Same age... this thread is really making me feel old. Generally I still feel like I'm just getting out here and just getting started still in terms of career, life, etc. I really hope it's not all downhill from 30!
Related to the main subject, I don't think my levels have ever been low, but I've always been surprised at how quickly I lose muscle mass when I'm not working out. That might be more related to protein intake and other genetic factors though, since I've always been pretty lean.
Nah, you can start gym/intense excercise anytime, I started about... 31? Major imporovement in about everything, including sex (you don't get tired so easily for example). There is no "too late" age.
As for losing muscles - our bodies run in "least necessary amount needed" mode, since muscles are nutritient-hungry to sustain if not needed. You need to constantly push them to even sustain your level of strength/endurance. If I stop all my activities for 2 weeks, you feel horribly weak when coming back. Marathon runner could write books about it :)
Related to the main subject, I don't think my levels have ever been low, but I've always been surprised at how quickly I lose muscle mass when I'm not working out. That might be more related to protein intake and other genetic factors though, since I've always been pretty lean.