MaxxReps
New member
I use gw with EC and no issues. I'm in my mid 40's as well and my resting heart rate is in the low 50's. I don't go quite as hard as you but do 30 min cardio per day at about 170bpm'ish. I'm not dead yet 
Actually I'm in pretty decent cardio shape and haven't noticed that the GW actually helps me that way much. What it does do though is make recovery quicker. I normally recover pretty quick but with GW its insanely fast.

Actually I'm in pretty decent cardio shape and haven't noticed that the GW actually helps me that way much. What it does do though is make recovery quicker. I normally recover pretty quick but with GW its insanely fast.