Originally Posted by
prathmann
Using your figure of 31 kcal/mile, the person riding at 12mph for 8-10 hours would be burning about 3000-3700 kcals which puts him at a severe calorie deficit if his diet is only 2000 kcals. And an average male may have a basal metabolism rate of about 1700 kcal/day (i.e. uses that many kcals just to maintain essential body functions and temperature). So his total calorie output (assuming no other significant physical activities) would be about 4700 - 5400 kcal. vs. an intake of only 2000 kcal. - not a sustainable level of exertion at that dietary intake.
And what do you mean by "isn't even aerobic"? Any muscular movement requires oxygen from the air. If it's a very intense exertion, such as the finishing sprint in a bike race, it uses up oxygen faster than the lungs can replenish it and is deemed to be anaerobic and leaves the participant gasping for breath. Exercise at lower levels is aerobic since the lungs can maintain reasonably constant levels of oxygen in the blood.
I misspoke. setting up training zones with my Garmin I discovered 12 mph on my bike was not much higher than walking the dog as far as heart rate. And while I did miscalculate the time a 12 mph cyclist would take it does seem as if it would take closer to 64 miles to burn just under 2000 calories at 12 mph. 31x64 = 1984. That is a bit more than 5.33 hours and the heart rate would still be under 120 or zone 1. For the people I ride with zone one is resting recovery.
That same zone is what is used for cool down and recovery in spin class. Zone 1 is not going to turn an obese person into a fit person with a two mile ride to work and a two mile ride home. At that pace you aren’t putting out any more effort than cruising down a MUP dodging strollers. So you will never get the calories out that you took in at that rate.
in zone two things start to change.
http://www.fitdigits.com/phone/perso...ate-zones.html
and the news for some gets even more complicated considering the more fit you are the fewer calories you seem to burn for the same effort.
yes it might be better than sitting on the sofa, I agreed to that. But it is not as effective of a tool for fat burning and fitness as riding a half Century or Brevet no matter how one feels while they do it.