INTRODUCTION: Numerous test procedures have been designed to quantify metabolic and respiratory function. Altering inspired oxygen concentration (FiO2) leads to several metabolic and cardio-respiratory reactions. HOLLMANN (1963) defined the so called "spirografic oxygen deficit" (SOD) as the excess oxygen uptake (V 02) above 100 ml/min after changing FiO2 from normoxia (NO) to hyperoxia (HE) during steady state load. The SOD was regarded as the sufficiency limit of submaximal endurance performance due to the limiting factors of peripheral oxygen consumption. The aim of the study was to determine whether the intensity at which SOD appears relates to an increase in lactate (La) accumulation. METHOD: 12 healthy male subjects (Age: 24.1±2.1yrs, BMI: 22.7kg/m*m, V`O2max: 51.4i8.7mf/min/kg) performed a ramp test (Start: 100W, increase: 30W/1min) on a cycleergometer to determine maximal power (Pmax). After three days rest, three test series were performed at 30 and 80%, 40 and 70%, 50 and 60% Pmax respectively followed with at least two days rest between series. Within-series rest-time between test-pairs was one hour. After five minutes of NO, FiO2 was increased to 100% O2 for five minutes. V´O2 and Ventilation (V´E) were calculated at rest after 4, 6 and 9 min by a modified bbb spirograph (ZAN 600 USB). La (EbioPlus) was measured at rest, after 4 and 9 min. RESULTS: Excess VO2 over 100ml/min from NO to HE were measured at 70% Pmax (245 Watt; 168 ml/min, see Fig 1). Significant excess was detected at 80% Pmax (288 Watt; 179 ml/min). After one minute of HE VE (-6.4%) decreased significantly (p<0.01). La began to accumulated significantly during HE vs NO at 70% Pmax (p<0.05). DISCUSSION & CONCLUSION: The results demonstrate a reproduction of the SOD. The SOD occurs in healthy subjects at 70% Pmax accompanied with a significant increase in La. The initial decrease in VE shows a dominant respiratory control of O2 at the beginning of HE. The results show that the SOD is a possible non-invasive tool for evaluating submaximal endurance performance.
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