Hi I am fairly new to cycling (about 4 months now) recently I joined TNT and I am riding harder and longer than I every have before, but have felt really good. I have noticed that my thighs seem to be swollen and my pants are really tight around my thighs but not so much my waist. Is this due to lactic acid build up or water retention? I know it can't be muscle yet it's just to soon!

Any wisdom would be greatly appreciated

Thanks
Jacquelynn