Question

Design a protocol that could be used to measure Critical power from lactate measurements?

Answer 1

The critical power test is a reliable tool to understand fatigue processes, evaluate human performance and prescribe training as it is able to provide aerobic and anaerobic parameters using a non-invasive method . The produced power is mathematically plotted against the respective exhaustion times to obtain the intensity of “fatigue threshold”, or critical power (CP), above which maximal oxygen uptake is evoked and the amount of work that can be performed above CP

the hyperbolic power-time relationship from the critical power concept aims to determine the highest intensity that may be sustained for a long time without fatigue The point of optimal respiratory efficiency onset of blood lactate accumulation ) and the so called thresholds concepts were also proposed with basis in the steady state phenomenon. Regarding the thresholds concepts, Wasserman and McIlroy proposed that during an incremental cycle ergometer exercise an “anaerobic threshold” may be detected based on the respiratory gas exchange ratio (i.e., the ratio between CO2 production to O2 consumption). The anaerobic threshold detection was originally proposed to avoid exhaustive and potentially dangerous exercise for cardiac patients. According to these authors, this phenomenon is defined as the onset of significant anaerobic metabolism during exercise.

Conversely, Kindermann challenged the concept based on a second exponential rise of the blood lactate concentration during the latter stages of an incremental treadmill exercise. Then, the former concept stated by Wasserman and McIlroy proposed the first elevation of blood lactate (~2 mmol.l−1) concomitantly with a non-linear increase of the ventilation and respiratory quotient, named the “aerobic threshold” (AT). On the other hand, the anaerobic threshold (AT2) was considered the steep part of the exponential rise in blood lactate. The anaerobic threshold concept (i.e., AT2) will be used throughout this review.

In the 3MT and predictive runs, the blood lactate concentrations were determined using the enzymatic method by spectrophotometry Lactate concentration was determined at 340 nm against a calibration curve with 5, 10, 15 and 30 mM standards.. Repeated measures ANOVA and post hoc Newman-Keuls were used to compare the variables of aerobic and anaerobic capacity, mechanical data and acute physiological responses of heart rate (HR F) and peak blood lactate (LAC P) of all the assessment methods used. ..The post-test lactate concentration indicates participation of anaerobic lactic metabolism , which strengthens anaerobic measures, despite not assuring maximal effort.