Intermittent oxygen inhalation increase maximal workload and maximal heart rate in elite athletes

OBJECTIVE Recent studies on pulmonary shunt during exercise suggest that oxygen per se could close shunts and thus increase arterial PO2. We hypothesized that a small increase in intrapulmonary PO2 (5–10kPa) would suffice to get performance enhancing effect of oxygen. We also hypothesized that intermittent addition of 10–20l/min of oxygen to inspired air could yield this increase without using premixed gas in athletes ventilating 150–250 l/min. Methods 7 athletes were tested on an ergometer cycle in a blinded cross‐over design on two separate occasions. Tests were done on two sub‐maximal workloads (160 and 240W) and thereafter a VO2max test increasing workload by 22.5W/min until exhaustion. Measurements included VO2max(air), heart rate, SaO2. O2 or Air was added intermittently to the inspired air with one exercise protocol ending with air and the other with oxygen. O2 was added at 10–20 liters/minute by an apparatus developed by Oxelerate™, Sweden. RESULTS Max workloads were 437(58)W (Mean(SD)) with air and 453(57)W with O2, p<0,001. Maximal heart rate were 188 (12) beats/min with air and 192(12) with O2 (p<0,001). VO2max(air) were 5,18(0,76)L/min. End‐tidal FO2 was 21,23(0,52)% at maximal workload with O2 addition. CONCLUSIONS These data suggest that intermittent addition of oxygen to the inspired air is enough to increase work performance and maximal heart rate in highly trained athletes.