Determining oxygen muscle saturation (SmO 2 ) 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 SmO 2 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 VO 2 max (Metalyzer 3B). In addition, we placed a Humon Hex device on the right thigh to measure quadriceps oxygenation. Heart rate, VO 2 , and SmO 2 ratios were obtained based on the exercise intensity. We obtained a SmO 2 at startup of 63.3%, standard deviation (SD) 9.2%; SmO 2 declined 61.8%, SD 11.4%; SmO 2 in VO 2 max 57.4% SD 10.2% and SmO 2 5 minutes after starting recovery 72.5% SD7.9%. There was a relationship between ventilatory thresholds and variations in SmO 2 . There were no significant differences between the sexes. We could conclude that the minimum values of SmO 2 were related to the VO 2 max. During the recovery phase, the values were higher than at rest. The information obtained could be used to control and plan the training. KEY WORDS nordic walking, muscle oxygenation, maximal exercise testing ORIGINAL SCIENTIFIC PAPER

Introduction: Near infrared spectroscopy (NIRS) is a non-invasive technique that is used in the assessment of tissue oxygenation and the monitoring of physical activity. Objective: To determine the influence of sexual, anthropometric and ergospirometric factors on muscle oxygenation of the quadriceps and gastrocnemius, obtained by NIRS during a stress test. Methods: Twenty healthy subjects participated in this study (10 women). Two Humon Hex® devices were placed on the dominant side of the quadriceps and gastrocnemius muscles to measure muscle oxygen saturation (SmO2). The stress test was performed on a treadmill with electrocardiographic control and measurement of oxygen consumption. SmO2 was obtained at rest and after maximum effort during the stress test. In addition, the height, weight, skinfold and waist contour were measured. Bioimpedance was used to obtain the percentages of fat mass and muscle mass, which were used to calculate the relative fat mass (RFM). Results: The SmO2 of both muscles at rest is higher in males than in females. At maximum effort, the SmO2 of the quadriceps is similar in both groups. The SmO2 of both muscles is positively related to height, body mass, percentage of mass muscle and waist contour, and negatively with percentage of mass fat, RFM and skinfold thickness. The negative correlation between fat percentage and oxygen saturation is more evident in females. It was observed that the variables that quantify maximum effort are not related to the SmO2 values, except for the correlation between HR max and SmO2 of the gastrocnemius muscle in males. Conclusion: The SmO2 of recreational athletes is influenced by the location of the device and the fat mass of the subjects. The biggest differences between the sexes are in the gastrocnemius muscle. Level of Evidence II; Diagnostic Studies - Investigating a Diagnostic Test .

The goal of this research is the Analyse the influence of age, experience and relative fat mass (RFM) on physical performance in women practising Nordic Walking during maximal treadmill exercise testing. The population was formed of 20 women, who underwent a maximum stress test with continuous electrocardiographic recording. The Bruce protocol on the ramp was modified with progressive increases in speed and incline. In addition, we measured their height, weight, and waist. A study of exhaled gases was carried out. Our population has an average RFM of 39.8±2.9. Experience subjects reach higher levels of intensity during the exercise, with a variable speed of 6.4±0.9 km/h, compared to newcomers at 5.6±0.7 km/h (p<0.05). We observe that with higher RFM, higher body mass index (BMI) and waist size index, there is a lower oxygen consumption (VO2) and metabolic equivalent (METS) (p<0.05). Likewise, a longer time increases both VO2 and METS (p<0.05). The results suggest that the indexes and anthropometric relationships RFM, BMI, and waist-size index (WSI) influence performance in women practising Nordic Walking. In addition, previous experience in this discipline is also an influential factor in the intensity of the exercise.

The military parachutists are responsible of special air operations who require certain capabilities in their physical condition, due to their intense professional career. The analysis of oxygen con-sumption (VO2) and heart rate (HR) allows the determination of aerobic (VT1) and anaerobic (VT2) thresholds and used to study the adequacy of the organism to exercise and in the analysis of sporting performance. The aim of this study was to determine the effect of tactical equipment on the stress test performance of elite parachutists. 10 parachutists parti-cipated in the study, between 22 and 36 years old with an average of 27.75 years (±4.20). Anthropometric values were determined of: weight 75.69 kg (±8.79), height 173.34 cm (±5.72) and body mass index (BMI) 25.23 (±2.98). Each one, performed 2 maximal treadmill exercise testing: one a conventional stress test (A) and another with the tactical equipment (weight 20 kg) (B). We obtained maximum oxygen consumption (Metalyzer 3B) and monitored the electrocardiogram continuously. The test started at a speed of 6km/h and a slope of 1%. The results of the two test were compared. The average value and standard deviation (SD) of different variables with equipment (B) and without it (A) and p-value were obtained: velocity (A: 14.80±3.29; B: 11.50±1.42 Km/h; p=0.073), HR (A: 182.7±58.62; B: 177.75±9.71 b/m; p=0.038), VO2 (A: 51.75±13.60; B: 54.00±30.82 ml/Kg/min; p=0.891). Al-so, the values of ventilatory thresholds: VT1 and VT2 of both tests were obtained, with sig-nificant differences. Tactical equipment causes a decrease in stress test performance with changes in VT1 and VT2.