Former elite triathlete Andy Blow struggled in hot races. He cramped and had to figure out a solution. He retired from triathlons in 2006 but that problem led to his post-racing career. He is the founder of Precision Hydration and has become an expert on hydration. In addition to endurance athletes he’s worked with NBA, NFL, and professional soccer teams.
Regardless of what you already know about hydration, you will learn more during this interview.
- For most people drinking to thirst will work, but many athletes need to follow a plan to make sure they don’t forget to drink. A range of 16-28 ounces of fluid replacement per hour is adequate in most cases, but some athletes have much higher sweat rates and will require more
- Over-hydration before a race can negatively affect performance
- The sodium concentration in your sweat is relatively static over many years and many different conditions
- Your body reabsorbs some of the sodium lost through sweat before it reaches the skin
- Caffeinated drinks don’t result in a net fluid loss
- And way more than I included here
During the interview I didn’t ask Andy specifically how much fluid loss is allowable for half and full Ironman distance races, so I followed up via email and this was his response:
“the data I’ve seen suggests the fastest finishers of those kind of races can lose between 2 and 6% on average (which tallies with personal experience for me). There may be some people who suffer at that kind of level of loss, and others who can tolerate a bit more (e.g. Gebrselassie who lost 10% during some marathons) but my best guess is that around 2-6% is in the zone for most people if they start the event very well hydrated.