that is the most sensitive measure for assessing postural stability [35,36]. Data about the CoP showed an significantly increased body sway in three specific conditions, i.e., when eyes were closed in the first position with the feet together (and therefore with the smallest support polygon) as well as in the fourth and fifth positions, where the dominant foot was 10 cm behind the other. ...
Background: It has recently been noticed that the quantity of stress affects postural
stability in young women. The study was conducted with the goal of investigating whether
increased stress may damagingly effect posture control in 90 young men (71 right-handed and 19 left-handed) while maintaining an upright bipedal posture, while keeping their eyes open or closed. Perceived Stress Scale (PSS) was administered and changes in free cortisol levels were monitored (Cortisol Awakening Response, CAR) in order to evaluate the amount of stress present during awakening, while the Profile of Mood States (POMS) was used to estimate distress on the whole.
Posture control was evaluated with the use of a force platform, which, while computing a confidence ellipse area of 95%, was engaged by the Center of Pressure through five stability stations and was sustained for a minimum of 52 s, with and without visual input. Another goal of the experiment was to find out whether or not cortisol increases in CAR were linked with rises of blood lactate levels. Results: CAR, PSS and POMS were found to be extensively related. Furthermore, it has been observed that increases in salivary cortisol in CAR are associated with small but significant increases in blood lactate levels. As expected, stress levels did affect postural stability. Conclusions: The
results of the present study confirm that the level of stress can influence postural stability, and that this influence is principally obvious when visual information is not used in postural control.
... The effects of acute physical exercise on the cognitive performances of an adult individual are still under discussion [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The existing literature tends to highlight a positive relationship if the exercise is of sub-maximal intensity, while the effects seem to be negative for exhaustive exercises [19][20][21][22][23][24][25][26]. ...
... Blood lactate was measured before as well as at the end and 15 min after the conclusion of the exercise, using a "Lactate Pro 2" portable lactate analyzer (Arkray Inc., Kyoto, Japan), since this automated lactate analyzer has a good reliability [1]. ...
The present study examined the effects of an exhaustive exercise on executive functions by using the Stroop Color Word Test (SCWT), Trail Making Test (TMT), A and B, and simple Reaction Time (RT). Thirty adults agreed to participate; 15 participants had a mean age of 24.7 years ± 3.2 Standard Deviation (SD, Standard Deviation) (group YOUNG), while the remaining 15 had a mean age of 58.9 years ± 2.6 SD (group OLD). Each subject performed the cognitive tasks at rest and blood lactate was measured (pre); each subject executed the acute exhaustive exercise and, immediately after the conclusion, executed the cognitive tasks and blood lactate was again measured (end). Cognitive tests were repeated and blood lactate measured 15 min after its conclusion of the exhaustive exercise (post). We observed: (1) a significant positive correlation between blood lactate levels and RT levels; (2) a significant negative relationship between levels of blood lactate and the SCWT mean score; (3) no significant correlation between blood lactate levels and TMT scores (time and errors), both A and B; (4) variations in blood lactate levels, due to exhaustive exercise, and parallel deterioration in the execution of RT and SCWT are significantly more pronounced in the group YOUNG than in the group OLD. The present study supports the possibility that high levels of blood lactate induced by an exhaustive exercise could adversely affect the executive functions pertaining to the prefrontal cortex.
... terschiedliche Analysesysteme (tragbare Feldmessgeräte gegenüber festinstallierten Labormesssystemen bzw. amperometrischen gegenüber fotometrischen Messsystemen) auch unter verschiedenen klimatischen Bedingungen berichtet (Bishop, 2001;Buckley et al., 2003;Medbo et al., 2000;van Someren et al., 2005) . ...
... Eine Frage mit der sich bislang keine Studie gezielt beschäftigt hat, ist der alleinige Einfluss von Ermüdung, d. h. ohne Glykogenverarmung, auf submaximale Laktatschwellen.Auch wird von veränderten Blutlaktatkonzentrationen unter verschiedenen klimatischenBedingungen berichtet(Bishop, 2001;Buckley, Bourdon, & Woolford, 2003;Medbo, Mamen, Holt Olsen, & Evertsen, 2000;van Someren, Howatson, Nunan, Thatcher, & Shave, 2005). So konnte eine Studie nachweisen, dass sich das MLSS im Mittel von 180 ± 11 W bei 22° C auf 148 ± 11 W bei 40° C signifikant reduziert(de Barros et al., 2011).Daneben kann die komplette Laktatleistungskurve auch von methodischen Faktoren beeinflusst werden, die bei einer Interpretation immer beachtet werden müssen). ...
Studie 1: Die anaerobe Laktatschwelle versucht, das maximale Laktat-Steady-State (MLSS) aus der Laktatleistungskurve eines Stufentests abzuleiten. Offen ist allerdings wie genau die unterschiedlichen Schwellenkonzepte bei der Bestimmung des MLSS sind. Ziel der Studie war es die Stegmann, Dickhuth, Dmax und 4-mmol-Schwellen auf ihre Genauigkeit im Abschätzen des MLSS zu überprüfen (Konstruktvalidität). 26 Männer (25 ± 4 J, 182 ± 5 cm, 79 ± 8 kg) absolvierten einen fahrradergometrischen Stufentest (ST; Start: 50 oder 100 W, + 50 W / 3 min). Es folgten zur Bestimmung des MLSS (242 ± 41 W) Dauerbelastungen über 30 min. Zur Bestimmung des MLSS durfte die Laktatkonzentration zwischen der 10. und 30. min nicht mehr als 1,0 mmol/l ansteigen. Anhand des MLSS wurden die Probanden in zwei Hälften unterteilt: Ausdauertrainierte (AT, n = 13): 3,7 ± 0,3 W/kg und Nicht-Ausdauertrainierte (NAT, n = 13): 2,6 ± 0,4 W/kg. Mittels Bland-Altman-Plots wurden die mittleren Differenzen (MD) und 95 %-Konfidenzintervalle (LoA) dargestellt. Zusammenhänge zwischen dem MLSS und den Schwellen wurden mittels Pearson-Produkt-Moment-Korrelationen berechnet. Im Mittel zeigen alle Schwellen sehr hohe signifikante Korrelationen zum MLSS (r = 0,91 bis 0,94). Die LoA liegen zwischen 10 % und 20 %. Dabei schätzen die Stegmann- (-4 ± 32 W) und Dmax-Schwelle (3 ± 32 W) unabhängig von der Leistungsfähigkeit das MLSS ähnlich genau ab (Homoskedastizität). Die Genauigkeit der Dickhuth- und 4-mmol-Schwelle ist hingegen von der Leistungsfähigkeit der Probanden abhängig (Heteroskedastizität). Im Mittel überschätzt 4-mmol (18 ± 48 W), wohingegen Dickhuth unterschätzt (-11 ± 38 W). Die individuellen Schwellenkonzepte Stegmann und Dmax schätzen das MLSS im Mittel unabhängig von der Ausdauerleistungsfähigkeit annähernd gleich gut und präzise ab. Die 4-mmol-Schwelle überschätzt es vor allem bei Ausdauertrainierten, wohingegen es die Dickhuth-Schwelle bei Untrainierten unterschätzt. Die individuelle Genauigkeit im Abschätzen des MLSS scheint für die Trainingssteuerung akzeptabel, sollte jedoch in Einzelfällen durch Trainingskontrollen überprüft werden. Studie 2: Das 40-km-Zeitfahren (TT) gilt als eine der wichtigsten Wettkampfdistanzen im Radsport. Unklar ist jedoch, inwieweit die Daten aus den klassischen Leistungstests in der Lage sind die Leistung im TT vorherzusagen. Daher war es das Ziel der zweiten Studie, die externe Validität der Laktatschwellenkonzepte hinsichtlich ihrer Genauigkeit in der Prädiktion der Leistung im TT zu überprüfen. 23 Wettkampfradfahrer (29 ± 8 J, 180 ± 6 cm, 74 ± 8 kg, VO2max 59,4 ± 7,4 ml/min/kg) absolvierten im Abstand von je 2 Stunden TT, einen 30-s-Wingate-Test (WT) und einen ST (100 W + 50 W / 3 min). Aus dem ST wurden die maximale Sauerstoffaufnahme (VO2max) und die oben genannten Schwellen bestimmt. Mittels Bland-Altman-Plots wurden MD ± LoA dargestellt. Zusammenhänge zwischen dem TT und den Schwellen wurden mittels Pearson-Produkt-Moment-Korrelationen berechnet. Signifikante Zusammenhänge zur Leistung im TT wurden für Pmax (r = 0,89), Stegmann (r = 0,83), Dickhuth (r = 0,80), Dmax (r = 0,79) und 4-mmol (r = 0,81) und die VO2max (r = 0,56) gefunden. Alle anderen Parameter zeigten keine signifikanten Zusammenhänge. Die MD lag für alle Schwellenkonzepte über 29 W und die LoA über 17 %. Mit einer MD von 103, aber LoA von 12 % hat die Pmax die geringste Streuung in der Differenz zum TT. Ziel einer Leistungsdiagnostik ist es auch, die aktuelle Wettkampfleistungsfähigkeit eines Sportlers zu ermitteln. Dazu scheint die Pmax für die Leistung im 40-km-Zeitfahren nominell ein besserer Prädiktor zu sein, als die submaximalen Laktatschwellen. Allerdings kann die individuelle Abweichung dennoch erheblich sein. Leistungstests, für die eine maximale Ausbelastung nötig ist, können störende Eingriffe im Trainingsalltag von Leistungssportlern darstellen. Daher wäre es vorteilhaft, einen Parameter der Leistungsdiagnostik zu haben, der unabhängig von Ausbelastung und Ermüdung die Ausdauerleistungsfähigkeit diagnostizieren könnte. Ziel der dritten Studie war es daher, den Einfluss einer Ermüdung auf die vier Laktatschwellen sowie andere Parameter der Leistungsdiagnostik zu überprüfen. Die gleichen Probanden wie in Studie 2 absolvierten ein 6-tägiges intensives Trainingslager. Vor, direkt nach und nach weiteren 2 Tagen Pause absolvierten sie folgende Tests: TT, WT und ST im Abstand von je 2 Stunden. Aus dem ST wurden die oben genannten Schwellen bestimmt. Zur Bestimmung der Unterschiede zwischen den Testtagen wurde eine ANOVA mit Messwiederholung berechnet. Bei signifikanten Unterschieden wurde ein post-hoc Scheffé-Test durchgeführt. Die Probanden absolvierten TT an Tag 1 im Mittel in 3942 ± 212 s, an Tag 8 in 4008 ± 201 s und an Tag 11 in 3929 ± 219 s (p < 0,001). Ebenso waren die mittlere Leistung im WT zwischen Tag 1 (701 ± 58 W) und Tag 8 (679 ± 65 W) sowie zwischen Tag 8 und Tag 11 (696 ± 69 W) und die maximale Leistung im ST (338 ± 30 W; 327 ± 31 W; 347 ± 30 W) signifikant unterschiedlich (p < 0,01). Für die submaximalen Schwellen nach Dickhuth (p = 0,34) und 4-mmol (p = 0,69) konnte kein Einfluss der Ermüdung gefunden werden. Die Stegmann-Schwelle lag nach den Regenerationstagen höher als im ermüdeten Zustand (Tag 1 - 8: p = 0,85; Tag 8 - 11: p = 0,03). Dmax lag an Tag 8 (256 ± 27 W) niedriger als an Tag 1 (p = 0,006; 265 ± 29 W) und Tag 11 (p < 0,001; 269 ± 25 W). Damit ist diese Arbeit die erste, die zeigen konnte, dass Ermüdung keinen Einfluss auf das Ergebnis in den submaximalen Schwellenkonzepten nach Stegmann, Dickhuth und 4-mmol hat. Lediglich die Dmax-Methode weicht auf Grund reduzierter maximaler Ausbelastung im ermüdeten Zustand im Mittel mehr als die Grundvariabilität vom erholten Zustand ab.
