We once thought no-one could run a mile in less than four minutes – and yet the current world record stands at three minutes, 43 seconds. So will records keep tumbling as people get fitter and technology takes off? Or is there a limit to human performance?

For physiologists, human performance is limited by the processes involved in energy production and muscle contraction.

Performance in a 100m sprint depends on many processes, including the rate at which energy can be produced and used, the speed at which electrical signals can reach muscles, and the rate at which calcium can initiate muscle contraction and relaxation.

By comparison, marathon performance is dependent on the ability to use oxygen, store and use fat and glycogen for energy, and to keep muscle calcium levels high to maintain contractions. In hot conditions, the ability to sweat is also important for endurance performance.

Based on current knowledge, there should be a limit to these processes, and therefore a limit to human performance. But athletic performance does not depend solely on physiological processes, and improvements in other factors have helped us to far exceed the limits previously placed on human performance.