ABSOLUTE LACTATE LEVELS ARE NOT ACCURATE WORK ESTIMATORS WHEN GLYCOGEN LEVELS CHANGE
Norris, S. R., Lefort, J. P., & Smith, D. J. (1998). Maximal lactate steady state and submaximal lactate threshold cycling speeds when glycogen depleted. Medicine and Science in Sports and Exercise, 30(5), Supplement abstract 1861.
This study examined the influence of glycogen depletion upon cycling speed at maximal lactate steady state (MLSS) and at the lactate inflection point as determined by a submaximal anaerobic threshold test (SMAT). Competitive recreation mountain bikers (N = 8) performed a 2K time-trial on stationary rollers to yield peak aerobic power. Further trials over 6K and 10K were performed. Results from these three performances were used to establish the MLSS and SMAT protocols. The protocols were performed three times over 14 days under the following conditions: normal mixed diet, after exercise-induced glycogen depletion, and after a return to normal diet.
No differences were observed between speeds at MLSS and SMAT across the three conditions. Blood lactate values were lower in the glycogen depleted condition than in the other two. Peak lactate values after the 2K time trial prior to each MLSS protocol were also lower in the depleted condition. Peak aerobic power levels were unaltered between conditions.
Implication. The reliance upon fixed blood lactate levels as decisive monitoring parameters is suspect unless rigid and probably invasive control measures are used.
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