Prescribing training loads for endurance athletes often incorporates the measurement of the blood lactate response to incremental exercise in conjunction with heart rate (HR), oxygen consumption ( V ˙ O 2 ), and exercise intensity, and the subsequent calculation of blood lactate thresholds
Pitre C. Bourdon, Sarah M. Woolford and Jonathan D. Buckley
Pedro L. Valenzuela, Javier S. Morales, Carl Foster, Alejandro Lucia and Pedro de la Villa
The lactate threshold (LT), usually defined as the maximum workload that precedes an exponential rise in blood lactate values during an incremental test, is one of the most popular markers of the so-called anaerobic transition. This marker has been extensively used as a predictor of endurance
Fiona Iredale, Frank Bell and Myra Nimmo
Fourteen sedentary 50- to 55-year-old men were exercised to exhaustion using an incremental treadmill protocol. Mean (±SEM) peak oxygen uptake (V̇O2peak) was 40.5 ± 1.19 ml · kg1 · min−1, and maximum heart rate was 161 ± 4 beats · min−1. Blood lactate concentration was measured regularly to identify the lactate threshold (oxygen consumption at which blood lactate concentration begins to systematically increase). Threshold occurred at 84 ± 2% of V̇O2peak. The absolute lactate value at threshold was 2.9 ± 0.2 mmol · L−1. On a separate occasion, 6 subjects exercised continuously just below their individual lactate thresholds for 25 min without significantly raising their blood lactate levels from the 10th minute to the 25th. The absolute blood lactate level over the last 20 min of the steady-state test averaged 3.7 ± 1.2 mmol · L−1. This value is higher than that elicited at the threshold in the incremental test because of the differing nature of the protocols. It was concluded that although the lactate threshold occurs at a high percentage of V̇O2peak, subjects are still able to sustain exercise at that intensity for 25 min.
Peter Pfitzinger and Patty Freedson
Part 2 reviews the literature concerning the lactate threshold in children. An analysis is presented comparing children to adults regarding responses to submaximal exercise, and the lactate threshold as a percentage of VO2max. Possible explanations for lower blood lactate concentrations during submaximal exercise in children are considered.
Sijie Tan, Chunhua Yang and Jianxiong Wang
The purpose of this study was to apply the lactate threshold concept to develop a more evidence-informed exercise program for obese children. 60 obese children (26 girls and 34 boys, age: 9–10 years, BMI: 25.4 ± 2.2kg/m2) were recruited and half of them were randomly selected to be trained for eight weeks with a controlled exercise intensity at lactate threshold. The trained children achieved significant improvements on their body composition and functional capacity compared with the control group. The findings suggested that the training program with intensity at lactate threshold is effective and safe for 9–10 year old children with obesity.
K. Fiona Iredale and Myra A. Nimmo
Thirty-three men (age 26–55 years) who did not exercise regularly were exercised to exhaustion using an incremental treadmill protocol. Blood lactate concentration was measured to identify lactate threshold (LT, oxygen consumption at which blood lactate concentration begins to systematically increase). The correlation coefficient for LT (ml · kg−1 · min−1) with age was not significant, but when LT was expressed as a percentage of peak oxygen consumption (VO2 peak), the correlation was r = +.69 (p < .01). This was despite a lack of significant correlation between age and VO2 peak (r = −.33). The correlation between reserve capacity (the difference between VO2 peak and LT) and age was r = −.73 (p < .01 ), and reserve capacity decreased at a rate of 3.1 ml · kg−1 · min−1 per decade. It was concluded that the percentage of VO2 peak at which LT occurs increases progressively with age, with a resultant decrease in reserve capacity.
Jacky J. Forsyth, Chris Mann and James Felix
In rowing ergometry, blood for determining lactate concentration can be removed from the toe tip without the rower having to stop. The purpose of the study was to examine whether sampling blood from the toe versus the earlobe would affect lactate threshold (Tlac) determination.
Ten physically active males (mean ± age 21.2 ± 2.3 y; stature 179.2 ± 7.5 cm; body mass 81.7 ± 12.7 kg) completed a multistage, 3 min incremental protocol on the Concept II rowing ergometer. Blood was sampled simultaneously from the toe tip and earlobe between stages. Three different methods were used to determine Tlac.
There were wider variations due to the method of Tlac determination than due to the sample site; for example, ANOVA results for power output were F(1.25, 11.25) = 11.385, P = .004 for method and F(1, 9) = 0.633, P = .45 for site. The greatest differences in Tlac due to sample site in rowing occurred when Tlac was determined using an increase in blood lactate concentration by >1 mmol/L from baseline (TlacΔ1).