... This threshold, called also "lactate threshold" [6] leads to a halt in physical activity and for that reason sport medicine requires to monitor the levels of lactate in order to predict the performance of an athlete. Different techniques have been used for the determination of blood lactate such as HPLC, ion exclusion chromatography, and enzymatic colorimetric assays or portable analysers [7][8][9]. However these methods are often time-consuming, expensive, invasive, and require laboratory equipment and trained personnel. Electro-chemical biosensors have proved to be specific, selective and easy to use in the determination of metabolites for clinical, environmental and food analysis. ...
... By comparing the values obtained in the two types of analysis before physical activity, we can observe a lactate concentration in saliva approximately 10 times lower than the values obtained in the blood. Comparing saliva and blood values after physical activity, the 1:10 relationship between the concentrations is preserved only for athletes 1,9,11,12. The values of other subjects could be caused by some possible causes such as different physical training of athletes participating in the study, but it should also be noted that, being the saliva a biological matrix, some variability can be expected. ...
Lactate monitoring is an important issue in the food industry, in clinical diagnosis and sport medicine. Biosensors that can quantify lactic acid in biological samples are extremely attractive because of their advantages such as simplicity, ease of miniaturization, high sensitivity and low-cost. The proposed biosensor is based on a screen-printed electrode modified with Prussian Blue, that senses the hydrogen peroxide produced by the reaction catalysed by the lactate oxidase enzyme immobilized onto the electrode surface, coupled with a portable instrumentation. This biosensor showed a working range of 0.025–0.25 mM with a detection limit of 0.01 mM. After recovery studies, the biosensor was employed for the analysis of 12 saliva samples, taken from athletes, whose lactate levels were compared with the blood lactate content measured with a portable lactate analyser. The results showed a good correlation. The developed electrochemical biosensor could be a useful, alternative and non-invasive tool for a correct and rapid monitoring of lactate in saliva. This method is easy to use, cost effective, rapid, and suitable for analysis performed outside the classical diagnostic laboratory.
... [48,56,[63][64][65] In addition, several studies reported partly considerable differences between various lactate analysers (portable field vs laboratory analysers, amperometric vs photometric method) and under various climatic conditions. [58,[66][67][68][69] The analysis of the whole blood lactate curve is a very global approach to evaluating endurance capacity. On the one hand, this approach is affected by the above-mentioned factors on overall lactate levels. ...
... There is evidence that approaches that analyse relative changes in bLa during GXTs may be favourable compared with the use of absolute lactate values in this regard. [56,67] This material is the copyright of the original publisher. Unauthorised copying and distribution is prohibited. ...
During the last nearly 50 years, the blood lactate curve and lactate thresholds (LTs) have become important in the diagnosis of endurance performance. An intense and ongoing debate emerged, which was mainly based on terminology and/or the physiological background of LT concepts. The present review aims at evaluating LTs with regard to their validity in assessing endurance capacity. Additionally, LT concepts shall be integrated within the ‘aerobic-anaerobic transition’ — a framework which has often been used for performance diagnosis and intensity prescriptions in endurance sports. Usually, graded incremental exercise tests, eliciting an exponential rise in blood lactate concentrations (bLa), are used to arrive at lactate curves. A shift of such lactate curves indicates changes in endurance capacity. This very global approach, however, is hindered by several factors that may influence overall lactate levels. In addition, the exclusive use of the entire curve leads to some uncertainty as to the magnitude of endurance gains, which cannot be precisely estimated. This deficiency might be eliminated by the use of LTs. The aerobic-anaerobic transition may serve as a basis for individually assessing endurance performance as well as for prescribing intensities in endurance training. Additionally, several LT approaches may be integrated in this framework. This model consists of two typical breakpoints that are passed during incremental exercise: the intensity at which bLa begin to rise above baseline levels and the highest intensity at which lactate production and elimination are in equilibrium (maximal lactate steady state [MLSS]). Within this review, LTs are considered valid performance indicators when there are strong linear correlations with (simulated) endurance performance. In addition, a close relationship between LT and MLSS indicates validity regarding the prescription of training intensities. A total of 25 different LT concepts were located. All concepts were divided into three categories. Several authors use fixed bLa during incremental exercise to assess endurance performance (category 1). Other LT concepts aim at detecting the first rise in bLa above baseline levels (category 2). The third category consists of threshold concepts that aim at detecting either the MLSS or a rapid/distinct change in the inclination of the blood lactate curve (category 3). Thirty-two studies evaluated the relationship of LTs with performance in (partly simulated) endurance events. The overwhelming majority of those studies reported strong linear correlations, particularly for running events, suggesting a high percentage of common variance between LT and endurance performance. In addition, there is evidence that some LTs can estimate the MLSS. However, from a practical and statistical point of view it would be of interest to know the variability of individual differences between the respective threshold and the MLSS, which is rarely reported. Although there has been frequent and controversial debate on the LT phenomenon during the last three decades, many scientific studies have dealt with LT concepts, their value in assessing endurance performance or in prescribing exercise intensities in endurance training. The presented framework may help to clarify some aspects of the controversy and may give a rationale for performance diagnosis and training prescription in future research as well as in sports practice.
... Another reason for an altered lactate level is a disturbed lactate metabolism which may be caused by diabetes. In sport medicine, blood lactate levels during exercise are an indicator for training status and fitness [12][13][14]. During the demand of high intensity exercise, the cell utilizes a substantial amount of glucose and glycogen. ...
... The importance of lactate determination has generated much interest in developing lactate biosensors. Some techniques including automated lactate analyzers, HPLC or UV methods [10,12,15] have been developed for the detection method of lactate. Additionally, screen printed amperometric biosensors based on enzymes have been generally considered a simple, inexpensive and sensitive detection of lactate in aqueous solution [1,[16][17][18][19][20][21]. ...
This work describes the fabrication of a new lactate biosensor. The strategy is based on the use of a novel hybrid nanomaterial for amperometric biosensors i.e. platinum nanoparticles (PtNps) supported on graphitized carbon nanofibers (PtNps/GCNF) prepared by chemical reduction of the Pt precursor at GCNF surfaces. The biosensors were constructed by covalent immobilization of lactate oxidase (LOx) onto screen printed carbon electrodes (SPCEs) modified with PtNps (PtNps/GCNF-SPCEs) using polyethyleneimine (PEI) and glutaraldehyde (GA). Experimental variables concerning both the biosensor design and the detection process were investigated for an optimal analytical performance. Lactate biosensors show good reproducibility (RSD 4.9%, n=10) and sensitivity (41,302±546) μA/Mcm(2), with a good limit of detection (6.9μM). Covalent immobilization of the enzyme allows the reuse of the biosensor for several measurements, converting them in a cheap alternative to the solid electrodes. The long-term stability of the biosensors was also evaluated. 90% of the signal was kept after 3months of storage at room temperature (RT), while 95% was retained after 18months at -20°C. These results demonstrate that the method provides sensitive electrochemical lactate biosensors where the stability of the enzymatic activity can be preserved for a long period of time in adequate storage conditions.
... Familiarization for the portable metabolic system (Cosmed K4b2, Rome, Italy), Borg Rating of Perceived Exertion (RPE) scale, Category Ratio Pain Intensity Scale (CR-10), and blood lactate (BLa) analysis equipment (Lactate Plus, Nova Biomedical, Waltham, MA) also took place. BLa sampling procedure followed previously established methodology [21][22][23][24]. Resting HR and blood pressure (BP) were assessed following a 5-min quiet supine rest using a Polar HR monitor and automated BP cuff (Omron HEM-907XL, Bannockburn, USA), respectively. ...
This study aimed to investigate the influence of body weight, exercise modality, and pace on physiological and perceptual responses to determine the relation between perceptual and physiological responses.
Aerobically untrained, normal weight, and overweight males and females participated. Participants were randomly assigned to one exercise condition for a 1-mile walk.
Prescribed pace resulted in a greater physiological stress than self-selected pace (all p < 0.001) through blood lactate (1.3 ± 0.4 vs 1.7 ± 0.5 mmol), systolic blood pressure (128.9 ± 10.3 vs 139.2 ± 13.2 mmHg), heart rate recovery (2.1 ± 1.7 vs 4.5 ± 2.6 min), oxygen consumption (15.1 ± 2.6 vs 18.1 ± 3.6 ml/kg/min), heart rate (111.7 ± 16.6 vs 134.4 ± 8.3 bpm), and energy expenditure (5.5 ± 1.4 vs 6.8 ± 1.7 kcal/min). Overweight individuals exhibited higher values than normal weight for heart rate (113 ± 8.8 vs 125.5 ± 13.2 bpm, p < 0.001), percentage of max heart rate (60.7 vs 69.0%, p < 0.001), percent of VO2peak (42.2 vs 55.6%, p < 0.001), and total energy expenditure (100.9 ± 27.4 vs 114.1 ± 33.5 kcal, p = 0.022). Greater perceived effort was seen on a treadmill (6.3 ± 0.5 vs 12.5 ± 2.0 RPE, p < 0.001) and at prescribed pace (6.5 ± 1.1 vs 8.9 ± 1.9 RPE, p < 0.001).
A novel finding of this study was the increased physiological stress and perception of effort on a treadmill and at a prescribed pace, while total energy expenditure showed no significant differences. This could indicate an unfavorable perception and less affective response to the treadmill modality. These results indicate exercise at self-selected pace in preferred environments promotes enjoyable experiences with similar health benefits as those during prescribed higher intensity exercise.
... Blood lactate was measured before as well as at the end of the exercise, using a "Lactate Pro 2" portable lactate analyzer (Arkray Inc., Kyoto, Japan), as this portable device has a good reliability [26]. Blood samples were taken from the fingertip. ...
Bipedal walking is a composite task requiring integration of many control circuitries in
the brain and spinal cord. The present study was carried out to verify whether an increase in blood lactate, such as that associated with a high intensity exercise, is able to significantly modify the qualitative and/or quantitative aspects of human walking. Eighteen healthy physically male participants, aged between 20 and 24 years (M = 21.8, SD = 1.22), were recruited for the study. For this purpose, the experimental protocol included the measure of blood lactate levels with the aim of assessing possible relations between lactate blood values and different aspect of walking after an exhaustive exercise. An exhaustive exercise was associated with a strong increase of blood lactate
levels and produced a significant worsening in the ability to maintain the bipodalic upright posture as well as the fluidity of walking. Our results suggest that exhausting bouts impose greater challenges on postural control.
... The LT 1 PO was defined as the power preceding a 0.4 mmol L −1 rise in BLa from resting levels (Bourdon, 2012). The LT 2 PO was determined using the modified D-max method (Bishop, Jenkins, & Mackinnon, 1998;Bourdon, 2012), defined as the power on a third order polynomial yielding the maximal perpendicular distance to the straight lined formed by the point of LT 1 PO and the power associated to the final lactate point (Bishop et al., 1998;Bourdon, 2012;Buckley, Bourdon, & Woolford, 2003). The methods used for LT 1 and LT 2 determination were chosen to reflect similar BLa concepts and methods commonly used for sprint kayak testing and training monitoring (Bishop, 2000;Bullock et al., 2012;Hogan et al., 2020a;Pilotto et al., 2019;Winchcombe et al., 2019). ...
