Fig 1.
Representative blood lactate curve with 14 LTs calculated from GXT4 (participant #9).
The power of the MLSS was 302 W and the blood lactate concentration was 2.85 mmol.L-1. Log-log = power at the intersection of two linear lines with the lowest residual sum of squares; log = using the log-log method as the point of the initial data point when calculating the Dmax or Modified Dmax; poly = Modified Dmax method calculated using a third order polynomial regression equation; exp = Modified Dmax method calculated using a constant plus exponential regression equation; OBLA = onset of blood lactate accumulation; B + absolute value = the intensity where blood lactate increases above baseline.
Table 1.
The mean ± standard deviation (SD) of the 14 lactate thresholds calculated from the 4 prolonged graded exercise tests (i.e., GXT3, GXT4, GXT7 and GXT10), and the respiratory compensation point (RCP) and the maximal lactate steady state (MLSS) estimated from the RCP (RCPMLSS) calculated from GXT1.
Table 2.
Mean, standard deviation, and range of the and power associated with the maximal lactate steady state (MLSS) expressed as a percentage of the maximal power (
) and
measured during each GXT.
Note: The at the MLSS was 81.4 ± 4.7% of the
. (Defined as the highest measured
during any GXT).
Fig 2.
(A-D) Forrest Plots of the difference (ES ± 95% CI) between the MLSS and the power calculated from the 13 lactate thresholds derived from (A) GXT3, (B) GXT4, (C) GXT7 and (D) GXT10 (52 in total and excluding log-log). The solid vertical bar represents no difference from the MLSS and the dashed vertical bars represents the threshold between a trivial and small difference (ES = 0.2) established by Cohen (50) and Hopkins (49). log = using the log-log method as the initial data point when calculating the Dmax or Modified Dmax; poly = Modified Dmax method calculated using a third order polynomial regression equation; exp = Modified Dmax method calculated using a constant plus exponential regression equation; OBLA = onset of blood lactate accumulation.
Fig 3.
Bland-Altman plots displaying agreement between measures of the power associated with the RCP regression equation (RCPMLSS) calculated from GXT1 and the MLSS.
The differences between measures (y-axis) are plotted as a function of the mean of the two measures (x-axis) in power (Watts). The horizontal solid line represents the mean difference between the two measures (i.e., bias). The two horizontal dashed lines represent the limits of agreement (1.96 x standard deviation of the mean difference between the estimated lactate threshold via the RCPMLSS and the maximal lactate steady state). The dotted diagonal lines represent the boundaries of the 95% CI for MLSS reliability (CV = 3.0%; 95%; CI = 3.8%) calculated from Hauser et al., 2014) (RCP = respiratory compensation point).
Fig 4.
Bland-Altman plots displaying agreement between measures of the power associated with the baseline plus 1.5 mmol.L-1 calculated from GXT3 and the MLSS.
The differences between measures (y-axis) are plotted as a function of the mean of the two measures (x-axis) in power (Watts). The horizontal solid line represents the mean difference between the two measures (i.e., bias). The two horizontal dashed lines represent the limits of agreement (1.96 x standard deviation of the mean difference between the lactate threshold and the maximal lactate steady state). The dotted diagonal lines represent the boundaries of the 95% CI for MLSS reliability (CV = 3.0%; 95%; CI = 3.8%) calculated from Hauser et al., 2014).
Fig 5.
(A-D) Bland-Altman plots displaying agreement between measures of the power associated with the (A) OBLA 2.5 mmol.L-1, (B) Modified Dmax, (C) Log-Poly-Modified Dmax, (D) Log-Exp-Modified Dmax calculated from GXT4 and the MLSS. The differences between measures (y-axis) are plotted as a function of the mean of the two measures (x-axis) in power (Watts). The horizontal solid line represents the mean difference between the two measures (i.e., bias). The two horizontal dashed lines represent the limits of agreement (1.96 x standard deviation of the mean difference between the lactate threshold and the maximal lactate steady state). The dotted diagonal lines represent the boundaries of the 95% CI for MLSS reliability (CV = 3.0%; 95%; CI = 3.8%) calculated from Hauser et al., 2014) (log = Modified Dmax method using the log-log method as the point of the initial lactate point; poly = Modified Dmax method calculated using a third order polynomial regression equation; exp = Modified Dmax method calculated using a constant plus exponential regression equation; OBLA = onset of blood lactate accumulation.).