The toe tip can be used as a suitable sample site for blood collection during rowing ergometry, but caution is needed when using the earlobe and toe tip interchangeably to prescribe training intensities based on Tlac, especially when using TlacΔ1 or at lower concentrations of lactate.
Samuel Chalmers, Adrian Esterman, Roger Eston and Kevin Norton
Athletes often seek the minimum required time that might elicit a physiological or performance change. It is reasonable to suggest that heat training may improve aerobic-based performance in mild conditions. Therefore, rather than providing a traditional heat-exposure stimulus (ie, 7–10 × 60–100 min sessions), the current article details 2 studies that aimed to determine the effect of brief (≤240 min exposure) heat training on the second lactate threshold (LT2) in mild conditions.
Forty-one participants completed 5 (study 1, n = 18) or 4 (study 2, n = 23) perceptually regulated treadmill exercise training sessions in 35°C and 30% relative humidity (RH) (experimental group) or 19°C and 30% RH (control group). Preincremental and postincremental exercise testing occurred in mild conditions (19°C and 30% RH). Linear mixed-effects models analyzed the change in LT2.
Heat training did not substantially change LT2 in either study 1 (+1.2%, d = 0.38, P = .248) or study 2 (+1.9%, d = 0.42, P = .163). LT2 was not substantially changed in the control group in study 1 (+1.3%, d = 0.43, P = .193), but a within-group change was evident in study 2 (+2.3%, d = 1.04, P = .001).
Brief heat training was inadequate to improve the speed at LT2 in mild conditions more than comparable training in mild conditions. The brief nature of the heattraining protocol did not allow adaptations to develop to the extent required to potentially confer a performance advantage in an environment that is less thermally stressful than the training conditions.
Nicolas Fabre, Laurent Mourot, Livio Zerbini, Barbara Pellegrini, Lorenzo Bortolan and Federico Schena
This study tested the hypothesis that the DMAX (for maximal distance) method could be applied to ratings of perceived exertion (RPE), to propose a novel method for individual detection of the lactate threshold (LT) using RPE alone during an incremental test to exhaustion. Twenty-one participants performed an incremental test on a cycle ergometer. At the end of each stage, lactate concentration was measured and the participants estimated RPE using the Borg CR100 scale. The intensity corresponding to the fixed lactate values of 2 or 4 mmol · L−1(2mM and 4mM), the ventilatory threshold (VT), the respiratory-compensation point (RCP), and the instant of equality of pulmonary gas exchange (RER=1.00) were determined. Lactate (DMAX La) and RPE (DMAX RPE) thresholds were determined using the DMAX method. Oxygen uptake (VO2), heart rate, and power output measured at DMAX RPE and at DMAX La were not statistically different. Bland-Altman plots showed small bias and good agreements when DMAX RPE was compared with the DMAX La and RER=1.00 methods (bias = −0.05% and −2% of VO2max, respectively). Conversely, VO2 from the DMAX RPE method was lower than VO2 at 4 mM and at RCP and was higher than VO2 at 2 mM and at VT. VO2 at DMAX RPE was strongly correlated with VO2 at DMAX La (r = .97), at RER=1.00 (r = .97), at 2 mM (r = .85), at 4 mM (r = .93), at VT (r = .95), and at RCP (r = .95). The combination of the DMAX method with the RPE responses permitted precise and individualized estimates of LT using the DMAX method.
Bo Fernhall, Wendy Kohrt, Lee N. Burkett and Steven Walters
This study evaluated the relationship between run performance, lactate threshold (LT), VO2max, and running economy in adolescent boys (n = 11) and girls (n = 10). Subjects completed laboratory tests to establish VO2max, LT, and running economy. The race performance was the finish time from a cross-country meet. The boys exhibited higher VO2max (67.7 vs. 54.6 ml · kg−1 · min−1) and VO2 at LT (61.7 vs. 48.4 ml · kg−1 · min−1) compared with the girls (p < .05), but there was no difference in running economy, peak lactate, or the %VO2max at LT (p > .05). VO2max (r = −.70) and VO2 at LT (r = −.74) were significantly correlated to performance for the boys, but running economy was not (r = .10). For the girls, VO2max (r = −.90), VO2 at LT (r = −.77), and running economy (r = −.86) were all significantly related to performance. LT was important for cross-country run performance. However, VO2max was an equally strong or better predictor than either LT or running economy.