The leash attaches to a belt around your waist instead of your hand, which frees both arms and puts the dog's pull through your hips rather than your shoulder.
Adjustable nylon waist belt with a bungee-sectioned lead, five colour options, fits most waist sizes.
Running with a dog
Hands free changes your gait for the better and lets you use your arms normally. It also means you feel the dog change direction through the belt a fraction before you would have seen it, which is genuinely useful once you are used to it.
Where it is not appropriate
Be honest about your dog's size. If the dog can pull you over, a waist leash means you go down with them, and you cannot let go. Use this with a dog you can already physically manage, on ground you know, and not in traffic.
It is also poor for training loose leash walking, because you cannot give the timely feedback a handheld leash allows. Train first, then run.
Clip to a harness rather than a collar.