This study utilised on-water graded exercise tests (GXT) to determine the power output (PO) corresponding to the first and second lactate thresholds (LT1PO and LT2PO), subsequently examining their relationship to the mean maximal power (MMP) and race time achieved across three on-water sprint kayak time-trials. Twelve well-trained sprint kayak athletes completed an on-water GXT and a 200-, 500- and 1000-m time-trial utilising novel instrumented paddle technology. Stepwise multiple regression was used to determine whether equations incorporating 200-, 500- and 1000-m MMP data could be used as an alternative method for estimating LT1PO and LT2PO. On-water GXT derived LT1PO and LT2PO were 151±34 and 194±39 W, respectively. For the 200-, 500- and 1000-m time-trials, MMP were 528±143, 358±92 and 287±67 W, respectively. Athletes’ LT1PO and LT2PO had very-large inverse relationships to 200-, 500- and 1000-m time-to-completion (r=-.71 to -.85, P≤.010) and very-large, to near-perfect positive relationships to 200-, 500- and 1000-m MMP (r=.81 to .94, P≤.001). The equation incorporating 1000-m MMP alone provided the best prediction of LT1PO and LT2PO, explaining 78% and 88% of the variance, and yielding a standard error of estimate (SEE) of 11.3% and 7.1% for these measures, respectively. The results of this study provide further evidence to support the ecological validity of recently developed on-water GXTs graded by PO, since LT1PO and LT2PO were significantly correlated to 200-, 500- and 1000-m performance. Practitioners could also predict LT2PO with reasonable accuracy based solely from a 1000-m time-trial; potentially providing an alternative, non-invasive, competition-specific protocol for threshold determination.
... Blood lactate levels were quantified before the exercise (pre), every 10 min during the exercise (during), immediately at the end of the exercise (end), and finally, 10 min after the exercise was completed (post). Lactate measurements were taken using a "Lactate Pro 2" portable lactate analyzer (Arkray Inc, Japan), which has proven to be highly reliable (Buckley et al., 2003). ...
The present study was carried out among 20 healthy young male athletes to determine
whether aerobic exercise performed at two different intensities is able to affect executive
functions. For this purpose, we used the Stroop Color Word Test (SCWT) to evaluate
the ability to inhibit cognitive interference and the Trail Making Test (TMT) to assess
organized visual search, set shifting, and cognitive flexibility. Simple Reaction Time
(RT), as a measure of perception and response execution, was also evaluated. The
experimental protocol included the measure of blood lactate levels with the aim of
assessing possible relations between lactate blood values and selected executive
functions after a 30-min steady-state test performed at 60% and at 80% of VO2max.
The results showed that a 30-min aerobic exercise is not associated with a worsening of
executive functions as long as the blood lactate levels stay within the 4 mmol/l threshold.
... Blood lactate levels were quantified before as well as at the end of the yoga session or gym session, by using a "Lactate Pro 2" portable lactate analyzer (Arkray Inc., Tokyo, Japan), as this lactate analyzer has proven to be highly reliable [36]. ...
Yoga techniques are increasingly popular all over the world. This discipline provides benefits both in relation to particular psychological disorders, such as anxiety disorders or those related to stress, but also in relation to certain clinical frameworks that involve significant life changes of people. Some studies have shown that this practice brings relevant benefits regarding cognitive functions such as memory and attention. The aim of this study was to verify, in women over 40 years of age, whether the practice of yoga can positively affect self-esteem, anxiety control, and body image. It was also intended to verify whether the potential beneficial effects of yoga are influenced by the personality’s profile of the individual who practices it. Results demonstrated comparable data on a high level of well-being and psychophysical balance for all samples involved. These results, therefore, confirm that the constantly practiced yogic technique affects the lifestyle of the subject by promoting the learning of effective methods for physical health and well-being.
... To obtain a consistent reading for the determination of lactate in the fermentation samples, the portable lactate biosensor that is used should not be interchangeable. Certain studies have revealed that the same portable lactate analyzer should be used throughout all the measurements in order to reach a consistent and accurate reading of the lactate concentration (Baldari and Guidetti, 2000;Buckley et al., 2003;Medbø et al., 2000). ...
The rapid and practical determination of lactic acid concentration during anaerobic digestion and in acidification samples is extremely important to ensure the digester is running properly and to avoid build-up of lactic acid. Thus, developing a simple and fast method for analyzing lactic acid in anaerobic digestion samples is important. The results of the present study revealed that lactic acid is an intermediate product of anaerobic digestion, which could be quickly measured using a portable lactate biosensor. We obtained linear standard curves from the relationship between various lactic acid concentrations of the standard solution and the lactate biosensor reading, which were tested at different temperatures (30, 45 and 55EC). A high value of coefficient determination,-0.98-0.99, was obtained from all standard curves. This suggests that the evaluated system was accurate, reliable, and reproducible.
... For the detec- tion of the RCT, VCO 2 was plotted against VE [3] and two regression lines fit to the data. The LT1 was determined in two different ways: the first fixed rise in BLa concentration by 0.4 and 1 mmol�L -1 above the lowest individual BLa value [5,35]. Additionally, the LT1 was deter- mined by breakpoints in the log-log transformed VO 2 -BLa relationship [4]. ...
Objectives
The primary aim was to compare physiological and perceptual outcome parameters identified at common gas exchange and blood lactate (BLa) thresholds in Paralympic athletes while upper-body poling. The secondary aim was to compare the fit of the breakpoint models used to identify thresholds in the gas exchange thresholds data versus continuous linear and curvilinear (no-breakpoint) models.
Methods
Fifteen elite Para ice hockey players performed seven to eight 5-min stages at increasing workload until exhaustion during upper-body poling. Two regression lines were fitted to the oxygen uptake (VO2)-carbon dioxide (VCO2) and minute ventilation (VE)/VO2 data to determine the ventilatory threshold (VT), and to the VCO2-VE and VE/VCO2 data to determine the respiratory compensation threshold (RCT). The first lactate threshold (LT1) was determined by the first rise in BLa (+0.4mmol·L⁻¹ and +1.0mmol·L⁻¹) and a breakpoint in the log-log transformed VO2-BLa data, and the second lactate threshold (LT2) by a fixed rise in BLa above 4mmol·L⁻¹ and by employing the modified Dmax method. Paired-samples t-tests were used to compare the outcome parameters within and between the different threshold methods. The fit of the two regression lines (breakpoint model) used to identify thresholds in the gas exchange data was compared to that of a single regression line, an exponential and a 3rd order polynomial curve (no-breakpoint models) by Akaike weights.
Results
All outcome parameters identified with the VT (i.e., breakpoints in the VO2-VCO2 or VE/VO2 data) were significantly higher than the ones identified with a fixed rise in BLa (+0.4 or +1.0mmol·L⁻¹) at the LT1 (e.g. BLa: 5.1±2.2 or 4.9±1.8 vs 1.9±0.6 or 2.3±0.5mmol·L⁻¹,p<0.001), but were not significantly different from the log-log transformed VO2-BLa data (4.3±1.6mmol·L⁻¹,p>0.06). The outcome parameters identified with breakpoints in the VCO2-VE data to determine the RCT (e.g. BLa: 5.5±1.4mmol·L⁻¹) were not different from the ones identified with the modified Dmax method at the LT2 (5.5±1.1mmol·L⁻¹) (all p>0.53), but were higher compared to parameters identified with VE/VCO2 method (4.9±1.5mmol·L⁻¹) and a fixed BLa value of 4mmol·L⁻¹ (all p<0.03). Although we were able to determine the VT and RCT via different gas exchange threshold methods with good fit in all 15 participants (mean R²>0.931), the continuous no-breakpoint models had the highest probability (>68%) of being the best models for the VO2-VCO2 and the VCO2-VE data.
Conclusions
In Paralympic athletes who exercise in the upper-body poling mode, the outcome parameters identified at the VT and the ones identified with fixed methods at the LT1 showed large differences, demonstrating that these cannot be used interchangeably to estimate the aerobic threshold. In addition, the close location of the VT, RCT and LT2 does not allow us to distinguish the aerobic and anaerobic threshold, indicating the presence of only one threshold in athletes with a disability exercising in an upper-body mode. Furthermore, the better fit of continuous no-breakpoint models indicates no presence of clear breakpoints in the gas exchange data for most participants. This makes us question if breakpoints in the gas exchange data really exist in an upper-body exercise mode in athletes with disabilities.
... Measurement of blood lactate levels was performed through the portable analyser "Lactate Pro", (FACT Canada Consulting, Quesnel, BC, Canada), which has proven to be highly reliable [27]. The athletes regularly performed measurements of their blood lactate levels, so we simply required their values. ...
Purpose
In the last decades, several studies have been conducted on a particular martial art, judo, to evaluate performances and psychology of its athletes. In the present study, to investigate other possible variables, we analyzed, in adult athletes of both sexes practicing judo from at least 5 years, the relation between blood lactate levels and short-term memory.
Methods
Furthermore, in all subjects we evaluated personality’s aspects with the Sensation Seeking Scale V, the amount of stress with the Mesure du Stress Psychologique and the ratio between the second (index) and fourth (ring) finger. Participants in the research were 217 adult athletes practicing judo from at least 5 years. The research protocol was divided in two parts: (1) administration to each participant of SSS-V and MSP and measurement of Digit ratio; (2) administration to 50 athletes performing a 5 min combat, a digit span test and evaluation of blood lactate in three moments: before the competition, just after the conclusion, and 10 min after the end.
Results
Results showed, at the end of combat, an increase blood lactate above 4 mmol/l and an association between blood lactate levels and backward memory capacity, with relevant correlation between SSS-V, MSP and the Digit ratio. Lactate production, even if minimal, has a protective role against fatigue toward frontal cortex and define worse performances in backward memory capacity by conditioning strategic ability of the athletes.
Conclusion
We concluded that judo turns out to be a sport discipline useful to help women for manifesting disinhibition and their personality and men to control their aggressiveness and to try of overcoming their limits. These positive implications are more likely in individuals, both men and women, with a low digit ratio.
... Another reason for an altered lactate level is a disturbed lactate metabolism, which may be caused by diabetes. In sports medicine, blood lactate levels during exercise are an indicator for training status and fitness [4][5][6]. During the demand of high intensity exercise, the cell utilizes a substantial amount of glycogen and glucose. ...
An improved amperometric L-lactate biosensor was constructed based on covalent immobilization of lactate oxidase (LOx) onto zirconia coated silica nanoparticles (SiO2@ZrONPs)/chitosan (CHIT) hybrid film electrodeposited on the surface of a gold electrode (AuE). The enzyme electrode was characterized by cyclic voltammetry (CV), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and electrochemical impedance spectroscopy (EIS), while SiO2@ZrONPs were synthesized by chemical reduction method and characterized by transmission electron microscopy (TEM), UV spectroscopy and X-ray diffraction (XRD). The biosensor showed an optimal response within 3s at pH 7.5 in 0.05M sodium phosphate buffer and 30°C, when operated at 20 mVs-1. The biosensor had a low detection limit of 0.2 nM with a wide working / linear range between 0.1 – 4000 μM. The biosensor was employed for measurement of L-lactic acid level in plasma of apparently healthy and diseased persons. Analytical recovery of added lactic acid (5.0 mM and 10.0 mM)) in plasma was 99% and 96.6% respectively. Within- and between-batch coefficients of variations were 1.79% and 2.89% respectively. There was a good correlation (R2=0.99) between plasma lactate values as measured by standard enzymatic spectrophotometric method and the present biosensor. The enzyme electrode was used 160 times over a period of 120 days, when stored dry at 4°C.
... The i-STAT and Accusport lactate analyzers produced similar results for blood lactate for samples taken at rest, during moderate exercise, and during maximal exercise (Dascombe et al., 2007). However, others have found that the portable analyzers, and the Accusport in particular, do not agree with laboratory-based lactate analyzers (Buckley et al., 2003). Erroneous lactate measurements can be problematic because their readings are used to establish the intensity of workouts. ...
