Changes in SmO2 Levels During the March on a Treadmill and Rest in Healthy Subjects

Assessment of the current physical performance of an athlete relies on monitoring several parameters in response to a stimulus. One of them is a fast march on a treadmill with regulated speed and incline. Because traditional parameters describing physical performance (heart rate, blood lactate concentration, VO_2max ) do not provide specific information about muscle activity, an alternative approach is needed. This applies to muscle oxygen saturation (SmO₂ ), which can be acquired in a noninvasive way based on near-infrared spectroscopy (NIRS). The changes of SmO₂ are evaluated as fitting the linear regression to three phases of the experiment: the march with the velocity of 4 mph (6.44 km/h), the march with the highest walking velocity, and the rest. The coefficients of linear regression indicate the decrease of SmO₂ level during the phases 1 and 2 and the increase of SmO₂ level during the rest. Observed values of linear regression coefficients of SmO₂ during the analyzed phases indicate the usefulness of NIRS in evaluating muscle fatigue, which may find its use in monitoring the interval training.