Relationship between muscle oxygenation by NIRS and blood lactate

Abstract

The aim of the study was to investigate the relationship of muscle oxygenation in term of oxy-hemoglobin concentration change (ΔHbO2) by NIRS and blood lactate (BLA) in local skeletal muscle and evaluate the capability of NIRS in the research of exercise physiology Twenty-three athlete in the national fin-swimming team took the increasing load training on the power bicycle while their ΔHbO2 and BLA were simultaneously recorded. The initial powers used in the training were set as 100 w for males and 40 w for females. During the experiment, the power kept constant for 3 min before each abrupt increment of 30 w until the limit of the athlete's capability. Statistical analysis and data visualization were performed. Following the increasing load training, ΔHbO2 step-likely increased in the phase of aerobic metabolism but linearly decreased in the phase of anaerobic metabolism. The variation tendency of BLA was the same as ΔHbO2 and the concurrency of crucial turning points between ΔHbO2 and BLA was revealed. This relationship between ΔHbO2 and BLA presented in the increasing load training suggested that ΔHbO2 might be capable for taking the place of the invasively measured parameter BLA. Considering that ΔHbO2 can be noninvasively measured by NIRS, ΔHbO2 has the potential in the evaluation of athletes' physiological function and training effect on the athletes and accordingly NIRS can be well used in this field.