Effects of Gender on Oxygen Saturation of Thigh Muscles during Maximal Treadmill Exercise Testing

Abstract

Currently, muscle activity can be assessed by oxygen muscle saturation (SmO2) measured with near-infrared spectroscopy (NIRS), which is a non-invasive technique that can be used in training planning and control, but more needs to be known about it. To analyse gender differences in the SmO2 of quadriceps and hamstrings, in several phases of a maximum stress test. A total of 20 subjects, with an average age of 21 years (10 males and 10 females), were the subjects of maximal treadmill exercise testing. We obtained maximum oxygen consumption (Metalyzer 3B) and monitored the electrocardiogram continuously. In addition, we measured the SmO2 of quadriceps and hamstrings in rest (R), start decline (D) and maximum effort (M), with two Humon Hex devices, one placed on the anterior side of the thigh and another on the back. Quadriceps SmO2 in males: R=59.4±11.5%; D=48.3±19.1%; M=52.5±13%. Quadriceps SmO2 in women: R=51±11.5%; D=48.5±9.4%; M=43.1±6.9%. Hamstrings SmO2 in males: R=56.2±13.1%; D=62.9±9.1%; M=57.5±13.9%. Hamstrings SmO2 in women R=56.9±18.9%; D=49.7±7.4%; M=38.2±14.6%. There are no significant differences between muscles. There are only significant differences in M in hamstrings (p-0.009). SmO2 during treadmill exercise is similar in both sexes, but the overall decrease with maximum exercise is greater in women’s hamstrings.