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Validation of modified D-max method for calculating individual anaerobic threshold in well trained male cyclists
Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences, Åstrand Laboratory of Work Physiology, Björn Ekblom's research group.ORCID iD: 0000-0002-7743-9295
Swedish School of Sport and Health Sciences, GIH, Department of Sport and Health Sciences. (Forskningsgruppen för fysisk aktivitet, prestation och hälsa)ORCID iD: 0000-0002-0642-4838
2015 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Introduction

To predict endurance performance and evaluate adaption to training in endurance athletes a laboratory test for retrieving the anaerobic lactate threshold is often used. The maximal rate of oxidative metabolism that can be sustained during prolonged exercise indicates preserved homeostasis and thereby sets the upper limit for long term endurance. Exercise intensities above the anaerobic threshold require an additional input from anaerobic energy sources resulting in blood lactate accumulation and reduced time to fatigue. The threshold is therefore a reliable and powerful predictor of performance in aerobic exercise lasting approximately 40-60 min. The work rate that elicits a blood lactate of 4 mmol/l (e.g. LT4) is widely used to determine the threshold, but by using a fixed lactate concentration, flexibility to account for inter- and intra-individual differences in aerobic and anaerobic metabolism is lost. Our hypothesis was that our modified D-max method (D-maxmod) would provide a more accurate performance related value by calculating the individual anaerobic threshold (IAT).

Methods

20 males cyclists age 36 ± 5 years, weight 79.7 ± 5.8 kg, VO2max 4.4 ± 0.4 l/min performed an incremental test on a cycle ergometer for calculation of LT (D-maxmod, and LT4) at two occasions separated by 8 weeks. The test consisted of 5 minutes long stages separated by 1 min of rest were lactate was sampled. The increase in work rate was 30 W/stage starting at 100 W and ended above LT4. Short after, an incremental test to fatigue (start at LT4 power, increase 20 W/min) was performed for assessment of VO2max, calculation of maximal aerobic power (MAP) and maximal power achieved in the test (Wmax). On a separate day a 40 minutes time-trial (TT40) was performed for assessment of aerobic endurance performance. IAT D-maxmod was defined as the derivate to the exponential curve created from exponentially lactate increase, including maximal lactate concentration plotted at MAP. The increase in lactate relative to power was defined as the increase in blood lactate from the point where the exponential curve crossed the lactate baseline (See also Cheng et al. 1992 and Zhou & Weston 1997).

Results

IAT D-maxmod was calculated to 5.0 ± 0.8 mmol/l. Both D-maxmod and LT4 were highly significantly correlated with both TT40 and Wmax. Coefficients of determination were higher for D-maxmod compared to LT4 for both TT40 (r2 = 0.78 vs 0.69) and Wmax (r2 = 0.89 vs 0.64).

Conclusion

The calculated D-maxmod correlated better with performance than LT4 for parameters highly linked to performance in road- and mountain bike competitions.

References

Cheng B, Kuipers H, Snyder AC, et al. (1992). Int. J Sports Med. 13:518-22

Zhou S, Weston SB (1997). Physiol. Meas. 18: 145

Place, publisher, year, edition, pages
2015.
Keyword [en]
Lactate, Threshold, Testing, Endurance
National Category
Physiology Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
URN: urn:nbn:se:gih:diva-4099OAI: oai:DiVA.org:gih-4099DiVA: diva2:846367
Conference
ECSS, 20th Annual Congress of the European College of Sport Science, Malmö 24-27 June 2015
Available from: 2015-08-16 Created: 2015-08-16 Last updated: 2017-11-21Bibliographically approved

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CiteExportLink to record
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