"a limit is set by how efficiently the lungs can extract oxygen from the air. And peak oxygen consumption for modern elite athletes isn’t much different from measurements taken of top runners in 1937 [..] world records for most track-and-field events continued to be regularly broken throughout of most the 20th century. That was probably due to training regimes that concentrated on the right combination of speed, strength, and endurance for each event — plus the advent of professionalism, which allowed athletes to train harder and to have longer careers. [..] One exception is the men’s marathon, where performances still seem to be steadily improving, and where most of the top 100 times have been set in the last five years. [..] records for Olympic swimming events were all set after 2008. [..] “The waves that are created by the swimmers have been reduced significantly by the design of the pools and the lane dividers,”