it's about 2 main factors: first, the pool's size and shape (depth, width and also the gradient of the pool's sides -if the walls are perfectly vertical or not), which has an influence on the water mass movement following the swimmers' action (the more the walls can absorb the waves made by the swimmers, the faster they can go; meanwhile, the bigger the waves are, the more they slow the swimmers down); second, water hardness might also be a factor (less than the pool's technical features, but still) as in different Countries there might be different habits (if not laws) about the sanification of the water itself (for instance, here in Italy we use to put a lot of chlore in pools' water, more than in many other places)
environmental and water's temperature can also have an impact, but in the indoor events I think there's no big difference between places (and the water's temperature is standardized by FINA for sure)
altitude might also be a factor (as it is for all the aerobic efforts), but normally there are no swimming big events in high places, so it's more a chance than a real thing since the 1968 Olympics and the 1975 Worlds (which were held in Cali)
Recommended Posts