Monday morning; almost 48 hours after my long run...and I weigh 3.5 lbs more than I did all last week.
I know all about dehydration and sweat loss rate. I've experienced the very real effects of getting behind the water curve during my workouts. Usually it'll hit me between 30-45 minutes of heavy exercise. I don't know if I sweat more than average, but I can easily lose about 8 ozs. of water every 15 minutes. I remember one particularly strenuous hour session in which I weighed in 2 and 1/2 pounds less despite draining my entire 24 oz. water bottle. Driving home the point even more, I can recall two specific occasions when I "bonked" from poor water planning. So I've made it a point to place a prime emphasis on my hydration preparation before and maintenance during my runs.
So, when I weighed in 2.2 lbs heavier the morning after a difficult 2+ hour run, I was confused. I knew it had to be fluid. But why? SparkFriend Bethaney saw my posted comment and suggested it could be due to inflammation from the particular stress of my Friday and Saturday outings. I did a little research, and apparently it's not all that uncommon amongst endurance athletes or anyone participating in a hydration-stressing activity that lasts for a long time. Marathoners, ultra-marathoners and triathletes will often experience weight gains due to water retention. Even if they aren't elite athletes. In fact, the slower ones may more likely experience it because their time under stress is longer. From the sounds of it, it's actually an over-hydration response to the drop in sodium lost through sweat. You can lose water and natural salts, but the water you replace it with doesn't replace the sodium, resulting in dilution. The body then tries to restrict water loss, but if the athlete keeps drinking, hyponatremia can occur.
Marathon Dilemma
Water Intoxication
I know that my change in weight is fluids and not because I've suddenly stored 3 lbs of bulk in my innards. What I don't know is if this fluid retention is a manifestation of hyponatremia or not. I haven't had any of the other symptoms (which vexingly seem to mirror dehydration), though I am feeling bloated. But I am going to monitor my weight this week, watch my fluid intake and diet. If it doesn't resolve in the next day or two, I'll be checking in with the doctor.
This is all new to me. As I'm beginning my attempt to increase my long run distance, I need to be attuned to whether I'm susceptible to this or not.
