Hi all newbie here, looking for advice on max pulse rate. 65 year old male always been fairly fit, non smoker. Had heart attack in 2013, recovered well, no stent just meds. Been keeping fit with walking and treadmill. Wife bought me a fitbit for my birthday so I've been paying more attention to pulse rate. My max is 155 so exercising around 130, however I can easily exceed this as soon as i change from fast walk to jog, I'm not out of breath, and only light sweat. So are fitbits accurate, or is this just because I need to build up fitness further.