Originally Posted by pacemaker
Thanks CdCf. I'm almost convinced. The crow is thawing, but I'm not willing to cook it just yet. You mentioned in your post that you would multiply the 260 kcals by 5 for energy used by the body; why? I couldnt determine where the 5 factor came from.
That factor of 5 is to a count for the 20-21% efficiency of the body in converting food into mechanical movements. If you eat 1000-Calories of glucose, you only get only 200-Calories of work out of it. Actuall efficiency varies with energy-source, proteins being the lowest, while fat & carbs are much higher. Integrate with time to get power and the differences increase even further with carbs providing the most power (ATP/second) with proteins being slower and fats the slowest.
Originally Posted by pacemaker
Terry, so basically your saying in your last post that the SP will only use 149 kcals (626kj) and FL will use 427 kcals (1796kj) to accomplish the same amount of work. Impossible!
You're forgetting about the total power-requirements in this model. It's more than just moving a weight a certain distance, you also have to overcome
wind-resistance. That's something a lot of people forget, especially those not involved in performance bike-racing. If you're not testing riders in the 30-50mph range, you won't be able to see the non-linear increase in power needed to overcome wind-resistance.
Here's all the equations and measurements distilled down to an easy to see graph from
Damon Rinnard's site:
While trying to compare biking to running in the 5-10-15mph range shows fairly linear increases in power-requirements, that's because air-resistance hasn't built up very much. At 9.3mph/15kph, you need about 25-watts with roughly 1/2 to overcome rolling-resistance and 1/2 of that going to fighting wind-resistance.
Double that speed to 20mph/32kph and you'll need 175-watts of power with the majority it going to fight wind-resistance. That's a power-increase factor of 7x to go 2x as fast. I deal with 200mph cars all the time and can tell you that it required a substantial amount of extra power to hit 200mph compared to 100mph...