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Blood lactate accumulation is associated with development of muscle fatigue and negatively correlated to endurance performance. No research has quantified the effects of lactate presence at moderate levels of lactate accumulation. The purpose of this study was to test whether 2 moderate blood lactate concentration levels affect running economy (RE) when running at the individual lactate threshold (LT). Seven male world class endurance athletes with an average VO2max of 80.7 ± 2.7 ml/kg/min or 5.8 ± 0.5 L/min participated in this study. After the VO2max test, the subjects were resting or walking and in a random order tested for RE at their LT velocity when the blood lactate level reached either 3 mmol/L or 5 mmol/L. After a new 5-minute exercising period at maximal aerobic velocity, the crossover lactate value RE testing was performed. Running economy was significantly (p = 0.05) deteriorated from 0.668 ± 0.044 to 0.705 ± 0.056 ml·kg-0.75/m or 5.5% (p = 0.05) for blood lactate level of 3 mmol/L compared with 5 mmol/L, respectively. Increased lactate level from 3 to 5 mmol/L is thus accompanied by deteriorated RE at LT running velocity. The deteriorated RE at moderate levels of lactate concentration emphasizes the importance of avoiding intensities above LT in the early parts of a dominantly aerobic endurance competition. It also emphasizes the importance of a high VO2max for aerobic endurance athletes and may partly explain the VO2 slow component as impaired RE.
© Copyright 2016 The Journal of Strength and Conditioning Research. National Strength & Conditioning Association. Alle Rechte vorbehalten.