Is it possible to overhydrate?
So I ran into an interesting issue yesterday while racing the Little Smokies HIM. If it is possible, I think I over-hydrated. I urinated at mile 28, somewhere along the course at mile 40 (while I was riding, hooray) and at T2. During the 4 hour drive back I urinated another 3 times. This made for great kidney health 
however during the race I think it added an additional 3 minutes to my time. For the day, I consumed: 20 oz milk at 0200, 20 oz Infinit pre race, and 120 oz fluids during the bike. During the run, I drank a dixie cup of fluids at 10 of the aid stations.
I realize that it is better not to have gotten dehydrated but has anyone ever had this issue occur during a race. Should I cut back to 4 bottles (96 oz) per 56 miles or should I just drink the 120 oz/56 miles and pee like it was going out of style during the race?
Comments
How much is too much is also subjective, I think peeing on the bike is a good sign, and you simply just have to pee yourself to get around the whole time penalty. Having to pee on the run is a bit of a different story though. I cannot bring myself to pee while running, having wet pee filled shoes on the run is something I think that would do far more harm than simply stopping to go.
As far as recommendations on cutting back, first of all I would not think about fluid intake per distance, but rather fluid intake per hour. 120oz may be perfect for a 3 hour bike split, but too much for someone riding a 2:20. It's also highly individualized so I'm generally very cautious to make recommendations for other people, but I'm going to go out on a limb and say yes, this sounds like it is more than necessary and I would play around with cutting back in your training / RRs and see how you feel.
Of course it's possible to "over-hydrate", meaning take in more fluid than you need during a race or a ride. A LOT depends on the environmental conditions, I've found.
E.g., my race last weekend was a DU, which had two separate loops of 28 miles on the bike, with a lot of climbing, maybe 6150 feet total elevation gain. The run was three loops of 5 miles each, with 1750 total elevation gain. My fluid intake on the bike was a total of 42 ounces (one bottle each loop, a total of 10 oz/hour!); on the run , maybe 30 ounces total (a little more than 10 oz/hour); and maybe 12 ounces during transitions (there were 4). I peed twice during the race, once before the second run, and once on the second bike loop. And yet, about two hours after the race, I peed maybe 4 times in an hour, so I was clearly "over-hydrated" for that race - once my body realised I was done with the effort, it started to get rid of the extra fluid it didn't need.
The temp was about 52-54F, and it was drizzling the whole time; so I was basically not sweating at all the whole day.
What I've learned is that, unless the temp is above about 70-75, I really don't need to take in a lot of fluid at the start of a usual triathlon bike leg, when the temps are often in the range of 55-65. So I just drink by thirst, not by some fluid plan requiring a set volume per hour or anything like that. Otherwise, I'm spending excess time in the porta-potti.
Hypo-natremia according to some studies in endurance events, seems to occur primarily among people who are (a) going slower than most of the other competitors and (b) drinking at a fixed plan, trying to meet some pre-determined target for fluid intake.