I am guessing walking part is just there to prevent indigestion problems and throwing up the oil.
ABout 3% of people may have a problem keeping the mixture of oil and juice in their stomach and may throw up. One way to eliminate it would be by walking and staying vertical, as it would allowed any gas to exit without pushing the oil up.
You can walk indoor, it does not have to be outdoor, it is just to make sure that any gas goes vertically up, without pushing the oil first.