phases

[loulou85]

complete the phrase "more ? to your elbow

[Quizmonster]

Power.

[codger66]

quizmonster is right,
wonder where the saying originated though.

[Quizmonster]

There was a version that went: "More power to your arm." That is a clearer way of expressing the thought involved here...ie wishing someone the strength and determination to carry out some worthwhile project. However, the 'elbow' variant was the one that caught on.
The earliest recorded versions of each date back to the early years of the 19th century.

[springmoon]

power