LACTATE THRESHOLD CHANGES FROM JUNIOR TO SENIOR AGE IN ELITE OLYMPIC DISTANCE TRIATHLETES S. Pöller, T. Moeller & J. Wick
Triathletes aiming at competing in Olympic Games take part in competitions lasting between 20 minutes (team relay) and two hours (standard distance). These competitions can be regarded as endurance events. Therefore, the performance is highly determined by maximum oxygen consumption, lactate threshold and efficiency (Suriano & Bishop, 2009; Joyner & Coyle, 2007). Until today, no longitudinal research of performance tests on elite triathletes developing from junior to senior age has been published. The changes between the age of 19-23 years are of great interest as they demonstrate the ability of an athlete to adapt to the higher requirements in senior elite races. Lactate thresholds show a high sensitivity to performance enhancements and therefore enable assessments of improvements in athletes’ endurance capacity (Jones & Carter, 2000) and predictions of race velocities. The purpose of this study was to show the changes of a fixed blood lactate threshold in a group of high performance sprint and standard distance triathletes who successfully managed to develop from the junior elite to the senior elite national team.
During the four years athletes did significantly increase their maximum velocity during the last stage (z = -2.636; p = 0.008; r = -0.659; Table 2). Blood lactate production was reduced in senior athletes compared to their values four years earlier, expressed in higher velocities at the 3 mmol/L blood lactate threshold (z = -2.38; p = 0.017; r = -0.595; Figure 1). A typical rightward shift over time of the blood lactate curve during the incremental test is presented in Figure 2.
METHODS Sample The athletes were identified retrospectively from a comprehensive data base covering performance tests between 1993-2014. Inclusion criteria were: athletes were members of the German junior and senior national team and had completed the standardised 4x4.000 m incremental treadmill test at an age of approximately 19 and 23 years. A group of eight male ITU Triathlon World Championships medallists and Olympians was selected.
5,4 5,2 5 4,8 4,6 4,4 4,2 junior age
Figure 1. Changes of vL3 from junior to senior elite age 4 3 2 1 0
4,25 4,5 4,75 5 5,25 velocity [m/s] junior age senior age
Figure 2. Typical lactate curve changes in the 4x4.000 m incremental test Table 2. Variables in the four-step incremental running protocol (mean ± SD) junior age senior age vmax (m/s) 4,8 ± 0,1 5,3 ± 0,1* vL3 (m/s) 4,7 ± 0,2 5,1 ± 0,2* vmax = velocity of the last stage in the 4x4.000 m incremental treadmill test; vL3 = velocity at a blood lactate concentration of 3 mmol/L * p < .05 between junior and senior athletes
Table 1. Characteristics of subjects (mean ± SD) Age (yr) Body mass (kg) Body fat mass (%) Height (cm)
junior age 18,9 ± 0,7 71,3 ± 4,7 9,9 ± 1,6 183,7 ± 4,0
senior age 23,0 ± 0,6 73,4 ± 4,1 10,0 ± 1,6 184,8 ± 4,0
Body fat mass = Percentage of body fat determined by a GPM skinfold caliper based on the Parizkova method (Parizkova, 1977)
Printed at Universitätsrechenzentrum Leipzig
Four-step incremental running test Athletes performed a 4x4.000 m run with an increment of 0,25 m/s for each step. The last stage was aimed to be completed with the individual current 10 k competition speed. If the last step was incomplete, vmax (m/s) was normalised over the covered distance. For reasons of running technique the treadmill gradient was set at 0% (Neumann & Gohlitz, 1996). Between the steps, athletes had a one minute break respectively for blood collection from the earlobe to measure blood lactate levels (Lab; mmol/L). Velocity at a fixed 3 mmol/L lactate threshold (vL3) was determined. Statistical analysis Mean and standard deviation (SD) were calculated for all variables. Differences between junior and senior age were detected using Wilcoxon signed rank test. Effect size (r) was calculated to enable additional interpretation of mean differences. Effects were interpreted as small (0.1), medium (0.3) or large (0.5).
DISCUSSION & CONCLUSION Blood lactate thresholds, obtained from incremental tests, can be used as a criterion for aerobic endurance performance (Faude et al., 2009). In our analyses intraindividual changes of submaximal performance were assessed with running velocity at a blood lactate level of 3 mmol/L (vL3). vL3 increased significantly with age, which can be seen as a marker of enhanced aerobic endurance capacity (Jones & Carter, 2000). Over the time span of four years, mean improvements for vL3 of 2% per year have been found. The differences in this study are associated with large effect sizes. For elite triathletes, significant correlations between vL3 determined during the 4x4.000 m incremental step test and the 10.000 m race pace have been shown (Moeller, 2015). Furthermore, knowledge of vL3 can be seen as a basic tool to regulate run training velocities.
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Correspondence: Sabine Pöller, Research Group Triathlon Institute for Applied Training Science An Institute of the association IAT/FES e. V. Marschnerstraße 29, 04109 Leipzig, Germany Phone: +49 341 4945-184, E-Mail: [email protected]