I always throught the 220-Age thing for max heart rate was wrong since I'm 48 and have seen my heart rate go as high as 205 briefly, in an all out, run for your life, sprint. But when I did a TT test for threshold power, guess what? My maximum sustainable heart rate turned out to be 169, darn close to 220-48. So here I am my ranges using 220-Age after all.