Biking vs C2 calorie expenditure ?

[Bagger]

I ride a mountain bike about 1000 miles per year on a 'rail trail' ... flat cinder/gravel road. It takes me about 54 minutes to do 10 miles at 70% of maximum effort.

BTW, I am 66 years old, 6'2" / 210# and have constant atrial fibrillation, so maximum effort is not what I want to achieve. Just looking to keep fit and the fat at a minimum.

I typically use the C2 in the winter and inclement times. Not at all regularly. Working on technique is a journey, not a destination, I think. I believe I still use too much upper body. BTAIM.

Here's my question: does using the C2 burn more calories per unit of time than riding a 40 lb mountain bike on a trail? Yeah, I understand that there are many variables in this question. But, generally speaking ... say, 70% C2 vs 70% biking. How do they compare calorie expenditure speaking.

[ArmandoChavezUNC]

I would think the erg, since it involves the lower body, upper body, and core

[jamesg]

The bike will let you produce more work, by going for longer, the erg more power. On the erg you should be able to deliver 125-150W for an hour at 70% HRR, so a heat rate of around 5-600W - C2 suggests we have an efficiency of 25%, seen as fuel cells. On top of this the C2 readout gives us 300kCal/h (say 350W heat rate) just for tweaking the handle.

No idea about the heat rate on a bike, but being legs only I'd guess it's typically say 60-70% of erg power. To estimate, could weigh before and after and multiply the difference in kg by 500 kCal/kg (the latent heat of steam).

[jvincent]

I just started riding my bike into work (new office location) a few weeks ago so I'm on a rowing holiday right now.

My ride is 15km one way, and it takes me about 36 minutes. My route is generally pretty flat but there are a few small hills. During "rowing season" I usually row for 30 minutes in the morning before work.

I can say without a doubt that my rowing workout uses more energy. Now, I could probably go faster on the bike but I've got a different mindset when I'm riding into the office, not to mention there are some stops and starts due to traffic, other people on the path, etc.

[gregsmith01748]

Not sure I agree with any of this. If you are working at 70% of HRR, I think you are exerting the same amount of energy independent of activity. If you work harder, wouldn't you heart rate go up?

[sander]

Not sure I agree with any of this. If you are working at 70% of HRR, I think you are exerting the same amount of energy independent of activity. If you work harder, wouldn't you heart rate go up?

Perhaps but I would argue that (at least for me) heart rate zones are different on the bike and on the erg. At least for me. I think it is because energy has to be delivered only to the leg muscles on the bike. So climbing on a bike I can toast my legs completely at 160bpm HR, while on the erg I would have to go to 180 at least to get the same effect.

[kayakr]

You should compare your heart rate integrated over time. My garmin fr70 does this. Generally I burn a lot more calories on a bike because I'll go from 1-3 hours, whereas rowing sessions are a portion of an hour. Mountain biking is the king for me as my HR will by 160 BPM for hours at a time.

[bdsman]

Heart rate is not a good indicator of work load. HR can vary widely from workout to workout due to factors like how much sleep you've gotten, hydration, etc. Watts is the only thing that actually measures your power output. It does not appear that my PM3 (firmware version 107) allows me to input my weight. If the ergometer doesn't know you're correct weight, it can only estimate how many watts you are expending. Total watt output then translates to calories burned. I bike more than I row, so I can put out a lot more watts on the bike. The only way to really check which is burning more calories is to have a power meter on both machines and compare your results (assuming you can accurately input your weight and the 2 power meters are good quality).