Characteristics of changes in oxygen saturation in muscular tissue and ischemic episodes in cardiac muscle during the bicycle ergometry

There is a strong need for more studies devoted to the analysis of changes in physiological processes during the incremental bicycle exercise when increasing the intensity of physical activity, serious ischemic episodes in cardiac muscle occur. The aim of this study was a synchronous observation of physiological changes during bicycle ergometry. Participants of the study were 27 healthy male volunteers. All participants of the study performed a graded exercise test to maximal efforts. A 12-lead electrocardiogram was recorded during exercise test and the first three minutes of recovery. Heart rate and ST-segment depression (sum of negative amplitudes) was analyzed. InSpectra Standad System Model 325 (Hutchinson Technology, Hutchinson, Minnesota, USA) was used for the registration of changes in oxygen saturation during exercise and recovery. The InSpectra sensor was placed on m. vastus lateralis. The results obtained in this study showed that changes in oxygen saturation depended on the intensity of workload. During the incremental increase in workload, oxygen saturation decreased in active muscles. While performing the final stages of exercise, a gradual increase in oxygen saturation is observed in the muscles of some participants. Increasing the intensity of physical activity to maximal efforts, rise in oxygen saturation (second phase) coincides with augmentative ischemic episodes in cardiac muscle