My triathloner/Marathoner son has one. He uses it always before races/long distance trainings to warm up, after races to loose his tight muscles - it has a very gentle stretching effect.
He uses it when he has no-run days, because of rest or injury - gazelle is very easy on joints.
When I visit him I always use the motivational casette from Tony Little. It is so big fun for me:-)))
(My son somehow prefer B- old movies over Tony:-)))