The triskele can be thought to represent motion as all three arms are positioned to make it appear as if it is moving outwards from its center. Movement, or motion, is believed to signify energies, in particular within this Celtic Symbol the motion of action, cycles, progress, revolution and competition.
Secondly, and the more challenging area for symbolists, is the exact symbolic significance of the three arms of the triskele. This can differ dependent on the era, culture, mythology and history, which is why there are so many variations as to what these three extensions in the triple spiral symbol mean.
Some of these connotations include: life-death-rebirth, spirit-mind-body, mother-father-child, past-present-future, power-intellect-love and creation-preservation-destruction to name but a few.