Leggings have an advantage over other pants in as much as they are hugging tight and follow the contour of the body to ease understanding of postures and exercise work.
Ideal as an ease of movement garment, it makes comfort a major player.
Workout leggings by celebrity designers are popular. Stella McCartney produces a fine range of workout leggings

Ideal fitness wear whether you are developing your yoga positions or in workout routines of an intense gym exercise program. They are, of course, ideal for dance and other sports wear use. Short leggings as in either the calf length for women or the cycle shorts length for mens