Quadriceps Muscle Oxygenation during a Maximum Stress Test in Middle-Aged Athletes

Determining oxygen muscle saturation (SmO2) using near-infrared spectroscopy (NIRS) is an emerging technique that is increasingly used in sports science; therefore, it is necessary to know its results in different population groups. We analysed it in a group of recreational participants in Nordic Walking. The purpose of this research was to analyse the SmO2 values obtained at various times from testing in a group of athletes over 45. Thirty athletes (18 males) with a mean age of 51.3 years completed a maximal exercise testing in treadmill according to a modified Bruce protocol on a ramp. The electrocardiogram was continuously monitored. We measured VO2max (Metalyzer 3B). In addition, we placed a Humon Hex device on the right thigh to measure quadriceps oxygenation. Heart rate, VO2, and SmO2 ratios were obtained based on the exercise intensity. We obtained a SmO2 at startup of 63.3%, standard deviation (SD) 9.2%; SmO2 declined 61.8%, SD 11.4%; SmO2 in VO2max 57.4% SD 10.2% and SmO2 5 minutes after starting recovery 72.5% SD7.9%. There was a relationship between ventilatory thresholds and variations in SmO2. There were no significant differences between the sexes. We could conclude that the minimum values of SmO2 were related to the VO2 max. During the recovery phase, the values were higher than at rest. The information obtained could be used to control and plan the training.