Extreme environmental conditions can have a major impact on performance as we have seen with altitude. The effects of hot environmental condition on performance are also well known and well described and we do understand a great deal about the underlying physiological mechanisms. However, I have not seen the performance effects laid out as nicely as in a recent paper.
This review paper in the journal Sports Medicine describes the effects of heat on running performance is highly dependent on the distance. Whilst some running events may suffer in in the heat, other events may actually benefit.
Joshua Guy from James Cook University in Cairns Australia and colleagues reviewed all International Association of Athletics Federations (IAAF) World Championships results between 1999 and 2011 in hot environments (>25oC; >77oF) and cooler environments (<25oC; <77oF). There were 41 events in temperate conditions and 44 in hot conditions. I have depicted the results the authors describe in their paper in Figure 1. It is important to point out that this figure does not actually have values on the Y-axis and gives directional changes only. It illustrates what is described in the paper but for more detail the reader is referred to the original paper.
As can be seen from the figure, 100m and 200m sprint seem to benefit from the hotter conditions, whereas endurance events (5,000m, 10,000m and the marathon) seem to suffer. Middle distance events 400m, 800m and 1,500m seem to be unaffected by environmental temperature.
Trends were similar for men and women. The findings may have implications for heat acclimation strategies in different disciplines and this is discussed in detail in the paper by Guy and colleagues. We will explore heat acclimation in a future article.
Guy JH, Deakin GB, Edwards AM, Miller CM, Pyne, DB. Adaptation to hot environmental conditions: an exploration of the pe3rformance basis, procedures and future directions to optimise opportunities for elite athletes. Sports Med 201, 45: 303-311.