How important are heart rate zones for cardio/heart health?
I do cardio for the purpose of burning additional calories. (Because as a sedentary female in a healthy weight range, my TDEE is dreadfully low if I don't make the effort to move more!)
But I also do cardio because I know it is good for heart, lung health and overall fitness ability.
I'm 46, female, 5'5", and low 130's. I'm relatively healthy - good BP, cholesterol, etc. According to my Fitbit data my RHR is around 60-61. My BP tends to be low normal.
When I walk (not cardio level) at my desk 2.5 mph, my avg bpm is around 97.
When I walk (light cardio) around 3.25-3.5 mph, my avg bpm is a tiny bit higher, around 102-105.
When I walk (moderate cardio) around 3.75-4.0 mph, my avg bpm is about 113-115.
I can push my bpm higher by running, but I'm out of practice and can only run brief distances. And I'm not sure I want to work on running more at present.
I also average 115 bpm or so when I walk outside for an extended period of time, with moderate uphill/downhill terrain, around 3.5 mph.
Mainly I'm wondering if I should be working harder, pushing to go faster when aiming for cardio to get my heart rate higher.
What has brought this to mind? A Fitbit Bingo challenge where I fill in 'spaces' based on steps, distance, and 'active minutes'. Fitbit lists my 'fat burn zone' at 106+, 'cardio zone' at 129+ and "peak zone" at 157+. I'm not earning many active minutes but I'm not sure if these 'zones' even matter.