Well the other day I bought a tub of the powerade powder mix so I could bring a sports drink with me on some rides and not spend a fortune. I used it in 3 bottles so far on the MTB with lots of drinking of water from the camel back. Well today I headed out on the road with one bottle decently flavored and one with what I thought to be more water for earlier in the ride. I was only taking a small drink every mile or two which is typical of me. However when I got to mile 19 my chest started to hurt. It hurt when I was breathing, and hurt right behind my sternum. I have never had this happen to me before, I have been out of breath before but not this. I had not recently taken on any major hills and every other part of my body was fine.

My only theory as to why this could have happened was maybe I used too much powder in the bottle? Does this seem reasonable or any other suggestions?

I rode my MTB yesterday for 4 solid hours of some pretty tough climbs and stellar downhills and pysically I was drained but even then I was not out of breath...

???