What’s a good way to exercise a wounded dog?

My dog is recovering from a wound on his paw pad. I’m afraid to take him on long walks because the scab could split open again. But I can tell he’s getting very ancy at home. He’s a border collie mix so he’s very high energy. What can I do to tire him out and give him exercise without risk of injury? We do some tug-O-war but that’s not enough.