Those wing muscles have got to be strengthened slowly, carefully, or you will place too great a strain on them.

But I realized my wing muscles were getting tired and I'd better come down.

Overstretched wing muscles are very common when they are learning to fly.

Her wing muscles burned like an engine about to catch on fire.

So the team focused, instead, on the animals' wing muscle.

Bumblebees can twitch their wing muscles fast to create body heat.

The feathers and wing muscles begin to develop for flight in about 11-15 days.

Dolph, about to change to bird form, remembered his sore wing muscles.

His color changes, his jaw gets bigger, and the wing muscles begin to grow.

So had his chest muscles, which helped anchor the wing muscles.