Point-of-care or point-of-use diagnostics are analytical devices that provide clinically relevant information without the need for a core clinical laboratory. In this review we define point-of-care diagnostics as portable versions of assays performed in a traditional clinical chemistry laboratory. This review discusses five areas relevant to human and animal health where increased attention could produce significant impact: veterinary medicine, space travel, sports medicine, emergency medicine, and operating room efficiency. For each of these areas, clinical need, available commercial products, and ongoing research into new devices are highlighted.
... For physiological parameters, the HR (beats·min -1 ) was registered beat to beat by Polar Team Advantage Monitor Ltd. (Polar, Kempele Finland) [36]. For the [LA] analysis (mmol/L -1 ) the blood was taken with a pipette needle (YSI 1500, calibrated with 5 and 15 mmol/L -1 standard solutions) (Sport Yellow Springs Instrument Ltd., OH, USA) [37]. The measurements of composition and volumes of the breathed air were taken with equipment Jaeger Oxycon Pro Ltd. (Würzberg, Germany) [38] and VO max expressed in ml·kg -1 ·min -1 . ...
Extreme Altitude (EA) and himalayism in its alpine style became a study subject in recent years from the point of view of physiology and cineanthropometry usually these studies are carried out only on expeditions with no monitoring within the time, and less on elite himalayist or successful high altitude climbers. There are no scientific studies based on longitudinal studies neither at sea level (SL) or on international elite climbers whom attempt to climb the highest mountains. Purpose: To analyze the evolution and correlation between physiological and cineanthropometric parameters in an elite male himalayist climber at SL before, after and off climbing expeditions during the period while our mountaineer has climbed the last four "eigh- thousanders" and all of them without supplementary oxygen. Methodology: Our climber has been subjected to cineanthropometric measurement (weight, six skinfolds, sum of them, body mass index and body fat percentage) and to an effort test on a treadmill (staged, progressive, intervallic and maximal) in order to take the physiological data (VO2max, HR, LA and RQ) before, during and off expedition at SL. Results: Analyzed data presented no significant (p<0.05) changes in our climber within the time nor on the moment of the season (after, before and off expedition) but we have found some significant (p<0.05) and very significant (p<0.01) intra variable and inter variable correlations. Conclusion: The outstanding form of our climber combined with his gift for acclimatization in part due to a broad climbing career ensures that he does not suffer any kind of significant alterations in the analyzed parameters according to the scientific literature. Our subject does not suffer either, against the majority of scientific literature, changes in his body composition. On the other hand the correlation of analyzed parameters coincides with the classical physiological studies.
... During the test, heart rate was measured every minute using a Polar (Gays Mills, Wisconsin, USA) heart rate monitor. Blood lactate was measured before as well as at the end and 15 min after the conclusion of the exercise, using a ''Lactate Pro'' portable lactate analyzer (FaCT Canada Consulting Ltd), since this automated lactate analyzer has a good reliability [10]. ...
The accumulation of lactate in the blood after a high-intensity exercise is associated with an increase of lactate extractions by the brain. Previously, a negative influence of blood lactate on attentional processes has been observed. The present study was carried out to examine the association of high blood lactate levels, induced with a maximal cycling, with another cognitive domain: working memory. For evaluation of working memory two different protocols were used: the first (Self-Ordered Pointing Task) capable of analyzing non-spatial working memory requiring the ability to generate and monitor a sequence of responses and the second for evaluating motor working memory necessary to perform a motor task. The study was carried out in 30 students (15 males and 15 females) who performed exhaustive exercise. In each subject, blood lactate was measured and motor as well as non-motor forms of working memory were evaluated before the exercise, at its end as well as 15 min after the exhaustion. It was observed that an increase of blood lactate levels is associated with a worsening of both types of working memory.
... P<0.01). In order to correctly interpret the above differences one has to remember that analytical methods may significantly affect the values related to the fixed anaerobic threshold of 4 mmol·l -1 lactate [8]. ...
In an incremental exercise the heart (HR) and stroke (SR) rates can be periodically synchronized suggesting that changes in the course of a relationship between power output (PO) and HR, recorded in the Conconi test as the deflection point (DP), may be related to changes in SR. In view of this, the aim of the present study was to analyse the course of the PO/HR, PO/SR, and SR/HR relationships in the progressive incremental exercise as well as to evaluate the accuracy of determination of anaerobic threshold (AT) based on the above three relationships. In the investigation, 12 kayakers performed the following tests on a special ergometer: the Conconi test (CT), the 30-min test (PET) with power output at DP (PO DP), the critical power test (CP), and the graded exercise test until exhaustion (GT), in which power output at the anaerobic threshold (PO AT4 , PO Dmax) was determined based on the blood lactate level (LA). The lack of DP in the PO/HR and the PO/SR relationships was detected in two and one athlete, respectively. In contrast, in the SR/HR relationship DP was recorded in all the tested subjects. The times of occurrence of DP did not significantly differ. Although, as judged by the LA dynamics in PET, the intensity of exercising exceeded that at the maximal lactate steady state (MLSS), all the athletes managed to complete the test. No significant differences were detected between PO DP and PO AT4 , PO Dmax or CP, and the agreement of the results obtained in CT with those collected in CP and GT was similar to that determined within each of the tests. The obtained results suggest that the changes in the course of the PO/HR relationship may be associated with spontaneous changes of SR. The lack of diversity among the times of occurrence of DP in the three relationships tested allows for an easy and non-invasive determination of AT even in case of a linear PO/HR relationship. The power output estimated with use of the presented method is higher than that at MLSS, but it is sustainable for at least 30 min. The accuracy of determination of anaerobic threshold based on the analysis of the three DPs appears to be comparable with that obtained with use of AT4, Dmax, and CP.
... Several other studies have shown that the Accutrend 1 Portable Analyzer provides accurate plasma and blood lactate measurements in athletics, critical care, obstetrics and other settings 9,10,11,12,17,18 . In these studies the portable analyzer produced results comparable to reference devices (such as the one in this study) and other portable analyzers 19,20 (e.g. Lactate Pro). ...
Objective:
To determine whether a portable analyzer is valid for measuring cerebrospinal fluid (CSF) and plasma lactate levels in HIV infected individuals.
Method:
CSF and plasma were collected from 178 subjects. Samples tested by the Accutrend® portable analyzer were compared to those tested by a reference device (SYNCHRON LX® 20).
Results:
The portable analyzer had in plasma sensitivity of 0.95 and specificity 0.87. For CSF the specificity was 0.95; the sensitivity 0.33; the negative predictive value was 95% and the positive predictive value 33%.
Conclusions:
These findings support the validity of the portable analyzer in measuring lactate concentrations in CSF that fall within the normal range. The relatively poor positive predictive value indicates that a result above the reference range may represent a “false positive test”, and should be confirmed by the reference device before concluding abnormality.
... Antes (medida de repouso) e imediatamente após a conclusão de cada série, amostras capilares de sangue foram coletadas para a determinação da concentração de lactato sanguíneo com um aparelho portátil Lactate Pro (Akray, Tókio Japão). Desvios sistemáticos foram descritos para este aparelho 14,15 Na análise estatística, a normalidade de distribuição foi verificada pelo teste de Shapiro-Wilk. Os resultados estão apresentados da seguinte forma: i) médias ± 1 erro padrão (EP) com medidas repetidas de teste t; ii) estabelecimento do modelo de regressão linear (p < 0,05); e iii) gráficos de plotagem de Bland-Altman entre os métodos padrão e alternativo. ...
INTRODUCTION AND OBJECTIVES: Investigate whether the inclusion of the blood lactate (BL) energy equivalent at submaximal intensities would change the energy cost of running (CR) predicted to supramaximal high-intensity running as well as its precision. METHODS: The CR was determined from the slope of the VO2-speed regression. For each subject an alternative regression was established where an energy equivalent of 3 ml O2 kg-1∙mM-1 BL was added to the VO2. Paired t-tests, pairwise correlations and Bland-Altman plots were used to investigate whether the two methods represent the same phenomena. RESULTS: The main findings were that CR predicted to supramaximal intensities comprised between 110% and 160% of that corresponding to the individuals' peak VO2, increased significantly when the BL measurements were included in the regressions. The inclusion of BL measurements also increased the imprecision of the CR at 110%, 120%, 130%, 150% and 160%. CONCLUSIONS: Our results indicate that inclusion of lactate O2 equivalent in the VO2-exercise intensity regression increases the energy cost of running and lowers its precision.
... Australian Sports Commission, Canberra, Australia). Lactate threshold was determined as the intensity preceding a 0.4 mmol$L 21 increase in La above the baseline (7). The IAT was determined as the point on the La-exercise intensity curve at maximal distance from a line connecting LT and finishing intensities (5). ...
The purpose of the study was to investigate the effect of cold-water immersion (CWI) on physiological, psychological, and biochemical markers of recovery and subsequent cycling performance following intensive run training. Seven high-performance male triathletes (age: 28.6±7.1 y; cycling VO2peak: 73.4±10.2 mL·kg·min) completed two trials in a randomized crossover design consisting of 7 x 5-min running intervals at 105% of Individual Anaerobic Threshold followed by either CWI (10°C±0.5°C) or thermoneutral water immersion (TNI; 34±0.5°C). Subjects immersed their legs in water five times for 60-s with 60-s passive rest between each immersion. Nine hours post-immersion, inflammatory and muscle damage markers, and perceived recovery measures were obtained before the subjects completed a 5-min maximal cycling test followed by a high quality cycling interval training set (6 x 5-min intervals). Power output, heart rate (HR), blood lactate (La) and rating of perceived exertion (RPE) were also recorded during the cycling time-trial and interval set. Performance was enhanced (change, ±90% confidence limits) in the CWI condition during the cycling interval training set (power output (W·kg ), 2.1±1.7%, La (mmol·L), 18±18.1%, La:RPE, 19.8±17.5%). However, there was an unclear effect of CWI on 5-min maximal cycling time-trial performance and there was no significant influence on perceptual measures of fatigue/recovery, despite small to moderate effects. The effect of CWI on the biochemical markers was mostly unclear, however there was a substantial effect for interleukin-10 (20±13.4%). These results suggest that compared to TNI, CWI may be effective for enhancing cycling interval training performance following intensive interval running training.
... -These were measured from samples of capillary blood from a fi ngertip. Lactate concentrations were determined by using a portable lactate analyzer, Lactate Pro (FaCT Canada Consulting Ltd., Quesnel, BC, Canada), since it has been verifi ed ( McNaughton, Thompson, Philips, Backx, & Crickmore, 2002 ;Buckley, Bourdon, & Woolford, 2003 ) that this device is reliable and valid. Blood glucose levels were measured with an Ascensia Elite portable blood glucose monitoring system (Bayer AG, Leverkusen, Germany), which assures an acceptable reliability ( Kristensen, Christensen, Thue, & Sandberg, 2005 ). ...
In equestrian show jumping, attention is particularly important to
ensure maximum accuracy. Due to the anaerobic nature of the jumping and its requirement
for precision coordination between human and horse, there may be a relation
between the onset of lactic threshold and decrease in attention. In 12 healthy and
injury-free equestrians (6 men, 6 women), the eff ects (blood lactate and glucose)
of a show jumping course (250 m long with eight vertical obstacles with a height
of 1.15 m height) on capacity and selectivity of attention was assessed. A typical
reaction time paradigm and test of divided attention were administered. At the end
of the course, a signifi cant increase of blood lactate was observed, whereas blood
glucose did not signifi cantly change. A deterioration of attention (intensity and
selectivity) and a worsening of performance with increasing of blood lactate were
observed. The present results led to the conclusion that the increase in blood lactate
that occurs in riders executing a show jumping course is associated with worsening
of both attentive capabilities and performance.
