Kilocalories vs kilojoules on PT

[Van Hilliard]

This isn't directly related to training with power but it is related to one of the readouts on the PowerTap computer. According to the manual, the "E" reading on the PowerTap is "roughly equivalent to calories" yet it is expressed in kilojoules. As I recall, it takes 4.184 kilojoules to equal one kilocalorie. I don't see how the "E" reading in kilojoules then can be a rough equivalent of calories. Obviously, it would be proportional but certainly not "roughly equivalent" unless one is accustomed to very rough estimates.
Am I overlooking something here (for instance, are dietary kilocalories different from the usual expression in the 4.184kj to 1kc ratio)?

I'm undergoing a long rehab program to get back in shape after a series of health issues. I was interested in translating the total energy output during a ride to my dietary needs during the rehab period (I need to get rid of weight).

Any insights would be helpful.

 

[ric_stern/RST]

This isn't directly related to training with power but it is related to one of the readouts on the PowerTap computer. According to the manual, the "E" reading on the PowerTap is "roughly equivalent to calories" yet it is expressed in kilojoules. As I recall, it takes 4.184 kilojoules to equal one kilocalorie. I don't see how the "E" reading in kilojoules then can be a rough equivalent of calories. Obviously, it would be proportional but certainly not "roughly equivalent" unless one is accustomed to very rough estimates.
Am I overlooking something here (for instance, are dietary kilocalories different from the usual expression in the 4.184kj to 1kc ratio)?

I'm undergoing a long rehab program to get back in shape after a series of health issues. I was interested in translating the total energy output during a ride to my dietary needs during the rehab period (I need to get rid of weight).

Any insights would be helpful.

I've not read the manual for a while so can't comment on what's exactly written there. However, while you're perfectly correct (1 Kcal = 4.184 Kj) the reason that the manual says that they're the same is because humans riding bikes are ~ 20 - 25% efficient. As most people don't know their exact efficiency (which changes under different conditions), when you cancel everything out, the mechanical energy expended in Kj is roughly equivalent to the actual Kcal your body expended.

Ric