Great advice martinkap and Oak. I had been cycling 5 years before I started running and thought I was pretty fit. NOT! My heart rate would hit 180 within a couple minutes on the treadmill. It was the same for me as the two of them. I'm still running slowly (11-12 mm) but can run 5 miles now without stopping. I also found that running fitness progresses much slower than cycling fitness.
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"We don't stop playing because we grow old; we grow old because we stop playing." George Bernard Shaw
Luna Eclipse/Selle Italia Lady
Surly Pacer/Terry Butterfly
Quintana Roo Cd01/Koobi Stratus
1981 Schwinn Le Tour Tourist
Jamis Coda Femme