... The essential qualities of any tool are that they provide accurate and reliable results in a rapid and simple manner. With the advent of less expensive, rapid hand-held lactate analyzers that have proved accurate in animals (Coghe et al., 2000; Tennent-Brown et al., 2007; Thorneloe et al., 2007), critically ill human beings (Planche et al., 2001; Ivers and Mukherjee, 2006), even in sportsmen (Bucklay et al., 2003; Pyne et al, 2005), lactate measurement is likely to increase in sports community in order to improve performance, facilitate recovery and reduce the chances of injury. Thus, the purpose of the present study was to see test-retest reliability of Lactate Plus hand held analyzer in healthy human beings and day-to-day precision of the same in two control solutions. ...
The objective of the present study was to evaluate the test-retest reliability and day-to-day precision of a hand-held Blood Lactate Analyzer. Blood lactate levels were evaluated on 12 samples of human beings and blood was collected from both ring and middle finger for test-retest reliability. Day-to-day precision was determined by known concentration of two aqueous lactate control solutions once a day for 10 consecutive days. Results showed high test-retest reliability (r = 0.948; mean 2.41±0.86 in ring and 2.45±0.76 in middle finger) and high day-to-day reliability (r = 0.998; mean 1.1±0.08 in low control and 4.28±0.24 in high control solution). The results were similar to those previously reported. The results of this study support the use of the hand-held device in healthy human beings.
... Capillary blood lactate was measured at the end (0 min) as well as 5 and 10 min after the conclusion of the exercise by using a ''Lactate Pro'' portable lactate analyser (FaCT Canada Consulting, Quesnel, BC, Canada). It has been demonstrated ( McNaughton et al. 2002;Buckley et al. 2003) that this automated lactate analyser has a good reliability. Samples were collected from the index finger of the left hand, not involved in the exercise. ...
Abstract Excitability of primary hand motor cortex (PHMC), evaluated with transcranial magnetic stimulation by using the "1 mV resting motor threshold" method, and capillary blood lactate were measured at the end, as well as 5 and 10 min after a fatiguing hand-grip exercise. The relation between blood lactate and the amplitudes of motor-evoked potentials showed a significant direct proportionality. Blood lactate seems to exert a protective role on PHMC against fatigue reduction during extremely intensive isometric exercises.
... Blood samples were obtained via piercing of the ring fingertip of the right hand, collected in a 32-KL capillary tube to ensure equivalent blood volumes (16 KL), and then analyzed with an Accusport (Sports Resource Group, Hawthorne, NY) lactate analyzer. The Accusport lactate analyzer has good reliability (3,12,25) and has been reported to give slightly elevated blood lactate concentrations at simulated altitude (25). The client continued with the protocol until she reached a workload where lactate concentration increased 1 mmolIL j1 over baseline, followed by a subsequent increase in lactate Q 1 mmolIL j1 . ...
Purpose: The processes by which we assess, create an individualized exercise program, and monitor training of a breast cancer survivor who was participating in a fitness plan during and after surgery, chemotherapy, and radiation treatments were examined over a 391-d period. Case Study: A 57-yr-old female was diagnosed with stage I breast cancer (~1.2 cm diameter, estrogen positive, HER2/neu negative) with no lymph node involvement. After lumpectomy and axillary node dissection, the client completed chemotherapy treatment (cyclophosphamide, methotrexate, 5-fluorouracil (CMF)) followed by 33 bouts of radiation therapy. Assessment (body composition, V ˙ O 2max , lactate threshold, pulmonary function testing) was measured 4 d postdiagnosis and 2 months after treatments had ended. The client kept a daily log of exercise, average heart rate, and rating of perceived exertion in each exercise session. Results: Over 391 calendar days, the client exercised 343 days (88%) and completed 424 exercise sessions. The client's body composition (15.1%) and body weight (41.4 kg) remained stable for the entire period. There was a significant decrease in V ˙ O 2max (j7.8%) before and after treatment (56.4 to 52.0 mLIkg j1 Imin j1 , respectively). During the treatment phase (6.8 months), the client averaged 1.19 exercise sessions per day, with an average duration of 48.1 T 25.2 min at approximately 57% of V ˙ O 2max (~32 mLIkg j1 Imin j1). Posttreatment (~6.2 months), the client averaged 1.32 exercise sessions per day, with an average duration of 69.3 T 38.5 min at approximately 59.6% V ˙ O 2max (~31.2 mLIkg j1 Imin j1). Pre-and posttreatment exercise durations were significantly different (P G 0.01). Conclusions: A cancer survivor who engaged in a medically supervised and proactive fitness plan starting from the day of diagnosis maintained a realistic level of physiologic function during and after cancer treatment.
... Blood samples were obtained by piercing of the ring (third) fingertip, collected in a 32-l capillary tube to ensure equivalent blood volumes (16 l), and analyzed with an Accusport (Sports Resource Group, Hawthorne, NY) lactate analyzer. The Accusport lactate analyzer has good reliability (3,7,13) and has been reported to give slightly elevated blood lactate concentrations at simulated altitude (13). Subjects continued with the protocol until they reached a workload where lactate concentration increased 1 mmol·L Ϫ1 over baseline, followed by a subsequent increase in lactate Ն1 mmol·L Ϫ1 . ...
... Blood samples were obtained via piercing of the ring (third) fingertip with a lancet device (Sport Resource Group, Hawthorne, NY, USA) and collected in a 32 lL capillary tube to ensure equivalent blood volumes (*16-20 lL), and then analyzed with an Accusport (Sports Resource Group, Hawthorne, NY, USA) handheld lactate analyzer. The Accusport lactate analyzer has good reliability (Buckley et al. 2003;Fell et al. 1998) and has been reported to give slightly elevated blood lactate concentrations at simulated altitude (Medbo et al. 2000). The subjects continued with the protocol until they reached a workload where lactate concentration increased 1 mmol L -1 over baseline, followed by a subsequent increase in lactate [1 mmol L -1 . ...
Selected physiological responses, including lactate kinetics, to cardiopulmonary exercise testing (CPET) were evaluated among a group of cancer survivors (CS, n = 55) and healthy controls (HC, n = 213). It was uncertain if lactate testing in a group of cancer survivors could provide useful information about training intensity. It was hypothesized that chemotherapy, radiation, surgery, physical inactivity or some combination thereof would alter the normal lactate kinetics (curvilinearity) in the relationship of lactate concentration versus power. Physi-ologic responses of CS (heart rate, blood pressure, O 2 saturation, RPE, lactate, VO 2peak , and peak power) during cycle ergometry were compared to HC. Comparisons (t tests and Chi-square) were made between the groups and shape of lactate plots were analyzed for determination of a breakpoint. Multiple logistical regressions were then utilized to identify factors related to the inability to determine lactate breakpoints. Lactate breakpoints were common to all but one HC whereas among the CS there was a small subset of subjects (n = 5) who did not show a lactate breakpoint. Group differences indicated that female CS were significantly older, had greater BMI's, and lower work capacity than HC. Males CS had significantly lower work capacity than HC. Multiple logistical regression analyses, in all instances, yielded no statistically significant models predictive of the inability to determine a lactate breakpoint. In this sample of CS and HC, physiological responses and lactate kinetics during CPET were similar while work capacity among the CS was lower. Because lactate breakpoints were found, lactate threshold could be determined for all but a few individuals. For those working with CS, CPET with ECG monitoring and lactate threshold measures should be considered for those wishing for precise and safe training intensities.
... 4 Plasma lactate concentrations during exercise, and in particular lactate threshold (LT) and/or anaerobic threshold (AT), are commonly used to evaluate the effects of training, to set the training intensities. 5,6 As the determination of the AT through the invasive use of lactate concentrations or non-invasive use of respiratory gas exchange parameters is complex and expensive, Conconi et al. (1982) developed a field test for the non invasive determination of the AT, using HRDP in runners which later adapted by other various sport activities. Since the HRDP involves a testing method using non invasive parameters to assess the anaerobic threshold, a discussion of this concept could help for trainers and sport specialists to set the training programs intensities. ...
Aim:
The aim of the present study was to compare determined heart rate deflection point (HRDP) by the long distance maximum (L.Dmax), short distance maximum (S.Dmax) and plasma lactate measurements as criterion.
Methods:
Fifteen healthy and active male volunteers, aged 20-24, were selected as subjects and performed the exhaustive testing protocol which took place on a calibrated electronically braked cycle ergometer. To determine the HRDP, each subject's data was recorded during the exercise test and analyzed by a designed computer program. Venous blood samples were drawn for the measurement of plasma lactate concentration by a direct method.
Results:
Downward inflection of HRDP was noticed in all subjects. Comparison of the S.Dmax and L.Dmax methods with the criterion method (lactate method) showed that while HRDP determined by the S.Dmax and lactate methods were not significantly different (167±8.83 vs. 168±8.17 b/min; P=0.86), significant difference emerged between determined HRDP by the L.Dmax and lactate methods (167±8.83 vs. 139.56±6.73 b/min; P£0.001). Bland-Altman plots revealed a good agreement between S.Dmax and lactate methods (95% CI=-5 to +3.6 b/min), while there is no agreement between L.Dmax and lactate method (95% CI=+4.9 to +71.3 b/min). Significant correlation was observed between the criterion and S.Dmax model (r=0.944) whereas there was no significant correlation between the criterion and L.Dmax model (r=0.158).
Conclusion:
Based on these results, it could be suggested that S.Dmax method is an accurate and reliable alternative to the cumbersome, expensive, and time-consuming lactate method.
In diesem Kapitel werden verschiedene Laktatanalyseverfahren dargestellt, gefolgt von einer Übersicht verwendeter Analysegeräte mit Angaben zur Richtigkeit, Reliabilität und Präzision der jeweiligen Verfahren. Es stehen heute Analysemethoden zur Verfügung, die in der Lage sind, die Blutlaktatkonzentration in einem kleinen Probenvolumen mit ausreichender Präzision zu messen. Unterschiedliche Blutabnahmeorte, die angemessene Blutabnahmetechnik sowie Probleme bei der Selbstmessung von Laktat werden behandelt. Beim Vergleich von Laktatwerten ist darauf zu achten, ob Kapillarblut oder aber venöses Blut vorlag und ob die Messung im Vollblut oder Blutplasma vorgenommen wurde. Das Thema „Stabilität von Blutproben“ sowie Hinweise auf professionale Auswertungssoftware runden dieses Kapitel ab.
Conductive polymers with good flexibility, conductivity and film-forming ability attract a lot of attention. In this work, a large-area and ordered structure poly(3,4-ethylenedioxythiophene) (PEDOT) film is fabricated at the air-water interface through interface synthesis method. The PEDOT film can be directly placed on a flexible screen-printed electrode, but also has good adhesion between them. The surface of the PEDOT film is relatively smooth, and has good electrical conductivity and flexibility. Lactate oxidase is immobilized on the surface of PEDOT film through a combination of cross-linking and adsorption method to enhance the lactate sensitive performances. The results show that the PEDOT film sensor has excellent stability and reproducibility. The PEDOT film sensor shows a good response to lactate, the working range is 0.25-40 mmol·L⁻¹, and the detection limit is 0.083 mmol·L⁻¹ (S/N=3). Moreover, the electrochemical sensor has potential application in detecting lactate in sweat of the human body.
New technologies have speeded research in many areas of Exercise Science during the Post-Modern Era. Political interest in physical fitness and sport remains spasmodic, but the U.S. has finally introduced a scheme of universal health insurance. The cardiovascular disease epidemic is partially contained, but obesity and diabetes show a growing prevalence. Consensus conferences have underlined both the safety and the health benefits of physical activity and disease, and Universities offer an increasing range of doctoral programmes in Exercise Sciences and Kinesiology. However, optimal evidence-based exercise prescriptions have yet to be defined for many conditions. Health and fitness landmarks over the past 50 years include the standardization of test methodology, development of tools for population screening and testing, completion of representative National Health and Fitness surveys, quasi-experimental evaluations of school and employee fitness programmes, definition of minimum occupational fitness needs, demonstration of the beneficial effects of exercise on the aging process, and documentation of the high fitness levels associated with a hunter-gatherer lifestyle. Attempts to increase physical activity in the general population have as yet had only modest success. In Public Schools, the emphasis of Physical Educators is shifting from the training of sports teams to the teaching of life-long exercise skills. International sports programmes have received ever growing support from governments and commercial sponsors, with a multiplication of the corresponding professional associations. Olympic and Masters Games now cater to women, athletes with disability and the elderly, but athletic competition has lost much of its earlier idealism, and any positive impact upon population health and fitness is limited.
