The Relationship Of SpO2 And Intensity Related Parameters During Acute Hypoxic Exercise

Objective:Identify the relationship between the exercise intensity related parameters, such as oxygen consumption (V02), pulse arterial oxygen saturation (SpO2), blood lactate and heart rate (HR), during acute hypoxic exercise. Discuss the feasibility of SpO2 used as one of the exercise intensity markers during acute hypoxic exercise.Methods:29 healthy male collegiate athletes volunteered for the study. All the subjects finish four incremental exercise tests to volitional exhaustion in the normoxia, simulated 1500m,2500m and 3500m normobaric hypoxia. Gas exchange parameters, SpO2 and HR were recorded continuously during the whole process of exercise. Blood lactate was sampled during the last 15 seconds of each exercise intensity.Results:The resting HR increased as the ascending of altitude. The resting HR in 2500m and 3500m was significantly higher than in the normoxia (P<0.01) and 1500m (P<0.01). The maximal HR during normoxic exercise was significantly higher than during hypoxic exercise (1500m, P<0.05; 2500m, P<0.01; 3500m, P<0.01). The resting SpO2 decreased (P <0.01) as the ascending of altitude. The SpO2 decrease linearly as the increase of relative exercise intensity normalized as the percentage of V02max. The maximal blood lactate was significantly higher during normoxic exercise compared with 1500m (P<0.01),2500m (P<0.01),3500m (P<0.01). The VO2max was lower during hypoxic exercise compared with the value in normoxia. The percentage anaerobic threshold to V02max (AT/V02max%) decreased (P<0.01) significantly during 2500m exercise compared with the values in normoxia and the other simulated altitudes. The relationship of SpO2, HR and relative exercise intensity expressed as %VO2max was obtained from multiple linear regression. The %VO2max was expressed as the function of SpO2 and HR in different simulated altitudes as follow:1500m:%V02max=0.004HR-0.127SpO2%+11.885; 2500m:%V02max=0.006HR-0.054SpO2%+4.507;3500m:%V02max=0.008HR-0.048SpO2%+3.533。Conclusion:The exercise intensity related parameters altered significantly during acute hypoxic exercise. The SpO2 decrease linearly as the increase of relative exercise intensity normalized as the percentage of V02max. HR and SpO2 could be used as exercise intensity markers during acute hypoxic exercise.