The ventilatory anaerobic threshold (VAT) occurs when there is an isolated increase in the slope for ventilator equivalent for oxygen consumption (VE/VO2) with no change in the slope for ventilatoiy equivalent for carbon dioxide production (VE/VCO2) when both are plotted against time. The concept of anaerobic threshold remains controversial. However, it is a clinically useful tool in evaluating the exercise capacity of children. This paper will review the history, biochemistry, and methodology involved in determining the anaerobic threshold, as well as the ventilatory anaerobic threshold in children.
Reginald L. Washington
Tiago Turnes, Rafael Penteado dos Santos, Rafael Alves de Aguiar, Thiago Loch, Leonardo Trevisol Possamai and Fabrizio Caputo
running. 10 A similarity between [HHb]BP and maximal lactate steady state (MLSS) seems to occur in sedentary 7 and trained athletes. 10 Furthermore, contradictory results have been observed when comparing [HHb]BP with the anaerobic threshold (AnT) using a fixed BLC of 4 mmol·L −1 . 10 Although MLSS is
Georgine Gaisl and Peter Hofmann
Ethical and logistical limitations preclude the routine determination of anaerobic threshold in children by invasive measurement of blood lactate concentrations or ventilatory parameters. A noninvasive field test developed by Conconi can be used to determine anaerobic threshold through analysis of the heart rate curve during increased exercise workloads. Although this test was initially evaluated in adult athletes, recent data indicate that the Conconi test is applicable to children in both laboratory and field settings. Close correlation with lactate-derived anaerobic threshold appears to be possible when utilizing standard testing protocols.
Timothy R. McConnell, Jean H. Haas and Nancy C. Conlin
Thirty-eight children (mean age 12.2 ±3.6 yrs) were tested to (a) compare the training heart rate (HR) and oxygen uptake (V̇O2) computed from commonly used exercise prescription methods to the heart rate (HRAT) and V̇O2 (ATge) at the gas exchange anaerobic threshold, (b) compute the range of relative HRs and V̇O2s (% HRmax and % V̇O2max, respectively) at which the ATge occurred, and (c) discuss the implications for prescribing exercise intensity. The ATge occurred at a V̇O2 of 20.9 ml · kg−1 · min−1 and an HR of 129 beats·min−1. The training HR and V̇O2 computed using 70 and 85% HRmax, 70% of the maximal heart rate reserve (HRR), and 57 and 78% V·O2max, were significantly different (p<.05) from their corresponding ATge values. To compute training % HRmax, % V̇O2max, and % HRR values that would not significantly differ from the ATge, then 68% HRmax, 48% V̇O2max, and 41% HRR would need to be used for the current population.
The multisession maximal lactate steady-state (MLSS) test is the gold standard for anaerobic threshold (AnT) estimation. However, it is highly impractical, requires high fitness level, and suffers additional shortcomings. Existing single-session AnT-estimating tests are of compromised validity, reliability, and resolution. The presented reverse lactate threshold test (RLT) is a single-session, AnT-estimating test, aimed at avoiding the pitfalls of existing tests. It is based on the novel concept of identifying blood lactate’s maximal appearance-disappearance equilibrium by approaching the AnT from higher, rather than from lower exercise intensities. Rowing, cycling, and running case data (4 recreational and competitive athletes, male and female, aged 17–39 y) are presented. Subjects performed the RLT test and, on a separate session, a single 30-min MLSS-type verification test at the RLT-determined intensity. The RLT and its MLSS verification exhibited exceptional agreement at 0.5% discrepancy or better. The RLT’s training sensitivity was demonstrated by a case of 2.5-mo training regimen following which the RLT’s 15-W improvement was fully MLSS-verified. The RLT’s test-retest reliability was examined in 10 trained and untrained subjects. Test 2 differed from test 1 by only 0.3% with an intraclass correlation of 0.997. The data suggest RLT to accurately and reliably estimate AnT (as represented by MLSS verification) with high resolution and in distinctly different sports and to be sensitive to training adaptations. Compared with MLSS, the single-session RLT is highly practical and its lower fitness requirements make it applicable to athletes and untrained individuals alike. Further research is needed to establish RLT’s validity and accuracy in larger samples.
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.
Cameron P. Brewer, Brian Dawson, Karen E. Wallman and Kym J. Guelfi
Research into supplementation with sodium phosphate has not investigated the effects of a repeated supplementation phase. Therefore, this study examined the potential additive effects of repeated sodium phosphate (SP) supplementation on cycling time-trial performance and peak oxygen uptake (VO2peak). Trained male cyclists (N = 9, M ± SD VO2peak = 65.2 ± 4.8 ml · kg−1 · min−1) completed baseline 1,000-kJ time-trial and VO2peak tests separated by 48 hr, then ingested either 50 mg · kg fat-free mass−1 · d−1 of tribasic SP or a combined glucose and NaCl placebo for 6 d before performing these tests again. A 14-d washout period separated the end of one loading phase and the start of the next, with 2 SP and 1 placebo phase completed in a counterbalanced order. Although time-trial performance (55.3–56.5 min) was shorter in SP1 and SP2 (~60–70 s), effect sizes and smallest-worthwhile-change values did not differ in comparison with baseline and placebo. However, mean power output was greater than placebo during time-trial performance at the 250-kJ and 500-kJ time points (p < .05) after the second SP phase. Furthermore, mean VO2peak values (p < .01) were greater after the SP1 (3.5–4.3%), with further improvements (p < .01) found in SP2 (7.1–7.7%), compared with baseline and placebo. In summary, repeated SP supplementation, ingested either 15 or 35 d after initial loading, can have an additive effect on VO2peak and possibly time-trial performance.
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.
Volker Scheer, Tanja I. Janssen, Solveig Vieluf and Hans-Christian Heitkamp
criteria as described elsewhere. 1 , 6 Ventilatory thresholds (VT), lactate thresholds, individual anaerobic thresholds (IAT), and running economy (RE) were determined as described in the literature. 1 , 6 , 12 Mechanical power was calculated from values obtained in the trail test and expressed as (in
Donald R. Dengel, Peter G. Weyand, Donna M. Black and Kirk J. Cureton
To investigate the effects of varying levels of hypohydration on ratings of perceived exertion (RPE) during moderate and heavy submaximal exercise, and at the lactate threshold (LT) and ventilatory threshold (VT), 9 male subjects cycled under states of euhydration (EU), moderate hypohydration (MH), and severe hypohydration (SH). The desired level of hypohydration was achieved over a 36-hr period by having subjects cycle at 50% VO2max in a 38°C environment on two occasions while controlling fluid intake and diet. During submaximal exercise, oxygen uptake, ventilation, heart rate, blood lactate, and RPE were not significantly different among treatments. Hypohydration did not significantly alter LT or VT, or perceptual responses at LT or VT. It is concluded that hypohydration of up to 5.6% caused by fluid manipulation and exercise in the heat over a 36-hr period does not alter RPE or the lactate or ventilatory threshold, nor RPE at the lactate and ventilatory thresholds measured during moderate and heavy submaximal cycling in a neutral (22°C) environment.