Introduction: The brain needs a continuous supply of O-2 and its deficiency may interfere with cognitive function. It has been observed that, during the performance of a maximal exercise, in the central nervous system (CNS) increases the use of lactate and glucose. Moreover; it has been described that during a maximal exercise the increase of blood lactate is associated with a worsening of attentive processes. The aim of this study was to investigate whether high levels of Lactate are capable of influencing other cognitive domains as Short-term memory. Materials and methods: Fifteen male and healthy athletes participated in the research. Short-term memory span was carried through the Italian computerized version of Wechsler's Digit Span. The subjects were asked to perform an incremental cycling test on a mechanically braked cycloergometer. The measurement of values of blood lactate and the assessment of Short-term memory through the Italian computerized version of Wechsler's Digit Span were performed in three specific moments: 1) at rest (before); 2) immediately after performing an exhaustive exercise (end); 3) 10 minutes after the end of the exercise (10 min). Results: Blood lactate levels increased ftom 1.5 mmol/l (+/- 0.21) at rest (pre), to 12.0 mmol/l (+/- 2.14) immediately after the exercise (end), and decreased to 1.6 mmol/l (+/- 0.21) 10 min after its conclusion (post). In parallel, we observed that the digit span shows a worsening of short term memory at the end of exercised and returned to the pre-exercise values within 10 min after the conclusion of exercise. Conclusion: The present results show that high levels of blood lactate, as those induced with an exhaustive exercise, influence the cognitive domain of the memory in the same way observed for the cognitive domain of attention.
Objectives:
The XXI Century Academy was a 6-year state-initiated intervention program that served as an alternative to basketball clubs for players in the u-14 and u-18 age groups in Spain, under guidelines established by the Spanish Basketball Federation. It was an important and unique project on talent development in basketball. To the best of the authors' knowledge, no evidence has been reported on long-term athlete development programs in basketball worldwide. The main aim of this report is to describe the design and evaluation methods used for the XXI Century Academy as a long-term intervention program in the elite Spanish Basketball Academy, aiming to prepare basketball players to compete at the elite level.
Methods:
The monitoring time lasted from 1996 to 2001. A total of 55 players were assigned to the intervention groups based on age, position, maturation level, and country of origin. During this process, participants competed in up to two categories in addition to playing competitive official matches worldwide in international tournaments in their categories and with the national team in the European and World Championships (u-14 - u-18). Participants included 1 NBA player, 3 national A Team players, 10 ACB (First Spanish League) players, 5 LEB (second League) players and 39 LEB-2 EBA (third League) players. Assessments took place in a High-Performance Sports Center (CPT FADURA-GETXO- Basque Government, Getxo, Vizcaya, Spain) and consisted of health questionnaires, anthropometric measures, blood parameters, maturation level, birth age, fitness tests, training volume and intensity, physical activity, technical and tactical training, dietary intake, supplementation and injuries. Each player was assessed 4 times per year (September, December, April, June) for 4 years (16 data points).
Results:
This is a purely methodological paper describing the design and evaluation methods used in the XXI Century Project, which will be used as a basis for future reporting of results. Therefore, the results of the project will be reported in subsequent publications.
Conclusion:
The viability of the Century XXI Project protocols has been described. This national project of training in basketball closely replicates the physical and technical match-play conditions for professionals and may constitute a useful training tool.
The determination of blood lactate concentrations during exercise has become an important tool in endurance diagnosis and training control. Physiological measures are susceptible to several error components (biological, technical and methodological variability). Such factors cause either systematic bias or random error. The present article will provide an overview of such influencing factors. This may contribute to a realistic interpretation of lactate values in sports practice as well as in scientific studies. The lactate distribution in circulation leads to sys- tematic differences. For instance, arterial values are reported to be higher than venous concentrations with capillary values lying in between. Plasma concent- rations have also been foUND higher compared to those in erythrocytes and, thus, the analysed blood medium (plasma > hemolysed > non-hemolysed whole blood) causes systematic bias. In addition, systematically higher values are reported for capillary blood samples from the finger tip compared to the earlobe. The use of different lactate analyzers may also result in considerable, but less predictable, variability. The described confoUNDing factors indicate that several methodological aspects should be taken into account to allow for reliable interpretation of lactate values in science and practice. High quality standards regarding analyzers and methods as well as standardized methodological procedures -in particular for longitudinal analyses -should be guaranteed. Due to a high biological variability, together with the described methodological variability of lactate measurements, the interpretation of absolute lactate values in sports practice should be done with considerable care.
We studied, in healthy adult subjects, the association of high blood lactate levels, induced with an exhaustive exercise (12 subjects) or an intravenous infusion (four subjects) of a lactate solution (3 mg/kg in 1 min), with amplitude and latency of visual-evoked potentials. Amplitude of N75, P100, and N145 components did not show significant changes, whereas latency of P100 was reduced at exercise's end and that of N145 increased 10 min after the conclusion. Therefore, an increase of blood lactate induced by an exhaustive exercise or an intravenous infusion appears to induce an improvement in the conduction time between eye and striate cortex, while it seems to evoke a worsening of intracortical communication between striate and extrastriate areas.
The aim of this study was to establish the validity of the anaerobic threshold (AT) determined on the soccer specific Hoff circuit (ATHoff) in order to predict the maximal lactate steady state exercise intensity (MLSSHoff) with the ball. Sixteen soccer players (16.0±0.5 years; 63.7±9.0 kg, and 169.4±5.3 cm) were submitted to five progressive efforts (7.0 to 11.0 km·h), with ball dribbling. Thereafter, eleven players were submitted to three efforts of 30min at 100, 105, and 110% of ATHoff. The ATHoff corresponded to the speed relative to 3.5 mmol L lactate concentration. The speed relative to 4.0 mmol.L was assumed to be ATHoff4.0 and the ATHoffBI was determined through bi-segmented adjustment. For comparisons, Student t-test, intraclass correlation, and Bland & Altman analyzes were used. For reproducibility, intraclass correlation, typical error, and coefficient of variation were used. No significant difference was found between AT test and retest determined using different methods. A positive correlation was observed betweenATHoffand ATHoff4.0. The MLSSHoff (10.6±1.3 km h) was significantly different compared to ATHoff (10.2±1.2 km h) and ATHoffBI (9.5±0.4 km h) but did not show anydifference from LAnHoff4.0 (10.7±1.4 km.h). The MLSSHoff presented high intraclass correlations coefficients with ATHoffand ATHoff4.0 (ICC = 0.94; and ICC=0.89; p < 0.05, respectively), without significant correlation with ATHoffBI. The results suggest that AT determined on the Hoff circuit is reproducible and capable of predicting MLSS. The ATHoff4.0 was the method which presented a better approximation to MLSS. Therefore, it is possible to assess submaximal physiological variables through a specific circuit performed with the ball in young soccer players.
Background:
Individuals using their voice intensively during physical effort are at risk for developing voice problems. This study was aimed at examining the influence of physical activity on voice characteristics.
Methods:
Fourteen physical education students (age: 27 ± 4.23 years) were recorded in a resting position, and during mild, moderate, and high exercise intensities (active conditions). Participants were also recorded immediately after each activity, while standing (recovery condition). All recordings were analyzed acoustically.
Results:
A significant elevation in the fundamental frequency (F0) was observed with the increase in activity level (p < 0.05). For all other acoustic measures, a gradual increase was observed as the activity level was raised. This increase was statistically significant for a specific set of measures (jitter, PPQ5, and shimmer) during the active conditions. In most cases, significant contrasts were found only between the high activity level and the other levels. During the recovery conditions, a similar increase in values was observed. However, these findings failed to reach statistical significance.
Conclusion:
Findings imply that high levels of physical effort lead to a significant reduction in vocal stability and to an elevation in F0. These changes result from vocal effort and could therefore lead to voice disorders and pathology.
The aim of this study was to examine the effects of maximal aerobic power (VO(2)peak) level on the ability to repeat sprints (calculated as performance decrement and total sprinting time) in young basketball players. Subjects were 18 junior, well-trained basketball players (age, 16.8 +/- 1.2 years; height, 181.3 +/- 5.7 cm; body mass, 73 +/- 10 kg; VO(2)peak, 59.6 +/- 6.9 ml.kg(-1).min(-1)). Match analysis and time-motion analysis of competitive basketball games was used to devise a basketball-specific repeated-sprint ability protocol consisting of ten 15-m shuttle run sprints with 30 s of passive recovery. Pre, post, and post plus 3-minute blood lactate concentrations were 2.5 +/- 0.7, 13.6 +/- 3.1, and 14.2 +/- 3.5 mmol.L-1, respectively. The mean fatigue index (FI) value was 3.4 +/- 2.3% (range, 1.1-9.1%). No significant correlations were found between VO(2)peak and either FI or total sprint time. A negative correlation (r = -0.75, p = 0.01) was found between first-sprint time and FI. The results of this study showed that VO(2)peak is not a predictor of repeated-sprint ability in young basketball players. The high blood lactate concentrations found at the end of the repeated-sprint ability protocol suggest its use for building lactate tolerance in conditioned basketball players.
Blood levels of lactate and glucose were measured in 15 healthy male athletes with the purpose of evaluating possible correlation between their blood values and intensity and selectivity of attention, after a 30-min steady-state test performed at 60 and 80% of maximal oxygen consumption (VO2max). On the basis of the results, we conclude that, during aerobic exercise, a worsening of attentional capabilities does not occur unless there is an increase of blood lactate above 4mmol/l. © 2014 Informa UK Ltd. All rights reserved: reproduction in whole or part not permitted.
The influence of blood lactate on brainstem excitability was tested by using the blink reflex (BR) recovery cycle on 18 sprinters. Blood lactate was measured before maximal cycling, at the end, as well as 5 and 10 min after the exhaustion. Blood lactate was associated with a decrement of R2 whereas only small changes were observed after an intravenous infusion of lactate. It seems, therefore, that lactate influences BR mainly by acting at the cortical level.
Upper and lower body exercise was performed to assess the influence muscle mass has on plasma volume (PV) shifts. Nine male subjects (mean = 28 yr) completed a progressive intensity, discontinuous test with an arm crank (AC) and cycle (CY) ergometer. Power output (PO) levels for the AC were 25, 74, 98, and 133 W. PO levels for the CY were 49, 98, 147, and 263 W. At a given submaximal oxygen uptake (VO2), PV efflux was significantly greater for AC compared with CY exercise. When PV efflux was related to the relative intensity of the exercise (ergometer specific % peak VO2), responses were nearly identical. Maximal PV efflux was 18% for both AC and CY exercise. Mean arterial pressure (MAP) was significantly greater for AC compared with CY exercise for a given VO2. MAP plotted against the relative intensity of exercise, however, was similar for both AC and CY exercise. These results suggest that the amount of plasma efflux during exercise is related to the MAP, which is directly related to the relative intensity of the exercise.
