There's the maximum heart rate, which varies based on your level of fitness, but is commonly estimated as 220 - age (it was never intended to be used as an absolute rule). That number, whatever it is for you, is simply the fastest your heart will ever beat.
Well before that point, somewhere around 80% or so, you'll pass into the anaerobic zone where you are consuming more oxygen than your cardiopulmonary system can supply. Depending on intensity, you can sustain anaerobic exercise for a little while.
As long as you're doing reasonable cardio, you'll be able to tell when you hit your anaerobic threshold, so you shouldn't need to obsess over the numbers. Chances are you'll hit your lactic threshold even earlier than that.
The takeaway being don't freak out if your heart rate is a little higher than these estimation formulas predict, yet you feel like you're going along just fine. The more cardio you do, you'll notice it harder and harder to get your heart rate up anyway.
so I don't need to worry about my body "consuming" muscle if my heart-rate is over the "fat burning cardio" zone? That is what I have always heard and didn't know if it was BS or not.
How much are you eating? How long have you been working out at this consistency?
There's always a chance that you just aren't eating enough to sustain the workouts that you're doing, so your body is holding on to what it has. I would add in some weight training, but nothing you're doing really looks bad to me
I was thinking this might be my problem (not enough food) I would estimate that I have been eating around 1500 cal a day so w/ working out at the intensity that I have been that probably brings me down to around 1000-1200 net calories, I think I need to up my nutrition, I have been reading 'The Thrive Diet' and over the last few days I have eaten a lot more than I had been, but in a good, nutritious way. Big salads, lots of veggies and more hemp protein. I have been working out about 5 days a week for the last month... I would say???... with 2 kids my brain just can not retain that kind of information
I have definitely noticed a change in my body since I started getting serious about my workouts, things feel firmer and people have complimented me on weight loss in my face... but I want it to go faster! That's why I am thinking of upping the cardio...