Energy usage

[friday]

If someone cycles 1 mile in 10 mins and then another day takes 20mins. Do they use the same amount of energy (calories)?

[Loosehead]

Total calories no. Calories for the cycling only yes.

[Gnu]

The energy used to cycle a mile is needed to overcome the energy used through resistance to motion (friction within the bike, rolling friction of the tyres on the road and air resistance).  These forces increase with speed, particularly the air resistance, so doing the same journey more quickly uses more energy.

[Ward-Minter]

Sorry but I disagree.

Your calories burnt will depend on you aerobic heart rate. This figure is of course ignored in pure physics but must be applied to human combustion. Calories burnt are basically heat releases within the body ie calorific food such as fats, sugars, booze etc when burnt are scorching. Salads, and whole grains etc burn gently.

Therefore if you maintain your aerobic heart rate for twenty minutes as opposed to ten even over the same distance you will burn double. Aerobic activity is often referred to as the "fat burning zone"

Further if you do it in just ten minutes depending on your fitness levels you may go "anaerobic". Here you will merely burn oxygen from the body (very hot!) and not fat what I am sure most people want to do. Oxygen has no calories!!!   Vice versa if you are already fit your heart rate may not go up enough in a mere 10 minutes. Thats why they say excercise should be at least 20 minutes long.

The old adage "a walk is as good as a run" seems pertinent here.

[Gef]

I agree with loosehead. To move the bike and your body over a certain distance does not depend on the time taken.

By the way, Ward_Minter, oxygen does not burn and anaerobic means without oxygen.