Compared with air ( 9.4 + / - 5.2 min ) , exercise time was increased with hyperoxia ( 17.8 + / - 5.8 min ) and normoxic helium ( 16.7 + / - 9.1 min ) but the improvement with helium-hyperoxia ( 26.3 + / - 10.6 min ) was greater than both these gases ( p = 0.019 and p = 0.007 , respectively ) .
