A comparison of lactate indices during ramp exercise using modelling techniques and conventional methods

Thomas, Vincent; Costes, Frédéric; Chatagnon, Michel; Pouilly, Jean-Pierre; Busso, Thierry

doi:10.1080/02640410802104920

Cited by 18 publications

(17 citation statements)

References 25 publications

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“…Prior work has commonly used the INFL method, the 1mM method, and some of its variations (i.e., blood lactate increases of 0.5 or 0.75 mM above baseline values) (16,35,48), which are favored for their relative ease of application and objective nature. Furthermore, these approaches take into account individual variations in the subject's resting steady-state lactate level (which is not the case for the 4mM method).…”

Section: Discussionmentioning

confidence: 99%

Lactate threshold predicting time-trial performance: impact of heat and acclimation

Lorenzo

Minson

Babb

et al. 2011

Journal of Applied Physiology

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Lorenzo S, Minson CT, Babb TG, Halliwill JR. Lactate threshold predicting time-trial performance: impact of heat and acclimation. J Appl Physiol 111: 221-227, 2011. First published April 28, 2011 doi:10.1152/japplphysiol.00334.2011The relationship between exercise performance and lactate and ventilatory thresholds under two distinct environmental conditions is unknown. We examined the relationships between six lactate threshold methods (blood-and ventilation-based) and exercise performance in cyclists in hot and cool environments. Twelve cyclists performed a lactate threshold test, a maximal O2 uptake (V O2max) test, and a 1-h time trial in hot (38°C) and cool (13°C) conditions, before and after heat acclimation. Eight control subjects completed the same tests before and after 10 days of identical exercise in a cool environment. The highest correlations were observed with the blood-based lactate indexes; however, even the indirect ventilation-based indexes were well correlated with mean power during the time trial. Averaged bias was 15.4 Ϯ 3.6 W higher for the ventilation-than the blood-based measures (P Ͻ 0.05). The bias of blood-based measures in the hot condition was increased: the time trial was overestimated by 37.7 Ϯ 3.6 W compared with only 24.1 Ϯ 3.2 W in the cool condition (P Ͻ 0.05). Acclimation had no effect on the bias of the blood-based indexes (P ϭ 0.51) but exacerbated the overestimation by some ventilation-based indexes by an additional 34.5 Ϯ 14.1 W (P Ͻ 0.05). Blood-based methods to determine lactate threshold show less bias and smaller variance than ventilation-based methods when predicting time-trial performance in cool environments. Of the blood-based methods, the inflection point between steady-state lactate and rising lactate (INFL) was the best method to predict time-trial performance. Lastly, in the hot condition, ventilation-based predictions are less accurate after heat acclimation, while blood-based predictions remain valid in both environments after heat acclimation. heat stress; heat acclimation; heat acclimatization; critical power; endurance exercise SEVERAL PHYSIOLOGICAL PARAMETERS, namely, maximal O 2 uptake (V O 2max ), lactate threshold, ventilatory threshold, fraction of slow-twitch fibers, and running economy, are known to be related to (or predictive of) endurance exercise performance (12,13,19). As the margins for success in athletic competition are often quite small, coaches, athletes, and physiologists have long been interested in assessing an individual athlete's lactate or ventilatory threshold, in an effort to use such information to design more effective training plans, optimize an athlete's performance, or make race-day predictions. The terms "lactate threshold" and "ventilatory threshold" have generally been used to define the highest work rate or O 2 uptake (V O 2 ) at which athletes can maintain their efforts over a specified time frame. To the best of our knowledge, no study has focused on simultaneously determining the accuracy of lactate threshold vs. ventila...