Minimal measurement error (reliability) during the collection of interval- and ratio-type data is critically important to sports medicine research. The main components of measurement error are systematic bias (e.g. general learning or fatigue effects on the tests) and random error due to biological or mechanical variation. Both error components should be meaningfully quantified for the sports physician to relate the described error to judgements regarding 'analytical goals' (the requirements of the measurement tool for effective practical use) rather than the statistical significance of any reliability indicators. Methods based on correlation coefficients and regression provide an indication of 'relative reliability'. Since these methods are highly influenced by the range of measured values, researchers should be cautious in: (i) concluding acceptable relative reliability even if a correlation is above 0.9; (ii) extrapolating the results of a test-retest correlation to a new sample of individuals involved in an experiment; and (iii) comparing test-retest correlations between different reliability studies. Methods used to describe 'absolute reliability' include the standard error of measurements (SEM), coefficient of variation (CV) and limits of agreement (LOA). These statistics are more appropriate for comparing reliability between different measurement tools in different studies. They can be used in multiple retest studies from ANOVA procedures, help predict the magnitude of a 'real' change in individual athletes and be employed to estimate statistical power for a repeated-measures experiment. These methods vary considerably in the way they are calculated and their use also assumes the presence (CV) or absence (SEM) of heteroscedasticity. Most methods of calculating SEM and CV represent approximately 68% of the error that is actually present in the repeated measurements for the 'average' individual in the sample. LOA represent the test-retest differences for 95% of a population. The associated Bland-Altman plot shows the measurement error schematically and helps to identify the presence of heteroscedasticity. If there is evidence of heteroscedasticity or non-normality, one should logarithmically transform the data and quote the bias and random error as ratios. This allows simple comparisons of reliability across different measurement tools. It is recommended that sports clinicians and researchers should cite and interpret a number of statistical methods for assessing reliability. We encourage the inclusion of the LOA method, especially the exploration of heteroscedasticity that is inherent in this analysis. We also stress the importance of relating the results of any reliability statistic to 'analytical goals' in sports medicine.
An evaluation of the hand-held portable Lactate Pro Analyser (KDK) was undertaken to assess its accuracy, reliability and versatility. Capillary blood samples were drawn from elite athletes in both laboratory and field settings and analysed in parallel. Accuracy was determined in relation to three other lactate analysers: (1) the ABL 700 Series Acid-Base analyser (n = 172 cases), (2) the Accusport Lactate Meter (n = 118 cases), and (3) the YSI 2300 Stat lactate analyser (n = 22 cases). The level of agreement was determined over the range of 1-18 mM. The repeatability of results between two different Lactate Pro analysers was also determined over the same range. Versatility was assessed in the field, where the Lactate Pro was used with elite athletes under a range of outdoor and indoor testing conditions. The correlations between the Lactate Pro and the ABL 700 Series Acid-Base analyser, YSI 2300 and Accusport were r = 0.98, r = 0.99, r = 0.97. The correlation between the two Lactate Pro analysers on the same sample (n = 96 cases) was r = 0.99. The level of agreement between the Lactate Pro and other analysers was generally less than +/- 2.0 mM over the physiological range of 1.0-18.0 mM (range of mean difference: -0.06 mM to 0.52 mM). The Lactate Pro was easy to operate and successfully completed the sample analysis in 100% of the tests performed. In summary, the Lactate Pro is accurate, reliable and exhibits a high degree of agreement with other lactate analysers.
Information on the performance of different instruments used to measure blood lactate concentration is incomplete. We therefore examined instruments from Yellow Springs Instruments (YSI 23L and YSI 1500) and three cheaper and simpler instruments: Dr. Lange's LP8+, Lactate Pro from Arkray in the KDK corporation and Accusport from Boehringer Mannheim. First, a number of blood samples were analysed by standard enzymatic photofluorometry (our reference method) and, in addition, by one or more of the instruments mentioned above. Second, measurements using two or more identical instruments were compared. Third, since Lactate Pro and Accusport are small (approximately 100 g, pocket-size), battery-driven, instruments that could be used for outdoor testing, the performance of these instruments was examined at simulated altitudes (O2 pressure of <10 kPa) and at temperatures below -20 degrees C, while screening the instruments as much as possible from the cold. Most of the different instruments showed systematically too high or too low values (10-25% deviation). The observed differences between instruments may affect the "blood lactate threshold" by 2-5%. We found different readings between "equal" YSI 1500 instruments, while we could see no difference when comparing the other instruments of the same type. Lactate Pro gave reliable results at both -21+/-1 degrees C and at simulated altitude. Accusport gave reliable results in the cold, but 1.85+/-0.08 mmol L(-1) (mean+/-SD) too high readings at the simulated altitude. Of the three simpler instruments examined, the Lactate Pro was at least as good as the YSI instruments and superior to the other two.
The reliability of power in tests of physical performance affects the precision of assessment of athletes, patients, clients and study participants. In this meta-analytic review we identify the most reliable measures of power and the factors affecting reliability. Our measures of reliability were the typical (standard) error of measurement expressed as a coefficient of variation (CV) and the percent change in the mean between trials. We meta-analysed these measures for power or work from 101 studies of healthy adults. Measures and tests with the smallest CV in exercise of a given duration include field tests of sprint running (approximately 0.9%), peak power in an incremental test on a treadmill or cycle ergometer (approximately 0.9%), equivalent mean power in a constant-power test lasting 1 minute to 3 hours on a treadmill or cycle ergometer (0.9 to 2.0%), lactate-threshold power (approximately 1.5%), and jump height or distance (approximately 2.0%). The CV for mean power on isokinetic ergometers was relatively large (> 4%). CV were larger for nonathletes versus athletes (1.3 x), female versus male nonathletes (1.4 x), shorter (approximately 1-second) and longer (approximately 1-hour) versus 1-minute tests (< or = 1.6 x), and respiratory- versus ergometer-based measures of power (1.4 to 1.6 x). There was no clear-cut effect of time between trials. The importance of a practice trial was evident in studies with > 2 trials: the CV between the first 2 trials was 1.3 times the CV between subsequent trials; performance also improved by 1.2% between the first 2 trials but by only 0.2% between subsequent trials. These findings should help exercise practitioners and researchers select or design good measures and protocols for tests of physical performance.
A randomized, double-blind, placebo controlled design was used in which 13 elite female rowers. all of whom had competed at World Championships, were supplemented with 60 g . day(-1) of either bovine colostrum (BC; n = 6) or concentrated whey protein powder (WP; n = 7) during 9 weeks of pre-competition training. All subjects undertook the study as a group and completed the same training program. Prior to, and after 9 weeks of supplementation and training, subjects completed an incremental rowing test (ROW 1) on a rowing ergometer consisting of 3 X 4-min submaximal workloads and a 4-min maximal effort (4max), each separated by a 1-min recovery period. The rowing test was repeated after a 15-min period of passive recovery (ROW2). The 4max for ROW1 provided a measure of performance, and the difference between the 4max efforts of ROW1 and ROW2 provided an index of recovery. Blood lactate concentrations and pH measured prior to exercise and at the end of each workload were used to estimate blood buffer capacity (beta). Food intake was recorded daily for dietary analysis. There were no differences in macronutrient intakes (p > .56) or training volumes (p > .99) between BC and WP during the study period. Rowing performance (distance rowed and work done) during 4max of ROW2 was less than ROW1 at baseline (p < .05) but not different between groups (P > .05). Performance increased in both rows by Week 9 (p < .001), with no difference between groups (p >.75). However, the increase was greatest in ROW2 (p < .05), such that by Week 9 there was no longer a difference in performance between the two rows in either group (p >.05). beta was not different between groups for ROW1 at baseline (BC 38.3 +/- 5.0, WP 38.2 +/- 7.2 slykes; p > .05) but was higher in BC by Week 9 (BC 40.8 +/- 5.9, WP 33.4 +/- 5.3 slykes; p < .05). beta for ROW2 followed the same pattern of change as for ROW I. We conclude that supplementation with BC improves beta, but not performance, in elite female rowers. It was not possible to determine whether beta had any effect on recovery.
In clinical measurement comparison of a new measurement technique with an established one is often needed to see whether they agree sufficiently for the new to replace the old. Such investigations are often analysed inappropriately, notably by using correlation coefficients. The use of correlation is misleading. An alternative approach, based on graphical techniques and simple calculations, is described, together with the relation between this analysis and the assessment of repeatability.
In order to determine the ventilatory threshold (VT) and the lactate threshold (LT) in a reliable way, a new method is proposed and compared with conventional methods. The new method consists of calculating the point that yields the maximal distance from a curve representing ventilatory and metabolic variables as a function of oxygen uptake (VO2) to the line formed by the two end points of the curve (Dmax method). Male cyclists (n = 8) performed two incremental exercise tests a week apart. Ventilatory/metabolic variables were measured and blood was sampled for later lactate measurement during each workload and immediately after exercise. No statistical differences were observed in the threshold values (expressed as absolute oxygen uptake; VO2) determined by the Dmax method and the conventional linear regression method (according to O2 equivalent; EqO2) and venous blood at the onset of blood lactate (OBLA), while VT assessed with the conventional linear method (according to the slope of CO2 output; Vslope) yielded significantly lower threshold values. Similar results were obtained from the reproducibility test. Thus, the Dmax method appears to be an objective and reliable method for threshold determination, which can be applied to various ventilatory or metabolic variables yet yield similar results. The results also showed that breathing frequency can be used to determine VT.
The aim of the study was to investigate the distribution of lactate in plasma, whole blood, erythrocytes, and capillary finger blood, before and during submaximal exercise. Ten healthy male subjects performed submaximal graded cycle ergometer exercise for 20-25 min. Venous blood samples and capillary finger blood samples were taken before exercise and every 5th min during exercise for lactate determination. The plasma lactate concentration was significantly higher (P less than 0.001, approximately 50%) than in the erythrocytes. This difference was not altered by the venous blood lactate concentration or exercise intensity. A significant difference (P less than 0.01) in lactate concentration was also found between capillary whole blood and venous whole blood. It was concluded that direct comparisons between lactate in capillary finger blood, venous whole blood and plasma could not be made.
The pattern of arterial lactate concentration ([La-]) increase during incremental exercise was studied using a transformation defined by plotting log([La-]) vs. log(VO2), where VO2 is O2 uptake. A plot of this function exhibits a phase of very slow increase followed by a phase of rapid increase, defining a transition in the underlying relationship between [La-] and VO2. These phases were found to be linear on the log-log plot; linear regression analysis may therefore be used to locate the transition between them (lactate threshold). A transition point was found at a lower VO2 on the semilog plot of log([La-]) vs. VO2. Consideration of the data from all studies led to the conclusion that a more accurate result is provided by the log-log transformation. This analysis shows lactate to have a small, but significant, increase before the transition and to increase beyond it with a power law having an exponent of about 2.9. This result shows that, during incrementally increasing work rate tests, arterial lactate exhibits a threshold behavior, i.e., an abrupt transition from a phase of slow increase to a phase of rapidly accelerating increase.
The purpose of this study was to examine the effect of increment durations of 1-min and 4-min during progressive incremental exercise tests on: 1) the distribution of lactate between plasma and red blood cells (RBCs), and 2) lactate threshold (LT) detection via three conventional methods using whole blood lactate concentration ([La]) or plasma [La]. Eight males (age, 22.5 +/- 0.6 yr: height, 170.6 +/- 2.3 cm, weight, 76.0 +/- 3.1 kg, and VO2peak, 42.8 +/- 2.0 mL.kg-1.min-1) performed two progressive load tests to volitional fatigue on a cycle ergometer. Work rate was increased 30 W at 1-min or 4-min intervals. All data were normalized to individual LT work rates. For both protocols, whole blood [La], plasma [La], RBC [La], and [La] gradient increased significantly (P < 0.05) after exercise intensity exceeded LT. However, the RBC:plasma [La] ratio remained at the resting value throughout the progressive exercise tests. The increase in [La] gradient after LT, with no change in the RBC:plasma lactate ratio, suggests that given an incremental work rate increase of 30 W, 1 min is adequate for equilibration of lactate between the plasma and RBCs. Also, under the conditions of this investigation, neither blood fraction analyzed nor exercise protocol had any effect on estimations of LT (in terms of VO2) by the Visual and Log-Log methods. However, LT determined by a fixed [La] of 2 mM may underestimate LT when plasma samples are used.
