Messner and Habeler were criticized by many for their techniques. Some climbers considered them foolhardy, risking brain damage and death from the severe oxygen restriction. Despite this, they continued with their minimalist methods, forcing some exercise physiologists to reconsider their theories about human limitations at high altitudes. Surprisingly, although Messner has been found to have a very strong physique, his respiratory ability is similar to that of "an above-average marathon runner," according to Jamie Murphy in Time, meaning that although he is genetically gifted, he is not unlike thousands of other athletes. What sets him apart, Murphy noted, is his drive to succeed.