I believe it's to get the legs straight so they maintain good blood flow, and for the bird or you to move them to start to get movement back. So while the bird is in the sling it can be helpful to move the legs and see if the bird has the strength to push against your hand.hi, i'm with colliebirds. i'm her engineer. think we got a rough draft of our first chicken sling worked out tonight. please help me with the next iteration. what's the goal by getting our girl in the sling? thank you, zdb