An investigation of the Accusport Lactate Analyser (ACC) was undertaken to assess its accuracy, linearity, reliability, and versatility. Accuracy was determined by comparing 32 blood assays on the ACC with those obtained using the Kodak Ektachem E250 (E250). Linearity was determined over the range 1.2-18.7 mmol/L. Reliability was measured at 1.7 (low) and 14.4 (high) mmol/L concentrations. Versatility involved determining the optimal sample volume, influence of haematocrit, and the effect of time delay from sampling to assay. Assays determined using the ACC confirm good agreement with the E250. The difference between the two methods compared for lactate determination does not exceed 1.1 mmol/L for concentrations up to approximately 20 mmol/L. Linearity is demonstrated by the regression equation y = 0.026 + 0.970x, r = 0.995. Reliability is expressed by the coefficient of variation of 7% (low) and 4.6% (high). The optimal sample size for accurate assay was determined to be between 20 microL and 50 microL. Mean lactate value did not vary significantly between a haematocrit of 35% and 45%. The Accusport is accurate, linear up to at least 18.7 mmol/L, has good reliability at high and low concentrations, and is able to analyse whole blood up to 15 minutes after sample application to the reagent strip.
The relationship between six descriptors of lactate increase, peak VO2, Wpeak, and 1-h cycling performance were compared in 24 trained, female cyclists (peak VO(2) = 48.11 +/- 6.32 mLxkg(-1)xmin(-1).
The six descriptors of lactate increase were: 1) lactate threshold (LT; the power output at which plasma lactate concentration begins to increase above the resting level during an incremental exercise test), 2) LT(1) the power output at which plasma lactate increases by 1 mM or more), 3) LT(D) (the lactate threshold calculated by the D-max method), 4) LT(MOD) (the lactate threshold calculated by a modified D-max method), 5) L4 (the power output at which plasma lactate reaches a concentration of 4 mmolxL(-1), and 6) LT(LOG) (the power output at which plasma lactate concentration begins to increase when the log ([La(-1]) is plotted against the log (power output). Subjects first completed a peak VO(2) test on a cycle ergometer. Finger-tip capillary blood was sampled within 30 s of the end of each 3-min stage for analysis of plasma lactate. Endurance performance was assessed 7 d later using a 1-h cycle test (OHT) in which subjects were directed to achieve the highest possible average power output.
The mean power output (W) for the OHT (+/- SD) was 183.01 +/- 18.88, and for each lactate variable was:LT (138.54 +/- 46.61), LT(1) (179.17 +/- 27.25), LT(log) (143.97 +/- 45.74), L4 (198.09 +/- 33.84), LT(D) (178.79 +/- 24.07), LT(MOD)(212.28 +/- 31.75). Average power output during the OHT was more strongly correlated with all plasma lactate parameters (0.61<r<0.84) and W(peak) (r = 0.81) than with peak VO(2) (r = 0.55). The six lactate parameters were strongly correlated with each other (0.54<r<0.91) and of six lactate parameters, LT(D) correlated best with endurance performance (r = 0.84).
It was concluded that plasma lactate parameters and W(peak) provide better indices of endurance performance than peak VO(2) and that, of the six descriptors of lactate increase measured in this study, LT(D) is most strongly related to 1-h cycling performance in trained, female cyclists.
The purpose of this study was to measure the amount of lactate produced, as an indication of fatigue, in response to maximal and submaximal stairstepper (SM) and treadmill (TM) exercise.
Thirty volunteers (15 males, mean age 23 yrs; 15 females, mean age 22 yrs) completed maximal and submaximal SM and TM protocols on four separate visits to the laboratory to determine maximal oxygen consumption (VO2max), and blood lactate concentrations. Maximal TM testing consisted of the Bruce protocol, while the maximal SM protocol involved progressing in increments of 2 levels every 2 minutes. Eight minutes of submaximal TM and SM exercise was performed at an intensity of 65% of VO2max, as measured during maximal TM and SM testing. Fifty microliters of blood was collected via fingerprick of the index finger prior to, and immediately post maximal and submaximal TM and SM exercise, and during minutes 3, 5, and 7 of active recovery. Red blood cells were lysed and analyzed immediately using the YSI # 1500 Sport lactate analyzer.
TM-VO2max, was significantly higher for both, males and females, compared to SM-VO2max. Repeated measured analyses of variance revealed significantly higher blood lactate levels during the same relative submaximal workloads for SM compared to TM exercise.
These findings suggest that an increased lactate production during submaximal SM exercise may result in early fatigue and, thereby, limit maximal performance on the SM.
The practical use of lactate electrochemical analysers in exercise testing has not been adequately examined. Initial studies have reported differences in lactate concentration between that measured spectrophotometrically and that measured electrochemically. The study described here was undertaken to compare, using the statistical technique of Bland and Altman (1986), two widely available methods of measuring lactate using lysed and non-lysed blood samples and the lactate thresholds derived from the measured lactate values using a log-log transform technique. Thirteen normal, healthy young adults (11 male) undertook progressive exercise tests to exhaustion. Arterialised venous blood samples were taken each minute and the lactate concentration therein was measured both spectrophotometrically and electrochemically and either with or without lysis of the blood samples. The lactate concentrations measured in lysed blood using both methods (182 pairs) were in close agreement. The electrochemical values obtained using non-lysed blood were systematically lower than spectrophotometric values (206 pairs), the difference becoming progressively greater at higher lactate concentrations. Results for the lactate threshold comparisons are given as mean difference (limits of agreement with 95% probability). Lactate thresholds (12 pairs) derived from lysed blood lactate concentrations measured spectrophotometrically and electrochemically were not significantly different -30 (240) ml O2 x min(-1). Lactate thresholds (11 pairs) derived from lysed spectrophotometric and non-lysed electrochemical measurements were also not significantly different + 20 (250) ml O2 x min(-1). Thus, despite the difference in the measured lactate concentrations, the derived lactate thresholds are in agreement and, therefore, electrochemical analysers can be used for lactate threshold determination using the log-log transform technique without sample lysis.
To estimate, upon competition heart rate (HR), exercise intensity during time trials (TT) in professional road cycling.
Eighteen world-class cyclists completed an incremental laboratory cycling test to assess maximal power output (Wmax), maximal HR (HRmax), onset of blood lactate accumulation (OBLA), lactate threshold (LT), and a HR-power output relationship. An OBLA(ZONE) (HR(OBLA) +/- 3 beats x min(-1)) and a LT(ZONE) (HR(LT) +/- 3 beats x min(-1)) were described. HR was monitored during 12 prologue (<10 km, PTT), 18 short (<40 km, STT), 19 long (>40 km, LTT), eight uphill (UTT), and seven team (TTT) time trials. A HR-power output relationship was computed to estimate each cyclist's power output during TT racing from competition HR. Competition training impulse (TRIMP) values were estimated from HR and race duration.
%HRmax were 89+/-3%, 85+/-5%, 80+/-5%, 78+/-3%, and 82+/-2% in PTT, STT, LTT, UTT, and TTT, respectively. The amount of TRIMP were, respectively, 21+/-3, 77+/-23, 122+/-27, 129+/-14, and 146+/-6. Competition HR values relative to HR(OBLA) and HR(LT) were, respectively, 100+/-3%, 114+/-8% in PTT, 95+/-7%, 108+/-9% in STT, 89+/-5%, 103+/-8% in LTT, 87+/-2%, 101+/-5% in UTT, and 91+/-4%, 105+/-11% in TTT.
%HRmax, TRIMP and time distribution around HR(OBLA) and HR(LT) reflected the physiological demands of different TT categories. HR(OBLA) and HR(LT) were accurate intensity markers in events lasting, respectively, < or =30 (PTT and STT) and > or =30 min (LTT, UTT, TTT).
Clough et al. (1997) reported that 95% of lactate values obtained using an Accusport analyser may be up to 2.6 mM below or 2.1 mM above YSI 2300 analyser values over the range 0-16 mM. This variability is substantial and unsuitable for research purposes, The objectives of this study were to re-examine the specific validity and reliability of an Accusport analyser and to develop a regression equation to improve the accuracy of Accusport measurements. Duplicate measurements of lactate concentration were made on both an Accusport (Boehringer Mannheim) and Analox LM3 Multi Channel analyser on 17 blood samples taken from two subjects performing a discontinuous incremental exercise protocol. Analysis of duplicate measurements revealed good test-retest reliability for Accusport (TEM 0.35 mM; SEM 0.24 mM; ICC r = 0.995) and Analox (TEM 0.07 mM; SEM 0.09 mM; ICC r = 0.999). The mean values for duplicate samples recorded on both the Accusport and Analox between the lactate range of 1-13 mM revealed an average difference between the two analysers of 1.7 mM (P< 0.01, range 1.0-2.9 mM) but values demonstrated a high level of association (ICC r = 0.853; P< 0.05). The level of agreement indicated that in 95% of cases the differences would lie between + 0.5 to + 3.0 mM with the Accusport values always higher than Analox. Linear regression analysis calculated the following equation to predict Analox values from Accusport values: Analox = -0.749 + 0.837Accusport (R2 = 0.990). The results showed the portable Accusport analyser to be reliable and it demonstrated good association with Analox LM3 lactate analyser measures. However, a need exists to develop specifically generated regressions from Accusport and Analox LM3 analyser measures to provide more accurate results when interpreting lactate values from Accusport measures taken in the field.
A randomized, double-blind, placebo controlled design was used in which 13 elite female rowers, all of whom had competed at World Championships, were supplemented with 60 g day-1 of either bovine colostrum (BC; n = 6) or concentrated whey protein powder (WP; n = 7) during 9 weeks of pre-competition training. All subjects undertook the study as a group and completed the same training program. Prior to, and after 9 weeks of supplementation and training, subjects completed an incremental rowing test (ROW1) on a rowing ergometer consisting of 3 3 4-min submaximal workloads and a 4-min maximal effort (4 max), each separated by a 1-min recovery period. The rowing test was repeated after a 15-min period of passive recovery (ROW2). The 4 max for ROW1 provided a measure of performance, and the difference between the 4 max efforts of ROW1 and ROW2 provided an index of recovery. Blood lactate concentrations and pH measured prior to exercise and at the end of each workload were used to estimate blood buffer capacity (beta). Food intake was recorded daily for dietary analysis. There were no differences in macronutrient intakes (p >.56) or training volumes (p >.99) between BC and WP during the study period. Rowing performance (distance rowed and work done) during 4 max of ROW2 was less than ROW1 at baseline (p <.05) but not different between groups (p >.05). Performance increased in both rows by Week 9 (p <.001), with no difference between groups (p >.75). However, the increase was greatest in ROW2 (p <.05), such that by Week 9 there was no longer a difference in performance between the two rows in either group (p >.05). b was not different between groups for ROW1 at baseline (BC 38.3 5.0, WP 38.2 7.2 slykes; p >.05) but was higher in BC by Week 9 (BC 40.8 5.9, WP 33.4 5.3 slykes; p <.05). b for ROW2 followed the same pattern of change as for ROW1. We conclude that supplementation with BC improves b, but not performance, in elite female rowers. It was not possible to determine whether b had any effect on recovery.
Pretest preparation In Physiological Tests for Elite Athletes
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Lactate concentration differences in plasma, whole blood, capillary finger blood and erythrocytes during submaximal graded exercise in humans. (20) Miles DS Plasma volume shifts during progressive arm and (22) Hopkins W Reliability of power in physical performance tests
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University of New South Wales Press Protocols for the physiological assessment of rowers
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Protocols for the physiological assessment of rowers
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