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Section: Discussionmentioning

confidence: 99%

Lactate threshold predicting time-trial performance: impact of heat and acclimation

Lorenzo

Minson

Babb

et al. 2011

Journal of Applied Physiology

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“…The Rest+1,27 28 fixed 2.0 and 4.0 mmol/l markers were determined by linear interpolation within the raw data sets. Because [LA − ] was too high (>2.0) throughout some of the trials, the 2.0 mmol/l marker was indeterminate in seven of 67 trials involving five of the 11 subjects.…”

Section: Treatment Of Datamentioning

confidence: 99%

Low reproducibility of many lactate markers during incremental cycle exercise

2011

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Reports on reproducibility of lactate markers usually considered only two trials. The authors assessed reproducibility of power output at seven markers in 11 fit subjects over at least six trials under tightly controlled conditions. Subjects undertook incremental exercises (50 W start, +50 W every 3 min to exhaustion) on a cycle ergometer. At each trial blood lactate concentration was determined at rest and within the final 30 s of each stage. The Rest+1, 2.0 and 4.0 mmol/l markers were determined by interpolation, the D-max and nadir using a quadratic model and the lactate slope index using an exponential plus constant model, and a visual turnpoint was determined empirically. Intraclass correlations and coefficients of variation assessed reproducibility. Power output at all markers differed significantly between subjects, but not between trials. Intraclass correlation coefficients were respectively 0.799, 0.794, 0.807, 0.903, 0.677, 0.769 and 0.648, and corresponding standard errors of measurement 11.9, 9.2, 9.1, 2.5, 9.2, 10.8 and 24.7 W. Statistical powers of detecting a 30 W increment at these markers were 0.30, 0.43, 0.42, 0.98, 0.58, 0.38 and 0.18 respectively. These results indicate that only the D-max marker has good reproducibility and that it alone can identify small but meaningful changes in training status with sufficient statistical power.

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“…Currently, several methods exist that can be used to detect the LT, although these methods sometimes produce diff ering estimates on this point [7,22,23] . The existing methods include both subjective methods, such as the visual detection of the LT (LT Visual ) [6] , and objective methods, such as methods based on a fi xed value of lactate concentration [13,15,21] .…”

Section: Introduction ▼mentioning

confidence: 99%

The Dmax is Highly Related to Performance in Middle-Aged Females

Machado¹,

Moraes²,

Peserico³

et al. 2011

Int J Sports Med

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The present study examined whether the running speed at the lactate threshold estimated by the maximal deviation method (LT (Dmax)) is highly correlated and in agreement with 10-km road race performance (S (10 km)) in middle-aged female runners. Additionally, the LT (Dmax) was compared with the visual detection of the inflection point (LT (Visual)), the fixed lactate level of 4 mmol.L (-1) (LT (4)) and the peak speed (S (peak)) in relation to performance. Sixteen middle-aged, recreational female runners performed a discontinuous, incremental treadmill test. The initial speed was set at 7 km.h (-1), and this speed was increased every 3 min by 1 km.h (-1) with a 30-s rest between the stages used for earlobe capillary blood sample collection. All of the participants took part in the same local 10-km road race, and S (10 km) mean speed was calculated. The speeds (mean ± SD) were 10.5 ± 1.0 (S (10 km)), 10.5 ± 1.0 (LT (Visual)), 10.9 ± 0.9 (LT (Dmax)), 11.4 ± 1.3 (LT (4)) and 13.5 ± 1.1 km.h (-1) (S (peak)). The LT (Dmax) had the narrowest limits of agreement (0.3 ± 0.4 km.h (-1)) and was the most highly correlated with the S (10 km) ( R=0.98), followed by the S (peak) ( R=0.95), LT (4) ( R=0.85) and LT (Visual) ( R=0.81). In conclusion, the LT (Dmax) should be more widely used to estimate long-distance performance and to verify improvements in training.

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A comparison of lactate indices during ramp exercise using modelling techniques and conventional methods

Cited by 18 publications

References 25 publications

Lactate threshold predicting time-trial performance: impact of heat and acclimation

Lactate threshold predicting time-trial performance: impact of heat and acclimation

Low reproducibility of many lactate markers during incremental cycle exercise

The Dmax is Highly Related to Performance in Middle-Aged Females

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