Is There a Study That Shows Improvement in Performance in a Half Ironman?

As part of my PhD I actually looked at doing a systematic review where I sort of tried to find every study that had ever been published looking at sodium replacement during exercise and endurance exercise performance. There were potential methodological issues with all of them for example none of the studies were done in hot weather, so we don't really have an impression of what happens in hotter weather. No study I've ever seen to date has actually measured people's sodium losses beforehand and then personalized the sodium replacement to their individual needs which is you know what the industry commonly advocates but it's literally never been done in a research studyso they just give arbitrary amounts of sodium. From those five studies only one of them showed a