A blood lactate concentration of 4 mmol x l-1 (OBLA) is frequently used as an indicator of the maximal steady state of lactate (MLSS) for workload planning in training programs. The aim of the present investigation was to compare several metabolic parameters determined at OBLA and at a fixed heart rate of 175 beats x min-1 (HR175) in amateur cyclists (AC) and professional cyclists (PC). Sixteen AC and 22 PC performed an exercise test on a cycle ergometer following a ramp protocol (25 W x min-1, 70-80 rpm) to exhaustion. Gaseous exchange was monitored throughout the test. VO2, %VO2 max, and power output (W) corresponding to OBLA and HR175 were determined and mean values compared using a Student's t-test. Findings indicated higher VO2 max and W in general in PC (p<0.01), and higher VO2 and W at OBLA and HR175 in PC (p<0.01). No significant difference was found between values determined at OBLA and HR175 in the AC group, while in the PC group, VO2, %VO2 max, and W were higher at OBLA. These observations suggest the possible use of a fixed, reference HR of 175 beats x min-1 to determine the exercise intensity corresponding to OBLA in amateur cyclists. This was not the case for the professional cyclists.
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