Fig 6.
(A-C) Bland-Altman plots displaying agreement between measures of the power associated with the (A) OBLA 2.5 mmol.L-1 (GXT7), (B) OBLA 3.0 mmol.L-1 (GXT7), (C) Log-Exp-Modified Dmax calculated from GXT7 and the MLSS. The differences between measures (y-axis) are plotted as a function of the mean of the two measures (x-axis) in power (Watts). The horizontal solid line represents the mean difference between the two measures (i.e., bias). The two horizontal dashed lines represent the limits of agreement (1.96 x standard deviation of the mean difference between the lactate threshold and the maximal lactate steady state). The dotted diagonal lines represent the boundaries of the 95% CI for MLSS reliability (CV = 3.0%; 95%; CI = 3.8%) calculated from Hauser et al., 2014) (log = Modified Dmax method using the log-log method as the point of the initial lactate point; exp = Modified Dmax method calculated using a constant plus exponential regression equation; OBLA = onset of blood lactate accumulation.).
Fig 7.
(A-B) Bland-Altman plots displaying agreement between measures of the power associated with the (A) OBLA 3.0 mmol.L-1, (B) OBLA 3.5 mmol.L-1 calculated from GXT10 and the MLSS. The differences between measures (y-axis) are plotted as a function of the mean of the two measures (x-axis) in power (Watts). The horizontal solid line represents the mean difference between the two measures (i.e., bias). The two horizontal dashed lines represent the limits of agreement (1.96 x standard deviation of the mean difference between the lactate threshold and the maximal lactate steady state). The dotted diagonal lines represent the boundaries of the 95% CI for MLSS reliability (CV = 3.0%; 95%; CI = 3.8%) calculated from Hauser et al., 2014) (OBLA = onset of blood lactate accumulation.).
Table 3.
Mean ± standard deviation, mean difference (MD), intraclass correlation coefficient (ICC), Lin’s concordance correlation coefficient (ρc), standard error of the measurement (SEM), effect size (ES) with 95% confidence limits, and coefficient of the variation (%CV) between the maximal lactate steady state (MLSS) and the eleven thresholds included in our analysis.
(RCPMLSS = MLSS estimate based on the respiratory compensation point; log = Modified Dmax method using the log-log method as the point of the initial lactate point; poly = Modified Dmax method calculated using a third order polynomial regression equation; exp = Modified Dmax method calculated using a constant plus exponential regression equation; OBLA = onset of blood lactate accumulation).
Table 4.
Mean difference (MD), effect size (ES), and p-value comparing the influence of graded exercise test stage length on all 14 lactate threshold methods.
Table 5.
Mean and standard deviation of —highest measured
during any graded exercise test (GXT); GXT
-highest measured
during each GXT; VEB
highest measured
during each verification exhaustive bout (VEB);
, highest measured
during either the GXT or corresponding VEB.
Mean and standard deviation of GXT duration, max power (Watts) from each GXT, percentage of maximum power from the prolonged GXT expressed as a percentage of W maximum power from GXT1 and power of each VEB (Watts) from the GXTs. Relative power of the verification exhaustive bout expressed as a percentage (%) of the maximal power measured during the GXT. The subscript (i.e., 1, 3, 4, 7 or 10) refers to the stage duration (minutes) for each test.
Table 6.
Mean difference (MD) and standard deviation, effect size (ES), coefficient of the variation (CV) and p-value (p) for the measured values from GXT1 compared with the
values from GXT3, GXT4, GXT7, and GXT10 and for the
values from GXT1 compared with the
values from the VEB following GXT3, GXT4, GXT7, and GXT10.
The subscript (i.e., 1, 3, 4, 7 or 10) refers to the stage duration (minutes) for each test.