Calorie burn at different times...

[lederr]

okay, i am not one to count calories i burn or calories i eat, but i just got a heart rate monitor a couple of weeks ago and have been keeping track of everything. i really want to use it when i can run again so i know when i am running in my different training zones deending upon the run i am supposed to do. anyway, here's my question:

i have done GS BSB and CT at least six times since i got my monitor. now, i always workout in the morning and i don't eat before i work out because i would puke (i've tried-not to puke, to eat before ;-) ). anyway, i usually do cardio then weights (it's just habit). so, the first two times i did GS BSB & CT (i do them one after the other), i burned approximately 290 for BSB with my avgHR at 133 and approximately 250 with CT and my avgHR at 120.

well, yesterday i didn't have time to do weights after my cardio (i did iTread circuit circus...i HIGHLY recommend it!), so i did GS when i got home from work. here were my numbers: BSB-kcal 201 avgHR 111; CT kcal 149 avgHR 101. i lifted the SAME samount of weight i did the previous two times and nothing was different except the time of day.

what is the reason for the big difference? i know it's obviously because my HR was lower, but why? i really don't care about the calories i burn (although i do want to stay in my training zone), but i was just shocked at the difference.

ANY IDEAS??? thanks in advance!

 

[pebblesus]

Just my input here.. I think cardio and weights at the same time has an effect similar to "supersetting". Get your heart rate up for the first exercise and then it carries on into the next.
I like to do my weights first so when I get into mny cardio right after.. 20 minutes will do it and I don't have to be at it for an hour.
I've heard many times over (but not sure if Im totally convinced just yet) that it takes about 20 minutes of cardio to start really burning fat off...I guess you have to get warmed up first.
Hmm.. would make for another good post..
but anyways, I think that the longer you are at it the faster you burn.. cardio will get your heart rate up much faster than just weights.. then when you get to the weights your HR is still high form the cardio (it's like getitng a head start) so you continue to burn calories faster as you lift... think of a bike.. it gets going really fast, then you coast for a while, then peddle some more.. it gets a lot further that way than if you coasted to a complete stop before you peddled again.
Make any sense? Not sure the complete validity of these statements however, but that is my opinion (hopefully I understood the question hehe).

 

[lederr]

thanks! that makes sense. maybe i will try the reverse (weights then cardio) and see what happens.

 

[DParker]

I'm really glad you asked this question - I've noticed the same thing! Whether it's cardio or weights, I can do the EXACT same workout in the afternoon and I burn way fewer calories. If I run my favorite 5-mile route in the morning, I burn about 450 calories. If I run the exact same route in the afternoon, I only burn around 350!

I agree with the other poster that doing the cardio first helps keep the HR elevated through the weight work, but I also think there's something going on with the am/pm calorie burn difference. Do you think it's just harder to do anything first thing in the am, so you burn more calories (glycogen stores are low, no food, etc)?

Dee

 

[lederr]

i think it must have to do with fasted cardio. i would like to try fasted versus non-fasted but for one, i wake up around 0430 to work out and i really don't want to eat brekkie earlier than that. second, i really, really can not eat and then workout. i would have to wait at least two hours and that's not goning to happen in the morning. i have to work out in the morning. it's just a habit and part of my "thing."

who knows?!